Murali & Wong (2024) A comprehensive review of biochar-modified concrete: Mechanical performance and microstructural insights. Construction and Building Materials. https://doi.org/10.1016/j.conbuildmat.2024.135986

In the face of rapidly increasing global population and urban infrastructure demands, the construction sector’s rising greenhouse gas emissions pose a significant threat to climate stability. The production of cement, a critical component of concrete, is notably responsible for a substantial portion of CO2 emissions worldwide, accounting for approximately 5-7%. This situation calls for innovative solutions to reduce the carbon footprint of cement manufacturing, including the utilization of solid recyclables and by-products to create environmentally friendly alternatives. Among these, biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More (BC) has emerged as a promising material for enhancing the properties of concrete while sequestering carbon.

Biochar is produced through the pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More of biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More, such as agricultural residues and forest waste, in a low-oxygen environment. This process not only helps in reducing CO2 emissions by transforming biomass into a stable form of carbon but also improves the mechanical properties of concrete. Studies have shown that incorporating BC into concrete can accelerate the setting time, optimize the material’s density, and significantly increase its compressive strength. However, the impact of BC on fracture energy remains inconsistent across scientific literature.

The benefits of BC are attributed to its high carbon content, substantial surface area, and notable porosityPorosity of biochar is a key factor in its effectiveness as a soil amendment and its ability to retain water and nutrients. Biochar’s porosity is influenced by feedstock type and pyrolysis temperature, and it plays a crucial role in microbial activity and overall soil health. Biochar More. These properties contribute to increased cement hydration, reduced permeability, and enhanced resistance against the ingress of detrimental agents, such as chloride ions and oxygen, which can lead to rebar corrosion. The optimal BC content for concrete has been identified as 5%, which achieves desired density and mechanical strengths. Despite these advantages, there is a need for further research to systematically explore the influence of various types of BC on the microstructural properties of cement mortar and concrete.

This review underscores the potential of biochar as a sustainable solution for the construction industry, aiming to mitigate environmental impacts while improving material performance. As the sector continues to seek carbon-negative elements to enhance concrete’s sustainability, BC represents a step forward in addressing the urgent need for greener construction materials.