Cracking Resistance for Drying Shrinkage of Concrete Mixed with Copper/Manganese Slag Fine Aggregates and Fly Ash

Abstract

Drying shrinkage is inevitable in concrete mixtures when exposed to dry environment. This is not only dependent on hardened cement paste comprising the types of cement and water content, but the properties of aggregates including water absorption capacity and elastic modulus. Generally, materials design with respect to enhance the resistance against drying shrinkage cracking aims at higher strength development and reduced drying shrinkage, which can be obtained by lower water content and the proper use of cement and mineral admixtures in concrete mixtures and the use of aggregates with lower water absorption capacity and higher elastic modulus. This study examined the resistance against drying shrinkage cracking in concrete mixtures mixed with two types of slag fine aggregates (copper and manganese slag) and fly ash, which was investigated using restrained reinforced concrete specimens. The results showed that the cracking resistance was enhanced in concrete mixtures mixed with copper slag fine aggregate and fly ash, which could be explained by the fact that the restrained stress was partially relaxed during the early stages of exposure to dry environment. In addition, fresh properties including slump, air content and bleeding rate were also tested for practical application.