Inspection of concrete after removal of formwork and Corrective Measures

1) On removal of formwork, the surface shall be examined by Engineer. The inspection shall

Vital steps for Concrete cube sampling

For Site Mixed Concrete:

The minimum frequency of cube casting shall be as follows

After concreting checks

1) All the flat portions of footings / underground structures shall be applied an epoxy based bituminous layer for protection against ground water.

Curing of shearwall , columns, slabs

Columns / Shear walls

1) Curing shall be done keeping the concrete surface wet by covering it with moist double Hessian cloth 2) Curing shall continue for at least 10 days.

Slabs
1) Curing of slabs shall be done as mentioned above.
2) Ponds shall be made within 24 hours of slab casting and till then slab shall be cured by spraying water.
3) Ponds shall be made at column locations first to cover from all sides and then to cover other portions of slab.
4) Care shall be taken to see to it that ponds are completely filled with water through out the recommended period for curing.
5) Vertical faces of the beams and area of slab out side ponds shall be cured by covering with wet Hessian cloth.
6) Incase where ponding is not done, whole slab should be covered with wet hessian cloth and care should be taken to keep it moist always. 

Footings
1) Flat portion of footings shall be cured by covering it with wet double Hessian cloth.
2) For flat portions of Rafts, curing shall be done in a similar way as that for slab and vertical faces shall be cured similar to the columns. 

How to protect fresh concrete

Protection of concrete


1) Newly placed concrete shall be protected from rain, sun and wind by approved means viz: Hessian cloth, plastic sheets etc.
2) Concrete placed below the ground level shall be protected against contamination from falling earth, during placing.
3) The area in and around the actual place of the concreting shall be kept sufficiently dry, by constructing sufficiently watertight forms / cofferdam around the area to be concreted, to prevent loss of mortar through walls.
4) Continuously dewatering the area through out the period of concreting and till initial set of concrete occurs with the help of dewatering pumps shall not be resorted to. 

How to achieve concrete strength by curing

Curing

1) Curing is the process of preventing the loss of moisture from the concrete whilst maintaining a satisfactory temperature regime. For all concrete works, curing shall be start

Checks for concreting sub- structures (columns shear walls slabs beams footings)

types 

               














 Footings

1) PCC should be done in level as per given size in drawing with Dobra marking.

RCC - Ready Mix concrete checks

Ready Mix Concrete:

1) Transit trucks shall comply with the relevant code, with an agitating speed between 2 and 3 RPM and mixing speeds in the range of 10-20 RPM.
2) Before unloading of any truck at the site, the

RCC - How to make concrete at Site

I. Site Mixed Concrete: 

site mixer

1) Weights of aggregates shall be adjusted in the first 5 batches to get required slump, without changing the water cement ratio given in the

RCC - During Concrete checks

During Concreting Checks   

1) Before starting concrete for the day, the gradation of fine and coarse aggregate shall be checked and if any deviation in combined gradation is observed, necessary corrections in

RCC - Pre Concrete Checks

Step 2 – Site Preparation

Dewatering of area to be concreted shall be carried out if required. Also area shall be cleaned of any dirt, debris, waste material, binding wires etc.

Step 3 – Pre Concreting Checks

RCC (part3 )- Ready Mix Concrete

slab pour self compacting concrete

Site representative with a preprinted delivery ticket for each delivery of concrete on which is printed, stamped or written the minimum information detailed below. The delivery ticket will form the basis of invoicing. The following information shall be included in the delivery ticket to accompany the load to engg

RCC (part2) Ready Mix concrete

hose pour slab

3. 3)  Minimum Cement Content, Maximum Water Cement Ratio and Maximum Cement Content shall be as per the requirements of IS 456:2000 with respect to the exposure conditions specified there in.
   

3. 4)  Site Engg  requirement of workability at the pump point as measured by slump test shall be between 140-160 mm, so that after pumping to the desired location the slump is minimum120 mm. Any concrete shall be designed for a minimum three hours retention/open time. The workability of the concrete shall be controlled on a continuous basis during production and any corrective action necessary taken. No additional water, other than the amount required to produce the specified grade of concrete as per mix design, shall be added to the truck mixer drum before discharge unless specifically requested and signed for representative. 
   
4. Redosing or split dosing shall be allowed subject to the written permission of trained technicians and Engineers . In any case, the total dose should not exceed the maximum dose of admixture declared by Supplier or recommended by Admixture supplier. The supplier shall stock at least 50 litre of admixture with  Quality Control department at site.
5. 
   
6. 5)  Any concrete poured should get finally set within maximum 24 hours.
   
7. 
   
8. 6)  Any concrete of a specified Grade shall meet the characteristic strength in 28 days. Any concrete being supplied to our site, which does not achieve minimum characteristic strength at 28 days, shall be considered as failure and no other acceptance criteria shall be entertained.
   
9. 
   
10. 7)  It is important to maintain the water cement ratio constant at its correct value. The amount of added water shall be adjusted to compensate for any observed variations in the moisture contents in the aggregates. Suitable adjustments should also be made in masses of the aggregates due to this variation. Any change in water content due to change in aggregate grading shall be taken care of by forward control by suitable modifications to mix design.
    
11. 
    
12. 8)  Batch sheets, moisture correction calculation/sheet shall be submitted along with challans for every pour of concrete. The scope of addition of extra admixture (over and above the quantity which has already been added at the time of batching at plant) shall be declared by concrete supplier. Immediately before discharging the concrete at the point of delivery, the producer or his representative shall provide