Mechanical Properties of Waste Tyre Ash (WTA) Concrete

Abstract

In this study, effect of Waste Tyre Ash on the mechanical properties of concrete was investigated. The WTA used was obtained by open burning of waste tyre slices to a temperature of about 500oC for about five (5) hours at the local open burning sites in Kano, it was then allowed to cool and sieved through 75 μm and characterized using X-Ray Fluorescence (XRF). The effects of WTA on cement paste and concrete were investigated at replacement levels of 0, 5, 10, 15, 20, 25 and 30%, respectively by weight of cement. The workability of fresh normal concrete and WTA - concrete were determined at fresh state and hardened concrete tested for compressive, splitting tensile and flexural strengths, respectively at curing ages of 3, 7, 28, 56 and 90 days in accordance with standard procedures. The results of the investigations showed that the WTA was of low reactivity with a combined SiO2, Al2O3, and Fe2O3 content of 40.2%. Since the oxide composition is 70%, it cannot be used as a pozzolanic material. The workability significantly decreased with increase in WTA content at constant water – binder ratio. For increased WTA – content, the compressive, splitting tensile and flexural strengths of concrete initially increase up to 15% WTA replacement level for the compressive strength and 20% WTA replacement for the splitting and flexural strengths, respectively. Thereafter, all the strengths decrease with increase of WTA content. The 28 days compressive strength of WTA – concrete with up to 20% WTA content was equal to or higher than the characteristic strength of the concrete used (or targeted) and 10–15% would be considered as the optimum percentage replacement.