Concreting is one of the important process for any kind of construction. Contractors & builders pay huge money for concreting process comparing to other civil works. Before and while concreting site engineer or supervisor needs to monitor and certify the following aspects for proper execution of concreting work.
1. Shuttering Stability
The shuttering and centering should be checked for proper Level, alignment and their support. If the supports are not strong and stable, it may collapse during concreting work. This can be serious safety concern and leads to wastage of time and material. Before and during concreting work supervisor person should observe the stability of all shuttering and centering supports.
2. Releasing Agents
Proper Planks or plates should be provided. These planks or plates must be properly oiled or should be verified by site engineer. If the plates are not properly oiled, the surface of concrete will get damage during striking plates and cause difficulty during this process. Further, it leads to poor surface finish.
Gaps in shuttering plates shall be properly sealed by mortar, Rubber, etc. and should be checked thoroughly. If not sealed it leads to leakage of concrete through gaps and gives improper finish.
4. Placing Reinforcement
Before commencing concreting work, the reinforcement details should be verified as per the drawings. Bar diameter, cut length, lap joints, Beam-column joins, column extension length at footing should be checked thoroughly. Improper detailing and placing leads to poor functioning of structural element or even collapse of the structure.
5. Reinforcement Cover
Reinforcement Cover is one of the most important aspects of concrete work. The reinforcement bars should not be exposed to atmosphere and the minimum recommended cover should be provided if not shown in drawings. Proper spacer blocks or bars should be also provided. If proper cover not provided to the steel rods and are exposed to air, it leads to corrosion of reinforcement and rust formation. Finally, it causes spalling of concrete and loss in strength.
|S.No||Structure||Minimum cover in mm|
|1||Slab||20 to 30|
|2||Beam||25 to 35|
|3||Column||25 to 40|
|5||Shear wall||25 to 30|
6. Reinforcement Support
Enough no of chairs must be provided while laying reinforcement. It holds the reinforcement in position and maintains the top and bottom cover to reinforcement. If enough chairs are not provided, the rods may get disturbed or the spacing of rods will be non-uniform. During concreting work the reinforcement losses its position.
7. Material Supply
Availability of adequate quantity of cement, sand and aggregates at site should be ensured before construction. If enough materials are not available during concrete work it may cause work disruption and undesirable construction joints.
8. Embeds in Concrete
Embeds and concrete inserts like Fan Box, Insert plates, anchor bolts and hooks are to be checked properly, anchored, and placed. If these are not checked properly before concreting work it’s difficult to achieve these after construction.
10. Mixing location
Ensure proper access for labor and materials from the location of placement to mixing need to checked and minimized. If the distance is not maintained it can slow down the work reduce the workability of concrete. If it is not possible to maintain it. Proper admixtures must be used to ensure workability and delayed setting of concrete.
11. Joints in Concrete
The construction Joints must be properly planned in advance during the concreting works. If not planned well concrete may cause cracks in the surface, loss in structural integrity and poor durability.
12. Proper Curing
In order to attain complete strength of concrete, curing is very important. To ensure that proper curing can be done, the condition of pump, water tank and water availability need to be checked. If above facilities are not available the concrete curing will be affected and affects the strength of concrete.
Following arrangements should be properly planned in advance for the unforeseen concrete drying situations.
- Placing wet bags over concrete
- Providing of curing compounds like Admixtures.
If the above facilities are not available, the concrete gets dry and the nominal water for hydration is reduced and concrete doesn’t attain the desired strength.
14. Protection of Concreting
Precautionary arrangements must be planned well in advance to protect the concrete from rain. Immediate exposure of concrete to rain before initial setting time will affect its final strength and exposure during concreting will change the consistency of concrete.
15. Pouring of Concrete and Compaction
The pouring concrete height should not be more than 1m (or 3 Feet) in order to avoid segregation. If the distance is more than 1m, it leads to segregation in concrete and leads to voids in concrete work. After poring, concrete must be properly compacted and finished.