A comparative study on deflection-hardening behavior of ductile alkali-activated composite

Alkali-activation technology as an environmental friendly approach to produce construction materials can lead to a great CO₂ emission reduction and provide high potential for waste reutilization. Alkali activated materials (AAMs) generally exhibit better durability and comparable or superior mechanical performance in comparison to traditional cementitious materials. However, like cementitious binders, AAMs are inherently brittle (quasi brittle). When it comes to engineering practices, the size effect also contributes to a more severe brittleness, which limits the applications in large scale structures. Fiber reinforcement is one of the solutions, which can be used to control the brittleness of AAMs. This paper presents a comparative study on the deflection-hardening behavior of ductile alkali-activated slag/fly ash (DAASF) composites reinforced with three types of synthetic fibers. All the developed DAASFs exhibited a deflection hardening with multiple cracking behavior under four-point bending tests. The influence of different fiber types, different slag/fly ash ratio as well as liquid/solid (L/S) ratio were investigated. The obtained results are a first step contribution to understanding the feasibility of using different fiber types in AAMs and development of mixture design of DAASF composites.