Amin Al-Fakih

Engineered geopolymer composite (EGC) is becoming an uprising product in the civil industry as a substitute and solution for conventional geopolymer concrete (GPC) as GPC exhibits brittleness and has poor cracking resistance. In this paper, we explored high strength engineered geopolymer composite (EGC) made of polyvinyl alcohol (PVA) fibre and without coarse aggregate constituents characterised as high-performance geopolymer concrete. Varying alkaline solution to fly ash ratio (AL/FA) was investigated. Bond-slip behaviour and the mechanical properties, including compressive, tensile, and flexural strengths, were studied. PVA-EGC mix designs in this research was optimised using response surface methodology (RSM). Various parameters, including the amount of ground granulated blast slag (GGBS) and silica fume, were included in the parametric and optimisation study. Based on the RSM study, the use of quadratic studies found the responses to be well-fitted. Next, the optimised mix design was utilised for the casting of all the samples for the mechanical and bond-slip tests in this study. The main parameters of bonding behaviour include multiple embedment lengths (7 d, 10 d, 12 d and 15 d) and various sizes of rebar diameter used for pull-out tests. Moreover, the mechanical properties and bond behaviours of EGC were compared with those of conventional geopolymer concrete (GPC). The compressive strength of EGC and GPC at 28 days were designed to be similar for comparison purposes; however, EGC shows higher early compressive strength on day 1 compared to GPC. In addition, results indicate that EGC has superior mechanical properties and bond performance compared to GPC, where EGC is approximately 9 and 150% higher than GPC in terms of flexural and tensile strength, respectively. Pull-out tests showed that EGC samples exhibited higher ductility, as evidenced by the presence of multiple cracks before any exhibited failure in tension and flexure. Ductile failure modes, such as pull-out failure and pull-out splitting failure, are observed in EGC. In contrast, GPC specimens show brittle failure, such as splitting failure.

Global carbon dioxide emissions can be attributed to Portland cement production; thus, an alternative cementitious system is essential to reduce cement demand. Ceramic waste powder (CWP), which contains high proportions of silica and alumina, has emerged as a promising alternative because of its chemical composition. This review discusses the potential of CWP as an alternative cementitious system and its effects on the physical, mechanical, and durability properties of cementitious systems. The findings revealed that the utilization of CWP in cementitious systems has positive effects on their physical, mechanical, and durability properties owing to the chemical composition of CWP, which can act as a filler material or contribute to the pozzolanic reaction. A pozzolanic reaction occurs between the silica and alumina in the CWP and calcium hydroxide in the cement, resulting in the production of additional cementitious materials such as calcium silicate hydrates and calcium aluminate hydrates. These additional materials can improve the strength and durability of cementitious systems. Various studies have demonstrated that CWP can be effectively used as a partial replacement for cement in cementitious systems. This can reduce the carbon footprint of construction activities by reducing the demand for Portland cement. However, the optimal amount and particle size of CWP have not been fully determined, and further research is required to optimize its use in cementitious systems. In addition, the technical and economic challenges associated with the use of CWP in construction must be further investigated to ensure its effective implementation.