Impact of cleaning methods on the properties of cement mortars with cockle shell fine aggregates

Growing environmental concerns over discarded seashells and the depletion of natural aggregates have prompted extensive research into the use of waste seashells as alternative aggregates in cement-based composites to promote sustainability. Although several studies have employed cleaned seashells, residual contaminants on seashell surfaces may still compromise the durability and mechanical performance of these composites. To address this issue, this study investigates the effect of different cleaning agents and ultrasonic treatment on the performance of mortars incorporating cockle shells as fine aggregates. Various cleaning materials were employed to remove surface contaminants, and their effectiveness in cleaning, as well as the resulting mechanical behavior of the mortars, were evaluated. Compressive strength tests were performed to assess mechanical properties, whereas X-ray diffraction was used to characterize mineralogical composition. Ion chromatography was employed to evaluate the efficiency of the cleaning methods, and microstructural characteristics were examined using image-based techniques. The results show that mortars prepared with cockle shells cleaned using an anion exchange resin exhibit compressive strength comparable to that of control mortars. This finding demonstrates that thoroughly cleaned cockle shells can be effectively used as alternative fine aggregates in cementitious materials, thereby promoting more sustainable construction practices. • Thoroughly cleaned cockle shells can be used as alternative fine aggregates. • SN and AER effectively removed ion on the shell surface. • AER-cleaned shells gave mortars strength similar to control with natural sand. • Ultrasonic treatment had mixed effects depending on the cleaning agent used. • Effective cleaning of cockle shells improves mortar microstructural quality.