Abstract
A set of 39 different volcanic rocks was studied for performance as crushed stone for road surfacing (wearing course) aggregates using two technological tests: the polished stone value (PSV) test, aimed at evaluating resistance to polishing (skid resistance), and the Nordic abrasion value (A (N)) test, as a proxy to wear by studded tires (resistance to abrasion). In order to understand better the observed relationships, the studied volcanic rocks were split into five petrographic-technological subgroups (rhyolite/porphyry, phonolites, basalts s.l., spilites, and melaphyres/diabase) based on their composition, rock fabric, geological age, and post-genetic history.
Response of each of these subgroups to the applied tests is not always the same, but generally is controlled by composition and rock macro- and microfabric. Despite the fact that positive contributors to skid resistance (e.g., increasing contrasting hardness of rock-forming components, presence or absence of certain phenocrysts) have the opposite effect on wear by studded tires, it is not possible to make any reliable prediction of PSV from A (N) or vice versa.