Building Envelope Membrane as
Flexible Formwork for Concrete Panels
by
Chelsea Lynn Sprague
Bachelor of Science in Civil and Environmental Engineering
University of Maryland, 2007
Submitted to the Department of Civil and Environmental Engineering
in Partial Fulfillment of the Requirements for the Degree of
MASTER OF ENGINEERING IN CIVIL AND ENVIRONMENTAL ENGINEERING
at the
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
June 2014
@2014 Chelsea Lynn Sprague. All Rights Reserved.
7
MASSACHUSETTS INS
OF TECHNOLOGY
JUN 13 2014
LE R R IES
The author hereby grants to MIT permission to reproduce and to distribute publicly paper
and
electronic copies of this thesis document in whole or in
part in any medium now known or hereafter created.
Signature of Author:
_______Signature redacted
Department of Civil and Envionmental engineering
0 4
Ma4
/
Certified by:
Signature redacted
John A
hsendorf
Professor of Architecture and Civil and Environm
al Enginee ng
*is Superv or
Accepted by:
Signature redacted
Heidi M. Nepf
Chair, Departmental Committee for Graduate Students
fTE
Building Envelope Membrane as Flexible Formwork for Concrete Panels
By
Chelsea L. Sprague
Submitted to the Department of Civil and Environmental Engineering
on May 9, 2014 in Partial Fulfillment of the
Requirements for the degree of Master of Engineering in
Civil and Environmental Engineering
ABSTRACT
This thesis investigates the use of a building envelope membrane as fabric-like formwork
for exterior cladding systems in buildings. The exterior wall system (i.e., fagade) has
evolved to meet the demands of the built environment including protecting occupants and
interior space from the environment and, at times, create the building form and provide
support for the roofs, floors and ceilings. To accommodate the demanding needs of the
industry, integrated exterior wall systems have emerged. This type of panel uses traditional
building materials in innovative applications. However, existing products continue to
encounter some similar issues associated with traditional building methods. This research
aims to propose a concept for an integrated exterior wall system that uses traditional
building material in a unique application. Overall, the system will function as the building
envelope as well as a load transferring mechanism. The main objective is to study the
feasibility and limitations of the design through two experiments. The first experiment
assesses the effect of a flexible formwork on the 28-day compressive strength of concrete
formed with an array of different types of membranes. The second experiment determines
the possibility of implementing an air/water barrier in a physical form-finding application.
The desired outcome of the work is to evaluate the practicality of the proposed design and
further understand the implications and limitations associated with the system. As a result
of the experiments, the application of air/water barriers as tension-like fabrics was found
to be applicable. In addition, it was concluded that permeable membrane formwork has a
greater impact on the surface properties than the bulk concrete; however, overall the
permeable membrane formwork produced a higher strength concrete.
Thesis Supervisor: John A. Ochsendorf
Title: Professor of Architecture and Civil and Environmental Engineering
Thesis Reader: Caitlin T. Mueller
Title: MIT Research Assistant Building Technology
Acknowledgements
First and foremost, I would like to express my sincerest gratitude to my advisor Caitlin T.
Mueller for her continuous support and dedication. Without her patience, motivation and
guidance this thesis would not have been possible. Dr. Mueller's knowledge aided me in the
research and writing of this thesis. Thank you to Professor John Ochsendorf for his
insightful recommendations, feedback and encouragements. His efforts were instrumental
in the final product of the research.
Thank you to Steve Rudolph for allowing me to store materials and mix concrete in MIT
facilities. In addition, I greatly appreciate his willingness to help me conduct the
experiments as well as his recommendations and ideas.
I would like to thank students in my program for their support of conducting my
experiments: Jessica Friscia, William Finney, Olivier Sylvestre, Jonathan Ellowitz and Grant
Iwamoto. I would like to show my sincerest appreciation to all the contractors who
supplied the air/water barrier material for the experiments. In addition, I would like to
offer my sincerest thanks to the structural design lab for their encouragement and
insightful comments.
I would like to extend my appreciation to Dr. Pierre Ghisbain and Dr. Jerome Connor for
their dedication and support throughout this program.
Lastly, I would like to thank my family for their unconditional support and love throughout
this entire process.
5
Table of Contents
1 INTRODUCTION
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CURRENT EXTERIOR WALL TYPES
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CONCERNS WITH CURRENT EXTERIOR WALL DESIGNS
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INTEGRATING THE STRUCTURE AND BUILDING ENVELOPE
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INTEGRATED EXTERIOR WALLS
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PROBLEM STATEMENT
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THESIS OUTLINE
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2 INTEGRATION OF ENCLOSURE AND STRUCTURE
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PROPOSED EXTERIOR WALL PANEL
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RESEARCH'SCOPE
CURRENT RESEARCH
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3 METHODOLOGY - EXPERIMENT 1
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EXPERIMENT SCOPE
MEMBRANE FORMWORK
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CONCRETE CYLINDERS
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CYLINDER PREPARATION
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COMPRESSION TESTING
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4 RESULTS - EXPERIMENT 1
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OBSERVATIONS
EMPIRICAL RESULTS
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DISCUSSION
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5 METHODOLOGY - EXPERIMENT 2
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EXPERIMENTAL SCOPE
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AIR/WATER BARRIER FORMED THIN SHELL STRUCTURE
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THICKNESS MEASUREMENTS
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6 RESULTS - EXPERIMENT 2
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OBSERVATIONS
DISCUSSION
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7 CONCLUSIONS
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SUMMARY OF FINDINGS
DESIGN RECOMMENDATIONS
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SIGNIFICANCE OF EXPERIMENTAL WORK
FUTURE WORK
SUMMARY OF CONTRIBUTIONS
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APPENDIX A - CONCRETE POURING SEQUENCE
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APPENDIX B - CYLINDER DIMENSIONS AND EMPIRICAL RESULTS
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APPENDIX C - BIBLIOGRAPHY
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8
Table of Figures
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1-1 Types of Wall Systems
1-2 Insulated Concrete Formwork
1-3 Kenzo Unno "Unno Reinforced Concrete"
1-4 Integrated Building Skin
2-1 Steel stud construction with exterior sheathing installed
2-2 Schematic design of envelope membrane formed concrete panel
2-3 MFC panel schematic details
2-4 MFC panel schematic details
2-5 MFC panel schematic details
2-6 Representation of permeable formwork vs. control
2-7 Schematic of permeable formwork
3-1 Membrane pieces to assemble a CCW705ip cylinder
3-2 Slits in the cap for a CCW705ip cylinder
3-3 Slits adhered to a body of a cylinder composed of CCW705ip
3-4 Slit cut in PAB1
3-5 The CCW705vp membrane was not able to completely be removed
3-6 View of cylinder C1-24 being capped
3-7 Baldwin-Tate-Emery Testing Machine
4-1 Cap made of 60-mil PVC roofing membrane by Sika Sarnafil
4-2 View of mold composed of 60-mil PVC roofing membrane
4-3 View of cylinder CCWvp12
4-4 View of cylinder CCWvp23
4-5 View of cylinder CCWvp23
4-6 View of cylinder CCWvp33
4-7 View of cylinder SV2
4-8 View of cylinder PAB2
4-9 View of the bottom of cylinder PAB2
4-10 View of the top surface of PAB1
4-11 View of the top of cylinder PAB2
4-12 View of the bottom of cylinder PAB1
4-13 View of the top and bottom caps for cylinder PAB3
4-14 View of cylinder SV1
4-15 View of cylinder SV2 and the air/water barrier formwork
4-16 View of cylinder SV3
4-17 View of top surface of cylinder SV3
4-18 View of cylinder CW3
4-19 View of cylinder CW1
4-20 View of cylinder CW2
4-21 View of the bottom surface of cylinder CW2
4-22 View of the top surface of CW1
4-23 View of cylinder HW1 and the membrane formwork
4-24 View of cylinder HW2
4-25 View of the bottom of cylinder HW3
4-26 View of the top surface of HW2
4-27 View of the top surface of C1-48
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Figure 4-28 View of cylinder C2-48
Figure 4-29 View of the top surface of cylinder C1-36
Figure 4-30 View of cylinder C2-36
Figure 4-31 View of cylinder C3-36
Figure 4-32 View of cylinder C1-24
Figure 4-33 View of the top surface of cylinder C2-24
Figure 4-34 View of cylinder CCWip14 and the air/water barrier formwork
Figure 4-35 View of the bottom surface of cylinder CCWip14
Figure 4-36 View of the membrane formwork for cylinder CCWip24
Figure 4-37 View of bottom cap of cylinder CCWip24
Figure 4-38 View of cylinder CCWip34
Figure 4-39 View of the top surface of cylinder CCWip24
Figure 4-40 View of cylinder CCWip23
Figure 4-41 View of the slits on the bottom cap of cylinder CCWip23
Figure 4-42 View of the bottom cap of cylinder CCWip33
Figure 4-43 View of top surface of CCWip23
Figure 4-44 View of the membrane formwork for cylinder CCWip33
Figure 4-45 View of cylinder CCWip12 and the membrane formwork
Figure 4-46 View of the formwork for cylinder CCWip22
Figure 4-47 View of the bottom surface of cylinder CCWip22
Figure 4-48 View of slits in the bottom cap of cylinder CCWip32
Figure 4-49 View of cylinder CCWip12
Figure 4-50 View of cylinder CCWvp14
Figure 4-51 View of cylinder CCWvp24
Figure 4-52 View of the top surface of CCWvp24
Figure 4-53 View of cylinder CCWvp34
Figure 4-54 View of cylinder CCWvp24
Figure 4-55 View of cylinder CCWvp23
Figure 4-56 View of the top surface of cylinder CCWvp33
Figure 4-57 View of cylinder CCWvp23
Figure 4-58 View of the top surface of cylinder CCWvp13
Figure 4-59 View of cylinder CCWvp12
Figure 4-60 View of the top surface of cylinder CCWvp12
Figure 4-61 View of cylinder CCWvp32
Figure 4-62 PAB1
Figure 4-63 PAB1
Figure 4-64 PAB2
Figure 4-65 PAB2
Figure 4-66 PAB3
Figure 4-67 PAB3
Figure 4-68 SV1
Figure 4-69 SV1
Figure 4-70 SV2
Figure 4-71 SV2
Figure 4-72 SV3
Figure 4-73 SV3
Figure 4-74CW1
Figure 4-75 CW1
Figure 4-76 CW2
Figure 4-77 CW2
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4-78 CW3
4-79 CW3
4-80 HW1
4-81 HW1
4-82 HW2
4-83 HW2
4-84 HW3
4-85 HW3
4-86 C1-48
4-87 C2-48
4-88 C3-48
4-89 C1-36
4-90 C2-36
4-91 C3-36
4-92 C1-24
4-93 C2-24
4-94 C3-24
4-95 CCWip14
4-96 CCWip14
4-97 CCWip34
4-98 CCWip34
4-99 CCWip13
4-100 CCWip23
4-101 CCWip23
4-102 CCWip33
4-103 CCWip33
4-104 CCWip12
4-105 CCWip12
4-106 CCWip22
4-107 CCWip32
4-108 CCWip32
4-109 CCWvp14
4-110 CCWvp14
4-111 CCWvp24
4-112 CCWvp24
4-113 CCWvp34
4-114 CCWvp34
4-115 CCWvp13
4-116 CCWvp13
4-117 CCWvp23
4-118 CCWvp23
4-119 CCWvp33
4-120 CCWvp33
4-121 CCWvp12
4-122 CCWvp12
4-123 CCWvp22
4-124 CCWvp22
4-125 CCWvp32
4-126 CCWvp32
5-1 Simple frame constructed of wood
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5-2 25 ft x 25 ft square traced on CCW705vp membrane by Carlisle
5-3 CCW705ip hanging from a wooden frame
5-4 View of the underside of the hanging CCW705ip membrane
5-5 CCW705ip membrane hanging from a wooden frame
5-6 Vie of the CCW705ip membrane hanging from a wooden frame
5-7 View of the CCW705vp membrane hanging from a wooden frame
5-8 The nine places the specimens thickness was measured
5-9 Inverted envelope formed concrete shells
6-1 View of CCW705 hanging from a wooden frame
6-2 Wrinkles developed in the CCW705ip membrane
6-3 View of the CCW705vp membrane hanging from a wooden frame
6-4 The CCW705vp membrane developed wrinkles and corrugations
6-5 View of the underside of the CCW705ip membrane
6-6 View of the underside of the CCW705vp membrane
6-7 View of the concrete poured over the CCW705ip membrane
6-8 View of the concrete poured over the CCW705vp membrane
6-9 View of the concrete shell cast on the CCW705ip membrane
6-10 View of the concrete shell cast on the CCW705vp membrane
6-11 Thickness measurement locations for the thin shell formed on the CCW705ip
6-12 Thickness measurement locations for the thin shell formed on the CCW705vp
6-13 View of concrete shell cast on the CCW705ip membrane
6-14 View of the center of the concrete shell cast on the CCW705ip membrane
6-15 View of concrete shell cast on the CCW705vp membrane
6-16 View of the center of the concrete shell cast on the CCW705vp membrane
6-17 View of the inverted concrete shell cast on the CCW705ip membrane
6-18 View of the inverted concrete shell cast on the CCW705ip membrane
6-19 View of the exposed concrete from removing the CCW705ip membrane
6-20 Indentation from a crease that developed in the CCW705ip membrane
6-21 View of inverted concrete shell cast on the CCW705vp membrane
6-22 View of the inverted concrete shell cast on the CCW705vp membrane
6-23 Indentations in the concrete from creases that developed in the CCW705vp
6-24 Concrete dome formed from CCW705vp membrane
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Table of Tables
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Table
1-1
3-1
3-2
4-1
4-2
4-3
4-4
4-5
6-1
6-2
Advantages and disadvantages of current wall construction
Permanence rating of air/water barriers
Specimen designations
Observation of cylinders after removing air/water barrier formwork
Observation of cylinders after failure
Cylinders with highest compressive strengths
Cylinders with lowest compressive strengths
Normalized values for Batch 2
Thickness measurements recorded for concrete placed on the CCW705ip
Thickness measurements recorded for concrete placed on the CCW705vp
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Table of Graphs
Graph
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4-4
6-1
6-2
Compressive strength of cylinders
Compressive strength of cylinders in Batch 1 versus Batch 2
Compressive strength of 4"x8" cylinders
Compressive strength of three different size cylinders
Thickness measurements recorded for concrete placed on the CCW705ip
Thickness measurements recorded for concrete placed on the CCW70Svp
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1
Introduction
The primary intention of this research is to develop the framework for an exterior wall
system that integrates structural engineering and building technology. The structure of a
building provides an independent function as that of the building enclosure layers. Hence,
current practice involves installing the enclosure materials subsequent to completion of
the structure. However, what would happen if the sequence of installation was reversed?
