Interaction Between Poly-Napthalene Sulfonate-Type Superplasticizers and Cements During Initial Hydration
N. Mikanovic, M.-A. Simard, and C. Jolicoeur
Appears on pages(s):
adsorption; cement; heat of hydration; superplasticizer
The time dependence of the interaction between hydrating cement particles and a poly-naphthalene sulfonate (PNS) superplasticizer has been investigated using rapid response calorimetry and other physico-chemical approaches. The study focuses on the processes which occur during the first instants following the immersion of the cement particles into the solution, in the presence, or absence, of the PNS superplasticizer. Specifically, the investigation aims to elucidate the dominant phenomena in the coupled processes taking place in the water/cement/sulfate/PNS system, and the consequences of these phenomena on 1- the reaction rates and products and 2- the cement-superplasticizer compatibility The systems discussed here are cement pastes at W/C=3 containing cements having highly different alkali sulfate contents and a normal PNS super-plasticizer. The kinetics of the initial reactions (O-30 min.) are monitored by fast response adiabatic calorimetry; the superplasticizer adsorption, and variations in the ionic composition of the interstitial solution, are also determined at short time intervals during the same period. The evolution of the hydrate phases as a function of time is monitored through XRD analyis.