الفهرس | Only 14 pages are availabe for public view |
Abstract Concrete is the key building material used for construction activities and development projects throughout the world. Portland cement is ordinarily used as the main binder to produce concrete; however, it is not an enviro-friendly material as the production of Portland cement depletes natural resources and results in the emission of a large amount of greenhouse gases. Therefore, geopolymer concrete (GPC) has received considerable attention in recent years because of its significant environmental benefits where it utilizes solid industrial aluminosilicate-based waste materials, such as fly ash (FA), rice husk ash, silica fume, or ground granulated blast furnace slag (GGBFS) to produce a low-cost and environmentally friendly material as an alternative to Portland cement. Heatcured GPCs have been studied extensively to establish their properties and it has been found that they can achieve comparable and, in some cases, better properties than ordinary Portland cement concrete. However, very few attempts to assess the properties of ambient-cured GPC are reported in the literature. The main objective of this research is to investigate the efficiency of using ecofriendly pozzolanic materials (GGBFS + FA) to create GPC under ambient curing conditions and investigate the effect of main parameters on the fresh, hardened, and durability characteristics of the produced GPC. The experimental program consists of two main phases: the first phase investigates the fresh and hardened properties of ambient-cured GGBFS-FAbased GPC. Nine mixes (designed by Taguchi method) were carried out considering the four most effective parameters: GGBFS to FA ratio, binder content, sodium silicate (SS) to sodium hydroxide (SH) ratio, and activator molarity (M). Slump test was conducted to investigate the workability of fresh concrete while compression test, splitting test, and flexure test were conducted to investigate the hardened properties. The second phase investigates the durability vii characteristics (sulphate acid resistance, water absorption, and chloride penetration) throughout carrying out six mixes considering the effect of GGBFS:FA ratio and SH (M). The experimental results of the first phase showed that using GGBFS as 100% of binder content could increase the mechanical properties at the expense of workability which can be improved using fly ash as a ratio of binder content. However, the test results of the second phase showed that increasing the proportion of GGBFS content compared to FA content as well as utilizing the lower SH (M) lead to enhancing the microstructure and the homogeneity of the GPC, therefore enhancing the durability of the GPC In contrast, increasing FA content leads to increase in sulphate resistance. Keywords: Mechanical Properties; Geopolymer concrete; Slag; Fly ash; Ambient curing; Taguchi method |