Abstract

In military applications, concrete structures are intended to withstand impact loads induced by missiles and bombs. Under such attacks, elevated temperatures induced by fire are expected to increase the concrete damage. Several research studies have explored cement-based concrete performance under such loading conditions. However, limited studies in the literature investigated alkali-activated concrete behaviour under impact loads and elevated temperatures. Therefore, this dissertation aims to cover this knowledge gap regarding alkali-activated slag (AAS) impact behaviour.
A comprehensive experimental program was conducted to investigate the effects of activator nature on mechanical and impact performance of the developed AAS binding system at ambient and elevated temperatures. The results represented a benchmark for the following phase focusing on AAS concrete mixtures properties and degradation. Finally, the study assessed the potential enhancement in the static and dynamic performance by applying different strategies (i.e. rubber and fibre incorporations).
Generally, AAS exhibited better static and dynamic performance after exposure to elevated temperatures than ordinary Portland cement (OPC) systems. Alkali activator properties significantly affected AAS impact performance. Moreover, the difference in hydration products nature between AAS and OPC systems had a dominating effect. Improvement of impact performance due to rubber addition was limited to ambient temperature and up to 200oC. At higher temperatures, the melting and decomposition of rubber eliminated the desired improvement. Fibre-reinforced alkali-activated slag concrete exhibited significantly higher mechanical properties and impact energy absorption capacity at ambient temperature. However, at elevated temperatures, the improvement was mainly controlled by the fibre stability at various temperature levels. Hence, the dissertation provides a fundamental understanding and first-time data on AAS impact behaviour at various exposure conditions, emphasizing different mixture ingredients' roles.