Mechanical strengths and ultrasonic pulse velocity evaluation of supersulfated cement mortar containing sodium sulfate

Abstract

The purpose of this study is to evaluate the mechanical strengths and ultrasonic pulse velocity (UPV) of supersulfated cement mortar incorporating sodium sulfate (Na2SO4) with various amounts of SO3 at 0 wt.%, 2.5 wt.%, 7.5 wt.%, and 10 wt.%. The results exhibited that the inclusion of Na2SO4 could significantly improve the 28-day compressive strength by about 2.94 to 4.26 times higher and the 28-day flexural strength by about 2.89 to 3.78 times higher, when compared with the mixture without Na2SO4. The 28-day UPV value for the mixture without the addition of Na2SO4 was 2931 m/s, which can be classified as very poor mortar quality; however, with the addition of Na2SO4, the 28-day UPV value could improve to 3687-3942 m/s, which can be classified as good to excellent mortar quality. In addition, an exponential equation with a coefficient of determination (R2) of 0.975 was also proposed to predict the relationship between compressive strength and UPV value. Based on the experimental findings, it could be concluded that the inclusion of Na2SO4 had a beneficial effect on enhancing the mechanical strengths and mortar quality of supersulfated cement mortar.