Evaluating the Effect of Incorporating Slag Cement with Pre-wetted Lightweight Aggregate on Reducing Cracking of Concrete Bridge Decks

Abstract

Abstract Early-age cracking is a severe problem in concrete bridges because it reduces the durability of the superstructure. One of the techniques to minimize early-age cracks is the addition of pre-wetted lightweight aggregate (LWA). There is limited research regarding the effect of pre-wetted LWA on the early-age performance of concrete. This paper aims to evaluate the efficiency of incorporating slag cement with pre-wetted LWA to reduce the potential cracking of the concrete decks. Also, the effect of fly ash on the shrinkage properties of concrete was investigated. Mixtures used in this study consist of replacements of total aggregate with pre-wetted LWA and partial replacements of cement with slag cement or fly ash. The performance of concrete specimens containing slag cement with pre-wetted LWA was evaluated in terms of mechanical properties, plastic shrinkage, free shrinkage, and restrained shrinkage. The results showed that the tensile strength was not the most significant parameter affecting the cracking potential of the concrete. The cracking potential of the concrete was strongly related to the tensile strength and free shrinkage. It was observed that incorporating slag cement with pre-wetted LWA significantly enhances the early-age performance of concrete as the tested specimens showed no sign of cracks. The results also showed that the shrinkage of the mixtures containing coarse LWA was reduced by 43 % compared with the control mixture. Moreover, it was noted that the LWA with higher absorption increases plastic shrinkage cracks for concrete decks under severe conditions.