Concrete Method Statement 2dx1e

TABLE OF CONTENT 1.0 SCOPE AND PULPOSE 2.0 SAFETY 3.0 INVIRONMENTAL 4.0 REFERENCE DOCUMENTS 5.0 RESPONSIBILITIES 6.0 GENERAL 7.0 MIX DESIGNS 8.0 TRIAL MIXES 9.0 MATERIALS 10.0 PRELIMINARIES 11.0 LABORATORY 12.0 BATCH PLANT 13.0 FORMWORK 14.0 REINFORCEMENT 15.0 MIXING & BATCHING OF CONCRETE 16.0 TS 17.0 PRE-PLACEMENT INSPECTION 18.0 TRANSPORTATION AND PLACING 19.0 CONSOLIDATION 20.0 INSPECTION DURING PLACEMENT 21.0 CURING 22.0 REMOVAL OF FORMWORK 23.0 POST POUR INSPECTION 24.0 REPAIR 25.0 PRECAST CONCRETE 26.0 CROUTING 27.0 TOLERANCES 28.0 QUALITY RECORDS

1.0 SCOPE AND PULPOSE 1.1 The purpose of this document is to further develop existing CCECC procedures to satisfy the specified standards and requirements and to establish the responsibility for implementing them. 1.2 The documents cover all aspects with regards to concrete production, transportation, pouring, curing and final inspection of individual pours and precast element. 2.0 SAFETY 2.1 All safety measures shall be in accordance with HSE plan 3.0 INVIRONMENTAL 3.1 All environmental measures shall be in accordance with the …..Environmental Management Plan 4.0 Reference Documents 4.1 General Technical specification 4.2 General Technical Specification SEC 6. Concrete and Steel works. 4.3 BS EN 933-7:1998Testing aggregate 4.4 EN 12620 Aggregate for concrete 4.5 BS 1881 Testing Concrete 4.6 BS 5328 Concrete 4.7 BS 8110 Structural use of concrete 4.8 BS 4449 Carbon steel bars for the reinforcement of concrete 4.9 BS 8666 Scheduling, dimensioning, bending and cutting of reinforcement for concrete. 4.10 ACI 305R-91 Hot weather Concreting 4.11 EN 196 Tests of concrete. 4.12 EN 197 Common Cement 4.13 EN 1008 Mixing Water for Concrete. 4.14 HSE 4.15 Environmental management Plan 4.16 Quality records 4.17 Control of inspection, measuring and test equipment.

5.0 RESPONSIBILITIES 5.1 The Site Agent shall be responsible for the required submittals and for insuring that this procedure is properly executed. 5.2 The Site Engineer shall be responsible for all work inspection and the corresponding provision of documentation required by this procedure and General Technical specifications. The Site Engineer shall be thoroughly familiar with the plans, specification and workman ship requirements for the work. He is also responsible for insuring the 24-hours notification to Engineer prior to any works commencing.

5.3 The surveyor is responsible for setting out and as built survey data. He is also responsible for maintaining required survey quality control documentation. He is responsible for informing Site Engineer and Site Agent if there are any deviations from the design, immediately upon discovery of such deviations. The Site Engineer will raise the required documentation similar to process the deviation. 5.4 The Site Agent and the Site Engineer and Foramens are responsible for insuring that the works are carried out in accordance with the plans, specification and workmanship requirements, in safe working environments. They are responsible of informing the Engineer of all work undertaken, a minimum 24 hours in advance. he is also responsible for insuring that the workforce are informed off and comply with the Quality and HSE requirements for the works undertaken. 6.0 GENERAL. 6.1 Co-ordination of inspection and testing shall be achieved through the use of General Technical specifications, Concrete and Structural Steel. 7.0 MIX DESIGNS 7.1 The mix designs to be used are summarized below and detailed at annex A; Mix design No. 1 C16/20 WITH CEM III/B 32.5 Mix design No.2 C20/25 WITH CEM I 42.5 (OPC) Mix design No.3 C33/40 WITH CEM I 42.5 (OPC) 8.0 TRIAL MIXES 8.1 The trial mixes of each mix designs shall be carried out at Site in presence of the engineer using proposed plants and equipments and mixing method. 8.2 Fresh concrete tests shall be carried out in accordance with EN 12350-2:2009 8.3 Six concrete cubes shall be taken from each trial mix, 3 tested at the age of 7 days and other 3 at 28 days. And also shall be cured in accordance with EN 12390. 8.4 Correlations between 7 and 28 days results shall be ascertained from trial mixing and testing 9.0 MATERIALS 9.1 CEMENT 9.1.1 Cement will be delivered on site direct from supplier packed in cement begs of 50kg per each bags. With each shipment of cement, the supplier shall 9.1.2

provide manufacturer certificate that shows the cement has been tested. Each bag shall contain the following information; Manufacture name, Batch/charge number which relates to a batch/charge No. in the test certificate. Type of Cement, i.e. CEMII/B 32.5 HS OR Colour coding

9.1.3

Manufacture certificate shall contain, a minimum, the following

9.1.4

information; Batch/charge number relating to that on the outside of cement bags Date of manufacture Testing standard that was used Chemical test result Strength test result Cement shall be stored either in covered store with concrete floor or, if necessary an outside store with free draining gravel base. Cement stored outside shall be covered with tarpaulin.

