Question
In case of concrete pavement, why is requirement of 95% by mass of quartz grains are specified in contract?
Answer
In universal Specification of Civil Engineering, in Clause 10.09 it states "Fine aggregate for concrete shall be usual river-deposited sand consisting of at least 95 percent by mass of quartz grains". Aim of such requirement is to control excellence of river sand. As quartz is a strong and hard material, using a far above the ground percentage of quartz in aggregates of concrete is able to enhance strength and durability of surface texture of concrete carriageway.
In adding, such specification needs a high percentage of quartz content, thereby dropping the probability of being there of impurities as shell.