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For materials to be used in construction projects they must first be analyzed to check that they meet certain requirements and have the correct properties and characteristics to make them suitable for their intended purpose. In the past, the most common technique used for analyzing potential building materials was X-ray diffraction, with the alternative methods of thermal analysis and other microscopic techniques also proving popular. However, now, infrared spectroscopy has become increasingly popular as an easy to carry out and non-destructive method of material characterization. Below we discuss the principles of the method, and how it can be used to analyze different materials types.
How Infrared Spectroscopy is Used to Analyze Building Materials
The principle of how infrared spectroscopy works is relatively simple. Infrared radiation is directed at the material, with it being absorbed when the radiant energy matches that of a specific molecular vibration. The infrared spectra sit between visible light and microwaves, so any wavelength in-between these markers can be used to examine material. The specific vibration at which a material absorbs the radiant energy gives the analyst information on the groups existing within the molecule. The technique has been established as a reliable method of identifying compounds, however, it also has potential as a source of qualitative and quantitative analysis.
The most common building material types that infrared spectroscopy is used to analyze are hydrated cementitious materials, cement, and carbonated compounds. In general, commercial cement is created by firing the raw materials of limestone, clay, sand, and iron minerals. Under the heat, several chemical reactions are catalyzed, resulting in the formation of a “clinker”. This clinker is then cooled and mixed with setting regulators, to create the final fine powdered cement. There are many resultant common phases in commercial cement, including alite, belite, tricalcium aluminate, tetra calcium aluminum ferrite. It is these phases that are used to identify infrared vibrations and allow analysts to gain information on the composition of the cement.
On the other hand, hydrated cement gives rise to specific phases of calcium, and two crystalline phases. These phases are used to identify infrared vibrations and give analysis’s insight on the hydration of cement material.
Finally, studies have shown that the technique of infrared spectroscopy is incredibly sensitive to detecting carbonates within materials. Calcium carbonate phases exist within materials following a process of carbonation, these specific calcium carbonate phases are used as a marker of carbonation, with their absorption bands being used to determine certain properties of the carbonated compounds.
Green Buildings Boost the Importance of Material Analysis
As industries become increasingly pressured to minimize their carbon footprint and be proactive in the face of climate change, many are changing their ways of working to support green processes that do not negatively impact the environment. Green construction has been born out of this way of thinking, with a growing number of construction projects using green materials to construct environmentally conscious buildings. This boom in the sector of green construction is enhancing the importance of material analysis, making infrared spectroscopy relied on more than ever. This is because more and more new green materials are being innovated to replace standard building materials. This means that they need to be thoroughly analyzed before they can be confidently used, checking that they match or even exceed the properties of the materials that they are designed to replace.
Future Directions
Infrared spectroscopy has established itself as a reliable and effective method of analyzing building materials, overtaking previous methods of thermal analysis, X-ray diffraction, and microscopic techniques. While its use has mainly focused on identifying compounds, it has proven its use as a reliable method of qualitative and quantitative analysis of building materials. It is likely to be continued to be relied upon in the future, as building material analysis becomes even more important.
Sources and Further Reading
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