Process modeling guides operational variables that affect CO₂ utilization during the accelerated carbonation of concrete

Accelerated concrete carbonation is an expanding option for decarbonizing construction. Factors such as concrete mixture design and carbonation environment can influence the maximum CO2 utilization that can be achieved during such a process. A carbonation process designed to utilize a water-saturated dilute CO2 source wherein 2 < CO2 concentration (v/v%) < 16, was modeled in AspenPlus (c). A regression model was developed to correlate CO2 uptake, relative humidity (11%-100%), CO2 concentration ([CO2] = 2-16 v/v%), and temperature (T = 11-74 degrees C) conditions within a carbonation reactor. It was determined that [CO2] was the most significant variable as higher concentrations enhanced CO2 transport through the concrete. The energy use intensity per mass of CO2 utilized (kWh/kgCO(2)) was determined across a range of processing conditions. As a function of the operational conditions, accelerated carbonation provides a net CO2 reduction of up to 28 kgCO(2)/tonne of concrete; a reduction of up to similar to 45% compared to typical formulations.