Aggregates for Concrete

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The importance of using the right type and quality ofaggregates cannot be overemphasized. The fine andcoarse Aggregates generally occupy 60% to 75% of theconcrete volume (70% to 85% by mass) and strongly influ-ence the Concrete s freshly mixed and hardened proper-ties, mixture proportions, and economy. Fine Aggregates (Fig. 5-1) generally consist of natural sand or crushedstone with most particles smaller than 5 mm ( in.).Coarse Aggregates (Fig. 5-2) consist of one or a com-CHAPTER 5Aggregates for Concretebination of gravels or crushed stone with particlespredominantly larger than 5 mm ( in.)

Aggregates must conform to certain standards for optimum engineering use: they must be clean, hard, strong, durable particles free of absorbed chemicals, coat-ings of clay, and other fine materials in amounts that could affect hydration and bond of the cement paste. Aggregate particles that are friable or capable of being split are unde-sirable.

  Standards