Samples with different amounts of a commercial grade powder dispersion (vinylacetate/ethylene copolymer) have been compared with an unmodified concrete. To show the effect of the polymer additive alone all mixtures were prepared with constant w/c-ratio, air void content and workability. Using a wedge splitting test method it was shown that the polymer addition is very effective in increasing the bonding strength and the fracture energy of the interface between the polymer cement concrete and a prefabricated unmodified concrete, but it lowers the fracture energy and the strength of the polymer cement concrete itself.