Abstract
The over-extraction of river sand in Sri Lanka has reduced alluvial reserves in major basins by over 40% between 2010 and 2023, highlighting an urgent need for sustainable alternatives. This study presents the first comprehensive comparative analysis of four distinct sand typesriver (Polonnaruwa), sea (Muthurajawela), dune (Kandakuliya), and estuary (Kalutara)-using integrated physical, chemical, and mechanical evaluation. Tests included sieve analysis, chloride content measurement via Volhard’s method, and strength assessments at 7 and 28 days. Results showed that river and dune sands achieved compressive strengths exceeding 30 MPa and contained low chloride levels (<500 mg.kg-1), aligning with international standards for structural concrete. Although sea sand’s chloride content was high (1,796 mg.kg-1, 259% above limit), it could be viable if properly treated. Estuary sand reached 29.3 MPa strength but had borderline chloride levels, restricting its application. Failure mode analysis indicated strong structural performance for river and dune sands, whereas sea and estuary sands exhibited brittle failure patterns. Overall, processed dune sand and treated sea sand are promising substitutes for river sand, promoting sustainability. Ensuring chloride regulation and advancing treatment technologies are essential for successful adoption.