3D Printing in Construction: Review on
Processes, Materials mix, and Energy
Performance
Nora Soualhi
School of Science and Engineering, Al Akhawayn University in Ifrane, Morocco
n.soualhi@aui.ma
Table. 1. Printed Buildings in the World
Abstract—3D printing is a novel technology
used in construction. With growing population and
housing shortage, 3D printing may be the key to resolve
this issue. This paper reviews three common processes
used in 3D printing namely: D-shape, contour crafting,
and concrete printing. The mix design of 3D printed
concreted is discussed. This section highlights the
difficulty to determine the superplasticizer dosage and
suggests two approaches to simplify the operation.
Energy performance is critical indicator of sustainability
of 3D printing. Two case studies are discussed to
emphasize the energy performance of 3D printed
structures. Results indicated that 3D printable concrete
is not sustainable as compared to other conventional
materials.
Keywords—3D printed buildings, concrete
printing, extrusion, contour crafting.
I.
INTRODUCTION
The buildings and construction sectors are major
economic drivers. In recent years, it has been hard to
meet the targeted demand in terms of construction
time and waste due to shortage of skilled labors,
automation and safety concerns. In this context, 3D
printing technology appears to be the key solution to
building and construction problems. 3DP enables
engineers to build complex structures using computer
aided design in a short time without the need of
formwork or extra-workers [1]. 3D printing, also
known as additive manufacturing, is widely utilized in
many industries such as medicine, automotive, and
aerospace. Today, this technology has expanded to the
building and construction sector as to resolve a series
of issues in this field such as high production cost, lack
of skilled labor, health and safety concerns, and
construction time. Regarding the progress of 3D
printing technology, some constructions have already
been printed worldwide. Notorious printed buildings
include the 1st neighborhood in Mexico, pedestrian
bridge in Madrid, and printed offices in Dubai (Tab.
1). Currently, the major construction modes used for
extrusion-based 3D printing technology are concrete
printing and contour crafting. The materials used for
these two methods are geopolymer and cementitious
materials [2].
Project
Company
Construction
Material
Cement
mixture
3D printed office buildings in
Dubai [3]
Gensler
3D printed house in Nantes [3]
Batiprint3D
Cement filled
with
polyurethane
insulator in
the middle
3D printed Bridge in Madrid [3]
Acciona
Microreinforced
concrete
3D printed apartment building
[4]
WinSun
Recycled
concrete
Printed neighbourhood in
Mexico [5]
ICON
Concrete
printing
Gaia 3D printed house [6]
WASP
Earth
materials
This paper explores the methods used for 3D
printed buildings along with the mix design of
materials used. Also, an assessment of the sustainable
mix design of materials is discussed. As a final part,
two case studies are considered to investigate the
energy performance of 3D printed materials.
II.
METHODS
In recent years, three large scale 3D printing
methods commonly used at construction are: DShape, concrete printing and contour crafting.
Figure 1. D-Shape printer
1.
D-Shape printing
D-Shape is commonly considered as an offsite manufacturing process. It concretizes building
blocks from the computer by alternating layers made
of granular material and turning this latter into a shape.
D-shape method mainly deposits any fibres and mix of
granular materials. Ideally, the deposit is within a
range of diameter 0.1- 4 mm. The method discussed
incorporates multi material and multi binder, in other
words, the binder maybe of any additive, while the
granular material may be of any type. The print head
is fuelled using a tank and a hydraulic system, and the
gantry distributor is driven by a granular material
supplementing the system from the ground. All the
operations of this kind of printer are governed by a
personnel computer; although the process is
automatic, the presence of at least one employee is
mandatory for the good monitoring and the quality of
the manufacturing process. D-shape features a unique
material deposition technique which renders the
building self-sustaining while it is being built (Fig. 1).
This way, it is feasible to create buildings of any shape
if the material's resistance allows it. [7]
2.
Contour Crafting
Contour crafting (CC) is a layered
construction technology that uses trawling to produce
smooth and free-form surfaces. It mainly uses two
trowels that act as solid planar surfaces to produce
particularly accurate and smooth surfaces. CC is
favoured to other layered fabrication processes thanks
to its high fabrication speed, great surface quality, and
wide options of materials.
