The mining and civil underground construction industries have increasingly become reliant over recent decades on the use of grouted cable bolts for ground support especially in difficult ground conditions. Despite this there are still some key areas of cable bolt performance that are poorly understood. This paper details an investigation that compared the anchorage performance of a plain strand cable bolt that was grouted in a confining medium using in one case a resin grout and in a second case a cementitious grout. The impact of borehole diameter on the performance of the two grout types was also studied. The investigation involved a series of twenty pull-out tests with a plain strand bolt using the UNSW modified Laboratory Short Encapsulation Pull-out Test. In tests with the standard borehole diameter of 27 mm, it was found that the resin grout exhibited a lower average peak load carrying capacity than the cementitious grout. By contrast, with the larger diameter of 37 mm, the resin grout outperformed the cementitious grout in terms of average peak load carrying capacity. With a cementitious grout, an increase in borehole diameter size from 27 mm to 37 mm decreased the average peak load while the load doubled when using the resin.