Water transport and pore characteristics of mortar under sustained load

Sustained load is a common type of load for concrete structures during service. It may affect the pore structure of mortar, thereby affecting the transmission characteristics of water and the durability of concrete. In this paper, the pore structure and transport properties of mortars at low- stress levels were investigated. Non-destructive axial tensile and compressive loads were applied to the mortar to study the permeability and water absorption of the mortar under different loads. In addition, the mortar's pore structure was analyzed under varying sustained loads using the RapidAir 457 pore structure analyzer and micro-CT scans. Results show that within the stress levels of the experimental design, compressive loads tend to reduce the water transmission rate in mortar, whereas tensile loads have a positive effect on water transmission. The pore-size distribution of mortars with different water-cement ratios is affected differently by load. Finally, seepage simulation was carried out using the three-dimensional model established by CT scanning. The results show that the simulated values and experimental test values were consistent with the changing trend of the load. With increasing compressive load, the water seepage path is obstructed, resulting in decreased permeability. Conversely, under tensile loads, the number and density of streamlines increase, facilitating water penetration.