Physical and frost resistance of ternary geopolymer with SiC whiskers grafted APTES

Geopolymers feature as a new type of sustainable cementitious material. This study uses raw materials including a high volume of blast furnace slag, with auxiliary cementitious materials metakaolin, and fly ash, to prepare the ternary geopolymer. As modified nanomaterials, silicon carbide whiskers grafted with (3-aminopropyl)triethoxysilane at different contents (0.1, 0.3, and 0.5 wt%) are applied to modify and evaluate physical properties and frost resistance. Physical properties encompass fluidity, consistency, and water resistance; the frost test also evaluates mass and strength variations over 25–100 cycles. The microstructural and macroscopic properties of the modified geopolymer are investigated using various tests. The results reveal that the fluidity value of the modified geopolymer increased from 162 to 173 mm, and the consistency increased from 34.2 to 39.7 mm after the addition of 0.1 wt% modified SiCw. The coefficient of water resistance increased from 0.76 to 0.85. The uniaxial compressive strength loss rate for the 0.1 wt% modified matrix is 37.83% lower than that of the control matrix. The modified SiCw has significantly increased gel products of geopolymer. Moreover, the modified SiCw optimizes the pore structures of ternary geopolymers, resulting in a better microstructure.