Experimental study on properties of green concrete containing wood ash, silica fume, fly ash, and plastic waste

This study aims to investigate the use of waste material combinations to produce sustainable concrete. Wood ash (WA), silica fume (SF), and fly ash (FA) were used as partial replacements for cement in normal cement concrete (NCC), self-compacting concrete (SCC), and lightweight self-compacting concrete (LWSCC). Waste plastic aggregates partially replaced fine and coarse aggregates in LWSCC. Twenty mix designs were tested for flowability and mechanical properties. In NCC, 10% SF replacement maximized the compressive, splitting tensile, and flexural strengths. Increasing the FA (0-30%) and WA (0-15%) contents reduced the strength, although the reductions were relatively small and acceptable. In SCC, increasing the WA (0-15%) with 10% SF and 20% FA slightly reduced the strength. Meanwhile, the addition of WA to SCC reduced the flow properties. However, all flow properties met the guidelines developed by the European Federation of National Associations Representing Concrete (EFNARC), and no visible blocking was observed during the flow characteristics test. LWSCC incorporated 25-100% plastic powder, 5% WA, 10% SF, 20% FA, and 30% plastic aggregates. Increasing plastic powder reduced strength, flowability, and density (below 1950 kg/m³); however, all mixes remained within EFNARC limits. This study demonstrates the potential utilization of waste materials in concrete, reducing cement and natural resource consumption and offering significant environmental benefits.