INVESTIGATION OF THE RETARDING EFFECT OF SUPERPLASTICIZERS ON CEMENT HYDRATION BY IMPEDANCE SPECTROSCOPY AND OTHER METHODS

The influence of three different superplasticizers: sodium poly-naphth alene sulfonate (NaPNS), calcium poly-naphthalene sulfonate (CaPNS) an d sodium poly- melamine sulfonate (NaPMS) on portland cement hydration and micro-structure development was investigated. SEM, TGA and IS res ults indicated that, at high dosages, superplasticizers not only had a significant effect on the early cement hydration process, but on late r microstructure development as well. At the same w/c ratio, the micro structure of pastes containing superplasticizers developed at much slo wer rate than in the control paste. As empirical equation, P=P(o)-At(n ) appeared to best describe porosity development of hydrating portland cement pastes in these studies.