Interfacial tensile strength of arch dam transverse joints with casting intervals, concrete ages, and curing temperatures

In arch dam engineering, transverse joint apertures often fail to meet grouting requirements due to limited understanding and consideration of joint interfacial tensile strength. Before opening, the transverse joint is essentially the interface between new and old concrete. This study experimentally investigated the effects of four key factors—curing temperature of the old concrete, casting interval, age of the new concrete, and curing temperature of the composite specimen—on the interfacial splitting and direct tensile strengths of new-to-old low-heat Portland cement concrete (LHPC-C) composite specimens using an orthogonal design, followed by analysis of variance (ANOVA). The results show that the curing temperature of the composite specimen and the age of the new concrete have highly significant influence (P < 0.001), whereas the casting interval and the curing temperature of the old concrete have no significant influence. Maturity-based predictive models for estimating the development of interfacial splitting and direct tensile strengths were developed with coefficients of determination (R²) of 0.96 for both, and validated, achieving mean absolute percentage errors (MAPEs) of 4.15 % for splitting tensile strength and 1.02 % for direct tensile strength. To assess engineering applicability, the models were applied to predict interfacial splitting tensile strength under time-varying curing temperature histories and the opening temperatures of transverse joints in a certain arch dam, with relative errors below 5 % and 7 %, respectively. These results demonstrate that the proposed models accurately describe interfacial tensile strength development in response to variations in key influencing factors, and are applicable to engineering practice.