Biochar as building and road materials
Harn Wei Kua
Abstract
Using biochar as an additive or partial cement replacement in concrete and asphalt is an emerging area of research and commercial development. Biochar affects the hygro-mechanical properties of these construction materials by modifying their microstructure as a result of changing the moisture distribution in them. Recent studies have revealed how the macro- and micro-porosity, permeability, particle size, shape, filler effect, and the “reservoir effect” afforded by biochar play major roles in this hygro-mechanical influence. An improved understanding of biochar enables us to apply it to enhance specific mechanical properties of concrete and asphalt, including the resistance toward chloride infiltration and accelerated carbonation of concrete as a strategy for carbon reduction in concrete. Given its versatile nature, the fact that it is a by-product of pyrolysis or gasification, and the relative ease for its properties to be economically modified, biochar will continue to play an important role as a sustainable and high-performance construction material.