Improving elevated temperature performance of geopolymer concrete utilizing nano-silica, micro-silica and styrene-butadiene latex

Abstract Geopolymer binders (GPBs) have gained an increasing research potential in recent years due to their environmental, economic and durability advantages. This paper aims to improve elevated temperature performances of volcanic tuff (VT) based geopolymer concrete (GPC) by utilizing nano-silica (NS), micro-silica (MS) and styrene-butadiene latex (SBL). To this end, NS, MS and SBL additives were added to GPC samples at 2%, 2% and 5% ratios by weight of binder, respectively. GPB was obtained by activating ground VT with 12 M NaOH solution. Produced GPC samples were exposed to elevated temperatures (100, 300, 500 and 700 °C) for 1 h after reaching the target temperature. Changes in compressive strength, water absorption, visual appearance, weight and microstructure of GPC samples were investigated after the influence of elevated temperatures. The experimental findings displayed that compressive strength of GPCs increased up to 300 °C independently of the type of additive used, but higher temperatures than 300 °C caused decrease in compressive strength values. As a result of mechanical tests and microstructure investigations, it was determined that MS additive significantly increased the elevated temperature performance of GPCs. Additionally, color of GPC samples turned gray after elevated temperatures due to dehydration of GPB and microstructural transformations occurring in aggregates.