By rethinking the application of these components, could material waste be reduced or
construction time shortened?
This chapter provides a general background of exterior wall construction and introduces
the emerging concept of an integrated exterior wall. The advantages associated with these
types of systems will be presented as well as several concerns. This chapter will familiarize
the reader with the primary objective of the research before a more elaborate discussion in
Chapter 2.
1.1 Current Exterior Wall Types
Over time exterior wall systems have changed to meet the demands of the evolving built
environment. However, the overarching objectives have remained the same: protect
occupants and interior space from the environment and, at times, create the building form
and provide support for the roofs, floors and ceilings.
The exterior wall system, or building envelope, functions as an air, water, thermal and
vapor barrier to protect the interior from the surrounding environment. A design of an
enclosure system can range from a system of multiple layers each performing an
independent function to one material that resists all elements. In today's practice, an
exterior wall's construction is classified into three categories: cavity, barrier or mass walls.
A cavity wall is also known as a screen or drained wall that relies on an unobstructed gap
between the fagade and building enclosure to allow drainage and ventilation (see Figure
17
1-1) (Lemieux and Totten, 2010). In a barrier wall design, the fagade is installed directly
over the building envelope (see Figure 1-1) (Lemieux and Totten, 2010). This system relies
on the exterior surface and joints in the fagade to resist water penetration and moisture
ingress. As the name indicates, a mass wall is constructed of a solid material (see Figure
1-1) and relies on the wall thickness and material's storage capacity to protect the building
from the surrounding environment (Lemieux and Totten, 2010).
It
LOW.
-
LI
-
W
RRMP. POR1
Figure 1-1 Types of Wall Systems: Barrier Wall (LEFT), Cavity Wall (MIDDLE), Mass Wall
(RIGHT), Photos from Lemieux and Totten, 2010.
1.2 Concerns with Current Exterior Wall Designs
As indicated in Figure 1-1, each wall composition incorporates several standard
components. First, an outer surface or fagade is installed as the defense mechanism to
protect against the surrounding environment as well as provide an aesthetic appeal. In the
mass wall, the fagade layer is considered the solid material typically consisting of masonry,
whereas, the barrier/cavity wall usually incorporates a metal panel, exterior insulation and
finish systems (EIFS), masonry or similar. Inboard of the fagade, in no particular order, is
the thermal insulation, air/water barrier, interior finishes and structural elements. The
air/water barrier can be self-adhered or loose-laid sheets or a trowel-applied liquid
membrane. This type of air/water barrier is used in a cavity or barrier wall construction;
the mass wall relies on the solid material.
18
Table 1-1 outlines the advantages and disadvantages of each system:
I
Advantages
Wall Type I
Disadvantages
-
-
Cost-effective
*
Reduced exterior wall thickness
-
Barrier
M
m
I
One line of defense against
environment
Corrosion of structural elements
concealed
Performance related to
workmanship
Regular maintenance required
Table 1-1 Advantages and disadvantages of current wall construction. Adapted from Lemieux &
Totten, 2010 and Donaldson, 1991.
1.3 Integrating the Structure and Building Envelope
The general objective of this thesis is to evaluate the feasibility and limitations of a system
that integrates the structural and enclosure components of a building. However, it should
be noted that the terms 'structure' or 'structural' referred to in this document do not signify
the superstructure of a building. The superstructure denotes the primary structural system
that transfers forces to the ground (i.e., columns, beams, slabs, etc.). The structure specified
in this thesis refers to the fagade structure that transfers lateral forces to the
superstructure to distribute to the ground. Typically this is accomplished through steel
19
studs and sheathing, but this thesis investigates the concept of an alternative system to
provide this function.
1.4 Integrated Exterior Walls
As the industry's requirements intensify, building methods and materials must evolve.
Sustainability, reduced maintenance, high quality construction and lower cost are several
demands that are becoming more difficult to accommodate with the common building
technology. Hence, integrated exterior wall systems have emerged. The integrated system
refers to a self-supported wall that integrates the building envelope with the structure. In
several cases, this refers to expanding the standard function of the enclosure layers to
unconventional roles allowing for a potential diminution in cost and increased speed of
construction.
Different products have been introduced in practice while others are still under
development in research. The following provides a generalized list of existing integrated
exterior wall systems:
Figure 1-2 Insulated Concrete Formwork, Photo from Insulating Concrete Formwork Association.
* Dual-PurposeFormwork - Insulating panels are used as formwork for concrete and
remain in-place to provide the thermal insulation layer. Several examples include:
20
"
Insulated Concrete Forms (ICF) - Two foam layers (i.e., insulation) are used as
formwork and remain in-place to function as the buildings thermal insulation (see
Figure 1-2).
FastFoot- Developed in 1986 by Fab-Form Industries, FastFoot is a high-density
=
polyethylene fabric used to form concrete footings. The formwork can remain inplace and perform as the damp proof membrane that inhibits moisture from
entering the interior.
=
Kenzo Unno - After the Kobe earthquake on January 17, 1995, Japanese architect
Kenzo Unno invented the cast-in-place fabric-formed concrete walls known as
"Unno Reinforced Concrete (URC)" (see Figure 1-3). This entails using a
combination of rigid insulation and plastic netting as formwork. The rigid insulation
becomes the permanent insulation layer for the building.
Figure 1-3 Kenzo Unno "Unno Reinforced Concrete". This is a cast-in-place fabric-formed
concrete wall. Photo by CAST: The Centre for Architectural Structures & Technology.
** Insulated Wall Panels- A multitude of products have been patented that integrate the
fagade with insulation panels. For example, the Sandwich Wall System by Landheer
(1990) consists of metal panels installed over an insulating core. The Foam-in-Place
Double-Skin Building Panel, invented by Howell, Tischuk and Welsh (1977), is a system
21
that separates an outer and inner facing sheet with a foam-in-place core to prevent
thermal bridging. A more common product is Structural Insulated Panels, SIPs (founded
by Structural Insulated Panel Association). SIPs include an insulated foam core
sandwiched between two facings, typically oriented strand board (OSB).
Figure 1-4 Integrated Building Skin developed by Block and Veenendaal. Photo from Block and
Veenendaal (2013).
+
Integrated Building Skin - Currently under research by Block and Veenendaal, this panel
includes an ultra-thin concrete shell with soft PV thermal cells, a solar thermal
distribution layer, waterproofing, AeroGel insulation and a radiant heating distribution
component (see Figure 1-4). The intent of the panel is to optimize the thermal
performance while minimizing the thickness (Block and Veenendaal, 2013).
+ Vertical Form-finding Concrete Panels - The Centre for Architectural Structures and
Technology (CAST) is performing research related to thin-shell concrete panels
constructed using form-finding techniques. This project includes producing molds for
thin-shell wall panels by vertically hanging sheets of fabric and spraying concrete
against the material. The structure is able to obtain the necessary strength and stiffness
from the curvature and folds that develop when hanging the material.
All of the integrated systems offer large reductions in material waste typical during
construction. For example, traditional building practices for constructing concrete walls
use timber formwork. This type of material requires not only time to install but time to
remove and clean after the concrete has cured. In addition to the increase in labor, a large
22
volume of the material cannot be reused. The dual-purpose formwork removes the need
for disposable rigid molds, decreases the amount of construction waste and increases the
economic benefits.
The performance of conventional walls are highly workmanship-dependent and require a
great deal of coordination between multiple trades. Considering the majority of integrated
exterior wall systems are pre-formed units, the systems are built under factory conditions
and are typically more accurate and dependable. This provides reduced construction time
and lessens the demand for traditional building skills, which is associated with a cost
savings. Pre-formed units also provide single source responsibility allowing accountability
to be encapsulated by one manufacturer.
1.1.1
Concerns with Existing Products
The systems presented above have the capacity to improve construction and reduce waste,
ultimately improving the cost of a project. However, the products currently in practice
continue to encounter some similar issues associated with traditional building methods.
For example, the ICF includes casting a concrete wall between two panels of rigid
insulation. Although the insulation remains in-place to act as the insulating layer, reducing
construction waste and labor, the wall continues to consume a large volume of area,
diminishing a sizeable amount of occupiable space. Additionally, considering the systems
are panelized, the aesthetic design is restricted.
The existing systems do not completely integrate the building envelope with the structure
and are missing critical enclosure layers. The designs require further development to
provide a fully integrated system in terms of the envelope membrane and structural
support. This thesis addresses this need.
1.5 Problem Statement
What if a panel was developed that used minimal material while providing improved
performance from a building technology standpoint as well as allows architectural
flexibility? What if an enclosure membrane could act as the tension fabric in a physical
23
form-finding technique to construct an integrated exterior panel? The primary objective of
this thesis is to explore the feasibility and limitations of an integrated exterior wall system
that uses traditional building material in a unique application. This document proposes a
schematic design for a thin shell concrete structure fabricated with physical form-finding
techniques using an envelope membrane as a fabric-like material.
1.6 Thesis Outline
Chapter 2 introduces the proposed integrated exterior wall system. This system includes
using enclosure membranes in a unique application to ultimately combine the building
technology and structural components of a building. This chapter provides an overview of
the research questions as well as a critical literature review outlining previous work in this
area.
Chapter 3 provides a detailed description of the first experiment that evaluates the
feasibility and limitations of the proposed system. This chapter emphasizes the procedures
performed to allow the reader to understand the experimental practices. Chapter 4
presents the results and provides a discussion assessing the outcome.
Chapter 5 and 6 present the methodology and results of the second experiment as well as
provide a discussion assessing the outcomes. The final chapter, Chapter 7, provides a
summary of the findings and contributions as well as recommendations for future work to
improve the understanding and design of the proposed integrated panel.
24
2 Integration of Enclosure and Structure
This chapter introduces the proposed integrated exterior wall panel and outlines a general
design. Several advantages of the system are discussed as well as a broad comparison with
existing systems. This study investigates the potential design limitations as well as the
feasibility of the proposed panel. Specifically, this chapter presents the research scope
followed by a literature review.
It should be noted that the premise of this thesis is to investigate the concept of an
integrated system and does not provide a complete design. This research primarily focuses
on qualitatively and experimentally analyzing several possible limitations of the panel.
Further work is needed to fully develop the design for the integrated exterior wall panel.
2.1 Proposed Exterior Wall Panel
Air/water barriers are conventionally installed outboard of interior finishes to prevent
infiltration of bulk air and water. The placement within the exterior wall assembly varies
depending on the location and function of the building.
Figure 2-1 Steel stud construction with exterior sheathing installed. Photo by Lemieux, 2010.
The construction sequence for standard building practice entails first erecting the primary
structural frame (i.e., beams, columns and slabs) followed by placing studs between floors
25
and attaching the exterior sheathing (see Figure 2-1). The enclosure material, such as the
air/water barrier, can then be installed on the building. This process requires multiple
levels of coordination between trades and an abundance of material waste. In addition, the
performance of the wall is highly workmanship dependent.
c (ET-IANF L
Figure 2-2 Schematic design of envelope membrane formed concrete panel installed on building.
This thesis explores the feasibility of the concept for a Membrane Formed Concrete Panel
(MFC) (see Figure 2-2). Using form-finding techniques, the panel expands the standard
function of typical building materials to integrate structure with enclosure layers. The
integrated exterior wall panels, introduced in Section 1.4, address the same basic concerns
of building practice that the MFC aims to tackle. However, MFC includes a thin shell
concrete structure molded from an air/water barrier. The result is a system that in theory
contains no bending or shear forces, reducing the amount of material consumed and
ultimately producing less construction waste. This is not only a sustainable construction
method but also provides an economic benefit.
2.1.1
MFC Design
The overarching objective of the MFC is to provide a system that functions as part of the
building envelope as well as transfer lateral forces to the structural frame. The panel is
26
fabricated using vertical form-finding techniques with an air/water barrier as opposed to a
tension fabric. The membrane overhangs the concrete along the bottom and two sides to
allow integration between adjacent panels. In this application, the air/water barrier
prevents bulk water and air from infiltrating into the interior as well as functions as the
formwork for the thin shell. This will produce a lightweight structure that is able to
transfer self-weight and wind loads to the primary structural components (i.e., beams,
columns and slabs). It should be noted that this panel can resist only lateral loading and is
not intended to perform as a primary structural element. Schematic drawings detailing the
panel components explained below can be found at the end of this section.
Panels will be installed in a staggered pattern on the face of the slabs with the membrane
facing the exterior as shown in Figure 2-2. Between panels, a gap several inches wide will
prevent the panels from damaging each other; the size of the gap will depend on the
building design and constraints for the project. Inserts will be embedded into the concrete
during fabrication. The inserts will be located, as necessary, along the top of the panel to
allow a slotted connection to the face of the slab. Each panel will include a groove along the
width of the bottom edge. A structural element with a hook geometry embedded into the
top of the slab below will project outward above the panel underneath and be captured in
the groove of the panel. This mechanism inhibits lateral but permits vertical movement.
