The present invention provides compositions useful as a replacement for cellulose ether in cement, plaster or mortar compositions comprising i) nonionic or substantially nonionic vinyl or acrylic brush polymers having pendant or side chain polyether groups, and having a relative weight average molecular weight of from 140,000 to 50,000,000 g/mole, and ii) aromatic cofactors containing one or more phenolic groups, such as catechol tannins, phenolic resins, polyphenolics, and napthhols or, in combination, one or more aromatic groups with at least one sulfur acid group, such as naphthalene sulfonate aldehyde condensate polymers, poly(styrene-co-styrene sulfonate) copolymers, and lignin sulfonates, preferably branched cofactors, including phenolic resins, aldehyde condensate polymers and lignin sulfonates. The compositions may comprise a dry powder blend of i) and ii), one dry powder of both i) and ii), or an aqueous mixture.