Eco-friendly hollow mortar bricks using pine needles for sustainable construction

The construction sector is under increasing pressure to reduce its environmental footprint caused by conventional materials such as fired clay bricks and cement, which contribute significantly to greenhouse gas emissions and natural resource depletion. This study investigates the development of eco-friendly solid and hollow mortar bricks by incorporating pine needles into a standard 1:4 cement-to-sand mortar mix. Pine needles, a forest biomass waste that contributes to wildfire hazards, were used at dosages of 1.0%, 1.5%, and 2.0% by weight of cement in a 1:4 cement-sand mortar mix. The prepared bricks were evaluated for compressive strength, water absorption, and density under both normal and accelerated curing conditions. Results indicated that bricks with 1.5–2.0% pine needle incorporation demonstrated enhanced strength and reduced weight, with hollow bricks achieving a maximum compressive strength of 18.62 MPa after 28 days of accelerated curing. To demonstrate practical applicability, a pilot-scale constructed wetland was designed using the hollow bricks, enabling natural wastewater treatment through a decentralised system. This innovative application demonstrated the effective integration of eco-friendly bricks into sustainable infrastructure. The study highlights a dual-benefit approach transforming pine needle waste into a value-added construction material while reducing wildfire risks and advancing green wastewater treatment solutions.