Mechanical Behavior of Fiber-Reinforced Self-Compacting Rubberized Concrete Exposed to Elevated Temperatures

Self-compacting concrete (SCC) is a cementitious composite that serves complex formworks without mechanical vibrations. SCC has been widely used in modern concrete structures because of its superior performance, including excellent deformability and high resistance to segregation. A new kind of SCC, called self-compacting rubberized concrete (SCRC), is developed when crumb-rubber aggregates from waste tires are blended with different fractions in SCC to replace part of traditional aggregates; this developed SCRC achieves a better economic benefit and recycling of wasted tires. Meanwhile, polypropylene and steel fibers are also used in SCRC to improve the mechanical properties, especially at elevated temperatures. In this study, eight polypropylene and steel-fiber-reinforced SCRC mixture designs were produced. Slump-flow and J-ring experiments were performed to investigate the properties of fresh SCRC (flowability, flow speed, filling ability, and passing ability). The mechanical properties of hardened SCRC (compressive strength, tensile strength, and modulus of elasticity) after 28 days of curing were also tested. In addition, high-temperature resistance for SCRC is measured as the essential performance parameter, including mass loss, spalling distribution, and residual mechanical performance at 100°C, 300°C, and 600°C. The 0.25% optimum fiber ratio for polypropylene fiber and the 0.75% optimum steel-fiber ratio in SCRC were determined to obtain high-temperature resistance for hardened and fresh SCRC.