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This thesis was created to ensure the quality of the rock which would be crushed to base layer construction material, in a road cut at Swedish highway 51, and to find a possible link between the rock's abrasion resistance and its mineralogy. Rock samples were collected, and among other things, several ball mill tests were carried out. The design of the road project was carried out by Loxia Group AB with NCC Group as contractor.A total of 18 rock samples and 2 base layer samples were taken in the area and they were all tested in a ball mill. The results showed that of the 18 rock samples, 2 samples had a ball mill value of less than 16 on the scale, 10 samples had values from 16 to 20, in addition to this, 3 samples had values from 20 to 21 and 3 samples had values in excess of 21 on the Swedish ball mill scale.Of the 3 samples with a ball mill value higher than 21, all contained a larger amount of biotite. Biotite did not appear to the same extent among the samples that ended up further down the ball mill scale. This link was so clear that a conclusion was subsequently drawn from this. The samples taken on the prefabricated base layer both had a ball mill value between 16 and 20. Overall, both the base layer and the rock material passed the Swedish Government’s Transport Administration’s requirements according to "TRVKB 10, Obundna lager". The rock type that was on the south part of the rock cut, adjacent to a deformation zone, had way too poor quality to undergo a ball mill test and therefore there are no values taken from that area.The conclusion of the work is that the rock material overall meets the Swedish Government’s Transport Administration’s requirements for base layer construction materials according to "TRVKB 10 Obundna lager", that a clear link between the proportion of biotite in a rock material and its abrasion resistance exists, and that the broken rock in the south should not be used as construction materials since the rock has insufficient mechanic