Curing Management and Quality

In two-lift paving, bond strength at the interface of the RCC lifts is a critical engineering property. Bond strength determines whether RCC pavements constructed in multiple lifts will behave as a single layer or as partially bonded or unbonded lifts. The load-carrying capacity of partially bonded or unbonded lifts is much lower than that of bonded lifts of equal thickness.

The practice of two-lift paving has been based on the assumption that adequate bond strength can be achieved when pavement lifts are placed within an hour of each other, but the key to bonding the lifts together is minimizing the separation movement of the upper lift during the hardening period. The critical areas for separation are along slab edges and corners and, in extreme cases, in the slab interior areas. RCC surfaces should be cured to a greater degree since they typically have an open, textured surface (besides having a lower water to cement ratio) that otherwise tends to make RCC pavements more susceptible to early warping movements that may separate them from the lower layers. The curing quality for RCC construction is a key aspect of limiting slab movements for a sufficient period of time to allow the bond to develop between lifts.