A building's durability and performance relies on the continuity of the enclosure systems
over the face of the wall. Considering the MFC is a panelized system, integration of the
air/water barrier between panels is imperative to prevent water and air from penetrating
to the interior. Additional membrane along the bottom will overlap panels beneath in a
shingle-style in that, the upper pieces will overlay the lower panel. This configuration
prevents reverse laps and provides a drainage plane to direct incidental water down the
wall. The air/water barrier along the sides will overlap adjacent panels. Compressive
material (e.g, foam backer rods) will be installed between panels to form a bellow-shape
for movement capabilities.
See Figure 2-3 through Figure 2-5 for schematic details of the panel.
27
S
S
S
S
-,
V
Figure 2-3 MFC panel schematic details.
28
S
...........
I
I
I
1
-
~
I
IN
kA~
I>
A
U
Figure 2-4 MFC panel schematic details.
29
4
?4U1X
t~WQ~
-
--
-
, .
....
.......
..................
-................
.......
.....
...
....
1===r4M=
--
iv~-Il
11
II
N
Figure 2-5 MFC panel schematic details.
30
2.1.2
MFC Advantages
This design approach investigates the feasibility of combining multiple functions into one
material to decrease construction waste and reduce coordination between multiple trades.
Using one material to form and protect the wall will reduce cost and save time as the need
for removable formwork is eliminated. In addition, the single source construction will
provide sole responsibility to one manufacturer, which will reduce interface issues
between multiple materials and allow one-step installation. Considering the panel is
prefabricated, the risk of construction error is reduced given the panel will be produced in
a controlled environment.
An ongoing maintenance program should be implemented to maintain the aesthetics and
function of a fagade over the life span of a building. Without a reasonable level of
maintenance, premature deterioration of the fagade elements can occur, entailing costly
repairs. Given the panelized construction and simple detailing, the MFC require minimal
maintenance and are easy to remove without interfering with adjacent panels. Provided a
panel needs to be replaced, the membrane can be effortlessly cut around the edges in order
for the panel to be lifted out of place. Once a new MFC is installed, the additional membrane
around the edges can be integrated with the existing panels. A strip of membrane will be
placed between the top of the new panel and the bottom of the panel above to provide a
continuous enclosure; all exposed edges of the strip will be sealed with a compatible
sealant.
2.1.3
MFC vs. Existing Systems
The concepts of existing systems (see Section 1.4) such as the dual-purpose formwork or
insulated wall panels are similar in scope to the envelope membrane formed concrete
panels. Both designs incorporate a notion regarding the integration of the enclosure
materials with the structural elements of a building. However, the MFC highlights the
importance of an air/water barrier, where as, the existing systems are focused on primarily
the thermal element. Both properties are critical from a performance standpoint, but
without a proper air/water barrier, the structural integrity of the building is compromised.
31
Specifically, the insulated concrete forms rely on a protective sealant applied to the exterior
face of the insulation to defending against the environment (this refers to the installation of
ICF above-grade). Although initially this may provide sufficient protection, the long-term
durability of the system will require frequent maintenance to conserve the integrity of the
sealant. From a waterproofing standpoint, a dedicated membrane is more effective than
sealant to resist bulk water. The MFC includes a more reliable system of waterproofing to
resist bulk water penetration.
A majority of the existing systems and the MFC employ a single material to perform
multiple functions, which reduces material consumption and construction time. Given the
MFC are fabricated in a controlled environment and transported on site, the probability of
construction error is reduced and the quality of the panel increased. The existing systems
are erected in situ and rely heavily on the workmanship of the contractors to provide an
adequate panel. In addition, prefabrication will potentially lessen construction time as the
panels will only need to be installed and integrated upon arriving on site; the existing
systems entail installation of the components as well as construction of the system.
2.2 Research Scope
The existing products rely on the concept of integrating the structural and building
envelope components. This research is similar in scope; however, the feasibility and
limitations of installing an air/water barrier in a physical form-finding application is an
original idea that will be assessed in this research.
The MFC employs an air/water barrier in two ways: to prevent bulk water and air from
entering the interior and to perform as the formwork for a thin shell concrete structure.
The latter is an anomalous function for an air/water barrier and the implications of such an
application are unknown. To better understand the feasibility and limitations of the
proposed design, two experiments were conducted.
The first experiment studies the relationship between formwork permeability and the
compressive strength of the concrete. The building enclosure is composed of a variety of
32
materials to control the migration of air, water, vapor and heat. Thermal insulation
prevents heat flow, air barriers restrict airflow, a water resistive barrier inhibits bulk water
and a vapor retarder averts vapor diffusion. All components must work together to
provide a well-controlled indoor environment for occupants. Although each barrier is
designed to manage a specific element, various products are able to perform multiple
functions. For example, an air/water barrier provides protection against air infiltration and
water penetration but can also behave as a vapor retarder. An air/water barrier is deemed
either vapor impermeable or permeable based on the physical properties of the material
composition. According to the Building Science Corporation (2006), a material's vapor
permanence characteristics are classified as follows:
1. Vapor Impermeable -- 0.1 perm or less
2. Vapor Semi-impermeable + 1.0 perm or less and greater than 0.1 perm
3.
Vapor Semi-permeable 4 10 perms or less and greater than 1.0 perm
4. Vapor Permeable - Greater than 10 perms
To provide a flexible design for the MFC that can be installed in multiple climates and
building types, the air/water barrier could also function as a vapor retarder. Given that
standard formwork is a vapor impermeable material and the panel could potentially
incorporate a vapor permeable membrane, Experiment 1 assesses both the effect an
air/water barrier and air/water/vapor barrier membrane formwork has on the 28-day
compressive strength of concrete.
The second experiment studies the constructability issues related to using an air/water
barrier as flexible formwork. Typically an air/water barrier is installed subsequent to the
exterior sheathing to provide a surface for adhering the membrane. However, the MFC
includes physical form-finding techniques that entail first hanging an air/water barrier
followed by pouring concrete over the membrane to form a thin shell concrete structure
with an integral air and moisture resistive layer. A second experiment (i.e., Experiment 2)
implementing the air/water barrier in a form-finding application will determine the
feasibility of such practice.
33
........
...
.........
.
Although installing an air/water barrier in physical form-finding techniques is a new
concept, similar work has been conducted regarding the effect of permeable formwork on
concrete's strength properties. The following section will present existing work that has
been conducted in this field.
2.3 Current Research
Overall, there is no work that addresses the application of an air/water barrier in a formfinding application or as concrete formwork. However, limited research has been
conducted regarding the use of permeable formwork, similar to the idea of employing a
vapor permeable air/water barrier as concrete formwork. The following describes the
recent work conducted to better understand the effect of permeable formwork on concrete.
1 (Refcrtenx)
2 With drainage hole and
Type I geotext
+
Hessian)
D
*nsIe
A-A cvcwi on
Frord vt 0
(With dramnage hole and
Type I gcotextIe)
Top ve
A
Figure 2-7 Schematic of permeable formwork.
Photo by Arslan 2011.
Figure 2-6 Representation of permeable
formwork vs. control. Photo by Arslan 2011.
"Controlled Permeable Formwork (CPF) is a technique developed specifically for improving
the near surface of vertical and inclined concrete without employing the use of additives or
surface coatings" (Elliott, Jones, Schubel and Warrior, 2008). The premise behind the
permeable formwork is that voids created in the layer of concrete in contact with the CPF
34
are filled with cement, aggregates and water from surrounding areas. This movement
eventually produces concrete in the surface zone with a lower water-to-cement ratio
compared to that of the bulk concrete (Suryavanshi & Swamy, 1997). In summary, the
permeable formwork allows air and water to escape but retains the cement and other fines.
CPF decreases the occurrence of blowholes and provides a more aesthetically pleasing
surface. In addition, the permeability of the concrete is lessened (Price & Widdows, 1991).
These reductions increase the durability of the concrete as the quality of the cover (i.e.,
surface zone) increases and provides better protection against an environmental attack
(Arslan, 2011). Experiments have been conducted to determine the effect CPF has on the
compressive strength and surface hardness of the near surface zone for concrete. A distinct
increase in the compressive strength was noted and attributed to the fact that permeable
formwork yields a surface zone with a greater volume of cement (Price &Widdows, 1991).
The surface hardness showed improved strength compared to that of concrete cast against
impermeable formwork (Price &Widdows, 1991).
The existing research conducted suggests that concrete formed with CPF has superior
surface properties than concrete cured in impermeable formwork (Arslan, 2011). The
experiments assessed permeable formwork including a spunbonded polypropylene fabric,
"Zemdrain Membrane", type I and II geotextile (non-woven) fabric, a polypropylene
drainage medium. Although these studies incorporate permeable fabrics, none of the
experiments investigate the effect a permeable air/water barrier has on properties of
concrete. In addition, the experiments apply the permeable formwork in a standard,
vertical wall configuration. Based on the outcomes of the existing work, this thesis will
assess the application of air/water barriers of varying permanence ratings in a physical
form-finding technique. The effect the formwork has on the bulk as well as the surface of
the concrete will be assessed.
The following chapters will present the methodology employed to evaluate the following:
1. The effects of air/water barrier formwork on the strength properties of concrete.
2. The effect of the permanence rating of the air/water barrier formwork on the 28-day
compressive strength of concrete.
35
3. If an air/water barrier (vapor permeable and impermeable) can function as a tensionlike fabric.
4. The bond between the air/water barrier (vapor permeable and impermeable) and
concrete.
Chapter 3 will present the methodology of Experiment 1 and Chapter 4 will discuss the
results. Experiment 2's methodology will be introduced in Chapter 5 and the results will be
examined in Chapter 6.
36
3 Methodology - Experiment 1
In this chapter, the methodology for Experiment 1 will be presented. The first section
provides an outline of the experiment's scope. The procedures to construct the formwork
and prepare the cylinders for testing will be discussed. Subsequently, the process of testing
the cylinders will be explained.
3.1 Experiment Scope
As mentioned in Chapter 2, the membrane formed concrete panel (MFC) will be fabricated
using physical form-finding techniques. However, alternative to the traditional tension
fabric, the MFC includes hanging an air/water barrier to shape the thin-shell concrete
structure. The following will be evaluated in Experiment 1:
1. Can an air/water barrier adequately perform as formwork for concrete as
conventionally air/water barriers function to only prevent the environment from
penetrating into the interior?
2. Considering certain air/water barriers act as vapor barriers, does the permanence
rating of the air/water barrier have an effect on the 28-day compressive strength
and/or only the surface properties of concrete?
The scope of the experiment includes casting and compression testing 4" in diameter and
8" tall (i.e., 4"x8") concrete cylinders to evaluate the effect the permanence of the
membrane formwork has on the compressive strength of concrete. Twelve molds were
constructed of four air/water barriers including Perm-a-Barrier by Grace Construction,
Sarnavap by Sika Sarnafil, Tyvek CommercialWrap and Tyek HomeWrap by DuPont.
Additionally, considering previous research concluded that permeable formwork only
impacts the surface properties of concrete (see Chapter 2), three different sized molds
were casted and compression tested. Eighteen molds, three 2" (diameter) x 4" (height), 3"
(diameter) x 6" (height) and 4" x 8" molds, were constructed from CCW705vp and
CCW705ip by Carlisle. It should be noted that for the reminder of this document
CCW707vp and CCW705ip represent Carlisle's vapor permeable and vapor impermeable
37
membranes, respectively. Plastic molds of each size were used as controls. The different
sized molds were constructed to provide insight regarding whether only the surface
and/or the bulk concrete properties are affected.
Table 3-1 outlines the permanence rating of each membrane.
_____
Product
Manufacturer
Perm-aBarrier
Grace
Perm
A/W Barrier
____
_______
Imperm
Perm
Rating
-(perms)
Thickness
Composition
X
0.05
0.041 in
Aluminum faced film
Aluminum
Sarnavap
Sika
Commerci
alWrap
HomeWra
Tyvek
Tyvek
SemiImperm.
0.017
0.032 in
X
23-28
0.0079 in
X
54-56
0.006 in
0.08-0.1
0.04 in
11-16
0.02 in
SBS modified
bitumen membrane
with a high-density
polyethylene grid
laminated between
two layers of
polyethylene film
p
CCW705ip
CCW705v
Carlisle
Carlisle
X
X
High-density
polyolefin
High-density
polyethylene
Composite
membrane with
rubberized-asphalt
adhesive laminated
to poly film
Composite
membrane with
breathable film
coated with a
permeable adhesive
Control
-
X
-
-
Plastic
Table 3-1 Permanence ratings of air/water barriers.
3.2 Membrane Formwork
The following outlines the methodology to construct the 4" x 8" membrane formwork. The
2" x 4" and 3" x 6" cylinders were constructed in a similar fashion.
38
Figure 3-2 Slits in the cap for a CCW705ip
cylinder.
Figure 3-1 Membrane pieces to assemble a
CCW705ip cylinder.
A. To construct the body:
a. Measure and cut an 8" x 13" rectangle (see Figure 3-1).
b. Roll the membrane into a cylinder with a 4" diameter.
c. Adhere edges or, where applicable, tape membrane edges together.
B. To construct the top and bottom:
a. Measure and cut two 5" diameter circles.
b. Draw a 4" diameter circle centered inside the 5" circle cutouts.
c. Make small cuts around the circumference of the cutouts from the edge to the 4"
diameter circle (see Figure 3-2).
C. To assemble the cylinder,adhered the slits of the bottom to the cylinder (see Figure 3-3).
Where applicable,tape the slits to the cylinder.
D. Subsequent to pouring the concrete,place the tops on the cylinders in a similarmanner to
step C.
Figure 3-3 Slits adhered to body of a cylinder composed of CCW705ip.
3.3 Concrete Cylinders
ASTM C172/C172M - 14 Standard Practice for Sampling Freshly Mix Concrete was
followed to cast twenty-one 4" x 8" cylinders with Quikrete concrete. ASTM C172/C172M is
only applicable to cylinders with a volume greater than 1 cu. ft.; therefore, only the 4" x 8"
39
cylinder were cast using the ASTM Standard. However, the 2" x 4" and 3" x 6" cylinders
were cast using a similar procedure.
