Investigation of the clay sensitivity and cement hydration process of modified HPEG-type polycarboxylate superplasticizers

In this work, three kinds of HPEG-type polycarboxylate superplasticizers (PCs) were synthesized with three kinds of typical functional monomers: [diallyl dimethyl ammonium chloride (DMDAAC), 2-hydroxyethyl methacrylate (HEMA), and 2-(dimethylamino) ethyl methacrylate (DMAM), respectively. The effects of montmorillonite clay on the fluidity of cement/PC pastes were investigated. It was found that the fluidity was negatively affected by the clays in the order: DMAM-PC<HEMA-PC<conventional PC (CPC)<DMDAAC-PC. The DMAM-PC was found to disperse cement well even in presence of montmorillonite clay. The dispersion performance of DMDAAC-PC was much more effectively affected by clay due to the reaction between ammonium and montmorillonite. More study including mortar fluidity, adsorption behavior and morphology of the cement samples were investigated in details. Thermogravimetric analysis and X-ray diffraction experiments allowed us to observe the influence of PCs on the hydrated products. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46572