Road Works

Good surface regularity for sub-base in concrete pavement

The surfaces of sub-base material for concrete carriageway should be constructed in a regular manner because of the following reasons :

(i) One of the main functions of sub-base in concrete pavement is to provide a smooth and even interface between concrete slab and subgrade so that a uniform support is established. A regular surface of sub-base assists in reducing the frictional and interlocking forces between concrete slab and sub-base and allowing easier temperature and shrinkage movement.

(ii) A uniform sub-base surface is essential in the construction of concrete slab of uniform thickness adopted in design. It saves the higher cost of concrete to make up the required level.

High-yield steel vs mild steel as road reinforcement

High yield steel is the preferred material for the reinforcement of concrete carriageway because of the following reasons :

(i) The principal function of steel reinforcement in concrete pavement is to control cracking. If mild steel is adopted for reinforcement, upon initiation of crack formation mild steel becomes overstressed and is prone to yielding. High yield steel offers resistance to crack growth. The above situation is commonly encountered where there is abnormal traffic loads on concrete carriageway exceeding the design limit.

(ii) High-yield steel is less prone to deformation and bending during routine handling operation.

(iii)In the current market, steel mesh reinforcement is normally of high-yield steel type and the use of mild steel as road reinforcement requires the placing of special orders to the suppliers.