Durability of rubberized concrete with recycled steel fibers from tyre recycling in aggresive enviroments

Abstract

An assessment of the chemical and physical behavior of rubberized concrete (RuC) during natural carbonation exposure, freeze–thaw degradation and acid degradation (sulfuric and acetic acid (C2H4O2)) with two types of crumb rubber aggregates, is presented: crumb rubber (CR) containing only rubber; and fibers partially coated with crumb rubber (FCR). The mixtures studied with rubberized concrete reach the point of total substitution of stone aggregate (0/20/40/60/80/100 vol%). To analyze and understand the behavior of concrete, physical and mechanical properties have been also studied and related. Weight loss and ultrasonic pulse test were done throughout 3 months in rubberized concrete under accelerated attack, and strength variation recorded after the tests. As well, Scanning Electron Microscope images have been studied after the degradation processes tested. The use of CR and FCR reduces mechanical strength and increases porosity, but rubberized concrete with CR aggregates presents lower carbonation when volume is over 80% and strength reductions stability improves when FCR are used in freeze–thaw attack and under acid corrosion environments, as fibers improve matrix cohesion. Moreover, effectiveness of Ultrasonic Pulse Velocity (UPV) as a method to assess the stages of the attack and final resistance estimation is also indicated after the research results.