Two 80-lb bags and one 60-lb bag of Quikrete were mixed according to the manufacturer's
instructions. Provided the Quikrete set fairly quickly, one bag was mixed at a time. Given
that the 80-lb bag yielded approximately 0.6 cu. ft., ten 4"x8" cylinders were poured with
one 80-lb bag and eleven 4"x8" cylinders with the other 80-lb bag. The 60-lb bag yielded
approximately 0.45 cu. ft. and allowed all eighteen 2"x4" and 3"x6" cylinders to be poured
at once. Table 3-2 outlines the abbreviations designated to each cylinder as well as which
cylinders were poured in each batch. It should be noted that the cylinders will be referred
to by their respective abbreviation for the remainder of the document.
The following delineates the procedures for mixing and pouring the concrete, see Appendix
A for photos of this process. The release liner on the Perm-a-Barrier, Sarnavap, CCW705ip
and CCW705vp cylinders was removed prior to pouring the concrete.
A. Mixing Concrete
i.
Empty concrete into mixing container.
ii.
For the 80-lb bag, approximately 3.7 L of water was added until a moldable
consistency was achieved. For 60-lb bag, approximately 3.1 L of water was
added.
B. 4"x8" Molds
i.
One layer of concrete was placed in the mold to a height of 4".
ii.
The concrete was consolidated by rodding the layer 25 times to evenly
distribute the aggregate.
iii.
The sides of the mold were tapped 10-15 times with a rubber mallet.
iv.
A second layer of concrete was poured into mold until slightly overflowing the
top edge.
v.
Only the second layer of concrete was rodded 25 times to consolidate the
concrete and evenly distribute the aggregate.
vi.
The sides of the mold were tapped 10-15 times with a rubber mallet.
vii.
The top of mold was struck with a back and forth motion to produce a flat, level
surface.
viii.
The cylinder was continually sprayed for the first 30 minutes after pouring to
ensure the surface remained wet. Subsequently, the cap was placed on the mold.
C. 2"x 4" and 3"x 6" Molds
i.
One layer of concrete was placed in the mold until the Quikrete was slightly
overflowing the edge.
ii.
The concrete was consolidated by rodding the layer 25 times to evenly
40
distribute the aggregate.
The sides of the mold were tapped 10-15 times with a rubber mallet.
The top of mold was struck with a back and forth motion to produce a flat, level
surface.
The cylinder was continually sprayed for the first 30 minutes after pouring to
ensure the surface remained wet. Subsequently, the cap was placed on the mold.
iii.
iv.
v.
All completed cylinders were left to cure with two buckets of water under two plastic tarps
that were taped to the floor.
Perm-a-Barrier 2
4"x 8"
PAB2
1
Sarnavap 1
4"x 8"
SV1
Sarnava 3
4"x 8"
SV3
2
2
2
CommercialWrap 2
4"x 8"
CW2
2
HomeWrap 1
4"x 8"
HW1
2
CCWi 24
8"
CW0i24"x
CCW7Oai 23
CCW705i
6"
3"
4"xx 8"
6v1
CC
CW3
12
CCW7051
3P
4"
2"x
4x 68"
22
CCWi 134
CCW
3
CCW705i
3
3")x 6"
CCW* 33
3
"21x 4",
CCWip12
3
CCWvp32
3
C2-48
1
2
CCW705v1
2"x 4"
CCW705vp3
-
"- o~7
Control 2
-
--
4"x 8"
41
Control 3
Control 1
Control 2
4"lx 8"
3"0 x 6"1
3" x 6"
C3-48
Cl-36
C2-36
2
3
3
Control 3
3" x 6"
'2" x 4"
2"P x 4"
C0-36
3
CI-24
3
3
3
Control 1
Control 2
C2-24
C3-24
2"J' x 4"
Control 3
Table 3-2 Specimen designations. Note: The specimen name refers to the membrane (i.e., Perm-aBarrier by Grace Construction) and the number out of three specimens (i.e., 1 of 3, 2 of 3 and 3 of 3).
3.4 Cylinder Preparation
After 28-days of curing, the cylinders were uncovered and demolded. The majority of the
membranes could be completely removed from the concrete. In the case of the Perm-aBarrier membrane, a strong bond with the concrete was attained, and it could not be
detached from cylinders PAB1, PAB2 and PAB3. Instead, the material was cut along the
length to avoid constraining the cylinder (see Figure 3-4). CCWvp14, CCWvp24 and
CCWvp34 had similar issues; however, a portion of the membrane was able to be detached
(see Figure 3-5).
Figure 3-4 Slit cut in PAB1 to avoid constraining
the cylinder.
42
Figure 3-5 The CCW705vp membrane could not be completely removed from the concrete
cylinders CCWvp14 (LEFT), CCWvp24 (MIDDLE) and CCWvp34 (RIGHT).
Subsequent to demolding, all cylinders were weighed and measured (see Appendix B). The
molds were capped with Plaster of Paris by DAP to provide a level and smooth surface for
compression testing. The capping process went as follows (see Figure 3-6):
Metal Mold
with 2 Prongs
Cap of Plaster of
Paris
Rubber Band
Diamond Shaped
Plastic Sheet
Figure 3-6 View of cylinder C1-25 being capped.
A. The capping fixture (i.e., two prongs welded to a metal plate) was cleaned by scrapping
and removing excess material and dust.
B. The top surface of cylinder was cleaned with a brush.
43
C. An acrylic sheet cut in a diamond geometry was placed on the fixture and WD-40 was
applied to the top surface of the acrylic sheet.
D. 2-parts Plaster of Paris and 1-part water was combined until a workable consistency
was achieved.
E. A generous portion of the mixture was feathered around the top of the cylinder.
F. The cylinder was placed, plaster side down, onto the acrylic sheet with the side of the
cylinder placed directly against the two prongs on the capping fixture.
G. A rubber band was used to hold the cylinder against the prongs.
H. Once the Plaster of Paris hardened, steps A-G were repeated for the bottom surface.
3.5 Compression Testing
Each cylinder was compression tested in a 60 kip capacity Baldwin-Tate-Emery Testing
Machine to determine the strength properties of concrete cured in an air/water barrier
formwork (see Figure 3-7). The power-operated machine loaded the specimens
continuously at a rate of 1,000 psi per minute; the test was load-controlled.
The test provided the compressive strengths of each cylinder formed in an air/water
barrier. The results will be compared against each other as well as the control specimens to
conclude whether the formwork affects the 28-day compressive strength.
See Chapter 4 for the experimental results and a qualitative discussion regarding the
application of an impermeable versus permeable air/water barrier as formwork.
Figure 3-7 Baldwin-Tate-Emery Testing Machine.
44
4 Results - Experiment 1
This chapter presents the results of the experimental work illustrated in Chapter 3.
Experiment 1 assesses the performance of six air/water barriers with varying permanence
ratings. This includes monitoring the behavior of the membranes in a formwork application
as well as if the permanence rating of the air/water barrier has an affect on the 28-day
compressive strength and/or surface properties of the concrete. For each of the tests, a
qualitative analysis including observations from the construction process and
experimentation are described. The empirical results and a comparison of the
performance of the various air/water barriers is given.
4.1 Observations
4.1.1
Construction of Membrane Formwork
Each air/water barrier was formed into a mold (see Section 3.2). During construction of the
formwork, the following was observed:
Figure 4-2 View of mold composed of 60-mil PVC
roofing membrane. Note sand and water leaking
at the gap between the cylinder and caps.
Figure 4-1 Cap made of 60-mil PVC roofing
membrane by Sika Sarnafil. Note the rounded
edges and the use of duct tape to maintain the
desired geometry.
1. Initially, a 60-mil PVC roofing membrane by Sika Sarnafil was intended to be used as
formwork for the concrete cylinders. However, this membrane proved insufficient in
this application as the thickness of the membrane interfered with the construction of
the mold. A mockup testing was performed to practice forming the molds and become
aware of any unanticipated measures. The mockup included constructing three molds
with the 60 mil PVC roofing membrane, CommercialWrap and Perm-a-Barrier and
45
casting wet sand into the cylinders. During this process, the roofing membrane would
not bend to form an adequate top and bottom cap for the cylinder. The edges were
rounded and did not provide a tight seal around the body of the mold (see Figure 4-1).
As a result, sand leaked at the gap between the cylinder and bottom cap (see Figure 42). This membrane was removed from the experiment.
2. The CCW705vp membrane is a 20-mil-thick self-adhered composite membrane that is
coated with a permeable adhesive on one side. The material was easily molded into the
mold shape but would eventually separate (see Figure 4-3). All cylinders required
additional membrane to reinforce the molds (see Figure 4-4). Staples were inserted
where the strips continued to have issues adhering (see Figure 4-4).
3. The remaining membranes were easily formed into molds.
Note the membrane cylinder is
detaching allowing the membrane
cylinder to split open.
4.1.2
Figure 4-4 View of cylinder
CCWvp 12. Note the
reinforcing strips of
membrane and staple.
_ ,_7_- - _ _ _ _ _ ,j
CCWvp23. Note Tyvek Tape
wrapped around the cylinder
as reinforcement.
Concrete Cylinder Casting
ASTM C172/C172M - 14 Standard Practice for Sampling Freshly Mix Concrete was
followed to cast twenty-one 4" x 8" cylinders with the Quikrete concrete. The 2" x 4" and 3"
x 6" cylinders were cast using a similar procedure, as ASTM C172/C172M is only applicable
to cylinders with a volume greater than 1 cu. ft. The following was noted during
construction:
46
1. As mentioned above, the CCW705vp membrane had issues with adherence. The laps in
the cylinders CCWvp14, CCWvp24, CCWvp34, CCWvp23 and CCWvp33 began detaching
allowing concrete to leak (see Figure 4-3). Tyvek Tape was wrapped around the molds
as reinforcement (see Figure 4-5).
2. The top and bottom pieces were constructed by making small cuts around the
circumference of the caps. The slits were adhered in a shingle-style to the outer face of
the cylinder (see Figure 3-3). Upon pouring the concrete, cylinders CCWvp13,
CCWvp23, CCWvp33, CCWvp24, CCWip14, CCWip23, HW3, PAB1, PAB2, SV1, SV2, and
SV3 were noted leaking at this gap (see Figure 4-6).
3. The top of the molds became dirty as the concrete was poured and compacted. This
inhibited the top caps of cylinders SV1, SV2, SV3, CCWip14, CCWip24, CCWip23,
CCWip33, CCWvp14, CCWvp24, CCWvp34 and CCWvp12 from adequately sealing the
mold (see Figure 4-7).
Figure 4-7 View of cylinder SV2. Note the top cap
is not adhered to the cylinder.
Figure 4-6 View of cylinder CCWvp33. Note the
water leaking out the bottom.
4.1.3
Cylinder Preparation
The air/water barriers were removed from the concrete cylinders after 28-days of curing.
Table 4-1 displays the observations noted during removal of the formwork. It should be
noted that the 'bottom' of a cylinder refers to the end placed on the floor during curing.
Additionally, the bond between the membrane and concrete was ranked on a scale of 1-10.
A ten indicates the membrane formed a strong bond and could not be removed; the control
cylinders were not evaluated for bond strength.
47
Air/Water Barrier
PAnd PAB3
Concrete-to-Membrane Bond.
Concrete surface discolored.
PA1 A2
S1 V
and, SV3
an PB3
an V3
WC2
and, CW3
an C3
HW1,
HW2 and
HW3
10
8
1
1--77
X
X
X
X
C1-48, C248 and C348
X
CCWip14,
CCWip24 and
CCWip34
C1-24, C224 and C324
C1-36, C236 and C336
X
X
CCWip13,
CCWip23 and
CCWip33
CCWip12,
CCWip22 and
CCWip32
C~p4
andp2
anad
CCWvp34
7
5'
X
X
X
X
X
X
X
Cv1,C~p2
andp2
CCWvp33
S
andp2
ad
CCWvp32
3
X
Fine, powdery material developed on top
surface.
Small white dots appeared around the
circumference of the bottom surface.
X
I
I
I
I
Membrane facer on the bottom cap is
disintegrating, exposing the adhesive.
Slits in the bottom cap detached from the
outside face of the cylinder.
The adhered edges along the height that
formed the membrane cylinder were
separating.
Surface of cylinder imprinted with texture
of the membrane.
I
X
Surface of cylinder contained blowholes.
X
X
The top and bottom of the cylinder
developed pitting.
X
The surface of the cylinder had scouring.
The surface of the cylinder
had honeycombing.
The concrete was discolored where Tyvek
Tape was applied to the formwork.
Membrane facer turned gold at
membrane laps.
Tyvek Tape placed around the cylinder
caused the molds to become
partially distorted.
Pictures
I
I
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
4
- 4-13
44-
4-22
4-23 - 4-26
4-24-344-3-439
4-40
Table 4-1 Observations of cylinders after removing air/water barrierformwork.
48
4-44
4
-4
9
- 4-S
4--
61
Figure 4-8 View of cylinder PAB2. Note the
slit cut the full height of the cylinder.
Figure 4-9 View of the bottom of cylinder
PAB2. Note the discoloration of the concrete.
Figure 4-10 View of the top surface of PAB1.
Note the light dusting of fine, powdery
material.
Figure 4-11 View of the top of cylinder PAB2.
Note the blowholes in the surface.
49
Figure 4-13 View of the top (RIGHT) and
bottom (LEFT) caps for cylinder PAB3. Note
the aluminum facer on the bottom cap is
disintegrating.
Figure 4-12 View of the bottom of cylinder
PAB1. Note the small while dots around the
circumference.
I
Figure 4-15 View of cylinder SV2 (RIGHT) and
the air/water barrier formwork (LEFT). Note
that the membrane was completely removed
from the concrete and the discoloration of the
concrete.
Figure 4-14 View of cylinder SV1. Note the
slits in the bottom cap and the membrane
cylinder lap are detaching.
50
Figure 4-16 View of cylinder SV3. Note the
surface texture and blowholes.
Figure 4-17 View of the top surface of cylinder
SV3. Note the fine, powdery material and
surface pitting.
