Thermal Characterization and Quantification of Polymorphism in Calcium Carbonate Crystals

Importance of the topic

The study addresses the thermal characterization and quantification of calcium carbonate polymorphs in cementitious materials, a key factor for CO2‐absorbing concrete technologies. Understanding the stability and decomposition behavior of calcite, aragonite, and vaterite informs the durability, mechanical performance, and long‐term CO₂ fixation potential of carbonated concrete.

Objectives and overview

This work aims to (1) compare the thermal decomposition profiles of the three calcium carbonate polymorphs using simultaneous thermogravimetry and differential thermal analysis, and (2) develop a rapid ATR‐FTIR method to quantify their proportions in cement. Standard mixtures of polymorphs with cement were prepared to generate calibration curves for accurate compositional analysis.

Methodology and instrumentation

• Thermal analysis: DTG-60 simultaneous TG/DTA instrument under nitrogen, heating from 30 °C to 1000 °C at 10 °C/min, ~30 mg samples.
• FTIR analysis: IRTracer-100 with diamond ATR accessory, 4 cm⁻¹ resolution, 40 scans per spectrum, nitrogen purge to minimize atmospheric interference.
• Calibration samples: Four reference mixtures of calcite, aragonite, vaterite, and cement, each measured in triplicate.

Main results and discussion

• TG curves: Temperatures for 5 % weight loss were 702.7 °C (calcite), 661.9 °C (vaterite), 642.7 °C (aragonite), confirming calcite’s highest thermal stability. Calcite exhibited single‐step decomposition, while vaterite and aragonite decomposed in two and multiple steps, respectively.
• DTA profiles: Distinct endothermic/exothermic peaks below 600 °C and decarboxylation peaks above 750 °C allowed clear differentiation of polymorphs.
• FTIR quantitation: Second‐derivative spectra identified unique peaks at 1795 cm⁻¹ (calcite), 1440 cm⁻¹ (aragonite), and 746 & 513 cm⁻¹ (vaterite/cement). Calibration curves showed correlation coefficients ≥0.99 for all polymorphs.
• Quantitative accuracy: Simulated samples yielded average mass ratios within 1–2 % of predicted values, demonstrating the mixing ratio calculation method’s reliability.

Benefits and practical applications

The combined TG/DTA and ATR‐FTIR approach provides a comprehensive toolkit for both qualitative thermal profiling and rapid quantitative analysis of calcium carbonate polymorphs in cement. This supports quality control, materials optimization, and assessment of CO₂ fixation efficiency in advanced construction materials.

Future trends and possibilities

• Integration with in-situ monitoring techniques for real‐time carbonation tracking in concrete.
• Extension to other mineral polymorph systems and complex industrial matrices.
• Development of portable ATR‐FTIR probes for field analysis of construction sites.
• Data‐driven optimization of cement formulations to maximize CO₂ sequestration and structural performance.

Conclusion

This study demonstrates that DTG-60 simultaneous TG/DTA effectively distinguishes the thermal behaviors of calcium carbonate polymorphs, while IRTracer-100 ATR‐FTIR with derivative analysis enables accurate, rapid quantification in mixed cement samples. The methods offer practical value for research and industrial implementation in CO₂‐absorbing concrete technologies.

Reference

• Naohiko Saeki, Ryo Kurihara, Ippei Maruyama. Effect of RH on Carbonation of Hardened Cement Paste Particles Under General Atmospheric CO₂ Concentration Studied by FTIR Spectroscopy. Cement Science and Concrete Technology, Vol. 76, pp. 36–44 (2022).
• Sarah Steiner, Barbara Lothenbach, Tilo Proske, Andreas Borgschulte, Frank Winnefeld. Effect of relative humidity on the carbonation rate of portlandite, calcium silicate hydrates and ettringite. Cement and Concrete Research 135, Article 106116 (2020).