On the Theoretical CO2 Sequestration Potential of Pervious Concrete

Pervious concrete, which has recently found new applications in buildings, is both energy- and carbon-intensive to manufacture. However, similar to normal concrete, some of the initial CO₂ emissions associated with pervious concrete can be sequestered through a process known as carbonation. In this work, the theoretical formulation and application of a mathematical model for estimating the carbon dioxide (CO₂) sequestration potential of pervious concrete is presented. Using principles of cement and carbonation chemistry, the model related mixture proportions of pervious concretes to their theoretical in situ CO₂ sequestration potential. The model was subsequently employed in a screening life cycle assessment (LCA) to quantify the percentage of recoverable CO₂ emissions—namely, the ratio of in situ sequesterable CO₂ to initial cradle-to-gate CO₂ emissions—for common pervious concrete mixtures. Results suggest that natural carbonation can recover up to 12% of initial CO₂ emissions and that CO₂ sequestration potential is maximized for pervious concrete mixtures with (i) lower water-to-cement ratios, (ii) higher compressive strengths, (iii) lower porosities, and (iv) lower hydraulic conductivities. However, LCA results elucidate that mixtures with maximum CO₂ sequestration potential (i.e., mixtures with high cement contents and CO₂ recoverability) emit more CO₂ from a net-emissions perspective, despite their enhanced in situ CO₂ sequestration potential.

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