Modification of carbonation-cured cement mortar using biochar and its environmental evaluation

Despite being considered as a potential carbon capture method, carbonation curing of cement-based materials are still accompanied by serious concerns now. Strength loss and shrinkage can be induced by pre-conditioning and excessive carbonation exposure; Difficulty of inward diffusion of CO₂ leads to relatively low total carbonation degree. In this work, biochar prepared from corn straw at various pyrolysis temperature was added in cement mortars with dosages of 1–5% to solve these above issues. The results indicate that addition of biochar compensates for the strength loss and increase in water penetration of cement mortar caused by carbonation curing. It was also found that biochar-blended cement mortar possesses improved pore structure and promoted internal CO₂ uptake of cement mortar. Besides, environmental evaluation shows that the combination of carbonation curing and biochar can reduce the carbon footprint and energy consumption of concrete products effectively.