Describe the sequence of concreting operations
Describe the sequence of concreting operations -
Concreting operations :-
The following operations are involved in the process of production and placing of concrete.
(a) Batching :-
It refers to measurement of concrete materials viz. cement, coarse aggregated, fine aggregates, water and admixture. Aggregates, cement and water are measured with an accuracy of ±3% and admixture with an accuracy of ±5%.
(b) Mixing :-
After batching, mixing of materials is done primarily to coat the surface of all aggregates with cement to form a uniform and homogeneous mass. Concrete mixing is done either by manual mixing or by the use of mechanical mixers. At the end of mixing operation, concrete appears to be of uniform color.
(c) Transportation :-
Concrete from the mixer is required to be transported to a point where it is required to be placed. During transportation it is ensured that segregation of concrete does not occur. Where concrete is required to transported, the time lapse between addition of water to cement and aggregate and placing of concrete should not exceed two hours. At the time of placing of concrete, the temperature should not be less than 50C and not more than 320C.
(d) Placing, compaction and finishing :-
While placing the concrete, homogeneity of concrete must be ensured. The framework for concrete must be rigid and strong enough to bear the weight of concrete. Before placing, reinforcement is checked for tightness. Concrete is compacted to make it water tight. While compacting concrete, care must be taken to avoid segregation. Too much compaction also leads to bleeding. Compaction removes entrapped air from concrete thereby making the concrete dense.
(e) Curing :-
Curing of concrete is essential to bring about the hydration of cement thereby developing strength in concrete. Curing can be done by any of the following methods.
Describe the sequence of concreting operations -
Concreting operations :-
The following operations are involved in the process of production and placing of concrete.
(a) Batching :-
It refers to measurement of concrete materials viz. cement, coarse aggregated, fine aggregates, water and admixture. Aggregates, cement and water are measured with an accuracy of ±3% and admixture with an accuracy of ±5%.
(b) Mixing :-
After batching, mixing of materials is done primarily to coat the surface of all aggregates with cement to form a uniform and homogeneous mass. Concrete mixing is done either by manual mixing or by the use of mechanical mixers. At the end of mixing operation, concrete appears to be of uniform color.
(c) Transportation :-
Concrete from the mixer is required to be transported to a point where it is required to be placed. During transportation it is ensured that segregation of concrete does not occur. Where concrete is required to transported, the time lapse between addition of water to cement and aggregate and placing of concrete should not exceed two hours. At the time of placing of concrete, the temperature should not be less than 50C and not more than 320C.
(d) Placing, compaction and finishing :-
While placing the concrete, homogeneity of concrete must be ensured. The framework for concrete must be rigid and strong enough to bear the weight of concrete. Before placing, reinforcement is checked for tightness. Concrete is compacted to make it water tight. While compacting concrete, care must be taken to avoid segregation. Too much compaction also leads to bleeding. Compaction removes entrapped air from concrete thereby making the concrete dense.
(e) Curing :-
Curing of concrete is essential to bring about the hydration of cement thereby developing strength in concrete. Curing can be done by any of the following methods.
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