Investigating the correlation between ultrasonic pulse velocity and compressive strength in polyurethane foam concrete.

Using waste polyurethane foam as a partial replacement for natural coarse aggregates in concrete provides an eco-friendly solution by reducing waste and conserving natural resources. However, the strength behavior of polyurethane foam concrete differs from conventional concrete. To ensure effective design and quality control in the field, the viability of non-destructive testing methods for finding out the in situ mechanical properties of polyurethane foam concrete must be evaluated. This study establishes a correlation between compressive strength and ultrasonic pulse velocity (UPV) test to predict the compressive strength of polyurethane foam concrete using UPV test results. An experimental study was conducted on concrete specimens with varying percentages of polyurethane foam replacing natural coarse aggregate, ranging from 10 to 60% in 10% increments. The control concrete mix was 100% natural coarse aggregate without polyurethane foam. The properties of the specimens were evaluated after curing for 7, 14, and 28 days. It also examines polyurethane foam concrete workability, density, and microstructural properties. The findings show that the UPV and compressive strength of polyurethane foam concrete were lower than those of the control mix concrete for all replacement levels and curing ages. The empirical relationships between compressive strength and UPV were found to be exponential, with high correlation values ranging from 0.9012 to 0.9998. The predicted values and the experimentally measured results were compared in order to confirm the accuracy of the empirical equations for compressive strength prediction.