Assessment and development of high-performance fibre-reinforced lightweight self-compacting concrete including recycled crumb rubber aggregates exposed to elevated temperatures

Recycled crumb rubber is a material created by grinding and commutating used tyres. There is no doubt that the increasing piles of tyres create environmental concerns. The long term goal of this paper is to find a means to dispose of the crumb rubber in lightweight self-compacting concrete (SCC) and still provide a final product with good engineering properties. This paper has considered replacement of natural normal-weight aggregates with crumb rubber aggregates and lightweight scoria aggregate together with the addition of macro fibres which provides a sustainable alternative which assists in minimizing the environmental damages associated with the disposal of waste tyres. Also, the purpose of this study is to determine the effect of fibres on fresh and mechanical properties in additional to the performance of the concrete after exposure to elevated temperatures. Investigation has been performed after concrete exposure to both room and elevated temperatures. Fibre reinforcement were added to a control mix containing 80% replacement of traditional coarse aggregate with lightweight scoria aggregate and 20% replacement of traditional fine aggregate with crumb rubber aggregate. Steel and polypropylene (PP) fibres were explored so as to ascertain the benefits each fibre can provide through a range of temperatures. Nine mixes were prepared; a control mix and four mixes per each fibre with increasing fibre addition. Chemical admixture dosages were adjusted so as to achieve the desired slump flow. Experimental program investigated the fresh properties of the SCC through slump flow, slump flow T500 and J-ring tests. Mechanical properties were investigated after 28 days curing, standard 100 x 200 mm cylinder specimens were subjected to compressive and indirect tensile tests after exposure to 25, 100, 300, 600 and 900 degrees C. Compiled results will be compared to those of the control mix. (C) 2018 Elsevier Ltd. All rights reserved.