Design and Construct 2000 Living Units at ALKHOMS

Concrete Works Methodology Rev 1, 16 September 2009

Project

Location

District

Building No

DESIGN AND CONSTRUCTION OF 2000 LIVING UNITS

AND PUBLIC BUILDINGS

AL-KHOMS

AL-MARQAB

CONCRETE WORKS METHODOLOGY

Revision History

Rev # Description of Revision Submission

Date

Rev0 Concrete Works

Methodology

05 Sept 09

Rev1 Concrete Works

Methodology

Table of Contents

16 Sept 09

General/ Scope

Parameters

Applicable codes and Standards

Materials Specifications for Concrete

Production of Concrete

Preparation for Concrete Work

Transportation of concrete

Concrete work/ Casting

Finishing & Curing

Construction Joints

Concrete Defect Treatment

Concrete Sampling

Reinforced Concrete Structural Analysis

Concrete Mix Design

Concrete Mix Calculations

Documents and Records

Safety

Quality

Concrete Casting Flow Chart

By

Sohail

Moughal

Sohail

Moughal

Approval

Date



1.0

2.0

GENERAL/ SCOPE

This Construction Method and Quality Control Planning shall be applied to concrete work, including all kinds of concrete made elements. Based on the design and specification, this document provides a proper procedure and management of the concrete work.

PARAMETERS

3.0

2.5 Lean Concrete Quantity

Unknown (pending design)

2.6 Structural Concrete Quantity

Unknown (pending design)

APPLICABLE CODES AND STANDARDS

2.1 Name of the Project

Design and Construction of 2000 Living Units and Public Buildings

2.2 Location of The Project

Alkhoms, District Almarqab, Libya

2.3 Land Area

237 hectares

2.4 Building Area

414400 square meters

The following codes shall, wherever relevant shall be followed for design and execution of the concrete works on the project: a. ASTM C33

Standard specification for concrete aggregates b. ASTM C114/C150

Standard test for cement Portland Cement Type I c. ASTM C1437

Standard slump test for concrete d. ASTM C231

Air content determination e. BS 1881

Concrete cube sampling & compression test f. ACI 318

Building code requirement for reinforced concrete and supplementary


Concrete Works Methodology Rev 1, 16 September 2009 standards d. ACI 211

Standard practice for selecting proportions

4.0 MATERIAL SPECIFICATIONS FOR CONCRETE

4.1 The following materials are required to prepare concrete;

Course Aggregates (Crush stone size

Course Aggregates (Crush stone size

Fine Aggregates

Additives/ Admixtures (if required)

Water

4.2 Materials sources shall be jointly visited by the contractor and client to approve the sources for onward use for the project.

4.3 Materials as desired by the client, shall be tested by third party or the in house quality laboratory before use on the site.

4.4 After the test results, mock up results, or visual inspections are acquired, the contractor shall use the data from the tests for design purposes and for usage in quality documents.

4.5 Portland cement, ASTM C114 type I shall be used.

4.6 Fine aggregate shall be natural sand that is clean, hard, durable uncoated grains, free of dust or any other contamination. The fine aggregates shall be stacked with a polyethylene sheet on the ground.

4.7 Coarse aggregates shall be crushed stone and of the following sizes and proportions:

6 – 10mm @ 50% by volume

10- 20mm @ 50% by volume

4.8 Coarse aggregates of both sizes shall be clean hard, strong and durable particles free of chemicals, dust, clay or other materials that might affect the bonding properties of cement.

4.9 Mixing water shall be fresh, clean, and free from any contamination.

Locally available potable water shall be used for mixing concrete.

4.10 Mix Proportions of concrete for cement, fine aggregates, coarse aggregates and water shall be developed and submitted to CM/CS for approval.

4.11 Water cement ratio shall not exceed 0.5 by weight.

4.12 Concrete shall have a minimum crushing strength (f c

’) of 40MPa,

35MPa, 30MPa, 25MPa, 20MPa, 15MPa.



4.13 The lean concrete shall not require a mix design and a 1:4:8 ratio by volume shall be used.

4.14 A sheet of polyethylene 0.1 mm thick shall be laid on ground before pouring lean concrete.

4.15 All structural reinforced concrete shall require a mix design before execution and a total of 6 test specimens (cubes) shall be prepared. Three specimens shall be tested at 7 days for crushing strength and remaining three shall be tested at 28 days. Contractor’s testing equipment shall be used for tests in presence of CM/CS inspector.

