A comparative study of the behavior of engineered cementitious composites and engineered geopolymer composites containing metakaolin and magnetized water

Abstract Sustainable materials and technologies used in engineered cementitious composites (ECC) and engineered geopolymer composites (EGC) have gained significant attention from concrete researchers in recent decades, owing to their superior performance compared to traditional concrete. In this study, the performance of sustainable ECC and EGC made of metakaolin (MK) and magnetized water (MW) is evaluated and compared. This was carried out using 14 mixes (7 for ECC and 7 for EGC). The control ECC mix contained cement and ground granulated blast furnace slag (GGBFS) and the control EGC mix contained fly ash (FA) and GGBFS. In ECC, the cement and GGBFS were partially replaced by MK; and in EGC, the FA and GGBFS were replaced by MK. The replacement ratios were 20%, 40%, 60%, and 80% by volume. The tap water (TW) was completely replaced by MW in ECC and EGC mixes containing 0% and 20% MK. Fresh, mechanical, and durability properties were measured for both ECC and EGC such as; slump, compressive and flexural strength, water absorption, and sorptivity. The effect of different curing environments (tap water and seawater) on ECC/EGC compressive strength was also studies. Furthermore, microstructural analyses were performed on specific ECC and EGC mixtures. The microstructure analyses included scanning electronic microscope (SEM), energy dispersive X-ray (EDX), and mapping of the morphology surface. The fresh and mechanical properties indicated that EGC exhibited higher slump values (by up to 7.3 times) and higher compressive strengths (by up to 90%) than those of ECC, especially in the presence of MW. Seawater curing enhanced the EGC compressive strength by up to 16%. The durability results showed that absorption rates and sorptivity of EGC were relatively higher than those of the corresponding ECC. The SEM analysis showed that the concentration of gelatinous materials as CSH and ASG in the mixes using MW was higher than the similar mixes with made with TW, especially in the presence of MK. The EDX analysis and mapping showed that the ratio of Ca/Si was low in EGC compared to that in ECC.