The layering approach in this method
exploits some trawling tools to create various surface
shapes as compared with the traditional sculpting. It is
some sort of a hybrid method that forms the object
surfaces applying extrusion process in combination
with the filling process to construct the object core.
Figure 2. CC used for Adobe building [8]
In a single run, one house or multiple houses, each
designed differently, can be built automatically.
Traditional buildings, such as those
developed by CalEarth (Fig. 2), may be produced by
combining a support beam picking, a positioning arm,
and adobe structures. Shape features such as domes
and vaults can be used to construct structures that do
not require external support.
CC can utilize a variety of materials for outer
surfaces and as fillers for the voids. Multiple
chemically reactive materials can be injected through
the CC nozzle system and blended in the nozzle barrel
right before deposition. The amount of each material
can be adjusted by the computer and associated to
different areas of the geometry of the building being
constructed. This will allow the creation of structures
with varied quantities of different components in
distinctive areas. [8]
Regarding outer space applications,
supportless structures may be an ideal option to be
built employing in-situ materials. Contour crafting
technology may have the potential to build houses on
the Moon and Mars. According to NASA and NSF, the
Moon is ideal in terms of solar power generation.
Given that solar power is available, CC would be
adjusted to use its full potential and in-situ materials to
construct a printed hotels or cities. The material that
may be used for construction is lunar regolith.
Researchers have proven that sintering of lunar
regolith could succeed using a microwave to generate
bricks or other construction materials. [9]
3.
characteristics in the way that the three build
additively. Both concrete printing and D-shape need
extra support to produce freedom features such as
overhangs. Regarding materials, all three processes
are based on a curing process through which it
hardens. D-shape is a dry process while concrete
printing and contour crafting are wet processes.[10]
Concrete Printing
Concrete printing employs extrusion of
cement mortar. It enables great control and monitoring
of internal and external geometries due to a small
resolution of deposition. This technology is based on
high performance fiber-reinforced fine-aggregate
concrete, which creates excellent material properties
as compared to those produced by the contour crafting
technology.
Generally, to produce overhangs and
freedom features, additional support to concrete
printing is required. Also, a second material normally
used the same way as fussed deposition modeling
method. The downsides of this process are that the
second material requires an additional deposition
device. Hence, cleaning, control, monitoring, and
maintenance are needed through the process. [11]
To accommodate growing population in
Netherlands, the country seeks ways to tackle scarcity
of housing. One of the solutions that may be a
promising one is 3D printing. Within a program of
exploring ways to solve housing shortage, Elize Lutz
and Harrie Dekkers built a 94 m2 house (Fig. 3) using
concrete printing method complied with construction
codes. The house was built within 120 hours. In the
future, it is expected that 3D printing would cut
materials used in traditional construction methods by
30%. This way, housing shortage may be resolved.
The three techniques share some common
Figure 3. Concrete 3D printed house [12]
Figure 3. Comparison of discussed processes [10]
Table 2. Features of 3D printed processes [10]
D-Shape
Contour Crafting
Concrete Printing
Building mode
3D printing
Extrusion
Extrusion
Building material
Granular material
Mortar mixture and
cementitious material
Printable concrete
Binder
Chlorine-based liquid
None
None
High strengths
Table 2. Features of 3D printed
processes
Smooth surface trowel
Pros
Cons
-Rough surface.
-Slow process.
-Removal of unused material.
-Massive material placement.
-Limited printing dimension.
-Weak bonding.
-Additional process
(moulding).
4.
Mix Design
In the rational mix design method, selfcompatibility may be greatly impacted by the by the
characteristics of materials and the mix design
selected. Okamura and Ozawa suggested a simple mix
design assuming available resources. The mix design
is composed of fixed coarse and fine aggregates to
achieve
self-compatibility
by
adjusting
superplasticizer dosage and water powder ratio. Tab. 3
summarizes characteristics of a rational mix design.
Regarding the dosage of the superplasticizer, it is
difficult to be determined. The most efficient way is to
apply the three-water content approach; Meaning the
highest, the intermediate, and the lowest water/binder
ratio compatible with the strength targeted are used to
produce 3 trial batches different amount of water but
the same amount of binder. Then, the trial batches are
tested for slump loss and strength.
