Mathematical modeling of CO2 uptake by concrete during accelerated carbonation curing

Abstract

Accelerated CO2 curing is a promising carbon capture and storage technology that can provide durable, pre-cast concrete products. A mathematical framework for predicting CO2 uptake and distribution during carbonation curing is presented, incorporating equations describing CO2 gas transport, dissolution in concrete pore water and reaction with cement compounds. The numerical simulations show that carbonation reaction of tricalcium silicate, the most abundant and reactive compound in cement, was the rate-controlling process for CO2 uptake. The specific surface area of compounds available for reaction determines the rate and extent of uptake. The 30-minute carbonation efficiency increased from 16.5% to 23% with a two-fold increase in the total specific surface area. The rate of CO2 uptake by cement doubled with a two-fold increase in CO2 gas partial pressure, but the extent of carbonation did not change significantly due to the formation of solid carbonation products on reactive surfaces and in the pore space.