Important requirements of a concrete aggregate

Q. What is the most important requirement of a concrete aggregate?

A. Aggregate should be resistant to degradation and not undergo harmful reactions under the conditions to which it will be exposed. Deleteriously reactive constituents in an otherwise satisfactory aggregate will be rendered harmless if used with a portland cement having sufficiently low-alkali content or if a sufficient amount of pozzolan or slag is used. Testing the aggregate with the proposed job materials and considering the availability of alkalies from outside sources, such as deicing salts, are recommended.

References: SP-1(02); E-1(16); ACI 221R-96; ACI 213R-14; ASTM C33

Topics in Concrete: Aggregate; Concrete Fundamentals; Materials