ABSTRACT
This paper presents results that show slag concrete has less cracking tendency under restrained shrinkage than comparable ordinary Portland cement concrete, both with 7-days water curing. Four types of concrete mixtures (water/binder = 0.67) containing 0, 35, 50 and 65% replacement of OPC were studied. To study the influences of shrinkage, creep, elastic modulus and tensile strength on the cracking tendency, experiments were conducted utilising a novel restrained testing rig developed for this work. The indirect tensile strength tests were also determined in the same concretes under different curing conditions at different ages. During the 7-days curing, slag concretes swelled about three times more than that of OPC reference concrete. After 7-days curing, the specimens were subjected to standard drying conditions at 23 ± 1°C, 50% ± 5% RH. The 35% slag mix failed in one day at the same fracture time of OPC reference concrete, whereas 50% slag mix failed in three days. However, 65% slag test ended after four days without failing the specimen. The higher cracking resistance of slag concretes was due to less tensile stress induced by restrained shrinkage compared to the reference concrete.
