keywords: Concrete, durability, waste tyre ash, deterioration, aggressive media
This paper presents the findings of an investigation into the durability assessment of Waste Tyre Ash (WTA)-concrete in acid and salt media. The WTA used was obtained by open burning of waste tyre slices sieved through 75 µm BS sieve and characterized. The ash was subjected to chemical composition analysis using the X-Ray fluorescence (XRF) analytical method. The investigation was carried out using concrete of 29 N/mm2 compressive strength, water-cement ratio (w/c) of 0.65 and slump range of 10 – 50 mm. The durability assessment was conducted for water absorption by WTA-mortar of (1:3) ratio and concrete at WTA replacement levels of 0, 5, 10, 15, 20, 25 and 30% of cement weight, respectively, to determine the influence of WTA on resistance of concrete to acids (H2SO4, HCL) and salt (MgSO4) and also on the water absorption by mortar. A WTA-Cement: sand mortar of 1:3 mix by weight of cement and WTA was used with a water/cement ratio of 0.5. Mortar was cast in steel cube moulds of 100 mm and cured for 28 days. The WTA- concrete of mix 1:2:4 was also cast in steel cube moulds of 100 mm in accordance with BS EN 12390 – 3 (2009). At the end of every curing regime, three samples were air dried, then weighed before immersing in 5 percent concentration of diluted solutions of the stated acids and salty media at 7 days interval until the 28th day to determine the weight of the samples after the acid/salt degradation. Results indicated that water absorption increased with increase of WTA content implying that WTA-mortar absorbed more water as the ash content increased. The resistance to deterioration of WTA-concrete reduced with increase in the curing ages. The study demonstrated that concrete with WTA offered better resistance to deterioration by HCL than OPC concrete. Sulphuric acid was the most-aggressive to WTA-concrete followed by Magnesium Sulphate (MgSO4) and lastly Hydrochloric acid (HCL). The use of WTA content as partial substitute of cement in concrete is recommended for enhanced resistance of concrete in hydrochloric acid and magnesium sulphate environments. However, this is not recommended in Acidic medium with H2SO4.