Why are some cementitious products caused by soil stabilization or geopolymerization observed in the SEM micrographs, whereas they are not found in the XRD analysis? For example, many articles have clearly shown the formation of CSH or CAH gels in SEM images, however, these gels have not been seen in their XRD graphs. Note that some articles have indicated the formation of these gels in both analyses.
Kaushik Shandilya
XRD analysis is a bulk technique that provides information about the crystal structure and mineral phases present in a sample. It can detect the presence of crystalline phases with high sensitivity, but it may not be able to detect amorphous or poorly crystalline phases such as gels or short-range ordered materials that may be present in cementitious products. On the other hand, SEM can provide high-resolution images of the surface morphology and microstructure of the sample, allowing for the direct observation of these amorphous or poorly crystalline phases. The formation of some cementitious products, such as C-S-H gels or calcium aluminate hydrates (CAH), may occur at a nanoscale level, and their presence may not be detected in XRD analysis due to the small size of the crystals. SEM can provide images with much higher resolution, allowing for the visualization of these small structures. The sample preparation techniques for SEM and XRD analysis can be different, which can affect the detection of certain phases. For example, sample preparation for SEM typically involves coating the sample with a conductive material, which can alter the surface chemistry of the sample. XRD analysis requires a powdered sample, which can cause changes in crystal size and shape, and may also lead to the loss of amorphous or poorly crystalline phases that are more sensitive to sample preparation conditions. It is also possible that the cementitious products observed in SEM images may not actually be the same as the crystalline phases detected by XRD analysis. This could be due to differences in the chemical and physical properties of the phases, or to the fact that they are present in different parts of the sample.
Dear Mahdi Salimi
I did some research. There could be several reasons why cementitious products observed in SEM micrographs may not be detected in XRD analysis, even though both techniques are commonly used to study cementitious materials:
2 votes
0 thanks
- Badges
- Science method
- Similar topics
- Methodology
- Crystallography
- X-ray Diffraction
More Mahdi Salimi's questions See All
Similar questions and discussions