Synergistic effects of rubber-tire-powder and fluorogypsum in cement-based composite

Currently, the use of waste materials in Portland cement mixtures and the reduction of the use of clinker is important due to environmental issues. One of the waste materials of importance for the scientific community is end-of-life tires, because there are millions of tires in landfills; however, there are other materials in similar circumstances such as fluorogypsum. In this study, the effect of incorporating two waste materials (rubber-tire-powder and fluorogypsum) was studied in a Portland cement mixture diluted with CaCO3. The remnant of H2SO4 contained on the surface of fluorogypsum is an option to chemically treat the surface of the tire particles and improve their interaction with the cement matrix. The characterization of the chemically treated material, the hydration evolution and the physico-mechanical properties were evaluated. In the hydration process, it was observed that a low fluorogypsum content slightly accelerated the cement reactions, while the rubber-tire-powder inhibited them. Regarding the cement-rubber mixture, the cement-rubber-fluorogypsum mixture had a recovery of 28.3 % in the compressive strength and 36.0 % in the modulus of elasticity. The results of this research show that using the two waste materials simultaneously is advantageous because it improves the properties of the cement-tire and avoids the use of other surface treatments. This makes it possible to obtain a more ecological and relatively cheaper cementitious material than with the application of other surface treatments on the rubber-tire particles.