Optimization of alkali-activated concrete based on the characteristics of binder systems

Abstract

The characteristics of binder systems played vital roles on the properties of alkali-activated concretes (AACs), from strength development to long-term durability. Here, the sum of 102 binder systems with three levels of alkalinity of 5%, 6%, and 7% and three levels of blast furnace slag to fly ash mass ratio of 50:50, 60:40, and 70:30 activated by diverse compositions of activators (single sodium hydroxide, sodium silicate, and sodium carbonates or combination) were investigated. Based on that, a series of compositions-properties contours/maps considering the hardening strength, shrinkage behavior, and mechanical characters of these binder systems have been established. After that, a modified overall-calculation method was applied for the mix design of concrete. The AACs performance including basic mechanical behaviors in compression, flexure, and tensile load and volume stability (including drying shrinkage and alkali-aggregates reaction) were checked. It’s suggested that the performances of AACs were in a broad range depended on the binder systems. Thus, the selection of binder systems was in the most important position in designing concrete even other aspects, for example, aggregates type would also affect performances like mechanical and shrinkage of AACs. However, the complexity of alkali-activated binder systems make it difficult to establish the quantitative relationships between compositions and performances of AACs. Therefore, the compositions-properties contours/maps established here would deep the understanding for roles of constituents on the performances of AACs and guide the optimization of AACs in practice.