Reusing Demolished Concrete Waste in Pressed Concrete Brick Production

The rapid increase in construction and demolition waste (C&DW) has raised significant environmental concerns, particularly in fast-developing regions like Saudi Arabia. This study investigates the potential of incorporating C&DW as a partial or full replacement for natural aggregates in the production of pressed concrete bricks. A total of 20 mix designs were prepared using varying C&DW replacement levels (0,25,50, 75, and 100%), two pressing loads (15 MPa and 25 MPa), and two water-to-cement (W/C) ratios (0.35 and 0.45). Silica fume was also added as a supplementary cementitious material to enhance mix performance. The physical and mechanical properties of the samples, including compressive strength and density, were evaluated. The results demonstrated that increasing the replacement level of C&DW generally led to a decrease in density due to its higher porosity. However, higher pressing loads and W/C ratios significantly improved compressive strength, especially at high replacement levels. Notably, the mix with 100% C&DW, 25MPa pressure, and 0.45 W/C ratio achieved the highest compressive strength, suggesting that optimized compaction and water content can effectively mitigate the potential drawbacks of using recycled aggregates. This research supports the feasibility of C&DW in sustainable brick production and contributes to circular economy efforts in the construction sector.