4.16 The proposed mix design shall be accepted for execution if the 7-day strength test average of specimens proves to meet or exceed the required

40MPa, 35MPa, 30MPa, 25MPa, 20MPa, 15MPa.

4.17 If the 7-day strength tests prove to be at less than 70% of the design requirement, new specimens shall be prepared. If the 7-day strength tests meet the minimum required 7 day, but do not meet design requirement of 40MPa, 35MPa, 30MPa, 25MPa, 20MPa,15MPa, the 28-day tests on cubes shall be conducted.

PRODUCTION OF CONCRETE 5.0

5.1 An in-house 60 cubic meter / hour concrete batching plant shall be used to prepare concrete.

5.2 A 16 cubic meter/ hour mobile self loading batching machine shall be used for concrete works of smaller quantity.

5.3 Concrete shall be ordered from the batching plant in accordance with the specified design strength, being subject to quality control as indicated herein.

5.4 The speed of batching plant/ machinery shall be provided by the equipment manufacturer or the CM/CS.

5.5 In case a single bag mixing machine is used, the mixing shall continue for a minimum of 60 seconds from the time the last ingredient is dumped in the mixing drum.

6.0 PREPARATION FOR CONCRETE WORK

6.1 No formwork is required for the lean concrete.

6.2 Lean concrete shall be approximately 75mm thick and the finished surface shall be level with a minimum tolerance of ±6 mm from desired/


Concrete Works Methodology Rev 1, 16 September 2009 reference levels.

6.3 Approved systems for Steel forms, Aluminum forms or plywood forms shall be used for casting structural concrete. The forms shall be treated with non-staining oil to prevent adhesion to the concrete and to minimize damage during removal of forms.

6.4 The forms shall be installed such that the finished concrete shall conform to shape, lines, grade, and dimensions indicated in the approved construction drawings.

6.5 Forms shall be substantial and sufficiently tight to prevent leakage of mortar. Form bracing and supports shall be tied together to maintain position and shape before and after pacing the concrete. The inside seams of the forms shall be taped to prevent leakage. Concrete shall be vibrated to avoid honeycombing.

6.6 A 70-75mm thick concrete spacer shall be tied with binding wire to the reinforcement bars to ensure required concrete cover.

6.7 The twisted ends of the binding wire shall project towards the centre of the concrete beam and away from the exterior concrete surfaces. o. Formwork shall have wooden profiles at the levels ensuring chamfered top edges of the concrete beam.

6.8 In excessive hot climates, aggregates, cement and water shall be stored under shade or water chillers shall be used.

6.9 CM/CS shall be informed if the concrete work exceeds 4 cubic meters, and an inspection request shall be submitted. Work shall commence only after an approval to proceed is acquired.

6.10 All form work/ scaffoldings/ false work shall be inspected for stability, alignments and integrity and checked for fitness for concrete work operations.

6.11 M/E Inspector shall inspect the embedded M/E devices and their location before concrete work starts. Also during concrete casting, the condition of M/E device shall be checked to ensure their alignments and locations according to M/E drawings.

6.12 All related tools, equipment, manpower and supplies like water/ electricity sources shall be on site. Redundant sources shall be made available when necessary.

6.13 Before concreting, the moist condition shall be provided to all form work and to previous construction joint surfaces with water spraying.

6.14 Top level of concrete to be cast shall be made by marking on form with nail or red adhesive tape (at interval of 1,500 ~ 2,000mm). In case of


Concrete Works Methodology Rev 1, 16 September 2009 slab concrete, level shall be used for checking.

7.0 TRANSPORTATION OF CONCRETE

7.1 Mixing trucks shall be cleaned thoroughly after completing each concrete supplying trip. Remaining hardened concrete or any foreign material inside concrete compartment must be cleaned out.

7.2 Time of transportation from the batching plant to site shall not exceed 02 hours (otherwise truck of concrete shall be returned to the batching plant).

7.3 Any segregated concrete or any defective concrete shall be rejected.

7.4 Record of each mixing truck shall be made at the batching plant. A

Batching Plant Ticket Number shall be issued for reference in all quality records and reports.

8.0 CONCRETE WORK/ CASTING

8.1 All equipment for mixing concrete and transportation of concrete shall be in good mechanical condition and verified before the concrete work is started.

