Indirect assessment of cement-stabilized mine tailings’ compressive strength considering ultrasonic pulse velocity for road construction

Abstract This investigation examines the potential of ultrasonic wave propagation velocity (UPV) as a non-destructive method for estimating the compressive strength (CS) of cement-stabilized mine tailings (CSMT). Different cement contents (0%, 2%, 4%, and 6%) and curing periods (ranging from 1 to 90 days) were investigated for two distinct materials: phosphatic limestone and limestone. An experimental program was performed, including compressive strength (CS) tests and UPV measurements, also allowing for the estimation of the dynamic modulus of elasticity (ED). In order to analyze the connection between mechanical and dynamic properties, exponential relationships were initially established between (CS) and (UPV) and between (CS) and (ED). A global predictive model was developed in a second phase to enhance the accuracy of compressive strength prediction. This model incorporates a variety of influential parameters, such as UPV speed, cement content, dried density, Poisson’s ratio, and curing time. The results show the performance of the materials is considerably enhanced by an increase in the cement content. The strength of the materials can increase by a factor of 5 to 14 between 0% and 6% cement after 90 days. The coefficients of determination increase as the cement content increases, with variances observed between phosphatic limestone and limestone, ranging from R² ≈ 0.34–0.39 at 0% to R² ≈ 0.95–0.96 at 6%. The statistical evaluation based on RMSE, MAE, and MAPE shows a significant reduction in error, with MAPE values decreasing from over 25–35% at low cement content to less than 10% for stabilized materials. These results confirm that (UPV), when combined with important mechanical and physical characteristics, is a dependable and non-destructive method for estimating the strength of (CSMT), providing a useful instrument for the valuation of mining residues in road applications.