Effect of moist content on the bio-carbonated steel slag bricks

[Display omitted] •Carbonic anhydrase (CA) bacteria accelerate the carbonation process of steel slag.•Residual water-cement ratio (Re) value is crucial for the preparation of steel slag products.•Moisture content affects the diffusion of carbon dioxide, the carbonation reaction, hydration reaction and the survival of bacteria greatly. To deal with the problem of increasing serious environmental pollution caused by industrial solid waste such as steel slag, microbial carbonated steel slag bricks are studied in order to promote their utilization. Carbonic anhydrase (CA) bacteria are used to accelerate the carbonation process. The addition of CA bacteria improves the carbonation rate by accelerating the hydration of CO2. Water plays a significant role in the diffusion of CO2, the survival of bacteria as well as the carbonation reaction between carbon dioxide and the alkaline substance. The concept of residual water-cement ratio (Re) is adopted to study the influence of moisture content on the carbonation process of microbial carbonated steel slag bricks. Results indicate that a proper value of Re is vital for steel slag bricks to be well-carbonated. As Re decreases, the acceleration effect of bacteria on the carbonation process is weakened while the diffusion of CO2 is enhanced, as a result, the final carbonation depth decreases.