Properties of Concrete Containing Ground Waste Cockle and Clam Seashells

Seashells from marine by-product are potentially used in concrete as partial replacement of cement or fine aggregates substitute. The shells generally have high calcium content (CaO) which can improve the concrete physical and mechanical properties. In this research, two types of shells, namely cockle/blood clam (Anadara granosa) and marsh clam (Polymesoda expansa) were burnt and ground as powders to be used as the cement replacement. The shells were ground and replaced the cement at 4% by weight. Specimens were prepared from three different mixtures, i.e. Ordinary Portland Cement (OPC) as a control mix, concrete contains ground marsh clam (OPC Clam) and blood clam concrete (OPC Cockle). Setting time, density, compressive strength, tensile strength of the concrete mixtures were determined for each mixture. Test results indicate that the replacement of cement using different type of shells could yield to different concrete performance. Setting time, density, compressive and tensile strength of the OPC Cockle concrete are considerable lower than the OPC concrete up to 91 days. However, the OPC Clam concrete performed faster setting, higher density, higher compressive and tensile strength than the OPC concrete. Therefore, the CaO content of different type of seashells has the possibility of influencing the physical properties and strength development of concrete.