Fiber-reinforced cement matrix composites (CMCs) have gained significant attention due to their ability to enhance material properties for use in demanding environments. This study investigated the workability and mechanical properties of polyvinyl alcohol (PVA) fiber-reinforced CMCs, focusing on compressive strength, split tensile strength, and flexural strength. It also assessed water absorption capacity through immersive water absorption tests using cubes and capillary water absorption tests using cylinders, alongside bulk density measurements for both shapes. The results indicated that the dosage of PVA fibers significantly influences the workability of CMCs, while the water-to-binder ratio has a minimal effect. Increasing the dosage of PVA fibers in CMCs from 0.5 vol.% to 1 vol.% led to a decrease in several properties: compressive strength decreased by 13.38%, split tensile strength by 21.05%, flexural strength by 9.23%, bulk density of cube samples by 4.14%, and bulk density of cylindrical sample by 6.36%. Conversely, both immersive water absorption and capillary water absorption increased, rising by 10.87% and 77.71%, respectively. Compressive strength was found to increase with the bulk density of the cubes and to decrease with rising immersive water absorption. Similarly, split tensile strength increased with the bulk density of the cylinders and decreased as capillary water absorption increased. Strong correlations were observed among three key pairwise combinations: the bulk density of cubes and immersive water absorption (R² = 94%), compressive strength and bulk density of cubes (R² = 96%), and compressive strength and immersive water absorption (R² = 92%). Furthermore, the analysis and comparison of carbon fiber-reinforced and PVA fiber-reinforced CMCs will provide important references for the field, especially in cases where material availability or cost varies.

Capillary water absorption plays a critical role in the ingress of corrosive elements during the construction of concrete structures in corrosive environments. This study presented a novel approach for analyzing capillary water flow within unsaturated concrete based on the principle of stationary action. The flow of water within the concrete capillary pores can be regarded as a variational problem, while the principle of stationary action provides a method for determining the path solution. The evolution and distribution characteristics of water content and wetting front were explicitly determined using the exponential and power hydraulic functions. A simplistic yet effective approach for determining these hydraulic parameters was put forward based on the relationship between the position of the wetting front and the diffusivity parameters. The proposed approach exhibited enhanced theoretical robustness and entailed fewer hypotheses compared to existing methodologies. Furthermore, the material hydraulic parameters in the proposed approach can be determined explicitly. The governing equations for capillary water flow were derived in accordance with the principle of stationary action. Numerical simulations were carried out to verify the effectiveness of the proposed approach. The results demonstrated that the proposed approach can accurately predict capillary water flow and diffusivity parameters within unsaturated concrete. The findings of this study contribute to developing more effective strategies to mitigate moisture-related damage in concrete structures.