Figure 4-18 View of cylinder CW3. Note the
discoloration of the concrete at the top and
bottom edges as well as a strip along the
height.
Figure 4-19 View of cylinder CW1. Note the
scouring and blowholes.
51
Figure 4-20 View of cylinder CW2. Note the
blowholes and honeycombing.
Figure 4-21 View of the bottom surface of
cylinder CW2. Note the discolored concrete.
Figure 4-22 View of the top surface of CW1.
Note the pitting in the surface.
Figure 4-23 View of cylinder HW1 (LEFT) and
the membrane formwork (RIGHT). Note the
cohesive bond between the formwork and
concrete as well as the discoloration.
52
Figure 4-24 View of cylinder HW2. Note the
honeycombing and scouring.
Figure 4-25 View of the bottom of cylinder
HW3. Note the discoloration.
Figure 4-26 View of the top surface of HW2.
Note the pitting in the surface.
Figure 4-27 View of the top surface of C1-48.
Note the pitting.
53
Figure 4-28 View of cylinder C2-48. Note
blowholes and discoloration of the surface.
Figure 4-29 View of the top surface of
cylinder C1-36. Note the surface pitting.
Figure 4-30 View of cylinder C2-36. Note the
blowholes and discoloration.
Figure 4-31 View of cylinder C3-36. Note the
blowholes.
54
Figure 4-33 View of the top surface of
cylinder C2-24. Note the pitting in the surface.
Figure 4-32 View of cylinder C1-24. Note
blowholes.
Figure 4-34 View of cylinder CCWip14 (LEFT)
and the air/water barrier formwork (RIGHT).
Note the cohesive bond, blowholes and
discoloration.
i
Figure 4-35 View of the bottom surface of
cylinder CCWip14. Note the aluminum facer is
disintegrating.
55
Figure 4-36 View of the membrane formwork
for cylinder CCWip24. Note the aluminum
facer is disintegrating and turned gold at the
cylinder lap.
Figure 4-37 View of bottom cap of cylinder
CCWip24. Note the slits are detaching from
the membrane.
Figure 4-39 View of the top surface of
cylinder CCWip24. Note the pitting and fine,
powdery material.
Figure 4-38 View of cylinder CCWip34. Note
the honeycombing.
56
Figure 4-40 View of cylinder CCWip23. Note
the discoloration and blowholes.
Figure 4-41 View of the slits on the bottom cap
of cylinder CCWip23. Note the slits are
detaching from the membrane.
Figure 4-42 View of the bottom cap of
cylinder CCWip33. Note the aluminum facer
is disintegrating.
Figure 4-43 View of top surface of CCWip23.
Note the pitting and fine, powdery material.
57
Figure 4-45 View of cylinder CCWip12 (LEFT)
and the membrane formwork (RIGHT). Note
the cohesive bond between the formwork and
concrete.
Figure 4-44 View of the membrane formwork
for cylinder CCWip33. Note the gold color of
the aluminum facer.
Figure 4-46 View of the formwork for
Figure 4-47 View of the bottom surface of
cylinder CCWip22. Note the pitting on the
surface.
cylinder CCWip22. Note the gold color of the
aluminum facer.
58
Figure 4-48 View of slits in the bottom cap of
cylinder CCWip32. Note the slits are
detaching from the membrane.
Figure 4-49 View of cylinder CCWip12. Note
the blowholes and discoloration.
Figure 4-51 View of cylinder CCWvp24. Note
the bulge and indentation along the side from
reinforcing the cylinder during pouring with
Tyvek Tape.
Figure 4-50 View of cylinder CCWvp14. Note
the adhesive bond between the concrete and
formwork as well as the blowholes in the
surface.
I
59
8
Figure 4-52 View of the top surface of
CCWvp24. Note the pitting in the surface.
Figure 4-53 View of cylinder CCWvp34. Note
the scouring in the surface.
Figure 4-54 View of cylinder CCWvp24. Note
the discoloration and texture of the surface of
the concrete.
Figure 4-55 View of cylinder CCWvp23. Note
adhesive bond between concrete and
formwork as well as blowholes in the surface.
60
Figure 4-57 View of cylinder CCWvp23. Note
the discoloration and texture of the surface.
Figure 4-56 View of cylinder CCWvp33. Note
the indentation.
Figure 4-58. View of the top surface of
cylinder CCWvp13. Note pitting on the
surface.
Figure 4-59 View of cylinder CCWvp12. Note
the blowholes in the surface.
61
Figure 4-61 View of cylinder CCWvp32. Note
the reinforcement strips and slits in the top
and bottom caps are detaching from the
membrane cylinder.
Figure 4-60 View of the top surface of
cylinder CCWvp12. Note the pitting in the
surface.
62
4.1.1
Cylinder Compression Testing
The uniaxial compressive strength of the concrete was measured by compression
testing each cylinder in a Baldwin-Tate-Emery Testing Machine (see Section 3.5).
The cylinders were loaded at a constant rate of 1,000 psi per minute until failure.
The capacity of each cylinder was calculated based on the failure load and cross
sectional dimensions. See Appendix D for the failure loads, cylinder dimensions and
compressive stresses. The failure profiles of each specimen can been seen in Figures
below. Table 4-2 shows the observations noted during the failure of the cylinders.
63
Air/Water Barrie
PAB1
PAB2
PAB3
SVi
SV2
SV3
CW1
CW2
CW3
HW1
Failure
Concrete
Diagonal crack
Diagonal Cracking
Profile could
not be
observed
remained
adhered to
membrane
sheared
cylinder into
two halves
propagated along
height
X
X
X
X
Top - Conical
Shape
Sae
Bottom Conical Shape
Cnclhpe
Diagonal cracking
propagated across
the cylinder
Failure
Load
(ilbs)
Lod(b)
Compressive
Stress
i)
Srs(pi
6-63
3944
X
X
X
X
X
X
X
X
X
X
48,759
4,147
X
49,94?
47
474j4-75
42,569
3,705
4-76, 4-77
X
X
X
X
X
X
HW3
C1-48
C2-48
C3-48
C1-36
C2-36
C3-36
X
X
49,XZ8
4449
X
57,191
4
X
X
X
51,014
4,082
;sX
5o,200
51,009
4-7,4-79
4
X
X
42,990
41,656
26,198
4,110
45
3,433
3,308
3,701
X
X
486
4-87
4-88
4-89
X
26,724
3790
4-90
X
X
X
X
26,106
13,17O
13,508
3,692
4j#0$
4,095
X
1,9
4-91
4-92
4-93
424
43,446
3,477
oper4o
iror.
X
Operator
4-80,4-81
4483
4-84,4-85
X
X
-ue to
3,136
3,062
3,153
43,&
C1-24
Cylder not- Y
35,492
35,745
38,196
X
X
Pictures
-4X
4-64,4-65
4-66,4-67
4-68, 4-69
4-70,441
4-72,4-73
X
X
X
HW2
C2-24
C3-24
CCWip14
CCWip24
CCWip34
CCWip13
CCWip23
CCWip33
CCWip12
CCWip22
CCWip32
CCWvp14
CCWvp24
CCWvp34
CCWvp13
CCWvp23
CCWvp33
CCWvp12
CCWv 22
CCWvp32
Cylinder cracked
into several
fragments
X
X
error. Cylinder not
Tested due to
X
X
X
X
Operator error.
Cylinder not
42,748
X
X
X
X
X
26,91
X
A
X
X
X
X
X
X
X
X
X
Table 4-2 Observations of cylinders after failure.
64
26,625
X
X
X
X
X
X
X
Tested dueto
3,526
3A63
";84
3,978
4
4-95, 4-96
4-97, 4-98
4;440
4-101
934
4-102,4-103
12,163
3,976
12Z16
3,920
4-104, 4-105
44106,
4-107, 4-108
4-10% 4410
4-111,4-112
4-113;4-114
4-115, 4-116
4-117,4.118
4-119,4-120
4-121,4-122
4-123,4-124
4-125,4-126
12,155
4,092
44,8
3,476
48,476
45,491
31,176
26,530
28,496
13,239
12,614
12,865
3,782
%;690
4,559
4,217
3,946
4,207
4,098
4,384
Figure 4-62 PAB1. Note the crack between the
membrane edges.
I
Figure 4-64 PAB2. Note the crack propagating
between the membrane edges.
*
65
Figure 4-63 PAB1. Note the surface of the
concrete remained adhered to the
membrane, exposing the center of the
cylinder.
Figure 4-65 PAB2. Note the cracking
propagated several centimeters from the
surface.
Figure 4-66 PAB3. Note the crack propagated
between the membrane edges.
Figure 4-67 PAB3. Note the concrete adhered
to the air/water barrier.
Figure 4-68 SV1. Note the crack propagation
down the center of the cylinder.
Figure 4-69 SV1. Note the cylinder sheared
into two halves.
66
T
Figure 4-70 SV2. Note the diagonal crack that
begins several centimeters below the top
edge and propagates the height of the
cylinder.
Figure 4-71 SV2. Note the conical geometry of
the top portion (RIGHT) of the cylinder.
Figure 4-72 SV3. Note the crack propagating
down the center of the cylinder and
additional cracks extending from the top
Figure 4-73 SV3. Note the y-shaped cracking
(outlined with red lines).
edge to the vertical crack.
67
Surface
Fraament
Figure 4-74 CW1. Note the multiple lines of
cracking that divided the cylinder into
several shards.
Figure 4-75 CW1. Note the diagonal crack
(red line) splitting the cylinder into conical
shaped pieces. Cracks propagating from the
crack break the surface into fragments.
Figure 4-76 CW2. Note diagonal crack.
Figure 4-77 CW2. Note the top surface of the
cylinder cracked into fragments.
68
Figure 4-78 CW3. Note the cracks propagating
toward the center causing the surface to
break away from the center.
Figure 4-79 CW3. Note the surface fragments
and conical shape of the top half (outlined in
red).
r-
I
Figure 4-81 HW1. Note conical shape of the
top and bottom and the surface fragments.
1~
Figure 4-80 HW1. Note the diagonal cracking
pattern shown with red lines.
69
Figure 4-83 HW2. Note the crack propagating
through the surface scouring causing a
portion of the concrete to fracture.
Figure 4-82 HW2. Note the diagonal crack.
Figure 4-84 HW3. Note the cylinder sheared
into multiple pieces.
Figure 4-85 HW3. Note the diagonal cracking
,I fracturing the cylinder into multiple pieces.
70
Figure 4-87 C2-48. Note crack extending
down center of cylinder.
Figure 4-86 C1-48. Note diagonal crack.
Figure 4-88 C3-48. Note the crack shearing
the cylinder into two halves.
,
71
Figure 4-89 C1-36. Note the cone-shaped
fracture.
Figure 4-90 C2-36. Note the cone-shaped
fracture.
Figure 4-91 C3-36. Note the cylinder cracked
into a conical geometry.
Figure 4-92 C1-24. Note the conical fracture.
Figure 4-93 C2-24. Note the diagonal
cracking.
72
Figure 4-94 C3-24. Note the conical geometry
of the bottom half and vertical cracking.
Figure 4-95 CCWip14. Note the diagonal
crackina.
Figure 4-96 CCWip14. Note the diagonal
cracking and cone-shape of the top half.
Figure 4-97 CCWip34. Note the diagonal
cracking shearing the cylinder into a conical
shape.
73
Figure 4-98 CCWip34. Note the diagonal
cracking.
Figure 4-99 CCWip13. Note the conical shape
of the top half.
Figure 4-100 CCWip23. Note diagonal
cracking.
Figure 4-101 CCWip23. Note cylinder sheared
into two halves.
74
Figure 4-102 CCWip33. Note the diagonal
crackin.
Figure 4-103 CCWip33. Note the conical
Eeometrv of the bottom half.
Figure 4-11
Figure 4-104 CCWip12. Note diagonal
cracking.
75
CCWip12. Note conical shape of
bottom half.
Figure 4-106 CCWip22. Note y-shaped
cracking pattern.
Figure 4-107 CCWip32. Note curved, diagonal
cracking.
Figure 4-108 CCWip32. Note conical shape of
top half.
Figure 4-109 CCWvp14. Note diagonal
crackine.
76
Figure 4-110 CCWvp14. Note membrane
retaining concrete.
Figure 4-111 CCWvp24. Note diagonal
cracking.
Figure 4-112 CCWvp24. Note conical shape of
the top half.
Figure 4-113 CCWvp34. Note y-shaped
cracking pattern.
77
Figure 4-114 CCW vp34. Note conical shape of
top half.
Figure 4-116 CCWvp13. Note the conical
shape of the bottom half.
Figure 4-115 CCWvp13. Note diagonal
cracking.
Figure 4-117 CC 'vp23. Note diagonal
crackin.
crackina.
78
Figure 4-119 ",CWvp33.Note diagonal
cracking.
Figure 4-118 CCWvp23. Note conical shape of
top half.
Figure 4-120 CCWvp33. Note cylinder
sheared into two halves.
i
79
-e 4-121 CCWvp12. Note diagonal
cracking.
Figure 4-122 CCWvp12. Note conical
geometry of top half.
Figure 4-123 CCWvp22. Note diagonal
crackin2.
Figure 4-124 CCWvp22. Note cylinder was
sheared into two halves.
Figure 4-125 CCWvp32. Note diagonal crack.
80
Figure 4-126 CCWvp32. Note the c3 nder
sheared into two halves.
81
-
........
......................
..
4.2 Empirical Results
The purpose of Experiment 1 was to evaluate whether a formwork composed of
different air/water barriers with varying permanence ratings will have an effect on
the 28-day compressive strength of concrete and/or the surface properties. See
Appendix B for the failure loads and corresponding compressive stress of each
cylinder; the compressive strength was calculated by dividing the failure load by the
cylinder area. The results indicate the cylinders with the highest compressive
strength for the three different mold sizes were formed with permeable membranes
and the cylinders with the lowest compressive strength were molded with
impermeable membranes (see Table 4-3 and Table 4-4).
