Benefits of Chemometric and Raman Spectroscopy Applied to the Kinetics of Setting and Early Age Hydration of Cement Paste

The addition of water is used to past by internal post-curing of hardening cement. Hydration and curing of cementitious arewidely identified by non-destructive1H nuclear magnetic resonance (NMR) measurements of transverse relaxation time andself-diffusion. However, those non-destructive analytical methodologies do not give a truly chemical characterization of thecement matrix during the hydration and curing process. Indeed, the NMR studies only the water dynamics of hydrating cementwith internal post-curing. Recent research indicated chemometrics coupled with Raman spectroscopy allows for a betterunderstanding of chemical processes. Recent advances in computing gave industries and research centers the opportunity togenerate cost effective data. In this work, an original method is presented, which uses both a data analysis and a non-invasive,non-destructive Raman monitoring of the hydration reaction of a Portland cement. Data was then analyzed by means ofchemometrics methods (principal components analysis (PCA), independent components analysis (ICA), and multivariate curveresolution-alternated least-squares (MCR-ALS) with SIMPLe-to-use Interactive Self-modelling Mixture Analysi (SIMPLISMA)and Orthogonal Projection Approach (OP initialization). Results were compared to the ones obtained with thermogravimetricanalysis of this cement paste. Besides the consistency of results from both analytical measurements, chemometrics coupled toRaman spectroscopy accurately revealed the details of the setting without any samples collection. The acquisition frequencyallowed a proper identification of the occurrence of each of the various phases involved in the hydration and setting process.

Automated summary

This paper presents an original method for monitoring the hydration reaction of cement using non-invasive Raman spectroscopy, coupled with chemometrics analysis. The results are consistent with thermogravimetric analysis and accurately reveal the different phases involved in the hydration and curing process.