Effect of nano-silica on microstructure formation of low-cost geopolymer binder

Influence of Nano-SiO2 (NS) addition on properties of Geopolymer materials has been studied through measurement of physicomechanical and morphological characteristics of the hardened specimens. Alumino–silicate materials are water-cooled slag, albite, kaolin, and metakaoline. Materials were prepared at water/binder ratios in a range of 0.244:0.320 for water-cooled slag based materials, while it increased to 0.46 for albite-based mixes, whereas the used activator sodium hydroxide is 10 wt.%. The control geopolymer mix has been composed of water-cooled slag, metakaoline, and kaolin in the ratio of (4:2:1). Albite used for comparison with slag to demonstrates the possibility of producing lightweight geopolymer binder. Nano-silica was added in the range from 0:3% from the total weight with 0.5% increment. Results indicated that, compressive strengths of geopolymer mixes incorporating NS were obviously higher than those of control one, specially at early ages as well as up on using 2.5% NS with the lowest percentage of water absorption; also uses of albite instead of slag results in formation of light binder with promising mechanical characteristics.