The impact resistance effect of partially replacing coarse aggregate with ground-rubber aggregate in concrete

Abstract

The effect of ground-rubber used as aggregate on the impact resistance of concrete when partially replaced volume of mineral coarse aggregate (granite) was investigated. A total of six mix batches (using a mix ratio of 1:2:4 and a watercement ratio of 0.45) of concrete containing 0%, 5%, 10%, 15%, 20% and 25% ground- rubber aggregate by volume of granite were subject to impact resistance test using the Repeated Drop-weight Test method on circular concrete disc samples (150mm x 64mm). Fifty four (54) circular disc samples were cast for the impact resistance test after 14, 21 and 28 days of standard curing in water. The test results show that the density of the specimens at 28 days reduced by about 16%, having a value of 2072kg/m3 at 25% ground rubber content when compared to the control mix at 0%. The results also reveal that the incorporation of ground-rubber aggregate in concrete enhanced the impact resistance of the concrete greatly with the average no of blows to indicate failure ranging from 189 – 409 blows for 5 – 20% ground rubber content as compared to the control mixes, which had no ground rubber required an average of 106 blows at 28 days. The application could be practical if the rubber content is limited to a range of between 5-20% (Average of 13%) for structures which are exposed to impact loads in other to mitigate, minimize and dampen its effect on the structure. It is recommended for use in the construction of industrial floors.Keywords: Concrete, Density (Unit weight), Energy Absorption, Ground-Rubber, Impact Resistance, Toughness