Corrosion protection of fully grouted rock bolts has been the subject of considerable research in recent years. Corrosion protection is studied focusing on quantitatively determining how much encapsulation coating affect the bolt/resin bond capacity. Resin coating results in reduction of rib height and in turn causes a decrease in interlocking effect with the grout annulus. The laboratory tests performed have shown that there was a wide range of reduction in bonding strength (from 5 to 40 %), depending on the type of the bolt and media in which the bolt had been installed. The reduction of rib height was also responsible for lower lateral dilation during bolt pullout tests. This effect will make the confining medium become an important parameter, since higher confining medium results in higher confining pressure on the bolt surface which in turn, controls the bond capacity.