8.2 Concrete shall be transported using conveying systems, chutes or wheel barrows ensuring that segregation or loss of ingredients does not occur.

8.3 Concrete work shall be carried out as a continuous operation.

8.4 All concrete shall be deposited as nearly as practicable in its final position to avoid segregation and to ensure its plastic state.

8.5 In all cases, the concrete drop distance shall be less than 1.5 m, otherwise a chute shall be used or for intermediate height casting an opening shall be made.

8.6 All concrete shall be thoroughly consolidated by suitable means during placement and mechanical vibrators shall be used to ensure flow of concrete in corners, around the reinforcement and any embedded structures if any.

8.7 Partially hardened concrete or concrete contaminated with foreign particles shall not be used/ deposited.

8.8 Appropriate slump tests/ cube tests shall be done as per frequency agreed by the CM/CS and appropriate test records shall be maintained.



9.0

8.9 All concrete shall have a slump of 100mm (max) and 25mm (min).

FINISHING AND CURING

9.1 After depositing concrete from conveying systems, the concrete shall be even spread using wooden floats and steel trowels.

9.2 The new cast concrete surface shall be protected by keeping completely free of any load for at least 24 hours after the completion of concrete pouring. Concrete can be partially loaded after 7 days, according to the test results acquired from the concrete specimen testing.

9.3 The concrete shall be vibrated properly. Interval of vibration spot is about 600mm and duration of operation is about 20 seconds.

For shallow or long members of concrete a combination of vibration and tapping of form work shall be done to ensure proper placement of concrete. For narrower members, steel rods can be used for proper placement.

After vibration, concrete shall be wood floated to depress coarse aggregates and later steel floated to acquire smooth surface.

In excessive hot weathers, forms shall be lightly sprinkled with water before concreting to bring the temperatures down, and freshly poured concrete shall be covered with polyethylene sheets to avoid rapid evaporation/ dehydration.

Sprayed curing shall start 24 hours after the time the concrete was poured.

Formwork maybe removed after 24 hours or in such a manner as not to impair the safety and serviceability of the structure.

Concrete to be exposed by form removal shall have sufficient strength and not to be damaged by removal operation.

All concrete shall be maintained at 10 degrees C and in moist condition and protected from moisture loss for not less than 7 days after pouring concrete. Sand, burlap or straw can be used to contain moisture.

10.0 CONSTRUCTION JOINTS

10.1 Construction joints for slab shall follow specification on structure drawings.

10.2 The constructions joint for beams shall be located at 1/3 of span in concern; for columns, it shall be the bottom level of beams.



10.3 The previous construction joint surface shall be cleaned and free of laitance, being roughened with wire brush and made wet before the next concrete pour.

11.0 CONCRETE DEFECT TREATMENT

11.1 After removal of form, concrete surface shall be checked. If any defect exists (honeycomb, cold joint, unusual drying out), it shall be reported to

CM/CS. After consulting with CM/CS, it shall be repaired immediately with proper method.

11.2 Laitance (if any) on concrete surface shall be removed first, in case a concrete defect has to be repaired.

11.3 Spalls and Cracks less than 60mm deep are generally repaired using special premixed mortars.

11.4 In case cracks/ spalls are found in the concrete, then a crack repair or a spall repair method shall be submitted by the contractor for approval.

Locally available materials like bonding agents, polymer modified repair mortars and non-expanding/ expanding repair mortars etc can be used for repairs.

11.5 A methodology for concrete repair shall be prepared with product data sheets for approval before repair work.

11.6 Chamfered edges shall be rubbed after forms are removed and all objectionable irregularities shall be removed.

11.7 Honeycombed areas if any shall be cut back to solid concrete, with edges cut at right angles to the surface. A cement sand mortar with a ratio of

1:1 by weight shall be used to finish the honeycombed areas.

12.0 CONCRETE SAMPLING

12.1 Basically the sampling is prepared for every 150m3 of cast concrete.

12.2 Concrete Samples shall be made for major elements of building.

12.3 Concrete samples shall be cured in curing water tank on site until the day of test. Curing condition (water temperature, cleanliness) shall be maintained properly.

12.4 The information of casting (date, building, and element) must be indicated on each sample surface. A coding system can be developed as shown in the sampling record document.

