Due to rapid urbanization and industrialization, excessive exploitation of natural resources like river sand and gravels is a major concern. This study investigated the use of waste foundry sand and waste ceramics as partial replacements for M-sand in concrete. M25 grade concrete with a 1:1.1:2.2 ratio and a water-to-cement ratio of 0.45 was used. Waste foundry sand underwent pre-treatment with sodium silicate to improve its applicability. Treated waste foundry sand (TWFCS) and 10% powdered waste ceramics were combined to partially replace M-sand in different proportions (0%, 10%, 15%, and 20%). Mechanical tests, including compressive, tensile, and flexural strength assessments, were conducted after 7, 14, and 28 days of curing. The concrete samples were exposed to a marine and acidic environment for 60 days. TWFCS 3 exhibited the lowest compressive strength (26.39 N/mm²) after exposure to an alkaline environment, while TWFCS 1 showed the highest compressive strength (28.63 N/mm²). Treated foundry sand showed superior mechanical properties, surpassing M-sand by 15% in terms of compressive, split tensile, and flexural strength. SEM and XRD analysis were used to evaluate the concrete containing treated waste foundry and ceramics sand.

Keywords: Treated waste foundry sand, Waste ceramics sand, Characteristics analysis, SEM analysis and XRD analysis