Influence of sawdust on the mechanical behavior of C28 concrete containing ground glass

Recent studies have explored partial substitutions of fine aggregates in concrete with various materials to mitigate environmental impacts.This study aims to evaluate the effect of wood sawdust on the fresh and hardened properties of C28 concrete with an optimum proportion of ground glass and to address the environmental benefits. A control mix was designed to achieve a minimum required strength of 28 MPa with a constant water-cement ratio of 0.47. Ground glass (GG) was used at proportions of 10%, 20%, and 30% as a replacement for fine aggregates to identify the optimal level based on mechanical strength tests. The optimal GG proportion was then combined with different sawdust (S) ratios of 10%, 15%, and 30% for final evaluation. A total of 216 concrete samples were prepared to assess hardened properties. The workability of the concrete mix remained constant, but the unit weight and temperature decreased as the proportion of fine aggregate replaced by ground glass increased. The optimal crushed glass combined with varying sawdust ratios exhibited consistent workability, with minimal changes in unit weight and temperature, remaining within acceptable limits of international and Peruvian standards. The ideal combination of 20% ground glass and 10% sawdust enhanced mechanical properties, achieving a 2.65% increase in compressive strength, 1.68% in flexural strength, and 6.51% in modulus of elasticity. However, tensile strength decreased by 3.18% after 28 days of curing. These results indicate that replacing fine aggregates with local materials like ground glass and sawdust marginally improves short-term mechanical properties. The optimal mix design of 20% GG and 10% S shows promise as a fine aggregate substitute, with a 14.87% reduction in virgin material usage.