12.5 Compressive test for 7days age, 28 days age and extra age shall be done


Concrete Works Methodology Rev 1, 16 September 2009 at the laboratory and complete records shall be maintained for the whole project.

13.0 REINFORCED CONCRETE STRUCTURAL ANALYSIS

13.1 All reinforced concrete structures shall be designed using the American or British Codes.

13.2 The Analysis shall be submitted to CM/CS for approval.

13.3 The Construction drawings and details shall be prepared after the approval is provided on the submitted analysis.

14.0 CONCRETE MIX DESIGN

14.1 The mix design calculations are done for required grades of concrete according to the procedure adopted from ACI 211.

14.2 Ingredients of concrete required for the project are estimated and trial mixes are conducted until desired compressive strength is achieved.

14.3 Any adjustments to the proportions given in the mix design if necessary shall be done to ensure desired compressive strengths of concrete.

14.4 The final approval of the mix design shall be provided by CM/CS inspector after inspecting cube sampling and testing records.

14.5 Concrete Mixes for all grades of concrete shall be prepared. A sample of concrete mix is shown below;

Ingredients ( One cubic meter concrete)

Portland Cement Type I & II

Ref: ASTM C114/ C150

Source:

Quantity Units

Kgs

Litres Water

Ref: ASTM C150

Source: Potable water,

Fine aggregates

Ref: ASTM C 33

Source:

Medium aggregates

Ref: ASTM C 33

Source:

Coarse aggregates

Ref: ASTM C 33

Source:

TOTAL

Kgs

Kgs kgs kgs



15. CONCRETE MIX DESIGN CALCULATIONS

Description

1 fc @28days

2 fcr' @ 28 days

3 Initialslump

4 Final slump

5 Aggregate size

6 Entraped air (Non air entrained concrete)

7 Water

8 Water cement ratio for reqd concrete

9 Water cement ratio for severe conditions

10 Pozzolanic materials

11 Weight of cement (OPC) ( 7 / 8 )

12 Fineness modulus of fine aggregates

13 Volume of dry rodded coarse aggregate per unit volume of concrete

14 Dry rodded mass of aggregates

15 Required dry mass of coarse aggregates ( 13 x 14 )

16 20 mm coarse aggregate ( 60 % x 15 )

17 10 mm coarse aggregate ( 40 % x 15 )

18 Mass of water, cement, aggregates ( 7 +11 + 15 )

19 Density on concrete

20 Mass of fine aggregates sand ( 19 - 18 )

Qty. Units Remarks

Mpa

Mpa mm ACI 211 , table A1 5.3.3 mm mm maximum

ACI 211 , table A1 5.3.3 kg/m3 ACI 211 , table A1 5.3.3 by wt by wt

ACI 211 , table A1 5.3.4

(a)

ACI 211 , table A1 5.3.4

(b) kg/m3 kg/m3

ACI 211 , table A1 5.3.6

Per unit volume kg/m3 kg/m3 kg/m3 kg/m3

#10 #20

#10 #20 kg/m3 kg/m3 ACI 211 , A1 5.3.7.1 kg/m3

Mass Quantities for batching 1.0 cubic meter of concrete:

Water Cement 20 mm CA 10 mm CA

Mass Quantities for batching 0.5 cubic meter of concrete:

Water Cement 20 mm CA 10 mm CA

Fine Aggregates

Fine Aggregates



16.0 DOCUMENTS & RECORDS

16.1 The following records are maintained;

7. CONCRETE CASTING FLOW CHART

PLANNING

SCHEDULE

CONFIRMATION

W/SUPPLYER

INSPECTION

FORM WORK

CHECK SHEET

RE-BAR WORK

CHECK SHEET

CONC. CASTING

PLAN & RECORD

CONC. VOLUME

ESTIMATION

APPROVAL

ORDER

DELIVERLY

SUPERVISION

*FORM RE-BAR CHECK

*LEVEL TROWELING CHECK

*M&E SLEEVE, PIPING CHECK

*SAFETY CHECK

* etc.

SLUMP TEST

QUALITY CHECK

CASTING

CURING CONC. CASTING

PLAN & RECORD

CONC. CASTING

PROGRESS

REPORT

TEST CUBE

SAMPLING

CURING

COMPRESSIVE

TEST

GETTING

TEST RESULT

CONSULTING

FORM

REMOVAL

CONC. SURFACE

CHECKING

REPAIRING

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