Novel use of waste sawdust in green stormwater infrastructure (GSI)

• GSI elements can use low-strength concrete made with eco-friendly alternative materials. • Use of sawdust in concrete aggregates was studied for use in GSI applications. • Up to 15 % sawdust (v/v) produced concrete strong enough for non-structural GSI elements. • Concrete with 25 % sawdust absorbed over 3 % water, aiding GSI moisture retention. • Sawdust made concrete lighter, more absorbent, with moderate strength reduction. As urban populations grow, finding appropriate strategies for managing waste and stormwater is becoming increasingly more challenging. While the incorporation of waste materials into concrete has been studied for structural components, the use of waste materials in green stormwater infrastructure (GSI) is underexplored. Unlike load-bearing structural components, non-structural elements in GSI applications (e.g., stormwater planters, bioswales, curbs, infiltration trenches) do not need to meet conventional structural strength requirements and can be manufactured by incorporating alternative materials. This study investigates the feasibility of incorporating sawdust—a biodegradable, lightweight, and widely available waste byproduct—into concrete aggregates for non-load bearing GSI components such as bioswales, curbs, and infiltration trenches. Concrete samples were prepared by replacing sand with sawdust at 5 %, 10 %, 15 %, and 25 % by volume. To evaluate their suitability for GSI applications, the samples underwent compressive strength testing, water absorption analysis, and visual inspection of fracture behavior. The results showed that increasing sawdust content led to a reduction in compressive strength and unit weight, with the most significant strength loss observed at 25 % replacement. However, mixes with up to 15 % sawdust retained sufficient strength for non-structural use. Water absorption increased with sawdust content, with the 25 % mix absorbing over 3 % of its dry weight after 24 h, indicating enhanced porosity and moisture retention—desirable traits for GSI. Additionally, fracture patterns shifted from brittle to more ductile behavior as sawdust content increased. These findings indicate that sawdust-enhanced concrete offers a promising, sustainable alternative for GSI applications, contributing to waste reduction, resource efficiency, and improved stormwater management in urban environments.