Characterization of Clay and Sand Bivalve (Corbula trigona) Shells for the Design of a Building Material

Portland cement is a high-performance construction material widely used in the building industry. However, its high cost and the environmental pollution associated with its production have prompted the search for cost-effective and environmentally friendly alternative materials. Several studies have investigated the use of bivalve shells (e.g., clams, mussels, and oysters) as partial or complete substitutes for Portland cement in construction materials. The aim of this study is to valorize Corbula trigona bivalve shells, clay, and sand for the development of a sustainable construction material. To this end, the clay and bivalve shells were ground to a particle size of 80 μm and calcined at 700？C and 900？C, respectively. The raw materials, together with the sand, were then characterized to evaluate their suitability for mortar production. The characterization results showed that the sand had a 0/4 particle-size distribution, a sand equivalent value of 85%, a bulk density of 1.54 g/cm³, and a specific gravity of 2.55 g/cm³. X-ray fluorescence (XRF) analysis revealed that the sand contained approximately 95 wt.% SiO₂. XRD and IR analysis show that the clay is mainly composed of kaolinite and the TGA/TGA curve on the bivalve shells shows that the formation of CaO from CaCO₃ ends at a temperature of about 800？C, while the dehydroxylation of the clay ends at a temperature above 600？C. These results highlight the potential of these raw materials for future mortar design.