The paper summarizes the results of a laboratory study in which a common cationic tack coat was used between two layered slabs. The slabs were produced with a roller compactor and the adhesion of cores taken from the slabs was evaluated by means of direct shear testing according to Leutner. Furthermore, a common cationic, but not polymer modified, tack coat was compared to a polymer modified one. To evaluate the limits of the application of tack coats dirt and moisture was applied between the two layers before and after the application of a tack coat. For comparison the tack coat was applied on one side of the slab only, when the other stayed untreated. Besides, the influence of tack coats on fine milled surfaces and the influence of curing time on the adhesion were also investigated.