The effects of nano particles on freeze and thaw resistance of alkali-activated slag concrete

Alkali-activated slag (AAS) concrete could be considered as an environmentally friendly and economical concrete. The aim of this study was to investigate the effect of nanoparticles including nano-silica, nano-alumina, and nano-clay on the resistance of AAS concrete against freeze and thaw cycles. Sodium hydroxide and sodium silicate were used for the activation of slag in AAS concrete. In this investigation, a control mix without nano materials and 3 mixes containing 1, 2 and 3 wt% of nanoparticles were prepared. Samples were tested by the freezing-thawing test, according to the ASTM C666-B standard. The compressive strength and mass loss of AAS concrete specimens were measured. The results showed that nano-silica and nano-clay, respectively, performed better than the nano-alumina in improving the strength and durability of alkali-activated slag concrete subjected to freeze and thaw cycles. Adding 2% and 3% of nano-silica had a marginally smaller effect on AASC properties compared with 1% nano-silica.