An Experimental Study on Compressive Strength of the Concrete Containing Type II Cement and Tire-Rubber Particles at Various Ages

Compressive strength of concrete is one of the most important properties of concrete for designers and quality control engineers and the engineering community is interested in predicting 28-day compressive strength of concrete because of the strength of concrete at younger ages such as 7 days. Portland cement type II is one of the most widely used cements, which has the highest consumption because of the weather conditions and the construction process of structures in Iran. The relation for computing the compressive strength at the age of t based on the 28-day strength has been presented only for cement types I and III and there is no relation for type II cement in ACI codes of practice. In this study, the compressive strength of concrete at the age of t based on the 28-day strength has been experimentally investigated for the concretes containing cement type II and tire rubber particles. To this end, three cement grades of 350, 400, and 450 kg/m3 as well as water-to-cement ratios (w/c) of 0.5 and 0.65 were used. Moreover, cement was replaced with tire-rubber particles at contents of 5 to 20 % by volume. The values for alpha and beta coefficients to be applied in the concrete strength relation based on the age of 28 days according to ACI209 for the concretes containing type II cement and tire-rubber particles were obtained equal to 3.13 and 0.91 as well as 3.32 and 0.9, respectively. Finally, the best mix design was found to do with the ordinary concrete with cement grade of 400 kg/m3, w/c of 0.5 and tire-rubber particles of 5 % that leads to the highest compressive strength by which the environmental issues could be markedly mitigated.