How is the selection of mixture proportions affected by the materials to be used and the placing requirements?

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How is the selection of mixture proportions affected by the materials to be used and the placing requirements?

Q. How is the selection of mixture proportions affected by the materials to be used and the placing requirements?

 

A. Because the strength and durability establish the required w/cm, the consistency needed for proper placement will depend on the nominal maximum size of the aggregate, the size of the member, and the spacing of the reinforcing bars. The method and equipment of transporting (buckets or pumping) and the method of consolidation (internal or external vibration) will also be factors. The consistency may be changed considerably through the use of chemical admixtures, without changes in the hardened concrete properties, however.

 

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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