Multi‐objective optimization of green concrete incorporating recycled plastic and sawdust waste as fine aggregates using response surface methodology

Abstract This study investigates the development of Green Normal Concrete (GNC) by incorporating plastic waste aggregates (PWAs) and sawdust waste (SDW) as partial replacements for natural sand (NS). The research follows three experimental stages using Response Surface Methodology (RSM) and the Absolute Volume (AV) method to optimize compressive strength, workability, and density. Stage I establishes a normal concrete (NC) control mix based on British standards. Stage II examines the effects of replacing NS with gray and black ABS plastic granules (GABSR and BABSI), identifying the optimal mix (OPW) with 0.04% NS‐GABSR and 24.11% NS‐BABSI, achieving 20.50 MPa compressive strength, 25 mm workability, and 2276 kg/m 3 density. Stage III introduces sawdust (SDF) as a fine aggregate replacement in OPW, with silica fume (DSF) and superplasticizer (SP) enhancing performance. The optimal mix (OPWSD), with 60.32% BABSI‐SDF and 20.01% NS‐SDF, achieves 25.10 MPa compressive strength, 124.21 mm workability, and 2055 kg/m 3 density. The results highlight the feasibility of PWAs and SDW in concrete, emphasizing the need for further studies on long‐term durability and environmental impact.