Question

If the granite aggregate for the concrete mentioned in (i) is replaced by lightweight
aggregate. How would this affect the strength of concrete?

Answer 1

Aggregate size and gradation are the most important factors when selecting aggregate. Aggregate can be large or small, from fist-sized rocks to fine sand. Aggregates larger than ¼ inch are classified as coarse aggregate, while anything smaller than ¼ inch is termed fine aggregate. As a general rule, the largest aggregate should be no greater in diameter than one-third the depth of the slab, or one-fifth the smallest dimension of the form. For example, the largest piece of aggregate allowed for a 1 ½-inch-thick countertop slab is ½ inch. Generally coarse aggregate is blended with finer aggregates (such as sand) to fill in the spaces left between the large pieces and to “lock” the larger pieces together. This reduces the amount of cement paste required and decreases the amount of shrinkage that could occur.using fine grade aggregates always increases the strength of the concrete ,as smaller particles have larger surface area compared to larger particles and thus increasing the bond between cement and aggregates in concrete.Leading to greater strength of concrete.