Highest Compressive Strength
Specimen
Size
CW3
CCWvp13
4" x 8"
CCWvp32
2"x4"
3"x6"
Permeable Impermeable
X
X
X
Sompressive
Strength (psi)
4,552
4,559
4,383
Table 4-3 Cylinders with highest compressive strengths.
Lowest Compressive Strength
Specimen
Size
PAB3
4" x 8"
3"x6"
2"x4"
C3-36
CCWip22
Permeable
Impermeable
Compressive
X
X
X
Strength (psi)
3,062
3,692
3,920
Table 4-4 Cylinders with lowest compressive strength.
82
Compression Strength of Cylinders
4600
-
4400
4,092
4200
I-
3,996
3800
3400
3200
0
3,905
4,084
4000
3600
4230
,9 9
3,816
0
3,501
3
S-3650
3 215
3000
2800
Cylinder Speciments
Graph 4-1 Compressive strength of cylinders. The black outlines boxes represent the
individual results and the solid black boxes show the averages. It should be noted that the
following graphs will use identical standards.
Overall, the air/water barrier formwork did not appear to have a significant effect
on the compressive strength of the concrete for any size cylinder. As indicated in
Graph 4-1, all cylinders performed relatively similar to the control specimens. The
numerical values shown on the graph indicate the average compressive strength of
the three cylinders for each air/water barrier.
It should be noted that the cylinders produced from Batch 2 appeared to have a
higher compressive strength than those made from Batch 1 (see Graph 4-2); the
cylinders produced from the two batches were 4" x 8". A statistical hypothesis t-test
was performed and suggested that the data is statistically significant (p=0.24%).
This means that there was a measureable effect on the concrete formed with Batch 2
concrete than Batch 1. The values of Batch 2 were adjusted using the means of the
batches to allow the datasets to be compared. The following equation was used to
determine the normalized values (y2') of Batch 2 in reference to Batch 1:
Y2' = Y2 - M2 + M1
83
Where y2 is the initial Batch 2 compressive strength, M2 is the mean of Batch 2 and
M1 is the mean of Batch 1. Table 4-5 provides the normalized values for Batch 2
cylinders.
Batch 1 vs. Batch 2
5000
--
'4500
w4000
j
A 3500
-
3000
3
A~i3928
4
---
-
2500
1
2
Batch Number
Graph 4-2 Compressive strength of cylinders in Batch 1 versus Batch 2.
_____
_____
____
_____
Specimen
Sarnavap 1
Sarnavap 2
Sarnavap 3
CommercialWrap 1
CommercialWrap 2
CommercialWrap 3
HomeWrap 1
HomeWrap 2
HomeWrap 3
Control 3
____
Batch 2
Size
Abbreviation
4x8 in
4x8 in
4x8 in
4x8 in
4x8 in
4x8 in
4x8 in
4x8 in
4x8 in
4x8 in
SV1
SV2
SV3
CW1
CW2
CW3
HW1
HW2
HW3
C3-48
_
_
_
_
_
_
Actual
Ctual
Compressive
3,153
4,149
4,147
4,017
3,705
4,553
4,082
4,059
4,110
3,308
Normalization
______
2,671
3,667
3,665
3,535
3,223
4,071
3,600
3,578
3,629
2,826
Table 4-5 Normalized values for Batch 2.
Graph 4-3 shows the compressive strengths for the 4" x 8" concrete cylinders
formed in permeable versus impermeable/semi-impermeable formwork. The graph
illustrates that the majority of cylinders produced from a permeable air/water
barrier formwork performed better compared to that of the impermeable/semiimpermeable formwork. A statistical hypothesis t-test was performed (De Winter,
2013). The test indicated that the null hypothesis is rejected and the data is
84
significantly different (p=1.34%). The results emphasize that permeable air/water
barrier formwork has a positive effect on the compressive strength of concrete.
4" x 8" Cylinders formed in
Permeable and Impermeable
Formwork
4,700.00
? 4,500.00
4,300.00
4,100.00
-3,942
3,900.00
3,700.00
479
3,500.00
-
3,300.00
-
W 3,100.00
2,900.00
0
Impermeable
Permeable
Membrane Type
Graph 4-3 Compressive strengths of 4"x8" cylinders formed of permeable vs. impermeable
membranes.
Three different size molds were casted and tested to assess the impact permeable
and impermeable/semi-impermeable formwork has on the surface properties of
concrete. Graph 4-4 shows the compressive strengths for the three different size
molds formed from CCW705vp (permeable) and CCW705 (impermeable) air/water
barriers. Plastic containers (impermeable) were used as controls. A statistical
hypothesis t-test was performed to compare the cylinders formed from
impermeable (CCW705ip) and permeable (CCW705vp) formwork for each size; the
control cylinders were not considered. The results for the sizes indicated that the
null hypothesis is true for the 3"x6" and 4"x8" cylinders and the data is not
significantly different (p=7.19% and p=14.95%, respectively). The results for the
2"x4" cylinders suggested that the null hypothesis is rejected and the data is
statistically different (p=3.73%). This indicates that the permanence rating of the
membrane positively affects the surface properties of the concrete.
85
In addition, a statistical hypothesis t-test was performed to assess the compressive
strengths of the concrete molded in permeable formwork across the different size
cylinders. The data sets assessed included the 2"x4" and 3"x6", 2"x4" and 4"x8", and
3"x6" and 4"x8" concrete cylinders molded in permeable formwork. The null
hypothesis was rejected for the 2"x4" and 4"x8" (p=0.461%), and 3"x6" and 4"x8"
(p=2.07%) but was true for the 2"x4" and 3"x6" cylinders (p=47.91%). This
indicates that the surface properties of concrete are affected by the permanence
rating of the formwork.
Although the 4"x8" cylinders indicated that permeable formwork has a positive
affect on the compressive strength of the bulk concrete, comparing the three
different sized cylinders molded with a permeable air/water barrier suggests that
this formwork has a greater affect on the surface properties of the concrete.
Permeable vs. Impermeable of
Different Sized Molds
4600
ow4400
4200
_
4000
- 3A
Permeable
~3800
QImpermeable
360___
~3600
3400
3200
0
4"x8"
3"x6"
2"x4"
Cylinder Size
Graph 4-4 Compressive strength of three different size concrete cylinders formed from
permeable and impermeable formwork.
86
4.3 Discussion
The results provided insight to better understand the effect formwork composed of
an air/water barrier of varying permanence ratings has on concrete. The following
can be concluded:
1. All of the membranes, aside from CCW705vp (permeable), perform adequately
as formwork. The CCW705vp membrane had constructability issues regarding
maintaining the shape of the cylinder (i.e., the membrane laps separated). This
suggests that the membranes can be used as both the formwork for the thin shell
concrete structure as well as to prevent the environment from penetrating into
the interior.
2. The results indicated that the air/water barriers (permeable and impermeable)
do not degrade the strength of concrete. However, the results indicated that
higher compressive strengths were achieved in the surface and bulk concrete
molded in permeable air/water barriers. It should be noted that the surface of
the concrete obtained higher compressive strengths compared to the bulk
concrete molded in permeable air/water barriers. This was concluded from the
test of the three cylinders. The results indicated that the 2"x4" and 3"x6"
cylinders molded from permeable formwork attained significantly higher
compressive strengths than the 4"x8" cylinders.
3. The impermeable membranes formed the strongest bond with the concrete.
The design of the MFC uses physical form-finding techniques to construct a thin
shell concrete structure installed as a vertical fagade panel. The panel is designed to
transfer lateral loads to the primary superstructure; thus, the strength properties of
the thin shell concrete structure are a critical consideration. From a strength
standpoint, the results indicate that the permeable membranes would perform
better than the impermeable air/water barriers. However, the impermeable
membranes produced concrete with adequate compressive strengths.
Considering the watertightness of a building is achieved through a continuous
enclosure system, the adherence of the membrane is critical to ensure the laps
between panels will remain attached. If adherence is considered, the impermeable
membranes behaved superior to the permeable membranes. The permeable
membranes were not able to successfully form a cylindrical geometry. Considering
the scale of the cylinders and the shape of the MFC, this matter is potentially
87
insignificant. Further research is required to assess the permeable membranes
behavior on a larger scale or if accessory products could be applied to improve the
bond.
The remarks presented in this chapter are preliminary. Chapter 7 presents the final
conclusions as a result of Experiment 1 and Experiment 2. The methodology and
results for Experiment 2 are presented in Chapter 5 and Chapter 6, respectively.
88
5 Methodology - Experiment 2
This chapter presents the methodology for Experiment 2. The first section provides an
outline of the scope and procedures to construct the formwork and prepare the thin shell
concrete structure. Subsequently, the testing is described.
5.1 Experimental Scope
The MFC is constructed using form-finding techniques; however, contrary to standard
practice, an air/water barrier will replace the tension fabric. The purpose of the membrane
in the MFC is two fold: prevent bulk water and air from infiltrating into the interior and
function as formwork for a thin shell concrete structure. The later incorporates an
innovative application of the membrane and Experiment 2 assesses the feasibility.
Experiment 2 provides insight regarding the behavior of an air/water barrier in formfinding techniques. Several aspects of particular interest included:
1. Can the membrane support a thin shell concrete structure without becoming damaged?
2. Does the texture of the air/water barrier affect the thickness of the thin shell; does the
concrete remain stationary or congregate to the center over time?
3. Will the membrane affect the behavior of the shell?
4. Does the concrete adhere to the membrane?
A square specimen of the CCW705vp (permeable) and CCW705ip (impermeable) selfadhered membranes by Carlisle were attached, on all four sides, to a simple open frame.
The frames were constructed of eight 2x4 plywood planks and the membranes were hung
from the top edge, forming a double curved geometry. An approximate uniform thickness
(1 in) of concrete was placed by hand over the air/water barriers. The thickness of the
concrete was measured in nine locations at various times over the course of an hour. The
concrete was covered and left to cure for approximately 96 hours. Subsequently, the shell
structures were uncovered and inverted.
89
5.2 Air/Water Barrier Formed Thin Shell Structure
Figure 5-1 Simple frame constructed of wood.
lure 5-2 25 ft x 25 ft square traced on
CCW705vp membrane by Carlisle.
Two simple frames, one shown in Figure 5-1, were constructed identically with four
horizontal 2x4 plywood planks outlining a 2 ft x 2 ft opening and four vertical support
members. Approximate 28 in x 28 in samples of each membrane were cut and a 25 in x 25
in square was traced within the samples (Figure 5-2). The outlined square was centered
within the specimen of membrane. The 25 in x 25 in square of membrane was compressed
and fitted to the framed opening with the release liner facing upwards. Considering the size
of the membrane compared to the frame opening, the membrane was enabled to sag and
define its natural shape (see Figure 5-3 and Figure 5-4). The textiles' edges were stapled
every 2.5 in to the top surface of the frames. Marks were placed every 6.25 in around the
perimeter of the frame locating the nine positions to measure the thickness.
Figure 5-3 CCW705ip hanging from a wooden
frame. Note the membrane is sagging.
Figure 5-4 View of the underside of the hanging
CCW705ip membrane.
90
The release liner was removed within the 25 in x 25 in square (see Figure 5-5). One 80-lb
bag and one 60-lb bag of Quikrete was mixed according to the manufacturer's instructions.
Provided the Quikrete set fairly quickly and the time span between thickness
measurements, one bag was mixed and poured onto the formwork at a time. The 80 lb bag
was mixed with 3.6 L of water and hand placed over the CCW705ip membrane (see Figure
5-6); the 60 lb bag was mixed with 3.1 L of water and hand placed over the CCW705vp
membrane (see Figure 5-7). During initial placement, the thickness was measured in
various locations to ensure a uniform, 1 in thick slab was achieved. To avoid potentially
damaging the membrane, the concrete was not screed (i.e., finished), producing an
irregular surface.
VIP
Figure 5-6 View of the CCW705ip membrane
hanging from a wooden frame with a 1 in thick
concrete slab on top.
Figure 5-5 CCW705ip membrane hanging from a
wooden frame. Note the black material
indicates where the release liner (brown
material) has been removed.
91
Figure 5-7 View of the CCW705vp membrane hanging from a wooden frame. A 1 in thick concrete slab
has been poured over the membrane.
5.3 Thickness Measurements
The concrete thickness was measured after 1, 5, 8, 15, 20, 30, 40, 50 and 60 minutes of
pouring the concrete; the same nine locations were recorded each time (see Figure 5-8). It
should be noted that the locations depicted in Figure 5-8 are approximate and
measurements were taken within the respective location. A metal rod was vertically
inserted and marked with respect to the top surface of the concrete. The distance between
the end of the rod and mark was measured and recorded.
Each frame was inverted 96-hours after initial pouring and the membrane to concrete bond
was tested (see Figure 5-9). See Chapter 6 for experimental results and a qualitative
discussion regarding the use of an impermeable versus permeable air/water barrier in a
form-finding application.
92
Figure 5-8 The nine places the specimen's thickness was measured. View of the CCW705ip membrane.
Figure 5-9 Inverted envelope formed concrete shells; CCW705ip (FRONT) and CCW705vp (BACK).
93
6 Results - Experiment 2
This chapter describes the results of the experimental work illustrated in Chapter 5.
Experiment 2 assesses the feasibility and limitations of the fabricating process for the MFC.
An explanation for each test is provided with a corresponding qualitative analysis including
observations from the construction process and experiment. The empirical results and a
comparison of the performance of the air/water barriers are given.
Experiment 2 evaluates the feasibility and behavior of an air/water barrier in a physical
form-finding application. The experimental work includes constructing two wooden frames
and hanging the air/water barriers. A 1" thin shell concrete structure was cast over the
membrane. The thickness was measured and recorded in nine locations during the initial
hour after casting.
6.1 Observations
The following sections describe various observations noted during Experiment 2. It should
be noted that all remarks apply to both membranes unless otherwise stated.
