Sustainable use of sea sand and manufactured sand in concrete: Mechanical and durability insights

Abstract

In tandem with global urbanization and infrastructure development, the escalating demand for concrete has prompted a search for eco-friendly alternatives against the extraction of river sand for fine aggregate. This study investigates the use of blended sea sand and manufactured sand (M-sand) as an alternative to river sand in concrete, with a focus on mechanical properties and durability. In Stage 1, three control concrete mixes—comprising river sand (RS), sea sand (SS), and M-sand (MS)-were tested alongside blends in which M-sand replaced sea sand at 25%, 50%, and 75% proportions. Evaluations included particle size distribution, compressive strength, workability, and durability via accelerated corrosion and chemical exposure tests. Results identified the 50% sea sand–50% M-sand blend as the optimal mix. In Stage 2, this optimal blend was further assessed against RS and SS concretes for mechanical properties (elastic modulus, splitting tensile strength) and durability characteristics (water absorption, density, void content, and chloride penetration resistance). Stage 3 focused on determining a permissible chloride content for the blend using accelerated corrosion testing. A chloride threshold of 0.05% was established, at or below which the durability performance remained comparable to the control mixes. These findings highlight the potential of SS–MS blended concrete as a sustainable alternative to traditional fine aggregates in construction.