Experimental investigation of mechanical and durability performance of high-performance rubberized mortar reinforced with steel fibers

The replacing of rubber powder in high performance rubberized mortar promotes recycling of waste tires, reduce landfill burden and environmental pollution. This study investigates the fresh and hardened properties of high-performance rubberized mortar reinforced with steel fibers, focusing on the influence of waste rubber powder as a replacement for dune sand. Rubber powder was incorporated at 0%, 5%, 10%, and 15% by weight, and its effects on flowability, mechanical performance, and durability-related characteristics were experimentally evaluated. The flowability results showed a gradual reduction with increasing rubber content, decreasing from 240 mm in the control mixture to 190 mm at 15% rubber, representing a 20.8% reduction, primarily due to the hydrophobicity and irregular surface texture of rubber particles. Compressive strength showed a similar decreasing trend, declining from 112.5 MPa to 50.9 MPa, while flexural strength decreased from 19.42 MPa to 10.46 MPa, corresponding to strength reductions of 54.7% and 46.2%, respectively. Water absorption exhibited only slight variation, ranging from 1.63% to 1.73% as the rubber content increased from 0% to 15%, indicating that rubber powder does not significantly affect the moisture transport behavior of the mortar and may even slightly enhance impermeability at higher contents, while the void content decreased from 3.73% to 3.38%, suggesting a micro-filling effect of the fine rubber particles. A mortar mix with 10% rubber content exhibits better electrical resistivity. Overall, the results demonstrate that while rubber powder reduces mechanical strength and workability, it enhances certain durability characteristics and contributes to more consistent pore structures.