SGER: Nanoscale Investigation of Cement Hydration by Nuclear Resonant Reaction Analysis

University Of Connecticut, Storrs CT

Investigators

Abstract

Nanoscale Investigation of Cement Hydration by Nuclear Resonant Reaction Analysis Nuclear Resonant Reaction Analysis (NRRA) has been applied for the first time to study cement hydration. Through the use of this technique, the change in hydrogen concentration on a few nanometer scale (corresponding to a few unit cells) can be studied as a function of time during the induction period. Preliminary results have demonstrated that the surface layer formed during the induction period on the tricalcium silicate grains (used in this initial study) is consistent with a tobermorite-like material, based on the absolute value of the observed hydrogen concentration and the measured thickness of the surface layer. Optimum beam energy resolution is a critical parameter as the spatial resolution of the measurement is defined largely by the energy resolution of the incident ion beam. Therefore, the Dynamitron Tandem accelerator at the Ruhr Universitat, Bochum, Germany is being used for the experimental studies as this machine has had extensive work done over the last fifteen years to generate the best possible energy resolution for ion beams. The hydrogen concentration is obtained over a depth of a few nanometers at the surface of the grains and can be measured continuously to a depth of about 2 microns into the grains. An initial study of the hydration process of tricalcium silicate at 20 oC determined an induction time of 4.25 hours with a statistical precision of 0.07 hours. This proposal will support a detailed investigation of cement hydration by applying the NRRA technique. A series of experiments will investigate the effect of different parameters on the hydration process. The analysis of the experimental data will provide clear insights into the way different parameters, such as temperature, pH, and starting composition, affect the hydration process. This information will ultimately be used to improve the formulation of cements for construction and other purposes.