Fast Setting Stell Fiber Reinforced Geopolymer Mortar Cured Under Ambient Temperature

Abstract

Cement and cementitious materials are being used worldwide as the most popular multipurpose construction materials but cement is not a sustainable material and energy intensive. Greenhouse gas (CO2) produced by portland cement industries during the manufacturing process of cement causes environmental impact thus efforts have been made for alternative binders. Geopolymer technology is one of the new technologies experimented to reduce the use of portland cement in concrete industries because it shows the most hopeful green and eco-friendly alternative to cementitious materials (doesn’t emit green house gases during polymerisation process).The aim of this study is to produce fast setting fly ash and Ground Granulated Blast Furnace Slag (GGBS) based geopolymer mortar reinforced with crimped steel fibers. In this research, the influence of various parameters such as steel fiber volume content, the ratio of activator/binder ratio, the effect of variation of GGBS percentage on the setting time and compressive strength were investigated. Four different alkaline liquid to binder ratio (0.5 to 0.8), three different percentage of crimped steel fibers (0.5,1 & 1.5% by total volume of binder) with Six different binder combinations of Fly ash and GGBS (100%:0%, 90%:10%, 80%:20%, 70%:30%, 60%:40%, 50%;50) were used for preparation of steel fiber geopolymer mortar. The tests conducted include setting time and flow capacity of fresh geopolymer mortar, compressive strength and structural properties (SEM) of steel fiber fly ash and GGBS based geopolymer mortar. The tests for compressive strength were carried out on 70.6x70.6x70.6 mm cube steel fiber geo-polymer mortar specimens at 3, 7 and 28 days .The results obtained from this study, show that in all mixes, the setting time (both initial and final) of geopolymer mortar increases with the increase of alkaline to binder ratio and then decreases with the increase in GGBS content .they also show that incorporation and increase of steel fibers in plain mortar have improved significantly its compressive strength. Optimum fiber content showing the maximum strength value in all mixes is 1%. The highest 28 days compressive strength was found to be 69.5 MPa at 1% fibers content for alkaline to binder ratio of 0.6 with 50%:50% FA and GGBS content. SEM images show that there is a relatively good bond between the geopolymer matrix and the steel fiber which lead to higher compressive strength.