Advice about cement additives

CGAs are blends of different raw materials, such as glycols and amines as well as other organic and inorganic compounds. Each of these raw materials has been specifically selected, and the amount precisely defined, to ensure that the finished product provides the required performance. To ensure that these performance benefits are consistently achieved, it is crucial to implement robust quality control practices. Ensuring the quality and consistency of CGAs not only boosts operational efficiency but also ensures that the final product meets the required performance targets.

This article highlights best practices for controlling the quality of cement additives so that plants can ensure that they are receiving products of consistent quality.

Current practice

Following successful plant trials and the decision to commence routine supply, the product formulation is fixed and becomes the reference point. In current practice, the quality control of CGA products relies on basic parameters such as specific gravity and colour. However, these methods have significant limitations.

Specific gravity measures the density of the product, but it does not provide comprehensive insights into its chemical composition or performance characteristics. Variations in specific gravity may indicate changes in formulation, but they do not reveal detailed information about the effectiveness of the grinding aid or its consistency across different batches.

Colour is another parameter used to assess the product. While colour can offer a rough indication of consistency, it is highly subjective and can be influenced by various factors unrelated to the product’s quality or performance. This method lacks precision and does not account for critical aspects like chemical purity or the efficiency of the grinding aid in practical applications.

These basic methods, while useful for normal checks, do not provide the depth of information required for thorough quality control and performance evaluation. Therefore, integrating advanced analytical techniques such as Fourier Transform Infrared Spectroscopy (FTIR), Planetary Ball Mill (PBM), and calorimetry is essential for a comprehensive assessment of CGA products, ensuring that they meet quality standards and perform effectively in their intended applications.

Chemical analysis

There are a few chemical analysis techniques that can be used to verify the composition of the grinding aids, with some of the more common being gas/liquid chromatography and infrared spectroscopy.

Based on several notable advantages it offers over other techniques, FTIR is more favoured for analysing the composition of grinding aids. It provides detailed information about the molecular structure of a liquid product by measuring the absorption of infrared radiation at different wavelengths. Each functional group in a molecule absorbs infrared light at characteristic frequencies, creating a unique spectrum. By comparing the obtained FTIR spectrum with reference spectra of known substances, the presence of specific chemicals or compounds in the liquid product can be identified.

FTIR is known for its efficiency in testing. The process of obtaining an FTIR spectrum typically takes only a few minutes. This rapid turnaround is crucial for quality control, especially in high-throughput production environments. In many cases, FTIR requires minimal-to-no sample preparation, which further speeds up the process. For liquid samples, a small drop is often sufficient. The quick analysis allows for timely decision-making and faster response to quality issues during production.

FTIR can be a valuable tool for ensuring product consistency. Batch-to-batch comparisons are crucial for maintaining uniform quality over time and ensuring that each batch meets the desired quality standards. By analysing samples from each batch, FTIR verifies that the chemical composition and functional groups remain consistent across production runs. Any significant deviations in the spectra can indicate changes in formulation, raw material quality, or production conditions, allowing for early detection of issues. Consistency checking helps maintain uniform product quality, which is essential for customer satisfaction and regulatory compliance.

Contaminants or impurities often show up as additional or shifted peaks in the FTIR spectrum. By comparing the spectrum of the final product with its reference spectrum, any unusual peaks can be identified as potential contaminants. It helps in identifying the nature of the contaminants by comparing their spectra to a known reference spectrum, providing insights into their chemical composition. This capability is crucial for ensuring that the final products meet the required purity, and quality standards as well.

Read the article online at: https://www.worldcement.com/special-reports/26092024/advice-about-cement-additives/