Raman spectroscopy: applycation to cementitious systems

Abstract

Raman scattering was discovered by Krisma and Raman in 1928. Until approximately 1986, the Raman literature was dominated by physical and structural investigations, with relatively few reports of Raman spectroscopy applied to chemical analysis due to several technical and fundamental problems, such as weak intensity, fluorescence interference, and inefficient light collection and detection. When the introduction of Fourier transform (FT)-Raman, charge-coupled devices, small computers and near-infrared laser, the major impediments were solved and resulted in a Raman renaissance in the chemical analysis context. Spectroscopic techniques have proved to be appropriate tools for studying cement hydration; however, fluorescence effect in anhydrous cement can give anomalous results. With the micro-Raman technique, spectra can be obtained for surface samples just a few microns thick and with minimal interference from the surrounding water. On such a scale, the interference from fluorescence, so often a problem when working with bulk cement slurry is also minimized. Spectra can be obtained rapidly and extensive sample preparation is not needed.