A SUSTAINABLE APPROACH TO THE CONSTRUCTION OF COASTAL FACILITIES THROUGH THE INCORPORATION OF BEACH SAND & BRACKISH WATER IN CONCRETE PRODUCTION

Abstract

Advances in reinforcement technology has facilitated the transition from traditional steel rebar to non-metallic rebar in reinforced concretes. Consequently, chloride content can be dramatically increased without worry for the deterioration of the encased reinforcement in reinforced concretes that utilizes composite rebar and polymeric/ceramic fibres. The production of one tonne of concrete releases 900 kg of CO2 emissions. Reductions in CO2 emissions from concrete production can be achieved through the production of ‘greener’ cements, and utilization of localized aggregate sources. Construction of structures along the coastline provides a unique opportunity for the utilization of beach-sand and brackish water that together can improve the sustainability prospects for construction in these environments. The incorporation into concrete of beach-sand that has been previously excavated is a simple means of reducing reliance on traditional sources of fine aggregate for concrete production. Additionally, the use of brackish water from a nearby estuary has the added benefit of reducing the requirement for potable water. Compressive strength tests were conducted on twenty-two (22) groups of specimens at 7-days, 28-days and 42-days. Water-to-cement ratios (w:c) of 0.37, 0.39, 0.43 and 0.45 were employed. Analysis showed that at 0.37 w:c, batches that utilized beach-sand and brackish water, beach-sand and potable water, concreting-sand and brackish water were comparable to those produced with concreting-sand and potable water at about 40MPa.