The effect of adding nano-silica on the ultrasonic pulse velocity of geopolymer concrete

Nanotechnology plays an important role in the current construction industry. It has been observed that several properties of cement-based concrete are affected by different nano materials. In this study, different weight percentages of nano-silica (0, 1, 2, and 4 wt%) were used to build geopolymer specimens. The mechanical properties of the specimens were then measured, including the compressive and flexural strength. Results demonstrated that increasing the percentage of nano-silica from 0 to 4 wt% increases the compressive strength of the specimens from 50.4 to 75.2 MPa and the flexural strength from 11.4 to 26.2 MPa. Furthermore, it was observed that the ultrasonic pulse velocity was altered by increasing SiO2 (nano-silica), decreasing the ultrasonic pulse rate from 7.0 to 4.5 km.s-1.