إعادة تدوير مخلفات البناء لتحويل التحديات البيئية إلى فرص هندسية واستخدامها كمواد أساسية في الخرسانة

Abstract

Construction and demolition waste presents significant environmental and economic challenges, particularly with increasing quantities resulting from demolition, wars, and natural disasters. These effects are further compounded by the depletion of natural resources required to produce new construction materials and the rising costs associated with waste disposal. However, when properly managed, such waste can be transformed into valuable engineering and economic opportunities.

This study investigates the feasibility of recycling demolished concrete as a substitute material in concrete mixtures to produce acceptable-quality concrete and reduce reliance on conventional raw materials. The research involved testing the properties of recycled coarse aggregate and evaluating its impact on concrete mix performance. Four mixes were prepared with varying replacement ratios of recycled aggregate (30%, 50%, 70%, and 100%) and compared with a reference mix containing 0% recycled aggregate.

The results were generally positive for both fresh and hardened concrete. Mixes with 30%, 50%, and 70% replacement showed satisfactory slump values (2–10 cm), indicating good workability. However, the 100% replacement mix exhibited poor workability due to the high water absorption of recycled aggregate, which also led to a 12.5% reduction in 28-day compressive strength compared to the control mix. In contrast, the 30%, 50%, and 70% mixes showed minor reductions in compressive strength (6.25%, 8.75%, and 9.3%, respectively), suggesting their potential use in structural applications.

This study demonstrates the potential of using recycled aggregate as a partial replacement for natural coarse aggregate in concrete production, providing a sustainable solution for construction waste management while maintaining acceptable performance standards.