Another approach consists of creating a first trial
batch at a water/ binder ratio taking into consideration
the required strength with a superplasticizer dosage
that corresponds to 1%. Then, according to the output
results, essential adjustments to this dosage are
applied. Generally, the final superplasticizer dosage
and water/binder ratio are obtained by 3rd or 4th trial
batch. [13]
High performance concrete, also named selfcompacting high-performance concrete, is identified
as high durable concrete because it has a low water
cement ratio. 3D printed concrete differs in terms of
-High strengths.
-Minimum printing process
using reinforcement and
deposition.
Limited printing
dimension.
the composition in three ways. In addition to the base
ingredients, carbon fibre could be used as a reinforcing
ingredient, water used as an adhesive ingredient, and
sodium silicate can be used as a hydrator. This creates
a very different concrete that can maintain its shape
when wet.
Different mix designs are available in 3D printing. Le
et al. discussed a mix design of five trial mixes with
distinct sand/binder proportions (Tab. 4). Starting
from mix 1 to 5, sand was decreased in 5% increments
from 75-55% by weight of dry mixture while the
binder was increased from 25-45%. To optimize the
mix proportions for printing, the dosages of
polypropylene fibres, superplasticizer, accelerator,
and retarder were varied. The results of the study
showed that the optimum mix contains 10% silica
fume, 20% fly ash, 70% cement, and 1.2 kg/m3 of
polypropylene fibres. The mix comprises 1% of
superplasticizer by weight of binder, 0.5% retarder by
weight of binder, together to form water-binder ratio
of 0.26. [14]
Table 3. Characteristics of a rational mix design [13]
Material
Coarse
aggregate
content
Fine
aggregate
content
Waterpowder
ratio
Superplasticizer
dosage
Mix
proportioning
50% (of
solid
volume)
40% (of
the
mortar
volume)
0.9-1.0
_____
Table 4. Mix design of different trials [14]
III.
1.
Energy Performance
Case Study 1
The first case study is based on a 3D printed
single family home in Kansas. It compares 3 building
envelope scenarios and a typical residential building
as a reference to investigate the insulating capacity
concrete 3D printed walls and the expected energy
demand. The study uses two software: THERM and eQuest. THERM is used to estimate R-value and the
solar heat gain coefficient, which are then used as
output in e-Quest to simulate the energy consumption
and he utility cost of the high-performance concrete
3D printing. For scenario 1, the 3D printed wall
doesn’t incorporate any insulation, for scenario 2,
insulation is in the wall cavity, while in scenario 3.
Insulation is in the wall cavity and interior. Results
showed that scenario 3 has the lowest electric
consumption demand at 10 820 kWh compared to
scenario 1 which consumes 21 800 kWh (Fig. 4).
According to the results, energy demand for scenario
3 may be covered with solar PV panels. [15]
2.
Case Study 2
The second case study uses eq. 1, 2, and 3 to
get R-value instead of using THERM software.
Figure 4. Energy demand of different 3D printed
walls [10]
Using Revit simulation, the thermal comfort and the
energy performance of the house are modelled by
changing the external envelope with 3 different
materials: M25 concrete, 3D printable concrete, and
conventional brick masonry. The mix designs of M25
and 3D printable concrete are given in Tab. 5.
Table 5. Mix design of M25 and 3D printable concrete [16]
The results of this case study point out that 3D
printable concrete emits great amount of CO2
emissions compared with Conventional bricks or M25
concrete. Moreover, results indicated that thermal
performance of 3D printed concrete is not appropriate
in the long term compared to other conventional
materials.
IV.
CONCLUSION
This paper reviewed the common processes
used in 3D printing namely D-Shape, contour crafting,
and concrete printing. Then, the mix design used in 3D
concrete printing is discussed. The mix design
revealed to be the most challenging task in 3D
printing. Superplasticizer holds a critical role in
determining the proportional mix. The final part of the
review considers two case studies to highlight the
energy performance of 3D printable concrete. The
result indicated that 3D printable concrete emits higher
CO2 emissions compared to other conventional
materials. Indeed, more research and improvement of
materials used for 3D printing are still needed to
address the concerns of sustainability related to 3D
printing in construction.
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