9.2 COARSE AGGREGATES 9.2.1 Coarse aggregate will be delivered from KASCO or Nyanza Road supplies 9.2.2 Coarse aggregate will be tested in accordance with EN 12620 9.2.3 Coarse aggregate will be stored in open stockpile on stabilized ground 9.3 FINE AGGREGATES 9.3.1 Fine aggregates will be sourced from several local suppliers 9.3.2 Fine aggregate will be tested in accordance with EN 12620 9.3.3 Fine aggregate will be stored in open stockpile on stabilized ground 9.4 WATER 9.4.1 Water will be supplied from local water supply authority 9.4.2 Also water can be used from the water wells/Lake forming part of the work 9.4.3 Water shall be tested in accordance with EN 1008. 9.5 REINFORCING STEEL 9.5.1 Reinforcement shall conform to the requirement of BS 8666, 9.5.2 In general all reinforcement shall be stored in drained ground on suitably paced s, e.g. Concrete beams, and be protected against aggressive elements. 9.5.3 Reinforcing steel shall not be welded without the prior approval from the Engineer 9.6 SPACERS 9.6.1 Spacers shall be made of the same grade of concrete as the element for which they are intended. 9.7 IXTURES 9.7.1 All ixture to be used shall be approved by the engineer prior of using it. 9.7.2 Any kind of ixture to be used shall be free from chloride or Nitrate. 9.7.3 The manufactures data sheet will be submitted to the engineer prior to its approval. 10 PRELIMINARIES 10.1 The following document shall be approved and/or in place prior to the start of works;

10.1.1 This method statement, 10.1.2 Cement, reinforcing , aggregates test reports/certificates 10.1.3 Mix design 11.0 FORMWORK 11.1Formwork shall be in accordance with latest, approved released for construction drawing 11.2Formwork shall be inspected for compliance, immediately prior to the pouring and the inspection recoded on form. 11.3Material that are damaged or in any way unsuitable to produce a smooth concrete surface shall be discarded. 11.4Formwork removal shall be in accordance with specification, and shall be done under close supervision by the contractor competent personnel. 11.5The following is the minimum striking time of formwork from the date of casting concrete;  Soffits formwork minimum striking time is 10 days  Sides formworks minimum striking time is 4 days 11.6 Furthermore loading on concrete shall follow the following minimum indicated periods  Loading in columns, walls, beams, slabs and the like shall be after minimum 14 days  Foundations shall be 10 days. 12.0 REINFORCEMENT 12.1 Bending and placement of reinforcement shall be in accordance with latest approved construction drawings, BS 8666:2000, scheduling, Dimensioning, bending and cutting of reinforcement for concrete and BS EN 1992, Design of concrete structures. 12.2 The reinforcement shall be inspected for compliance, during placement and the inspection recorded on form. 12.3 All reinforcing including binding wire shall be free from loose material, rust, mill scale, dust, oil, paint, or any other foreign substances that could have detrimental effects on the bond with concrete. 12.4 The top reinforcement in slab shall be rigidly ed by mild steel chairs from the bottom reinforcement. 12.5 Cover to reinforcement shall be 40mm 13.0 MIXING AND BATCHING OF CONCRETE 13.1 The batching, measuring, mixing and delivery of the concrete shall be in accordance with BS EN 206-1, concrete and BS EN 1992, Design of concrete structures, Part 1-1 13.2 mixing shall be carried out using an automatic or semi-automatic batching plant; the batching plant shall be calibrated in every specific period of time found reasonable 13.3 Mix proportions shall be in accordance with approved mix designs,

13.4

During batching, six sample cubes shall be taken for testing after 7 and 28 days.

14.0 PRE-PLACEMENT INSPECTION 14.1 Prior to the placing of concrete inspection shall be performed to insure conformance to the design drawings and specifications. The site engineer and the client representative should perform the following inspection; I. Check the construction ts to receive concrete to ensure that they are free from latence, loose material or other harmful substances. II. In case of any horizontal construction ts, that they are prepared and clean in accordance with specification. III. that the survey team has checked the forms for line, grade and plumbness IV. Inspect form of cleanliness, correct fitting/tightness. V. Check embedded items Installation to minimize movement during concrete placement. type, height and position of embedded item. VI. the type and location of embedded piping, conduits and other embedded steel. VII. Check the reinforcing steel for location, grade, spacing, size, quantity, length and adequate means of ing. VIII. Insure that the minimum cover to reinforcing is in accordance with latest approved construction drawing and specification. IX. Insure that poker vibrators of the correct type and size are available. Ensure that sufficient reserve poker vibrators are available in case of mechanical failures. X. Ensure that adequate protection is provided in the event of heavy rainfall during pour XI. Make sure that inside the formwork is free from all deleterious matter such as water, mud, loose tie wire, etc. that all reinforcing steel and embedded are clean of any coating which may be detrimental to the bond with the concrete. XII. To insure that all surface to be in with concrete are damp but that no free water remains immediately prior to pouring. XIII. that all discrepancies identified in previous inspection has been corrected XIV. Check that all relevant items in pre pour checklist have been signed off, concrete shall not be poured until the Engineer have signed the bottom of form ing that all items are completed and in accordance with the approved drawings and specifications. 15.0 TRANSPORTATION AND PLACING 15.1 The mix will be transported by 8-10 m3 mixer truck to or close to final delivery site. Final Delivery shall be either by tremie, chute, conveyor, skip or concrete pump.