6.1.1
Construction of Frames
Eight 2" x 4" planks were nailed together to form a wooden structure; the air/water
barriers were stapled to the top of the frame. During construction, the following was
observed:
1. The air/water barriers were cut into 25" x 25" squares and finagled to fit into the 24" x
24" frame. The CCW705vp membrane was easily adapted to the boundary conditions
compared to the CCW705ip air/water barrier.
2. Each membrane developed corrugations and wrinkles during assemblage, particularly
around the corners (see Figure 6-1 through Figure 6-6).
95
6.1.2
Thin Shell Concrete Structure Casting
Quikrete concrete was placed starting at one corner and adding further handfuls, working
away from the edge. The concrete was spread over the membrane to ensure the formwork
was completely filled (see Figure 6-7 and Figure 6-8). To avoid potentially damaging the
membrane, the concrete was not screed (i.e., finished), producing an irregular surface (see
Figure 6-9 and Figure 6-10). The thickness was initially measured in various areas to
provide a continuous 1" slab; concrete was added/eliminated as necessary to achieve the
p uM
r1W-
desired thickness.
"I -
Figure 6-7 View of concrete poured over the
CCW705ip membrane. Photo taken after initial
placement.
Figure 6-8 View of concrete poured over the
CCW705vp membrane. Photo taken after initial
placement.
Figure 6-9 View of the concrete shell cast on the
CCW705ip membrane. Note the uneven surface.
Figure 6-10 View of the concrete shell cast on the
CCW705vp membrane. Note the uneven surface.
96
Thickness measurements were taken in nine areas at various intervals during the first hour
after placement (see Figure 6-11 and Figure 6-12). Table 6-1 and Table 6-2 show the
recorded thicknesses. It should be noted that the locations depicted in Figure 6-11 and
Figure 6-12 are approximate and measurements were taken within the respective locations
shown. The center of the concrete (position 5) displayed the largest change in thickness for
both membranes. The final thickness measurement at this location for the CCW705ip
(impermeable) and CCW705vp (permeable) formed concrete shells was 1.1875" and 1.75",
respectively.
Graph 6-1 and Graph 6-2 illustrate the variation in the recorded thicknesses from the initial
placement for the respective membrane. To clearly show the data on the graphs, the
positions 1, 3, 7 and 9 (i.e., the corners) were classified together as well as positions 2, 4, 6
and 8 (i.e., center of sides); position 5 was observed separately. The results show that the
concrete displaced more on the CCW705vp (permeable) than the CCW705ip
(impermeable) membrane. It was also noted that the bleed water filtered to the middle on
both shells, which increased the thickness at position 5 (see Figure 6-13 - Figure 6-16).
Figure 6-11 Thickness measurement locations for
the thin shell formed on the CCW705ip membrane.
97
Ure O-L
I 1eCIIuMSS IIIC45UI-CICIAL IUPdLI'
for the thin shell formed on CCW705vp
membrane.
CCW705ip Membrane (impermeable)
Time
Thickness Measurements (inches)
2
1
3
1
4
5
6
7
8
9
0 sec
1
1
1
1
1
1
1
1
1 min
1
1.125
1.125
0.875
1.125
1.125
1.1875
1
1.125
5 min
1
1.125
1.125
0.875
1
1.125
1.1875
0.875
1.1875
8 min
1
1.125
1.125
0.875
1
1.0625
1.125
1
1.0625
15 min
1
1.125 1.125
0.875
1.0625
1
1.125
1
1.1875
20 min
1
1.25
1.125
1
1.125
1.125
1.125
1
1.1875
30 min
1
1.25
1.125
1
1.125
40 min
1
1
1.125
0.875
1.125
1.0625
1
1.125
1.125
0.875
0.875
1.1875
1.1875
50 min 1.125
1
1.125
0.875
1.1875
1.125
1.1875
0.9375
1.1875
60 min 1.125
1
1.125
0.875
1.1875
1.125
1.125
0.9375
1.0625
Table 6-1 Thickness measurements recorded for the concrete placed on the CCW705ip
membrane.
Variation in Thickness for CCW705ip
Membrane (impermeable)
0.9
-
1,3,7,9
-
0.7
2,4,6,8
0.5
f-k
0
0.3
-3
- - - - - - -- ---
-
-
- - -
-
--
-
-
--
4
0.1
--
-0.1
min
-0.3
min
-V.-
min
min
-
Time Interval
min
-
min
-
75
-- 7
-9
Graph 6-1 Variation in thickness recorded for concrete placed on the CCW705ip membrane.
98
CCW705vp Membrane (permeable)
Time
0 sec
1 min
5 min
Time
1
1
1.25
1.25
8 min
15 min
1.25
1.25
Thickness Measurements (inches)
7
6
5
4
3
2
1
1
1
1
1
1
0.75 1.125
1.5
1
1.375 1.125
1.375 1.125 1.25 1.625 0.625 1.25
1.625 0.625 1.25
1
1
1.375
0.75 1.125
1.75
0.75
1
1.25
8
1
1.125
9
1
1
1.125
1.125
1.125
1.25
1
1.25
1.125
1.125
1.125
1.125
1.125
1.125
1.125
1.125
_
_
1.375 1.125
1.375 1.125
1.375 1.25
1
1.125
0.75
0.75
0.875
0.875
1.75
1.75
1.75
1.75
0.625
0.625
0.625
0.625
1.125
1.125
1.125
1.125
60 min 1.125 1.125 1.125
0.875
1.75
0.625
1.125 1.375 1.125
20 min 1.375
30 min 1.25
40 min 1.125
50 min 1.125
Table 6-2 Thickness measurements recorded for the concrete placed on the
CCW705vp membrane.
Variation in Thickness for CCW705vp
Membrane (permeable)
--
0.9
0.7
--
-
-
0.5
1,3,7 ,9
0.3
4-
---- 2,4,6 ,8
-
--
0.1
-
inrr5mn2
- se
1-
20
-
- -
~
---
_---
-5
-
min
-0.3-0.5
3mi
min
min
-~-
Time Interval
Graph 6-2 Variation in thickness recorded for the concrete placed on the CCW705vp
membrane.
99
6.1.2.1
Thin Shell Concrete Structure formed on the CCW705ip Membrane
The majority of the final thicknesses for positions around the perimeter of the shell (i.e.,
positions 1, 3, 6, 7 and 9) increased in thickness. However, positions 4 and 8 decreased in
thickness. The final measurements recorded at positions 4 and 8 were 0.875" and 0.9375",
respectively. Position 2's thickness varied throughout the experiment, but the final
measurement was recorded as 1". Position 5's thickness increased the most from 1" to
1.1875". Several other locations achieved a thickness of 1.1875" during the course of the
hour, but the final measurements were less than 1.1875".
6.1.2.2
Thin Shell Concrete Structure formed on the CCW705vp Membrane
The majority of positions around the perimeter of the shell (i.e., positions 1, 2, 3, 7, 8 and 9)
increased in thickness. Positions 4 and 6 decreased in thickness. The final measurements
recorded at positions 4 and 6 were 0.875" and 0.625", respectively. Position 5 gained the
most thickness, increasing from 1" to 1.75". No other locations achieved a thickness of
1.75" during the course of the hour.
6.1.2.3
Variation in Results
The thicknesses recorded at each time interval during both tests increased and decreased;
however, as illustrated in Graph 6-1 and Graph 6-2, the concrete shell cast on the
CCW705ip membrane had less variation compared to that of the CCW705vp membrane. It
should be noted that the measurements obtained are approximate and some fluctuation
should be expected due to the following:
1. The thickness was measured from the top of the membrane (i.e., the surface facing up)
to the top surface of the slab. In several locations, the top of slab included the top of the
bleed water. Considering a rod was inserted into the concrete to measure the thickness
of the concrete, the rod could have been pushed into the membrane causing the
material to move. As a result, the final reading would include the deflection of the
membrane as well as the concrete's thickness. Additionally, this could have induced
adjacent concrete to move, producing larger/smaller thicknesses.
2. The concrete mixture contained cement, sand and gravel. As mentioned previously, the
concrete was not finished, producing an irregular surface. Measurements could have
been measured to the top of the protruding gravel and others to the top of the
cement/bleed water.
100
3. In a physical form-finding application, the air/water barrier is hung, causing the
membrane to slope towards the center. Thus, the positions 1-4 and 6-9 were on an
incline. Given that the rod to measure the thickness was inserted vertically (i.e, at an
angle to top surface of the slab), the thickness in these locations will be marginally
higher.
6.1.3
Inverting Shells
The concrete shells were inverted after curing for 96-hours. Both thin shell concrete
structures' successfully held a dome shape and remained adhered to the air/water barrier
(see Figure 6-17 and Figure 6-21). The following was noted about the concrete structure
formed from the CCW705ip (impermeable) air/water barrier:
1. The membrane contained protrusions from the gravel in addition to the wrinkles and
creases that formed during construction (see Figure 6-17). The membrane did not
appear damaged.
2. An attempt was made to remove the air/water barrier from the concrete structure. The
concrete and membrane formed a strong bond inhibiting the membrane from being
completely separated (see Figure 6-18).
3. The exposed concrete was discolored and honeycombing was observed on the surface
(see Figure 6-19).
4. Indentations formed in the concrete from creases that developed in the membrane (see
Figure 6-20).
The following was noted about the concrete structure formed from the CCW705vp
(permeable) air/water barrier:
1. The surface of the air/water barrier did not contain protrusions but was creased in
various areas (see Figure 6-21).
2. The membrane was easily removed from the concrete (see Figure 6-22).
3. Indentations formed in the concrete from creases that developed in the membrane
during construction (see Figure 6-23).
4. The concrete was discolored and contained pitting (see Figure 6-24).
101
Figure 6-1 View of CCW705ip hanging from a
wooden frame. Note the wrinkles and creases.
Figure 6-2 Wrinkles developed in the
CCW705ip membrane during construction of
the formwork.
Figure 6-3 View of CCW705vp membrane
hanging from a wooden frame. Note the
wrinkles and creases.
Figure 6-4 The CCW705vp membrane
developed wrinkles and corrugations during
construction of the formwork.
102
Figure 6-5 View of the underside of the
CCW705ip membrane hung from a wooden
frame. Note the wrinkles that developed
while conforming the membrane to the frame
opening.
Figure 6-6 View of the underside of the
CCW705vp membrane hung from a wooden
frame. Note the wrinkles that developed
while conforming the membrane to the frame
opening.
Figure 6-13 View of concrete shell cast on the
CCW705ip membrane one hour after initial
placement.
Figure 6-14 View of the center of the concrete
shell cast on the CCW705ip membrane. Note
the bleed water congregated in the center.
103
I
Figure 6-15 View of concrete shell cast on the
CCW705vp membrane one hour after initial
placement.
Figure 6-16 View of the center of the concrete
shell cast on the CCW705vp membrane. Note
the bleed water congregated in the center.
Figure 6-17 View of the inverted concrete
shell cast on the CCW705ip membrane. Note
the small projections from the gravel.
Figure 6-18 View of the inverted concrete
shell cast on the CCW705ip membrane. Note
the membrane and concrete formed a strong
bond.
I
104
Figure 6-19 View of the exposed concrete
from detaching the CCW705ip membrane.
Note the discoloration, pitting and
honeycombing in the surface.
Figure 6-21 View of inverted concrete shell
cast on the CCW705vp membrane.
Figure 6-20 Indentation from a crease that
developed in the CCW705ip membrane.
Figure 6-22 View of the inverted concrete
shell cast on the CCW705vp membrane. Note
the membrane was easily removed from the
concrete.
105
I
Figure 6-23 Indentations in the concrete from
creases that developed in the CCW705vp
membrane.
106
Figure 6-24 Concrete dome formed from the
CCW705vp membrane. Note the discoloration
and pitting in the surface.
6.2 Discussion
The results validate the feasibility of installing an air/water barrier in a physical formfinding application. The following can be concluded:
1. Both membranes successfully functioned as tension-like fabric to form the thin shell
concrete structures. No issues were encountered during construction of the formwork
(i.e., hanging the membranes in the wooden frames). However, the CCW705vp
membrane was easier to configure compared to the CCW705ip membrane. This is
expected given that the CCW705vp and CCW705ip membranes are 0.02" and 0.04"
thick, respectively.
2. The thin shell concrete thickness varied for both membranes. This movement was
greater for the CCW705vp than the CCW705ip membrane.
3. Both thin shell structures were successfully inverted suggesting that the air/water
barrier does not affect the behavior of the shell.
4. The CCW705vp membrane had poor adhesion to the concrete after curing and was
easily removed. The CCW705ip established a strong bond and could not be completely
removed.
The MFC is a fagade system that will require a vertical form-finding application. The
CCW705vp membrane (permeable) would most likely not perform as well as the
CCW705ip air/water barrier in this configuration considering the results demonstrated
notable movement of the concrete on this membrane. In addition, it could be assumed that
since the CCW705vp membrane easily conformed to the boundary conditions compared to
the CCW705ip membrane, this air/water would be better from a constructability
standpoint. However, on a larger scale, this concern would not be as critical.
Although the membrane-to-concrete bond is one consideration in the design of the MFC,
this concern is not critical given the thin shell concrete structure will be anchored to the
slab. This implies that the air/water barrier will have minimal sources to cause detachment
considering the membrane will support only self-weight. Furthermore, the membrane laps
will provide redundancy to ensure the air/water barrier remains adhered to the concrete.
It should be noted that the results indicated that the CCW705ip membrane (impermeable)
developed a stronger bond to the concrete.
107
In terms of constructability and slippage, the results suggest that the CCW705ip
(impermeable) air/water barrier would perform better.
The remarks presented in this chapter are preliminary. Chapter 7 presents the final
conclusions as a result of Experiment 1 and Experiment 2.
108
7 Conclusions
This chapter will provide a summary of the findings from Experiment 1 and Experiment 2.
Design guidelines based on the results of the research will be presented. A review the MFC
design and recommendations for future work will be given. The chapter will conclude with
a summary of contributions to the industry.
