Question

What is function of a sand layer underlying paving slab or interlocking blocks?

Answer

Normally after laying of sub-base layer of paving slab or interlocking blocks, 30mm thick sand bedding is screeded and tamped over pavement area. Then paving slab is laid horizontally with joints of 2-3mm wide and is laid in uphill direction. Following completing laying of paving slabs, sand used for filling joints is increase over surface of units and brushed into joints such that all joints are completely filled. Paving slabs are after that bedded into final position by using plate vibrators.
Sand layer serves similar purpose of normal blinding layer under concrete structure-

(i) Provide level and flat surface for paving slab or interlocking blocks to lay on;

(ii) Protect the foundation for example underground sub grade and sub-base layer against adverse outside conditions as in bad weather during construction of the laying work of paving slab or interlocking blocks.