Forest-residue-derived constituents for low-carbon cementitious materials: evidence boundaries, quantitative trade-offs, and cold-region service qualification

Forest-residue-derived constituents are increasingly being considered for low-carbon cementitious materials, but their functions differ substantially and should not be treated as a single waste-substitution category. Wood ash may serve as a screened supplementary cementitious material or mineral filler, wood-derived biochar mainly modifies hydration and pore-water behavior at low dosage, and wood fiber acts primarily as crack-control reinforcement. This review compares these three material classes through their source-specific characteristics, quantitative performance ranges, and governing microstructural mechanisms. Direct evidence from wood-derived constituents is distinguished from mechanistic analog evidence from non-wood biomass ashes and lignocellulosic fibers. Published studies commonly examine wood ash at approximately 5%–20% cement replacement and biochar at low dosages, often at approximately 0.5–3 wt% of binder, while wood and related lignocellulosic fibers are generally used at low volume fractions. These ranges are screening values rather than universal design limits because performance depends strongly on processing, water demand, dispersion, interfacial behavior, and mixture composition. Cold-region exposure is considered a demanding service-qualification case rather than as a separate material theme. Freeze–thaw, salt exposure, and chloride transport are used to assess whether changes in pore-water distribution, air-void stability, interfaces, and crack connectivity remain beneficial under severe service conditions. The review concludes with a staged route from constituent characterization and mixture screening to mechanism verification, exposure-relevant testing, and field validation.