Abstract
This study investigated the potential use of tire derived rubber aggregates, particularly powdered rubber, and recycled steel-wire fibers in concrete subjected to impact loading. The fibers are approximately 0.4 mm in average diameter and 25 mm in length on average. There are two main portions to this study. The first phase of this study involved small-scale batching to investigate the fresh and hardened properties of concrete mixtures with powdered rubber up to 50% replacement of sand volume and recycled steel fibers up to 0.25% by mixture volume. Additional mixtures containing powdered rubber, crumb rubber, and tire chips were evaluated for their mechanical performance. Based on fresh concrete properties, compressive strength, modulus of rigidity, and impact resilience, mixtures were selected for a second investigative phase. In this phase, static and impact testing were performed on two sets of scaled beams. One beam set was produced with concrete containing 40% powdered rubber as a sand replacement and another beam set with a combination mixture incorporating rubber products of varying sizes (10% powdered rubber, 10% crumb rubber, and 10% tire chip) and 0.25% recycled steel fiber. Flexural performance improved initially with the inclusion of powdered rubber but decreased with increasing concentrations. Mixtures including recycled steel fibers at 0.25% outperformed industrial steel fiber mixtures in both flexural strength and impact resistance. For both the static and impact beams with the recycled powdered rubber and steel fibers in the combination demonstrated improved load distribution and load-carrying capacity, acting as a sufficient replacement for industrial steel fiber reinforcement.
Highlights
This study aims to investigate the use of recycled tire products in the Georgia Department of Transportation (GDOT)’s concrete mixtures, for use in barrier walls
This study aims to evaluate rubberized concrete while investigating the potential use of new materials consisting of powdered rubber and recycled steel fibers
Compressive cylinders, modulus of rupture (MOR) beams, and impact disc specimens were constructed for each Phase I mixture to provide a general understanding of the hardened properties of concrete incorporating rubber products and steel fiber, especially powdered rubber and recycled steel fiber
Summary
Silica fume, and fly ash have long been used as supplementary cementitious materials in concrete These waste stream products offer environmental and economic benefits, and oftentimes even enhanced concrete properties. According to the U.S Tire Manufacturers Association, 3,800,378,313 kg (4,189,200 tons) of scrap tires were generated in 2017 alone, and there were 60 million tires stockpiled in the United States in 2017 [1] While this number is down from the 1000 million stockpiled in the US in 1990, continued efforts are required to eliminate stockpiled waste tires as the existing stockpiles continue to pose a threat to public health. Waste tires pose environmental problems, such as contamination and fire hazards These tire fires generate toxic emissions, which have numerous negative effects to human health.
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