How does the use of recycled aggregate in concrete bins impact their durability?

The use of recycled aggregate in concrete bins presents both opportunities and challenges for durability. Recycled aggregate, sourced from crushed construction and demolition waste, can reduce environmental impact and material costs. However, its incorporation affects key durability factors. The primary concern is water absorption; recycled aggregate tends to be more porous than virgin aggregate, which can increase the concrete's permeability. This higher permeability may lead to reduced resistance against freeze-thaw cycles and easier penetration of chlorides or sulfates, potentially accelerating corrosion of any embedded steel and compromising structural integrity over time. The strength of the bond between the recycled aggregate and the new cement paste is also critical, as it influences crack resistance and overall load-bearing capacity. To mitigate these issues, precise mix design is essential. Techniques include using a lower water-to-cement ratio, employing supplementary cementitious materials like fly ash, or limiting the percentage of recycled aggregate. Proper processing of the recycled material to remove contaminants is equally crucial. When optimized, concrete bins made with high-quality recycled aggregate can achieve satisfactory durability for many non-structural or light-structural applications, contributing significantly to sustainable construction practices by conserving natural resources and diverting waste from landfills.