7.1 Summary of Findings
The MFC includes using an air/water barrier in physical form-finding techniques to
fabricate a thin-shell concrete structure. Experiment 1 assesses the feasibility of using an
air/water barrier as formwork for concrete in terms of structural strength. The effect of the
permanence rating of the air/water barrier formwork on the bulk and surface of the
concrete is also evaluated in Experiment 1. Experiment 2 provides insight regarding the
behavior of an air/water barrier in form-finding techniques. More specifically, Experiment
2 investigates whether the membrane would be damaged in form-finding techniques, if the
thickness or behavior of the concrete shell would be affected and if the concrete remains
adhered to the membrane.
7.1.1
Experiment 1
Overall, Experiment 1 confirmed that the air/water barriers, Perm-a-Barrier by Grace
Construction (impermeable), Sarnavap by Sika Sarnafil (impermeable), Tyvek
CommercialWrap by DuPont (permeable), Tyek HomeWrap by DuPont (permeable) and
CCW705ip by Carlisle (impermeable) are viable in a formwork application. The
overarching conclusion drawn from this work was that a permeable membrane is an ideal
membrane for the MFC. The following was deduced from Experiment 1:
1. The air/water barriers can perform adequately as formwork. It should be noted that the
CCW705vp membrane had issues maintaining a cylindrical geometry. On a larger scale,
this concern would potentially be insignificant. Further research is required to assess
the performance of the membrane on a larger scale.
109
2. The strength of concrete is not degraded when molded in vapor impermeable or
permeable air/water barriers. It should be noted that the permeable membranes
produced a concrete with a higher bulk and surface properties; the permeable
membrane had a greater impact on the surface strength than the bulk concrete.
3. The impermeable membranes formed the strongest bond with the concrete.
7.1.2
Experiment 2
The results indicated that the CCW705ip (impermeable) and CCW705vp (permeable)
membranes were successfully able to act as the tension fabric (i.e., formwork) in a formfinding application. The overall conclusion drawn from this study is that impermeable
air/water barriers perform better in physical form-finding applications. The following was
noted:
1. From a constructability standpoint, the CCW705vp membrane was ideal as the
membrane easily conformed to the boundary conditions compared to that of the
CCW705ip air/water barrier.
2. The concrete displaced more on the CCW705vp membrane than the CCW705ip
air/water barrier.
3. The CCW705ip (impermeable) membrane developed a stronger bond with the concrete
than the CCW705vp (permeable) membrane.
7.2 Design Recommendations
Based on the research, the superior strength properties achieved in concrete formed with
the permeable formwork make this air/water barrier the preferable membrane for the
design of the MFC. Although the CCW705vp membrane had constructability issues, further
research is required to determine the performance of the membrane on a larger scale. The
remaining permeable membranes (i.e., Tyvek CommercialWrap and HomeWrap by
DuPont) proved to be reliable to include in the design of the MFC. The slippage of the
concrete on the membranes was not tested. Further work is required regarding slippage of
concrete on the membranes.
The use of an impermeable membrane should not be discarded in the design if the climate
and building function require such properties. Although the compressive strength of the
tested impermeable membranes (i.e., Perm-a-Barrier by Grace Construction, Sarnavap by
110
Sika Sarnafil and CCW705 by Carlisle) was lower, the membranes still performed
sufficiently.
It should be noted that using either air/water barrier is contingent upon providing
insulation outboard of the membrane. If an impermeable membrane is installed, a
minimum thickness of insulation is required in the cavity depending on the type used.
Under a certain thickness or if no cavity insulation is installed, a vapor permeable
membrane is required. In addition, insulation placed inboard of the air/water barrier
should be considered to limit the risk of moisture condensing and accumulating inboard of
the air/water barrier.
7.3 Significance of Experimental Work
As the industry's demands evolve, the building methods and materials must improve to
accommodate the ever-changing standards. Sustainability, reduced maintenance, high
quality construction and lower cost are several criterions that are becoming more difficult
to provide with the common building technology. A system that uses traditional building
materials in innovative applications would potentially address these requirements as well
as offer a large reduction in material waste, decrease workmanship dependency, reduce
coordination between trades and lessen construction time. However, existing products
continue to encounter some similar issues associated with traditional building methods
such as consuming a large volume of occupiable space and restricting the aesthetic design.
The results of the experiments have validated the concept of a membrane formed concrete
panel from a constructability and strength standpoint. The panel combines multiple
functions into one material to decrease construction waste and reduce coordination
between multiple trades. More specifically, the panel applies one material to form and
protect the wall, potentially increasing available space and reducing construction time. In
addition, the single source construction will provide sole responsibility to one
manufacturer and the risk of construction error is reduced given the panel will be
produced in a controlled environment.
111
This thesis provided the first step for the concept of a membrane formed concrete panel.
The following section introduces several ideas for future work to further refine and
improve the design.
7.4 Future Work
What has been presented in this thesis is only the beginnings of a design for an integrated
exterior wall system. The following presents several ideas for future work to further the
design of the MFC:
1. The air/water barriers used to construct the concrete cylinders are only a limited range
of potential membranes that are possible to install. Further work is needed to
determine the optimal air/water barriers to use in the MFC design for a particular
climate and building function.
2. A complete design of the MFC was not presented as part of this thesis, but insulation,
cladding, anchor attachment or openings in the panel all have the potential to be
components of the system.
3. A further understanding regarding the performance of an air/water barrier in a full
scale mockup is needed (vertical and horizontal). This will provide insight regarding
the structural mechanical properties of the materials such as deformation. In addition,
further research is necessary to better understand the ideal shape of a vertically
hanging membrane to obtain optimal structural performance.
4. The current design incorporates installing the air/water barrier on one side and
allowing the opposite side of the concrete to be exposed. There is much opportunity for
further development regarding sandwiching the concrete between the air/water
barrier and another enclosure material.
7.5 Summary of Contributions
This thesis illustrates the feasibility of using traditional building materials in innovative
applications. The experimental work performed provides insight into several of the
limitations including the following:
1. A variety of conventional building envelope membranes (Perm-a-Barrier by Grace
Construction, Sarnavap by Sika Sarnafil, Tyvek CommercialWrap by DuPont, Tyek
HomeWrap by DuPont and CCW705ip by Carlisle) performed adequately as formwork.
112
2. The air/water barriers (permeable and impermeable) do not degrade the strength of
concrete. Permeable membranes produce a higher strength concrete and have a greater
impact on the surface properties.
3. Impermeable membranes develop a stronger bond with the concrete.
4. Air/water barriers (permeable and impermeable) can perform as tension-like fabric to
form a thin shell concrete structure.
5. The concrete displaced more on a permeable membrane compared to an impermeable
membrane.
113
APPENDIX A - Concrete Pouring Sequence
115
View of air/water
barrier molds prior to
pouring the concrete.
The picture shows CW1,
CW2 and CW3.
View of consolidation of
the first layer of
concrete. The concrete
is rodded 25 times to
evenly distribute the
aggregate.
View of tapping the
mold after two layers of
concrete have been
placed and rodded. Each
layer is tapped 10-15
times with a rubber
mallet.
116
View of a cylinder after
two levels of concrete
have been poured,
rodded and tapped. The
cylinder is being struck,
with a back and forth
motion, to produce a
flat, level surface.
View of cylinders prior
to capping.
View of cylinders prior
to capping.
117
View of cylinders being
sprayed. The molds
were continually
sprayed for the first 30
minutes after pouring.
View of the caps being
placed on the cylinders.
View of cylinders with
caps.
118
View of completed
cylinders curing under
plastic tarps. The
cylinders surrounded
two buckets of water.
119
APPENDIX B - Cylinder Dimensions and
Empirical Results
121
Failure
oa bs)
-
3,658
3,592
3,597
39,741
35,492
35,745
ress
Srs(pi
3,446
3,136
3,062
3.93
3.76
3.74
Top
Top
Bottom
3,755
3,765
3,711
38,196
49,228
48,759
3,153
4,149
4,147
12.43
3.91
Bottom
3,744
49,947
4,017
8.04
11.49
3.73
Top
3,509
42,569
3,705
3.99
7.99
12.52
3.97
Top
3,782
57,021
4,553
4.05
4.01
3.99
3.97
8.00
7.97
12.50
12.37
3.91
3.90
3.90
3.98
8.24
12.41
3.80
3,776
3,684
3,898
51,014
50,208
51,009
4,082
4,059
4.02
Top
Bottom
Bottom
4.02
4.00
4.00
4.05
3.98
4.02
4.02
3.99
4.00
8.07
8.20
8.09
12.67
12.52
-
-
-
3,860
3,940
3,887
43,534
42,990
41,656
3,435
3,433
3,308
7.08
7.57.07
-
-
1,595
26,198
3,701
-
1,589
26,724
3,790
1,604
26,106
3,692
Height (in)
Area (in 2)
8.02
8.04
7.98
11.53
11.32
11.67
-
-
-
3.89
3.93
3.74
3.93
3.89
3.87
8.20
8.09
8.03
12.12
11.87
11.76
3.98
3.91
3.98
8.06
3.87
3.85
3.76
3.82
2
4.02
4.00
3.97
3.91
3.93
4.01
3.96
HW3
2
2
2
4.01
C1-48
C2-48
C3-48
1
1
2
3.98
3.99
3.99
Size
Abbreviation
Perm-a-Barrier 1
Perm-a-Barrier 2
Perm-a-Barrier 3
4x8 in
4x8 in
4x8 in
PAB1
PAB2
PAB3
1
1
1
3.72
3.60
3.82
Sarnavap 1
Sarnavap 2
Sarnavap 3
4x8 in
4x8 in
4x8 in
SV1
SV2
SV3
2
2
2
3.95
3.78
3.93
3.94
3.95
3.94
CommercialWrap
4x8 in
CW1
2
4.04
CommercialWrap
2
CommercialWrap
4x8 in
CW2
2
4x8 in
CW3
HomeWrap 1
HomeWrap 2
HomeWra 3
4x8 in
4x8 in
4x8 in
HW1
HW2
Control 1
Control 2
Control 3
4x8 in
4x8 in
4x8 in
-.
Smallest
Loction of
Diameter
Smallest Dia.
(in)Lod(b)
Weight (g)
eDiameter n
Middle
Bottom
No. Top Bottom
Batch
Midle
3.85
3.92
3.81
3.98
3.85
3.90
Diaeter
Diamete
3.83
3.80
3.86
Batc
Specimen
Top
02
".-2.5
12.59-
-
6
Compressive
C
4,110
3,70
Control 1
Control 2
Control 3
3x6 in
3x6 in
3x6 in
Cl-36
C2-36
C3-36
3
3
3
2.98
2.98
2.99
3.00
3.00
3.00
3.02
3.01
3.02
3.00
3.00
3.00
5.96
5.90
5.98
Control 1
Control 2
Control 3
2x4 in
2x4 in
2x4 in
C1-24
C2-24
C3-24
3
3
3
2.03
2.03
2.03
2.05
2.05
2.05
2.06
2.08
2.06
2.05
2.05
2.05
4.01
4.00
3.98
3.29
-
-
3.30
-
-
499
499
497
13,170
13,508
13,912
4,003
4,095
4,234
CCW705ip
CCW705ip
CCW705ip
4x8 in
4x8 in
4x8 in
CCWip14
CCWip24
CCWip34
1
1
1
3.95
3.89
3.80
3.99
3.91
3.96
4.02
3.88
4.02
3.99
3.89
3.93
7.96
7.73
7.86
12.50
11.90
12.12
3.95
3.83
3.78
Top
Bottom
Top
3,715
3,588
3,644
43,446
42,748
3,477
3,526
CCW705ip
CCW705ip
3x6 in
3x6 in
CCWip13
CCWip23
3
3
2.90
2.86
2.97
2.94
2.95
2.96
2.94
2.92
6.06
5.94
6.80
6.69
2.87
2.85
Top
Top
1,531
1,489
25,848
26,625
3,803
3,978
122
3.29
"
1,518
26,917
1.91
Bottom
445
12,163
3,976
1.96
1.83
Bottom 1/4
Top
455
459
12,216
12,155
3,920
4,092
12.91
3.75
Top
3,903
44,889
3,476
12.82
12.33
3.76
3.77
Top
Bottom
3,946
3,766
48,476
45,491
3,782
3,690
6.84
6.29
7.22
2.91
2.66
2.75
Top
Top
Bottom
1,575
1,542
1,644
31,176
26,530
28,496
4,559
4,217
3,946
4.03
3.15
1.98
Top 1/4
474
13,239
4,207
4.18
3.94
3.08
2.93
1.94
1.89
Bottom
Top
466
446
12,614
12,865
4,098
4,384
2.95
5.94
6.84
2.92
1.94
2.02
1.97
4.04
3.06
1.97
1.97
2.03
2.03
1.99
1.94
4.03
4.02
3.12
2.97
3.81
4.22
4.14
4.05
8.07
3.86
3.77
4.19
4.24
4.07
3.88
4.04
3.96
8.08
7.62
3
3
3
2.94
2.66
2.99
2.99
2.99
3.01
2.92
2.84
3.09
2.95
2.83
3.03
6.49
5.96
6.02
CCWvp12
3
2.00
2.01
2.00
2.00
CCWvp22
CCWvp32
3
3
1.98
1.89
1.98
1.92
1.98
1.99
1.98
1.93
3x6 in
CCWip33
3
2.96
2.96
CCW705ip
2x4 in
CCWipl2
3
1.96
CCW705ip
CCW705i
2x4 in
2x4 in
CCWip22
2
CCWip3
3
3
1.98
1.84
CCW705vp
4x8 in
CCWvpl4
1
CCW705vp
CCW705vp
4x8 in
4x8 in
CCWvp24
CCWvp34
1
1
CCW705vp
CCW705vp
CCW705vp
3x6 in
3x6 in
3x6 in
CCWvp13
CCWvp23
CCWvp33
CCW705vp
2x4 in
CCW705vp
CCW705vp
2x4 in
2x4 in
123
3,934
Bottom
2.94
CCW705ip
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