Response of Oyster Shell Ash Blended Cement Concrete in Sulphuric Acid Environment

An experimental investigation was carried out to study the potentials of oyster shell ash (OSA) to be used as supplementary cementitious material (SCM) exposed to sulphuric acid environment. Experiments were carried out by supplementing 5 – 20 % of OSA by weight of cement in concrete. The mix ratio used was 1:2:4 (binder, sand and granite) with water cement ratio maintained at 0.5. A total of 320 cube specimens (150mm x 150mm x 150mm) were cast and tested for compressive strength at 7, 14, 21 and 28 days of curing in potable tap water and (5, 7.5 and 10 %) sulphuric acid solutions. It has been deduced that the compressive strength of concrete specimen progressively increased with longer curing periods and decreased with OSA content for specimen immersed in water whereas for specimen immersed in sulphuric acid solutions the compressive strength decreased with longer curing period, OSA content as well as sulphuric acid content. Generally, results of the statistical analysis showed that sulphuric acid concentrations, OSA contents and curing periods have significant effect on the compressive strength of concrete. The use of OSA as SCM did not mitigate the adverse effects of sulphuric acid on the compressive strength of cement blended with OSA. Keywords: Compressive strength, Oyster shell ash, Statistical analysis, Sulphuric acid environment, supplementary cementitious material DOI: 10.7176/CER/11-4-07 Publication date:May 31st 201