Mechanical properties and stress-strain response of rubberised one-part alkali-activated concrete

This study investigates the effect of crumb rubber replacement of natural aggregates on the mechanical properties and stress-strain response, both monotonic and cyclic, of rubberised one-part alkali-activated concrete. The aluminosilicate precursors used are blast furnace slag (80%) and fly ash (20%), and the solid activator employed is sodium metasilicate anhydrous. Crumb rubber particles are used to replace both the fine and coarse natural aggregates by up to 60 vol.%, and the effect of such replacement on the compressive strength, splitting tensile strength, and flexural strength, is investigated. The monotonic and cyclic stress-strain responses of the rubberised specimens are also investigated. The results show a deterioration in mechanical properties as a function of rubber replacement of natural mineral aggregates. The elastic modulus and axial crushing strain also reduce with higher crumb rubber addition, while the descending stress-strain response shows higher softening with greater rubber replacement of natural aggregates. The normalized crushing energy and ductility of the rubberised mixes are observed to increase with higher crumb rubber replacement. The cyclic stress-strain response of the rubberised specimens falls within the monotonic stress-strain curves. The unloading modulus reduces with higher axial strain, whereas the plastic strain increases with higher axial strain indicating compressive damage accumulation with the increase in loading/unloading cycles.