ABSTRACT
Concrete is by far the most used building material in the construction industry. Concrete constitutes of mainly, cement, water and aggregates. It is common practice to use potable water for concrete, however in South Africa a shortage of water has become an issue of concern. Other sources of water should hence be investigated. Seawater as a source of water to produce concrete is to be investigated. This paper aims to investigate the effect of simulated seawater on the compressive and tensile strength of concrete when used as a substitute for fresh potable water during both the mixing and curing stages. Samples were tested at 7, 14, 28, 56 days. Samples was mixed with CEM I and CEM II + 10% Fly Ash (FA). Depending on the concentration of alkaline in the sea water, strength can either be stronger than usual at 28 days but drop linearly at 56 days, a low concentration of alkaline leads to concrete strength being significantly lower than usual throughout all testing periods. Although long term effects found in literature such as carbonation (Diab, et al., 2011), sulphate attack (Mathers, 2009), carbonates and bicarbonates (Mathers, 2009) and alkalis (Guo, et al., 2018) might be a problem when mixing and curing concrete with simulated seawater, the results in this study shows that normal water can be replaced with seawater if the steel is sufficiently protected against corrosion and a solution can be found to overcome the long term effects of mixing and curing with seawater.
