Evaluating preamble clay bricks for mitigating urban heat Island effects and stormwater pollution

Abstract

Urban Heat Island (UHI) effects and stormwater pollution are pressing challenges confronting modern urban environments. Permeable clay bricks (PCBs) have emerged as a promising sustainable solution to address these issues simultaneously. Despite their potential, significant knowledge gaps remain regarding the dual functionality of PCBs in mitigating UHI effects and improving stormwater quality through pollutant removal. This study aims to evaluate the effectiveness of PCBs in reducing UHI impacts and enhancing stormwater treatment, contributing to a deeper understanding of their role in sustainable urban design. Porous PCBs were manufactured using locally sourced clay soil and sawdust from Saudi Arabia. Heat absorption tests of the PCBs were conducted under natural conditions and compared with those of conventional concrete bricks, while pollutant removal from stormwater was evaluated through laboratory-scale filtration experiments. PCBs manufactured with 10% sawdust yielded sufficient compressive strength (20.1 MPa), bulk density (2.48 g/cm3), porosity (40.5%), water absorption (18.3%), and permeability coefficient (0.042 cm/s) for use as pedestrian and light traffic paving bricks. In thermal performance tests, PCBs exhibited the lowest near-surface temperatures, with a 1.2–2.2 °C reduction compared to conventional concrete bricks. The relative cooling performance index (CPI) of PCB ranged from 0.33 to 5.0, indicating superior thermal efficiency and reduced heat retention. Laboratory-scale filtration tests revealed that PCBs effectively removed over 99% of suspended solids (SS) and turbidity, more than 65% of chemical oxygen demand (COD) and biological oxygen demand (BOD), 30% of total nitrogen (TN) and total phosphorus (TP), and 56–100% of various metal pollutants from stormwater runoff. PCBs provide a dual-function solution by reducing urban heat and enhancing stormwater quality, making them a promising and sustainable material for urban development.