Effect of nano-SiO2 on the efflorescence of an alkali-activated metakaolin mortar.

• The inhibited mechanism of the nano-SiO 2 on the efflorescence of geopolymer was analyzed. • A negative effect of the efflorescence on compressive strength of geopolymer was found. • The nano-SiO 2 could improve the transport property of geopolymer. To inhibit the efflorescence of geopolymers, nano-SiO 2 particles were used as an additive to modify an alkali-activated metakaolin mortar. In this work, the effect of the nano-SiO 2 on the compressive strength, pore structure and ion leaching of geopolymers was investigated. Based on these results, the inhibitory mechanism of the nano-SiO 2 on the efflorescence of the geopolymer mortar was analyzed. The results showed that the nano-SiO 2 improved the compressive strength and inhibited the efflorescence of the geopolymer mortar. The nano-SiO 2 decreased the efflorescence by consuming excessive alkali ions in the pore solution to form an amorphous gel phase, and the negative effect of the efflorescence on the compressive strength was also verified. Moreover, the pore structure and transport properties of the geopolymer were also improved by the addition of the nano-SiO 2 , which reduced the diffusion rate and leaching of the ions. [ABSTRACT FROM AUTHOR]