INFLUENCE OF POLYMER MODIFICATION ON THE HYDRATION OF PORTLAND-CEMENT

An investigation has been carried out into the influence of polymer modification on the transition zone between cement paste and aggregate. Three kinds of polymers were used, namely: a styrene acrylate (SA), a copolymer of vinylpropionate and vinylidene chloride (VVC) and an acrylate with a coupling agent (ACA). The effects of these polymer dispersions on the rate of cement hydration, calcium hydroxide (CH) orientation in the interfacial zone, and microhardness of the composites were studied. The results show that the acrylic polymers SA and ACA significantly retard the setting and the hydration of portland cement. Addition of the VVC polymer, however, tends to accelerate the hydration of the cement. In addition, X-ray diffraction studies indicated that at the interface between the aggregates and the cement paste, calcium hydroxide crystals are oriented with their c-axis perpendicular to the interface. The microhardness data of the plain paste were found to be higher than those of the modified ones.