How does the relative amount of each ingredient used in concrete influence the properties of concrete?

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How does the relative amount of each ingredient used in concrete influence the properties of concrete?

Q. How does the relative amount of each ingredient used in concrete influence the properties of concrete?

 

A. Each of the principal ingredients of concrete is indispensable in producing concrete, but each is detrimental to some of the desirable properties of fresh or hardened concrete. Cementitious material and aggregates provide strength, resistance to degradation, and volume stability to concrete. Too much water can destroy these properties. The paste consisting of the cementitious material and water provides the workability for concrete. The use of too much cementitious material makes concrete less volumetrically stable and uneconomical. Water is the most economical constituent of concrete, but the more water one uses, the lower the quality of the concrete. Aggregate is the second cheapest ingredient, but using too much aggregate makes the concrete unworkable. The fraction of coarse aggregate in the total aggregate should be the maximum without causing segregation and bleeding. Fine aggregate should be used in sufficient amount to provide cohesiveness, resist segregation, and permit easy finishing. Good concrete has a sufficient amount of cementitious material, paste with low w/cm, and an optimum amount of aggregates, which is as much as can be used without adversely affecting workability.

 

References: SP-1(02); ACI 211.1-91; ACI 211.4R-08; ACI 211.7R-15; ACI 211.6T-14

Topics in Concrete: Concrete Fundamentals; Mixture Proportioning; Specifications

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