METHOD STATEMENT FOR CONCRETING

METHOD STATEMENT FOR

CONCRETING

                                                                                                                                      

INTRODUCTION / SCOPE

This method statement describes the practices and methods to be used for mixing and placing of cement concrete.

OBJECT:

- To ensure that concreting is done in such a manner that it meets the criteria of I.S codes of practices for general concreting work.

- To ensure that the finished structure is of desired quality & specifications as prescribed in approved GFC drawings provided. 

MATERIAL:

Cement, Sand, Coarse Aggregates, Water, RMC

PRINCIPLE:

Concrete is basically constituted of cement, sand, coarse aggregates and water. Sand and coarse aggregates fill the volume & cement bind the constituents together.

APPARATUS / EQUIPMENT

·         Vibrator                    

·         Slump cone

·         Wheel barrow

·         Cube molds

·         Concrete pump

·         -Batching plant

·         -Concrete planer

·         -Mixer Machine

·         -Measuring box

·         -Belcha

·         -Kassi

·         -Trowel

·         -Tasla

·         -Level Pipe

·         -Measuring Tape

·         -Thread

HEALTH AND SAFETY PROVISION

a. Check that all persons that will be involved in the work have full personal protective equipment:

-Gum boots

-Eye protection

- Gloves

- Safety Helmet

-Safety jacket

 -Safety belt

-Nose Mask

b. Ensure that all the electrical wires on the slab are hung at least 2.1m above the slab and no wire shall be lying on the reinforcement.

c. Ensure suitable stability of gangways along with railing.

d. Ensure that roof slab has been protected with life-line rope.

PREPARATORY WORK:

·         Prior to the placing of any concrete quality checklist should be completed in all manners.

·         Ensure that the form-work is in line and level.

·         Ensure that the form-work is free from dust/soil debris and is thoroughly watered.

·         Ensure that finished level of concrete is marked.

·         Verify that the calculated cubic meter, correct concrete grade and slump has been ordered.

·         Ensure that all checklists for electrical, shuttering and reinforcement are completed before starting of concrete.

·         In case of concrete joints, remove all loose materials and apply cement slurry (1:2) before concreting.

·         Ensure that all joints at the bottom of shuttering of columns are sealed externally with cement sand mortar of 1:1 ratio, one hour prior to concreting.

WORKMANSHIP:

Following points need to be observed in the concrete work to achieve highest level of quality

1. Slump of concrete – 50-60 mm for dump concrete, 110-120 mm for pump concrete

2. Segregation – Maximum free fall of concrete should not be more than 1.5 m.

 -- Vibrator should be used adequately. Over-vibration should be avoided.

3. Concrete must be in line and level.

4. Cover block of adequate size should be placed as required.

5. Shear key must be provided in columns and shear walls.

6. Transit time for TM is not more than One Hour.

7. Placing of Concrete in column should not be more than one hour from receiving of TM at site.

8. Placing of Concrete in slab should not be more than a total of two hours from dispatch of TM from plant.

9. Edges of concrete should not be damaged during de-shuttering.

10. Hacking of concrete shall be done immediately after de-shuttering of slab and beam, wherever required.

11. Hacking of column shall be done along with the slab and beam above it.

 PROCEDURE OR METHODOLOGY:

- Concrete should be placed in following manners:

a)   Head Load (Manually)

b)    Direct (chute) discharge

 c)   Concrete pump

The method to be used shall depend on site conditions and pour volume.

·      Concrete is to be placed as close as possible to its final position and not moved laterally by vibration.

·    Concrete must be vibrated to such an extent to achieve proper compaction but bleeding should not occur.

·      Concrete is not to be dropped from a height exceeding 1.5m.

·      Mixing water/cement slurry (1:2) to improve the workability of concrete during pour is strictly prohibited.

·      If during concreting, rain is imminent, sufficient plastic/tarpaulin sheets should be on hand to cover the entire casting area.

·         Ensure the provision of a dewatering pump when concreting the excavated foundation during raining season.   

·         Ensure that the top level of concrete is in accordance with the marked finished level.

·         In concreting of slab/beams, construction joints are to be avoided, but if unavoidable then the joint must be given as recommended by structural consultant.

·         During continuation of previous cast concrete, the joint is to be hacked and applied with cement slurry (1:2) before casting further.

·         Cubes are to be taken at the correct intervals and to be marked with pour location.

·         Wet jute bags to be placed on slab after concreting during hot climatic conditions.

 QUALITY CONTROL

·         Batch report should be checked by Site Engineer at the time of receiving of concrete.

·         Fineness Modulus of Sand must be checked before every concreting done by mixer machine.

·         Moisture content of Sand must be checked before every concreting done by mixer machine.

·         Impact test on aggregates must be done at the time of receiving.

·         Sieve Analysis should be done for aggregates at the time of receiving.

·         RMC – Slump test must be conducted for every trip of Transit Mixer.

·         Mixer Machine – Slump test must be conducted at every 2 hours interval.

·         Cube strength testing must be conducted under supervision of Lab-in-charge.

·         Rebound hammer Test must be conducted for all column, slab and beam.

·         RMC

1.   Checklist of RMC must be filled up for every Transit Mixer.

2.   In case of columns, column checklist must also be filled.

3.   In case of columns, one sample set must be taken for every Transit Mixer. One sample set must be comprised of 3 cubes for 7 days test, 3 cubes for 28 days test and 3 cubes for Accelerated Cube test.

4.   In case of slab, one sample set (9 cubes) must be taken up to 50 cum. This sample must be taken at random from any Transit Mixer. After 50 cum, additional sample set must be taken for every 50 cum.

INSPECTION:

  Before Concreting:

1.   Surface of shuttering must be moist and free from dust and foreign materials.

2.   All old surfaces at joint are free from loose materials and cement slurry (1:2) is applied before start of concreting.

3.   Standby vibrator/nozzle should be available at the concrete site.

4.   All openings must be covered /barricaded.

5.   Finished level of concrete must be marked at appropriate intervals.

6.   Any Electrical conduit should not be damaged or left open-ended.

7.   Sleeves must be in line and level.

After Concreting:

1.   Any spread/left over concrete must be removed immediately after concreting.

2.   Dates are marked on every vertical member after de-shuttering.

Ponding (in slab)/Curing is being done for 7 Days.