No abstract

No abstract

NIR Infrared spectroscopy is a fast and easy-to-perform technique characterized by a high sensitivity towards water containing systems and for this reason it is a suitable tool for investigating structural modifications of hydrating cementing materials, even if the lack of knowledge in this field makes the interpretation of NIR vibrational bands very difficult.In this paper the NIR spectrum of a hydrated ordinary Portland cement is deeply investigated and an interpretation of the different bands is proposed on the basis of both experimental evidences and literature reference.The obtained results have been then applied to the investigation of the cement hydration advancing up to 28 days, analyzing the variations detectable in the shape of the spectrum as the reaction goes on. The entity of this variation, quantified through area calculations of main significant bands, revealed a good agreement with the hydration degree of the paste measured by thermal method.The findings of this research supply a solid base for future in-field application of NIR spectroscopy, for example for investigations on cements with different hydration behavior or to evaluate the effect of additives on cement pastes and, at a further level, for cement quality control.