Preliminary study on the application of waste bivalve shells as biofiller for the production of asphalt concrete

The shells of molluscs are a common by-product of the aquaculture industry, and their management represents a significant environmental challenge. Although mollusc farming is considered a low-impact food production, improper shell management could make bivalve farming less environmentally efficient. To address this issue, research is exploring new approaches to reduce waste accumulation and convert shell waste into a valuable resource. The shells of bivalves are functional materials from biological waste, composed mainly of CaCO₃, and can be used as secondary raw materials in various applications. In order to meet the demanding environmental target, the road sector is increasing the use of recycled materials in new construction or maintenance of old ones. The present work illustrates the results of several laboratory tests carried out to determine the physical and chemical properties of three different crushed bivalve shells waste for the application as filler in asphalt concretes. The present study highlighted the similarity of these materials with the limestone filler since no significant discrepancy between the mechanical (or technical) performance of the biofiller and the traditional limestone filler are detected through the test carried out, promoting their use in new asphalt concrete mixtures.