Concrete pavement construction process

The construction of concrete pavement involves sequential construction of subgrade, sub-base/ base and the concrete slab. These are discussed in the following.

Subgrade preparation

Subgrade preparation involves cleaning, earthwork (excavation or filling of soil, replacement of weak soil, soil stabilization etc.) and compaction.

Where the concrete layer is laid directly over the subgrade, the subgrade is moist at the time concrete is placed. If the subgrade is dry, water could be sprinkled over the surface before laying any concrete course, however, care should taken so that soft patches or water pools are not formed at the surface (IRC:15-2002, Chakroborty and Das 2003). As an alternative arrangement, concreting could be done over a water proof polyethylene sheet, and in that case moistening the subgrade surface becomes redundant. This polyethylene sheet acts as a capillary cut-off layer (IRC:15 2002). Figure-31 presents a photograph of subgrade construction in progress.

                                                                       Figure-31 Preparation of subgrade                                                                                    (photo courtesy: Mr. Pinaki Roychowdhury, Lea Associates South Asia Pvt. Ltd., New Delhi )