Synergetic effect of nano-silica fume for enhancing physico-mechanical properties and thermal behavior of MK-geopolymer composites

Abstract

• The nano silica fume has a positive effect on the physico-mechanical and thermal properties of MK-geopolymer. • The mechanical strength of MK-geopolymer mixtures incorporating NSF increased with temperature up to 700 °C and increases with increasing NSF up to 5%. Thermal Stability of geopolymer at high temperatures has attracted great interest from several researchers. The use of nanosilica fumes gets more attention Because of its great influence on the mechanical properties and thermal stability of geopolymer composites. Therefore, this work reviewed the effect of Nano-silica fume on thermal stability and mechanical behaviors of geopolymers at high temperatures. The main geopolymer mixes made up of metakaolin having various nano-silica fume ratios in addition to kaolin and lime stone. The activators used are Na 2 SiO 3 and NaOH (5 M) in the ratio of (1:1). The geopolymer mix control has been composed of metakaolin (MK), kaolin (K) and lime stone (LS) in the ratio of (2:1:1). Nano-silica fume (NSF) was added in the ratios from 0 to 7 wt% from the metakaolin. To realization investigate the effect of Nano-silica fume on MK geopolymer binder, classical tests of bulk density and strength at various ages. The results were analyzed by using advanced devices. The thermo-physical, micro-structural and mechanical properties of the MK geopolymers binder after the exposure to elevated temperatures of 500, 700, 800 and 1000 °C have been investigated. The results indicated that the NSF has a positive effect on the physicomechanical properties of MK-geopolymer. The inclusion of 5 % NSF to MK geopolymer binder enhanced the properties in terms of strength and microstructure. The mechanical strength of MK-geopolymer mixtures incorporating NSF increased with temperature up to 700 °C and increases with increasing NSF up to 5 %. The inclusion of 5 % NSF enhanced the physico-mechanical properties and microstructure before and after exposure to high temperature.