Early strength properties of geopolymer concrete composites: An experimental study

Abstract

The fundamental motive of this paper is the systematic investigation of geopolymer concrete (GPC) composites behaviour when different binding materials in certain percentages are replaced completely with cement, to analyse the mechanical properties and bonding between aggregates and geopolymer paste. The term Geopolymer was coined by French scientist Joseph Davidovits in 1978, a confection of compounds comprises of repeating units like silicon oxide (-Si-O-Si-O), silico-aluminate (-Si-O-Al-O) constituted through a process of geopolymerization by utilizing modern waste. The waste by-product material which contains the most part of silicon (Si) and Aluminium (Al) is a source material to produce geopolymer. Geopolymer is a man-made polymer composite which is an eco-friendly continual product by substituting the traditional concrete. Fly ash, Ground Granulated Blast furnace slag (GGBS), silica fume, metakaolin (MK), rice husk ash (RHA) and other alumino-siliceous materials are used as substitute binders to Portland cement under different alkaline Activating solutions [NaOH, KOH, Ba (OH)2 and LiOH]. GGBS, MK, and RHA were used as supplementary cementitious materials (SCM) to cement and as a substitute to cement and binder in this geopolymer concrete. The specimens are cured at ambient temperature conditions. Mechanical properties include compressive strength, split tensile strength and flexural strength of the GPC mix specimens are studied for different time periods (7,21 and 28 days) and the strengths were determined. NDT results are also matching with the DT results for some of the GPC mixes. Alkaline Activating Solutions (AAS) are prepared in the molarities of 8, 10 with the unification of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH). The source materials used in this study are widely available waste by-products from industries and these are eco-friendly materials due to very less carbon emissions in comparison with cement.