15.2

Whichever method of final placement is used, and concrete shall not be allowed to drop more than 2m. Unless otherwise agreed by the engineer.

16.0 T 16.1 All ts shall be as per approved construction drawings. 16.2 Any Additional ts will be done upon receipt of approval from Engineer 16.3 All reinforcement steel shall be continued across construction ts. 16.4 Prior of pouring concrete, old concrete forming part of the ts shall be cleaned, hacked to make rough surface, and air under pressure to expose aggregate and well wetted. 16.5 Polyvinyl chloride (PVC) water stops will be used in all ts, to make sure that there will be no penetration of water from one side to another through the ts. 16.6 Water stops shall be careful placed and maintained in position during concreting and compaction operation. 17.0

CONSOLIDATION; 17.1 Generally concrete shall be consolidated using proprietary porker vibrators

18.0

INSPECTION DURING PLACEMENT 18.1 The engineer and main contractor site engineer shall perform inspection and surveillance as follows to insure that the concrete is placed in accordance with specified requirements; 18.1.1 Prior to large pours, that the second batch plant is ready for operation in case of breakdown in the primary one. Also insure that one personnel is appointed special for taking cube sample as he will be instructed. 18.1.2 Ensure that porker vibrators are used by experienced workers and supervision to obtain adequate consolidation without segregation. Vibrator shall not be used to move concrete within the formwork or in any other way that could damage formwork and/or displace embedment and reinforcement. 18.1.3 that all steps and precautions have been taken to insure that placing, consolidation and finishing the concrete can proceed without interruption.

18.1.4 Ensure that the free fall of concrete does not exceed 2m to prevent segregation of the material during placing. 18.1.5 Ensure that concrete is deposited continuously and as near to its final position as possible. that a concrete pour plan exist when the form, 18.1.6 Ensure that the formwork remains tight and in line and that movement does not occur during concrete placement. that adequate construction personnel are available to correct any movement should it occur.

19.0

CURING 19.1 Curing of the concrete shall be in accordance with BS EN 1992 “Design of concrete structures” and accordance to general Technical Specifications. 19.2

20.0

REMOVAL OF FORMWORK. 20.1 formwork shall be removed in accordance with the requirement of BS 8110 structural use of concrete OR at other times with the approval of Engineer

21.0

POST POUR INSPECTION

20.1

The Site Engineer shall insure that the following requirements are met after each pour has been completed. 20.2 Ensure that the removal of formwork is in according to specified requirements. 20.3 Ensure that concrete surfaces receives any treatment required such as curing 20.4 Ensure that the concrete is cured in accordance with specified requirements in general technical specifications, concrete and structural steel works. 22.0 REPAIR 22.1 All repairs must be inspected before, during and after the repair by the site engineer 22.2 Repair shall be carried out in accordance with agreed procedures and General Technical Specification, concrete and steel works. 22.3 Repair shall be documented on form of concrete 23.0

PRECAST CONCRETE 23.1 Precast concrete shall be cast where required by the relevant approved released for construction drawing. 23.2 Precast concrete elements will be constructed in the site 23.3 Precast concrete elements shall not be moved from the casting beds at least 48 hours after casting. 23.4 Precast concrete elements shall be stacked in such a way that no “bridging” occurs

23.5

Precast concrete elements shall not be removed from storage for at least 7 days after casting. 23.6 Precast concrete unit shall be cured continuously for at least 7 days 23.7 All other elements of precast concrete production shall be in accordance with this document and the relevant specification codes and standard mentioned in this document. 23.8 Cares shall be taken during transportation of precast elements to ensure that no damage occurs to the precast elements by bridging or other physical forces. 24.0

GROUTING 24.1 When grouting is required, only non-shrink grouting complying with General Technical specification, concrete and structural steel works. The engineer shall approve the grout prior to use.

25.0 TOLERANCES 25.1 Dimension tolerances for individual cast elements and Insitu pours are as follows;  Position in plan ; + 15 mm Size and shapes  

Thickness of walls and slab Columns and beams

-5/+10mm -5/+10mm

Dimension of foundation  

+50 mm -0 mm

Variation from plumb;  

Exposed Backfilled

10mm per 3m 20mm per 3m

Levels to slab and beams + 10 mm Holes;  

Placement ; Sizes

+ 10mm + 3mm

Cast-in Items; 

Placement:

+ 10mm



Distance Between interconnected items + 2 mm

26.0 QUALITY RECORDS 26.1 Quality records shall be kept in site and shall be maintained and filed in accordance with specification requirements.