Photocatalytic high-performance fiber-reinforced cement composites with white Portland cement, titanium dioxide, and surface treated polyethylene fibers

In this study, titanium dioxide (TiO₂) and polyethylene (PE) fibers were employed to develop photocatalytic high-performance fiber-reinforced cement composites (HPFRCCs). To achieve high NO_x removal capacity, it was necessary to confirm the dispersion of the TiO₂ powder. For this purpose, various amounts of viscosity-modifying agent (VMA), ranging from 0% to 1% by weight to cement, were considered along with two types of white Portland cement: Union and Aalborg. Additionally, the PE fiber surface was modified via cold gas plasma and chromic acid treatment to improve the tensile performance of the HPFRCCs. The experimental results indicated that the plastic viscosity of the mortar increases with the addition of VMA. Optimum NO_x removal capacities of 5.72 and 8.10 μmol were respectively achieved for the Aalborg and Union cement types in the mortar at a VMA content of 0.5%. The compressive strength of the tested photocatalytic HPFRCC was approximately 72.7–91.8 MPa. In the case of the hybrid argon (Ar) and oxygen (O₂) gases being subjected to plasma treatment, optimum tensile performance—in terms of tensile strength, strain capacity, and g-value—was achieved, whereas the samples subjected to chromic acid treatment exhibited poorer tensile performance. Moreover, the single Ar–or O₂-gas-based plasma treatment yielded an intermediate tensile performance. The cracking behavior showed trends similar to those of the g-value: the hybrid plasma treatment produced the most microcracks because of its high fiber bridging capacity.