Abstract: To study the influence of internal soft rock water absorption on the strength of rock-filled concrete during pouring and working in water environment, we design and prepare rock-filled concrete specimens with soft sandstone in red bed area as coarse aggregates, and conduct water content tests and compressive strength tests on the specimens with different soaking time. The results show that compared with the self-compacting concrete, the specimens exhibit a greater capacity for continuous water absorption and an increased saturated water content. Specifically, the water absorption rate of the internal soft rock is 2 - 3.5 times that of the self-compacting concrete in the same region. Under wet conditions, the specimens’ failure mostly occurs in the external concrete, and their surface fractures after drying mostly extend through the soft rock aggregates. In the soaking environment, its strength remains stable after 2 days and has not been continuously 'weakened ' due to soaking. This study helps understand the compressive strength characteristics of rock-filled concrete with soft aggregates in water environment, also useful for engineering applications.

Key words: rock-filled concrete, soft aggregate, moisture content, compressive strength