Effect of elevated temperature on the properties of silica fume and recycled rubber-filled high strength concretes (RHSC)

This paper presents the influence of temperature on the compressive strength of HSC with silica fume and containing different ratios and sizes of recycled tire rubber. The aims of including elastomeric material in a cementitious matrix are reducing the stiffness of HSC in order to make it compatible with other materials of the building, recycling of solid wastes and improving fire resistance. The inclusion of low mass fraction recycled rubber reduces the high risk of explosive spalling of HSC under high temperature because water vapour can exit through channels where the polymeric material gets burned. Two groups of concrete were employed to carry out this study. The first group consists of four mixes produced with a cement content of 500 kg, 0.3 water–binder ratio, gravel as coarse aggregate and 0%, 10%, 15%, and 20% silica fume (SF) replaced of cement weight. The concrete formulation of the second group (four mixes) was produced with the replacement of cement by 20% SF along with 0%, 3%, 5% recycled fine rubber (2 mm) and 3% coarse rubber (5 mm). Dolomite as a coarse aggregate was used in the second group in order to improve the performance of concrete mixtures containing rubber under high temperature. The results obtained show high resistance to fire with increasing SF content up to 20% replacement of cement. Additional improvement was obtained with using dolomite and 3% of recycled rubber (2 mm, 5 mm)