Question

In water bound macadam roads, binding material, is __________

(a) stone dust

(b) sand

(c) brick dust

(d) cement

I had been asked this question during an online interview.

The doubt is from Detailed Specifications of Road Work topic in chapter Specifications, Estimation of Quantities of Materials and Transport of Civil Engineering Drawing

Answer 1

Right option is (a) stone dust

Easiest explanation: Stone dust is like a darker, coarser version of sand. It is a byproduct of running stones through a crushing machine to make crushed stone. Its exact composition will obviously depend on what kind of stone was run through the machine. For instance, sometimes granite is run through such a machine; in other cases, it could be limestone, for example. The machine has a screen that traps the larger material (that is, the crushed stone). The smaller material or “screenings” falls through the screen. Depending on the size of the holes in the screen used, it can be so fine in texture that it is basically a powder.