STUDIES OF GEOPOLYMER SAMPLES BY NON-DESTRUCTIVE TESTING

Geopolymers are inorganic materials that have been studied since 1972 due to their advantages over Portland cement concrete, such as greater inertia, lower CO₂ emissions, and greater chemical and fire resistance. The use of the ultrasonic velocity propagation technique, a non-destructive and widely used method for evaluating the quality of Portland cement concrete, has also been applied to geopolymers. However, the chemical composition and proportions of the materials used to produce geopolymers affect properties such as density, porosity, and absorption, which directly influence the propagation of ultrasonic waves. These factors indicate that the ultrasonic velocity propagation technique may not be entirely reliable for qualifying geopolymers, which is why more research on the subject is needed. Given this scenario, this study investigated how variations in the composition of geopolymer samples can impact the propagation speed of ultrasonic waves, considering an experimental design using response surfaces and taking into account the following variables: propagation speed of ultrasonic waves, compressive strength, absorption and specific mass. The results obtained demonstrated that the use of sodium silicate in geopolymer formulations to evaluate the propagation speed of ultrasonic waves, considering a significance level of 5%, was significant (p = 0.002), that is, less than p0.