Abstract: In order to solve the crack and leakage problem of concrete members such as side walls of underground structures, the green economy sisal fiber-engineered cementitious composite (ECC) was selected to replace concrete to improve the impermeability of members. The optimal ratio of sisal fiber-ECC was obtained by orthogonal experiment. An improved experimental setup was self-designed for realizing synchronous coupling of sustained compressive loading and water transfer by sisal fiber-ECC. The capillary water absorption performance test under sustained compressive loading was carried out on sisal fiber-ECC. The effects of stress levels (10%~40%) on the destruction morphology, cumulative amount of water absorption and capillary water absorption rate of sisal fiber-ECC specimens were analyzed, and compared with that of ordinary concrete specimens. The results indicate that within 10%~40% compressive stress level, the cumulative amount of water absorption and the average water absorption rate of the sisal fiber-ECC both decrease first and then increase with the increase of compressive stress level. The stress threshold for variation of capillary water absorption performance of specimens is 20% of its ultimate compressive strength. When the sustained compressive loading is in the range of 10% to 30% compressive stress level, compared with ordinary concrete, the sisal fiber-ECC can maintain a lower cumulative amount of water absorption and water absorption rate. Sisal fiber-ECC has better impeding effect on water tranfer. It shows that the impermeability of the structure at low compressive stress level (10%~30%) can be significantly improved by sisal fiber-ECC. The research results can provide theoretical support for the application of sisal fiber-ECC in the impermeability of side walls of underground structure.

Key words: sisal fiber, ECC, impermeability, short-term sustained compression, capillary water absorption performance, side wall of underground structure, concrete member