Investigating the mechanical and hydraulic properties of permeable concrete with binary combination of waste cockle, scallop and whelk shells

Abstract

The adoption of permeable concrete (PC) for pavement applications can mitigate the risk of flood events in urban areas, and the use of waste materials as a partial substitute for aggregate in concrete will play a significant role in decarbonising the construction sector. This paper presents an investigation conducted on PC incorporating crushed seashells as a substitute for natural aggregate. The experiments involved seven formulations, including a control mix, mixes with 20% aggregate replacement using crushed cockle, scallop, or whelk shells individually, and mixes containing binary combinations of the shells. The results show that the presence of seashells affects the mechanical properties of concrete, but the degree of influence depends on the type of seashell. The lowest compressive strength obtained in this investigation was 8.33 MPa, which is more than the minimum required for PC uses. The addition of seashells enhanced the void content and permeability performances of PC by up to 13% and 31%, respectively. This study presents the first investigation of binary combinations of seashells in PC production, demonstrating their potential to mitigate the limitations of individual shell types while enhancing permeability and reducing the environmental and climate impacts associated with natural aggregate exploitation and indiscriminate shellfish by-product disposal.