Accelerated carbonation of biochar reinforced cement-fly ash composites: Enhancing and sequestering CO₂ in building materials

Biochar produced from the pyrolysis of corn stover biomass was added as a filler material in the cement-fly ash blocks as 2%, 4%, 6% and 8% of total weight. The resultant blocks were subjected to two hours mineral carbonation at (3 day) after demoulding to enhance the CO₂ uptake and sequester carbon in the blocks. Along with that, 28 days compressive strength of un-carbonated blocks was determined to gauge the effect of biochar as the filler material on the strength of the specimens. Results showed that there was an enhanced CO₂ uptake on 3 days compressive strength and biochar dosage was optimised at 4% and 6% depending on the chosen mix. The 28 days compressive strength of un-carbonated blocks showed that there was an increase in the strength as biochar addition increased to a certain extent, however, thereafter it decreased with the further addition of biochar.