Effect of nano-silica on the efflorescence of waste based alkali-activated inorganic binder

The efflorescence caused by carbonate weathering is one of the dominant causes of deterioration of alkali-activated inorganic materials. In order to inhibit the efflorescence of waste based alkali-activated inorganic binder, the effects of nano -silica on the compressive strength, carbonate ions concentration, hydration rate and pore size distribution of the obtained alkali-activated inorganic binder have been investigated, and the efflorescence inhibition mechanism has been also analyzed. The results revealed that compressive strength and microstructural properties could be further developed with inclusion of nano-silica in alkali-activated inorganic binder. In addition, the efflorescence decreased with increasing nano-silica content and decreasing of the nano-silica particle size. Besides, the hydration rate results indicated that the hydration of waste based alkali-activated inorganic binder was accelerated before hydration for 3d with the incorporation of nano-silica. The suggested inhibition mechanisms discussed were mainly; micro-aggregate filling effect, induced nucleation, and accelerated hydration effects of nano-silica.