The Troubled Relationship Between PCEs and Cement in the Presence of Swelling Clays

摘要

Expandable clays are highly detrimental to PCEs because of the possibility to intercalate PCEs molecules into the clay interlayer. In this work, the interaction of PCEs with such type of clay was studied by XRPD and adsorption measurements and the effect of clay on the fluidity of cement pastes was measured by mini-slump test. Smectite clay has been mixed in synthetic cement pore solution with different PCEs based on methacrylic acid/ MPEG methacrylate copolymers. Results confirmed that the presence of expandable clays reduces the cement paste fluidity because of the possibility to intercalate PCE molecules and the formation of hydrogel between PCE and clay. It was found that the sensitivity to expandable clay depends on the PCE molecular weight and the shift in the position of the 001 diffraction peak of the clay, which is a direct measurement of the tendency of different PCEs molecules to intercalate into swelling clays.