On the quantification of degrees of reaction and hydration of sodium silicate-activated slag cements

The present study investigates the correlation between the degree of reaction (DoR) and hydration (DoH) of alkali-activated slag cements, prepared using a sodium silicate activator. The DoR of samples was measured by employing multiple techniques including ²⁹Si magic-angle-spinning nuclear magnetic resonance spectroscopy, scanning electron microscopy image analysis, and selective dissolution, while the DoH was quantified by bound water measurement of samples dried via various drying methods. Due to experimental errors it is recommended that the DoR is described using regression as a function of time, rather than directly using experimentally-obtained values. The DoH values obtained from the measurement of bound water content showed a linear relationship with the DoR values measured by selective dissolution within 20% error margin. From this, it is expected that DoR can be inferred from DoH values obtained by the drying method, which is much easier than selective dissolution.