Improving thermal characteristics and energy absorption of concrete by recycled rubber and silica fume

Abstract

The two conventional disposal methods as landfilling and incineration of waste rubber raise environmental concerns. It is while burying rubber in concrete enhances flexibility and thermal properties due to its inherent ductility and insulation properties. In this study, a comprehensive approach has been adopted to investigate the effects of the amount and size of rubber particles combined with silica fume on the thermal characteristics, energy absorption, and mechanical properties of concrete, including its workability, specific weight, thermal conductivity, thermal performance, compressive strength, flexural strength, and flexural toughness. In addition, statistical analyses were conducted to evaluate the experimental results. It was observed that in concrete containing 50% fine or 50% coarse rubber aggregates combined with 15% silica fume, the thermal conductivity decreases by 45% and 43%, respectively. The energy absorption of concrete samples with 100% fine or 100% coarse rubber particles increased by 2.8 and 4.5 times, respectively, compared to those with 20% rubber. Appropriate equations were developed to estimate the compressive and flexural strengths of concrete with rubber particles while statistical analyses exhibited error levels of 11% and 15%, respectively, for such equations. The compressive and flexural strengths decreased by an average of 68% and 62%, respectively, in samples containing 100% crumb rubber. Likewise, these factors experienced an average reduction of 73% and 71%, respectively, in specimens with 100% rubber powder compared to those with 20% rubber.