Abstract: A cement admixture which results in a cement mortar with excellent adhesion to various adherents and with excellent flexibility over a wide range of temperatures, including very low temperatures, contains cement, optionally but preferably sand, and an effective amount of an aqueous emulsion of a cationic acrylate polymer having a Tg between below 10.degree. C. and -40.degree. C. The polymer comprises (a) about 25 to 85% of an acrylate monomer (e.g., butyl acrylate, methylmethacrylate, or 2-ethylhexyl acrylate but not methyl or ethyl acrylate), (b) about 0.5-15% of an alkaline-curable cationic quaternary ammonium salt monomer, and optional monomer(s) other than (a) or (b). The alkaline-curable cationic quaternary ammonium salt units in the polymer are represented by the formula ##STR1## where R is hydrogen or a methyl group; R.sup.2 and R.sup.