Study of Optical Properties of Different Grades Indian Cement Samples Using Terahertz Spectroscopy

The paper reports the nondestructive (NDT) evaluation of different grades cement samples using time domain terahertz (THz) techniques. The THz system was indigenously designed using LT-GaAs antenna as a source and ZnTe crystal combined with polarizers in Electro-Optic (E-O) sampling mode as a detector. We have also ascertained the optical properties such as refractive index and absorption coefficients between 0.1 and 1.0 THz range. In addition, Raman and FTIR spectroscopy of these samples were also carried out to identify the vibration bands of calcium carbonate polymorphs and important hydrated phases present in different grade cements.