Ultra-High-Strength Lightweight Fiber-Reinforced Concrete: A Review

Abstract This study provides a comprehensive overview of the material and mechanical properties of lightweight fiber-reinforced cementitious composites (L-FRCCs), focusing on their classification as ultra-high-strength lightweight fiber-reinforced cementitious composites (UL-FRCCs). The L-FRCCs exhibit a density of 1440–2150 kg/m3, thermal coefficient of 0.22–0.33 W/mK, compressive strength of 45–145 MPa, and flexural strength of 4.3–37.5 MPa. The strength of the L-FRCCs increases linearly with matrix strength. Specifically, L-FRCCs with compressive strength > 100 MPa, flexural strength < 15 MPa, density < 1950 kg/m3, and thermal conductivity < 0.5 W/mK can be classified as UL-FRCCs. Pearson correlation analysis reveals that the structural efficiency (SE) of L-FRCCs increases with increasing matrix strength, fiber volume content, and reinforcing index; however, it decreases with an increase in the lightweight aggregate (LWA) ratio. For UL-FRCCs to achieve optimal SE, the LWAs should possess a crushing strength > 70 MPa and specific gravity < 0.5. Additionally, incorporating straight steel fibers at volumes < 2.5% is recommended to achieve strengths > 100 MPa. Compared to nonmetallic fibers such as polymeric fibers, steel fibers offer superior SE for flexural strength, despite their tendency to reduce workability owing to their high stiffness.