Efficient recycling of waste rubber in a sustainable fiber-reinforced mortar and its damping and energy dissipation capacity

A great number of waste tires are discarded in landfills, occupying land resources, and severely endangering the ecosystem. Upcycling these wastes as aggregates to partially substitute natural sand and develop structure -function integration in concrete structures is a desirable solution. In this study, a sustainable fiber-reinforced rubberized mortar with superior material damping and moderate strength is developed by combined use of waste crumb rubber (WCR) incorporated at 0, 30%, and 60%, by volume of sand, and polyvinyl alcohol (PVA) fiber added at 0, 0.5%, and 1%, by volume, in a high-volume fly ash binder system. Low-temperature plasma (LTP) pre-treatment of the WCR was applied to compensate for strength loss resulting from the incorporation of a large portion of the WCR, which increases the recycling efficiency of the WCR. The macro tests of static and dynamic mechanical properties were used to characterize the material damping and energy dissipation capacity, followed by microstructural tests to evaluate the enhanced damping mechanisms. Test results show that the combination of 60% LTP pre-treated WCR and 1% PVA fiber can secure the highest damping capacity and energy dissipation ratio without a significant strength drop. The use of discarded WCR is therefore promising to sub-stitute conventional sand and design functionalized intrinsic viscoelastic cement composites that can be adopted in anti-vibrational technology applications.