Experimental analysis of treated waste foundry and waste ceramics sand by replacement of fine aggregate in concrete

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.