Effect of Fiber Volume Fraction of Waste Originated Tire Fiber and w/c Ratio on Mechanical Properties of Functionally Graded Concrete

Abstract

The natural fine aggregates required for concrete works diminishes day by day with development in the construction industry. Also, the waste rubber obtained from used tires is nonrecyclable, severely impacts the environment and human health, and constitutes a large amount of global waste. In this quest, a systematic, detailed empirical examination has been carried out on the functionally graded rubberized concrete (FGRC) containing rubber fibers as a substitute of fine aggregates to assess the density, compressive strength, flexural strength, split tensile strength, abrasion resistance, water absorption, chloride penetration, and ultrasonic pulse velocity. FGRC was cast in two equal half layers of control concrete and rubber fiber concrete for different replacements (0%, 5%, 10%, 15%, 20%, 25%, and 30%) of rubber fiber and different water–cement ratios (0.35, 0.45, and 0.55). The focus was provided on the combined effect of the w/c ratio and fiber concentration on the FGRC. Microstructural analysis was done on the specimens through scanning electron microscopy and optical microscopy to gain indepth facts about the FGRC interface. Results proved that concrete with a lower w/c ratio proved best in compressive and flexural strength, and there was a decline in the results after the fiber replacement of 20%. Splitting tensile strength also showed less variation after a 20% replacement ratio. Based on the results, the up to 20% of the replacement ratio of waste tire rubber fiber are advised, which can be progressively used at members where desired flexural strength and compressive strength are needed, such as special slabs, bridges, pavements, flyovers, railway sleepers, and other structural members. © 2021, Shiraz University.