Shrinkage Cracking Potential of Lightweight Aggregate Concrete

Shrinkage cracking is one of the concerns in concrete constructions. Studies were performed to understand the potential of lightweight aggregate concrete’s (LWAC) shrinkage cracking. In the study, LWAC of different water/cement ratio (w/c - 0.30 to 0.56), aggregate volumes (0 to 0.50) and aggregate densities (NWA-2.65 g/cm 3 to L5-0.64 g/cm 3 ) were designed. The restrained ring specimens were prepared for testing and after 7-days moist curing, exposed in controlled environment for shrinkage cracking tests. The mechanical properties of splitting tensile strength and elastic modulus; deformational properties of shrinkage and coefficient of creep were also tested for use in theoretical analysis. It was observed from the shrinkage cracking results that for similar mix proportions, the potential risk of shrinkage cracking was higher in LWAC than normal weight concrete (NWC). The shrinkage cracking potential LWAC is found to be higher in concretes containing higher w/c ratio, lower volume of coarse aggregate and lower density aggregates. Based on the experimental data on restrained ring specimens, the age at which cracks appears can be prolonged or controlled by lowering the rate of shrinkage to lower than 4με/day. At cracking the average tensile strain for LWAC (213 με) was observed to be double that of NWC (100 με).