The effects of an amphoteric copolymer, poly(acrylamide-co-(2-(3-carboxyacryloyloxy)-N-(carboxymethyl)-N,N-dimethyl-ethanaminium) (PAC) on the properties of cement pastes or mortars were investigated. PAC was prepared from acrylamide and 2-(3-carboxy-acryloyloxy)-N-(carboxymethyl)-N,N-dimethylethanaminium (CAC) through free radical polymerization. The results indicate that the presence of the polymer delayed the setting of cement pastes; it also reduced the water demand so that the resulting mortars showed improved compressive strength and reduced length change. PAC with about 16.7% CAC and a weight-average molecular weight of about 5 x 10(4) was effective in promoting the material properties of mortars. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012