Effect of Sulphate Salt and Acid on the Strength Properties of Waste Tire Concrete

The indiscriminate disposal of waste rubber tyres poses significant environmental challenges, necessitating the investigation of their potential reuse as construction materials. This study investigated the effect of sulphate salt and sulphuric acid on the strength properties of concrete incorporating waste rubber tyre (WRT) as partial replacement for coarse aggregate. The objective was to evaluate the compressive strength, water absorption, and abrasion resistance of WRT concrete exposed to aggressive acid and salt environments. A total of 336 concrete cubes of 100 x 100 x 100 mm were produced at replacement levels of 0%, 10%, 20%, and 30% by weight of coarse aggregate, and cured in 5% and 10% concentrations of sulphuric acid and sulphate salt for 7, 14, 28, and 90 days. The results indicated a progressive reduction in workability with increasing WRT content, with zero slump recorded at 30% replacement. Compressive strength decreased with increasing WRT content but increased with curing age up to 28 days, after which a decline was observed at 90 days due to prolonged exposure to the aggressive media. Notably, concrete with 10% WRT replacement exhibited slightly higher compressive strength than the control at 90 days in both acid and salt environments, suggesting enhanced resistance to long-term chemical attack at low replacement levels. Water absorption increased with both WRT content and curing age, with values being slightly lower in salt environments compared to acid environments. The addition of WRT at 10% replacement improved abrasion resistance, while higher replacement levels (30%) significantly reduced it. It is recommended that up to 10% replacement of coarse aggregate with WRT is suitable for use in concrete, particularly in environments susceptible to acid or salt attack, as well as in pavements where abrasion resistance is required.