Mechanical and Durability Performance of Ultra-High-Performance Concrete Reinforced with Alkali-Resistant Glass Fibers and Textile Grid

This study investigates a hybrid composite comprising an ultra-high-performance concrete (UHPC) matrix, short alkali-resistant (AR) glass fibers, and an embedded AR-glass textile grid (GF-UHPTRC), with emphasis on measured mechanical response, elevated-temperature residual performance, and short-term sulfate-exposure behavior. Fourteen UHPC matrix formulations were screened, including seven plain matrices and seven containing 2% AR-glass fibers by cement mass. The mixtures were evaluated for flowability, compressive strength, and 28-day matrix flexural strength, and UHPC-P7 and UHPC-GF7 were selected for subsequent testing. The maximum 28-day compressive strengths were 115.3 MPa for UHPC-P7 and 105.2 MPa for UHPC-GF7. UHPC-GF7 reached a 28-day modulus of rupture of 10.45 MPa, approximately 39% higher than UHPC-P7. In TRC beam tests, GF-UHPTRC reached an average ultimate flexural strength of 47.5 MPa compared with 34.06 MPa for UHPC-TRC. After exposure to 400 °C, the residual compressive strengths were 66.0 MPa for UHPC-GF7 and 54.9 MPa for UHPC-P7; severe damage and spalling were observed at higher temperatures. After 28 days in 5% Na2SO4 solution, both mixtures showed mass gain and measurable length increase. The results demonstrate improved measured flexural strength with short AR-glass fibers, while conclusions regarding long-term durability, ductility, crack control, and structural-scale performance remain outside the scope of the available data.