Quality Control of Raw Materials and Formulations in Construction Industry

Significance of the Topic

Modern construction demands materials with optimized performance in terms of durability, workability, and setting time. Organic admixtures such as superplasticizers and water repellents play a critical role in enhancing concrete properties. Fast and accurate quality control of both raw materials and complex formulations is vital to ensure consistent product performance and to avoid costly production errors.

Objectives and Study Overview

This application note demonstrates the use of Fourier-transform infrared spectroscopy (FT-IR) for:

• Verifying the identity and purity of organic construction admixtures on incoming material inspection
• Quantifying specific polymer additives within formulations
• Reverse engineering unknown admixture mixtures from competitive products

The work aims to show how a compact FT-IR system can complement traditional XRF and XRD methods, which are limited to inorganic components.

Methodology

The method employs Attenuated Total Reflectance (ATR) FT-IR spectroscopy. Solid or liquid samples are placed directly onto a diamond ATR crystal. Spectra are recorded in seconds without sample preparation or consumables. Data evaluation includes spectral library search for identity verification, correlation comparison for quality assessment, and band-area integration or multicomponent fitting for quantification and mixture analysis.

Used Instrumentation

• ALPHA II FT-IR Spectrometer (Bruker)
• Platinum ATR module with monolithic diamond crystal (1.5 × 1.5 mm)
• OPUS Spectroscopic Software for spectral acquisition, comparison, quantification, and mixture analysis

Main Results and Discussion

Incoming goods control of hydroxypropyl methyl cellulose (HPMC) achieved 99.9% spectral correlation against a reference batch, ensuring correct raw material identity.
Quantification of thermoplastic polyolefin (TPO) in bitumen/limestone formulations showed linear calibration based on the TPO-specific band at 973 cm⁻¹, enabling rapid determination of additive content within less than one minute.
Mixture analysis of an unknown liquid initiator identified di-tert-butylperoxide (81%) and tert-butyl perbenzoate (19%) by fitting library spectra, illustrating effective reverse engineering of competitive products.

Benefits and Practical Applications

FT-IR ATR spectroscopy offers:

• Rapid, non-destructive analysis without consumables or reagents
• High specificity for organic and polymeric components
• Automated workflows for routine quality control and batch verification
• Quantitative capability for precise determination of additive levels
• Tools for product development and failure analysis via library searches and mixture fitting

Future Trends and Potential Applications

Integration of FT-IR systems with cloud-based spectral libraries and machine learning for automated defect detection and predictive quality monitoring.
Miniaturized and portable ATR-FT-IR instruments for on-site construction quality assurance.
Expanded reference databases to cover emerging bio-based admixtures and sustainable construction materials.

Conclusion

ATR-FT-IR spectroscopy on compact systems like the ALPHA II provides a versatile, fast, and reliable tool for the quality control of organic admixtures and complex formulations in the construction industry. Its complementarity to XRF/XRD for inorganic analysis and its capacity for identity verification, quantification, and reverse engineering make it indispensable for modern materials development and QA/QC workflows.