Determination of Asbestos in Mortar Admixture by TG-DTA

Significance of the Topic

Serpentine-based mortar admixtures often contain chrysotile asbestos, posing health risks. Reliable detection of chrysotile is essential to ensure construction safety and comply with regulatory standards.

Objectives and Study Overview

The study aims to establish a rapid and accurate procedure for identifying and quantifying chrysotile in serpentine mortar admixtures using thermogravimetric–differential analysis (TG-DTA) following X-ray diffraction screening.

Methodology and Instrumentation

• Initial screening by X-ray diffraction to confirm the presence of serpentine phases (chrysotile, antigorite, lizardite).
• Differential thermogravimetric analysis to distinguish serpentine types based on dehydration temperature peaks.
• Quantification of chrysotile content via peak area in differential TG (D-TG) curves.

Instrumentation Used

• Shimadzu TG-DTA analyzer (DTG-60/DTG-60H).
• X-ray diffractometer for mineral phase identification.

Main Results and Discussion

• Serpentine varieties dehydrate in distinct temperature ranges: lizardite (630–680 °C), antigorite (650–700 °C), chrysotile (750–800 °C).
• In standard samples, chrysotile exhibited a D-TG peak at ~680 °C and antigorite at ~760 °C.
• Analysis of four commercial mortar admixtures revealed chrysotile peaks near 650–670 °C and antigorite peaks around 770–780 °C.
• Sample C showed the highest chrysotile content, demonstrating the method’s quantification capability.

Benefits and Practical Applications

• Enables rapid screening of construction materials for asbestos contamination.
• Provides quantitative data to support regulatory compliance and risk assessment.
• Offers a straightforward protocol suitable for routine quality control.

Future Trends and Opportunities

• Integration with automated sample handling for higher throughput.
• Application to broader matrices such as soil or industrial by-products.
• Development of standardized reference materials for improved accuracy.

Conclusion

TG-DTA following XRD screening offers a reliable, quantitative approach for detecting chrysotile in serpentine mortar admixtures, contributing to enhanced safety and regulatory adherence in construction materials.