Evaluating the Quantity of CO2 Absorbed in Concrete by TOC Solid Sample Measurement System

Significance of the Topic

Reducing CO2 emissions from cement production is critical for climate change mitigation. Incorporating CO2-absorbing ingredients in concrete offers a pathway to capture atmospheric CO2 and lower the carbon footprint of construction materials.

Aims and Study Overview

This study demonstrates the application of a TOC solid sample measurement system combined with a solid sample combustion unit to quantify the amount of CO2 fixed in concrete by measuring its inorganic carbon content. Two types of concrete samples were compared: standard concrete and a modified formulation containing CO2-absorbing additives.

Methodology

Samples of each concrete type were pulverized to a fine powder. Fifty milligram aliquots were placed directly into sample boats without further pretreatment. Inorganic carbon was measured by acidification using phosphoric acid at 200 °C in a dedicated IC furnace, generating CO2 that was quantified by the TOC analyzer. A one-point calibration curve with sodium carbonate was used for quantification. Measurement conditions included oxygen carrier gas at 500 mL per minute and short cell length.

Used Instrumentation

• TOC-LCPH total organic carbon analyzer
• SSM-5000A solid sample combustion unit
• Phosphoric acid dispenser for IC measurement

Main Results and Discussion

Measurements revealed that the CO2-absorbing concrete exhibited an inorganic carbon concentration of 6.76 %, approximately five times higher than the 1.41 % measured in ordinary concrete. Reproducibility was excellent, with coefficients of variation below 3 % for both sample types. These findings confirm the effective incorporation and retention of CO2 in the modified concrete formulation.

Benefits and Practical Applications

• No extraction or complex pretreatment required; total analysis time of 6 to 8 minutes per sample
• Ability to measure sample masses up to 1 gram reduces distributional bias
• Simultaneous measurement of total carbon and inorganic carbon enables calculation of total organic carbon
• Rapid and accurate assessment supports formulation development of low-carbon concrete materials

Future Trends and Opportunities

Advancements may include integration of automated sample preparation, expansion to field-portable instruments for on-site analysis, and application to other construction materials such as recycled aggregates. Coupling this method with advanced carbon sequestration additives could accelerate the development of carbon-negative building materials.

Conclusion

The TOC solid sample measurement system with solid sample combustion provides a rapid, reliable approach to quantify CO2 absorbed by concrete. The method’s simplicity, throughput, and accuracy make it a valuable tool for evaluating and optimizing carbon capture performance in innovative construction materials.