Abstract: To address the poor understanding in previous experimental research of hydraulic concrete wet expansion on the influence of coarse aggregate volume fraction, this study adopts a representative concrete mix design often used in typical dam engineering practice, featuring a wet-screened two-stage aggregate gradation. Specimens with coarse aggregate volume fractions of 42%, 47%, 52%, and 57% are designed and tested in our wet expansion experiment, and their wet expansion strain is measured under the condition of different immersion durations. Then, the wet expansion coefficient for each of the volume fractions is determined using the gravimetric method; A new predictive model for wet expansion strain is developed that incorporates the factor of volume fractions explicitly. Results indicate that with an increasing coarse aggregate volume fraction, the wet expansion coefficient increases, but the wet expansion strain is reduced because the rate of reduction in the water absorption rate has a greater effect. Compared to those equipped with a cubic, logarithmic, or combined exponential functions, our new wet expansion strain model based on the hyperbolic function captures more effectively the influence of varying coarse aggregate volume fractions on the wet expansion behaviors of hydraulic concrete.

Key words: hydraulic concrete, coarse aggregate volume fraction, wet expansion strain, wet expansion coefficient, wet expansion strain model