SYMPOSIA PAPER Published: 01 December 2022

Conceptual Test Protocols for Measuring Carbon Sequestration of Manufactured Dry-Cast Concrete Products


Measuring the carbonation of cementitious materials has taken many forms over many decades. Objectives for understanding this chemical reaction with the atmosphere have varied. Some investigations have focused on quantifying the potential shrinkage of concrete as it carbonated to mitigate cracking, whereas other studies have measured changes in pH levels within the concrete and the resulting effects on the corrosion of embedded ferrous metals. Current market drivers, however, have shifted beyond the functional performance aspects of carbon sequestration of cement-based materials and are now placing much more emphasis on the embodied carbon, and potential carbon sequestration, of construction materials. The thesis of this investigation centers on the relatively porous nature of dry-cast concrete compared to wet-cast concrete, making it a potentially attractive candidate for carbon sequestration. While considerable research has been conducted on carbonation of wet-cast concrete, there has been limited research on quantifying carbon uptake in manufactured, dry-cast concrete products, including concrete masonry units (CMUs). Therefore, this research investigation was undertaken to develop and refine testing protocols that deliver repeatable, accurate measurement of the carbon dioxide (CO2) uptake of manufactured, dry-cast concrete products. This paper summarizes the testing methods used and the preliminary measurements of carbon sequestration of dry-cast CMUs sourced from multiple producers across North America. Raw materials and finished concrete products were characterized and analyzed using x-ray fluorescence and thermogravimetric analysis to quantify the amount of carbon sequestration that occurred over time due to the carbonation of the cementitious paste in the CMUs. Although testing associated with this project is still under way to define the long-term sequestration characteristics of dry-cast concrete, the 28-day (cradle-to-gate) carbon sequestration measured in this project averaged 1.30 lb/ft3 (21 kg/m3), a quantity significantly higher than would have been predicted using wet-cast concrete carbonation data.

Author Information

Walloch, Craig
ACM Chemistries, Norcross, GA, US
Powers, Laura
CTL Group, Skokie, IL, US
Broton, Donald
CTL Group, Skokie, IL, US
Thompson, Jason
National Concrete Masonry Association, Herndon, VA, US
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Pages: 59–86
DOI: 10.1520/STP164020210112
ISBN-EB: 978-0-8031-7728-4
ISBN-13: 978-0-8031-7727-7