Oyster shell concrete durability in marine environment

Each year, 6.6 million tons of oysters are produced worldwide, representing an important amount of waste that can be valorized in cementitious materials. In particular, oyster shell co-products can replace coarse aggregates up to a 50% volume replacement in load-bearing concrete. There is a lack of knowledge on the durability properties of oyster-based concrete, particularly in marine environments.

This paper aims to study the durability properties of oyster-based concrete in marine environments, using durability indicators from a performance-based approach, such as porosity accessible to water, air permeability, chloride diffusivity, and resistivity. Results show that oyster-based concretes present a higher porosity than reference concrete, including increased capillary pore volume in cement bulk paste and pores at the Interface Transition Zone (ITZ), between aggregates and cement paste. Oyster-based concretes have better chloride resistance than reference concrete, which can not be explained only by the potential barrier effect due to the shape of oyster aggregates, and that could be due to a potentially higher chloride binding in oyster-based concrete.