Use of tire rubber particles as addition to cement paste

The surface modification of powdered tire rubber to increase its adhesion to cement paste was studied. The particles were surface-heated with NaOH saturated aqueous solutions for 20 min. Scanning electron microscopy (S.E.M.), water absorption, density, flexural strength, compressive strength, abrasion resistance, modulus of elasticity and fracture energy measurements were performed using test specimens (water/cement ratio = 0.36) containing 10% of as-received or 10% of NaOH-treated rubber The results of fracture energy and flexural and compressive strength show that the addition of rubber particles improves the toughness and reduces the porosity of the specimens. Mass loss by abrasion (- 1.2 +/- 0.4% for control specimens; - 1.7 +/- 0.4%, using treated rubber and - 4.0 +/- 1.2% using as-received rubber, after 600 cycles) and electron microscopic examination show that the NaOH surface treatment enhances the rubber-matrix adhesion. The use of thus treated tire rubber particles, as addition, instead of a coarse aggregate, in cement-based materials is promising for applications such as driveways or in road construction. (C) 2000 Elsevier Science Ltd. All rights reserved.