Biochar waste biomass in pervious concrete

Urbanization has brought significant improvements to the quality of human life; however, associated construction activities have led to several global concerns, such as climate change, flash floods, and urban heat islands. Pervious concrete has been regarded as one of the promising solutions for stormwater management and mitigation of the urban heat island effect. However, pervious concrete still contributes significantly to climate change issues due to the use of cement, a material known for its high carbon footprint, in its mixture. Hence, various decarbonization approaches used in concrete have been applied to pervious concrete, such as the utilization of industrial by-products or wastes into the mixture. Recently the incorporation of biochar in pervious concrete has gained significant interest. However, its investigation remains scarce, providing limited insights. Thus far, biochar is mainly added to pervious concrete as a cement replacement material and as an additive, with its impacts on pervious concrete’s properties, namely mechanical strength, porosity, permeability, water absorption, and albedo, discussed. Recent investigations indicate that the addition of biochar in pervious concrete as a cement replacement material tends to improve the mechanical strength of pervious concrete at low dosages, but it has no significant impact on its permeability and water absorption. Unfortunately, it may exacerbate the urban heat island effect as it reduces the albedo of pervious concrete. Conversely, incorporating biochar in pervious concrete as an additive can increase the mechanical strength due to the refinement of pore structure. However, this would reduce its porosity, thereby influencing its benefits in stormwater management. Thus, the addition of biochar in pervious concrete is highly dependent on its application, and more in-depth investigations are required to fully understand its impact on pervious concrete.