Synthesis of Quaternized Lignin and Its Clay-Tolerance Properties in Montmorillonite-Containing Cement Paste

To improve the dispersion capacity of poly(carboxylate ether) (PCE) in clay-containing cement paste, lignosulfonate (LS) was quaternized with 3-chloro-2-hydroxypropyl trimethylammonium chloride (CHPTAC), and the product quaternized lignosulfonate (QL) was characterized by FT-IR spectroscopy, element analysis, and zeta potential. The fluidity of the montmorillonite- (MMT-) containing cement paste was clearly improved upon the addition of 0.010 wt % QL, as the yield stress and the rheological behavior index of the paste were reduced. XRD analysis indicated that the adsorption of QL on MMT was driven by a strong electrostatic attraction, rather than intercalation, which was much stronger than that for LS. DLS also showed that the steric effect of QL was much stronger than that of PCE. As a result, when QL and PCE were added to the MMT-containing cement paste, QL adsorbed on the MMT surface preferentially and hindered the adsorption of PCE.