Influences of styrene-acrylate latexes on cement hydration in oil well cement system at different temperatures

Influences of styrene-acrylate (SA) latexes on cement hydration were investigated by isothermal calorimetry and the mechanism wasdiscussed. Super-retardation phenomenon caused by addition of SA latexes on oil well cement hydration was found at 80 degrees C by setting time measurement. Quantitative analysis of hydrolysis of SA latexes in cementitious systems and their effect on cement hydration were investigated by FTIR, zeta potential and surface charge density measurements. Results show that the hydrolysis of ester groups in acrylate units is significantly accelerated by elevated temperature in alkaline condition. The continuous production of carboxyl groups promotes the adsorption of polymer particles on the surface of cement grains and/or leads to continuous Ca2+ sequestration from pore solution. These two aspects are the causes of the super-retardation effect. It is concluded that unless special chemistry is involved in the preparation of SA latexes, such as construction of core-shell structure of the colloidal particles, SA latexes with high content of acrylate units, due to the severe hydrolysis of the ester groups in the polymer chains, are not recommended to be used in oil well cement system. (C) 2016 Elsevier B.V. All rights reserved.