Deterioration of Sustainable Hardened Concrete under High Temperatures and Sulphuric Acid Solution: A Laboratory Study

Natural sand extraction for concrete manufacturing is a global issue for ecological balance and environmental concerns. This study introduced three mixes with 3 newly developed sand types to replace natural sand in concrete manufacturing. Additionally, three more mixes were made by incorporating optimized 10% silica fume. The durability of the prepared mixes was evaluated at high temperatures of (150-750°C) at the interval of 150°C and against a 5% sulphuric acid solution immersion period of 28, 56, 91, and 182 days, respectively. The study's results reported the stability of the samples up to 300°C, and then the fall of the samples started at 450°C. Severe damage in the samples was formed at about 600°C, and finally, a total collapse was seen at 750°C. The mixes with optimized 10% silica fume content showed better resistance against 5% sulphuric acid solution than those without silica fume. The mix with sustainable TYPE 3-Sand combination (50% recycled sand + 45% desert sand + 5% crumb rubber) performed almost the same as the reference mix with TYPE 1-Sand (100% manufactured sand). The mix with TYPE 2-Sand (100% recycled sand) revealed inferior results, low stability, and high damage. Thus, 100% recycled sand is not recommended for structural concrete.