Amsler Wear Test

The Amsler test measures the resistance of materials to the abrasive solicitations, and it is done with two testing bodies, scrubbed with metrically granulated and selected quartzite sands. Wear measurement, expressed in millimeters, is done after 500 and 1,000 turns of the test bodies fixing wheel on the test equipment.

The wear resistance is usually proportional to the hardness of the stone constituent minerals, under the scale of Mohs. Silicate stones (granites) are more wear-resisting than the carbonate ones (marbles and travertine). Among the granites, the resistance will be as big as the amount of quartz there existent. Among the marbles, the wear resistance will be higher as the dolomite character (magnesian) is bigger.

It is observed then, as a function of the minerals hardness, that granites show greater resistance to the cuts (scratches) and abrasive wear, becoming for this reason the ideal specification for floors, specially in those cases where a great pedestrian traffic is expected.

The texture of the rocks constitutes also a very significant element, because their wear may occur as well by abrasion, as by disruption, paring (scarifying) of the mineral constituents. The metamorphic textures of the saccharoid type, common in the quartzites, and of the grainoblastic type, common in the migmatite (fantasy active granites, under the commercial point of view), lead to the paring process. Known examples of migmatite, with 30-35% of quartz, have shown an index of wear superior to the one of granites with 5-10% of quartz. Rough grenade crystals, fragile and frequent mineral in metamorphic stones, are also submitted to thrusting that provoke sockets on the surface of polished plates.

These features confirm the reach of petrographic studies by optic microscopy, that allow the definition of the mineral constituents and the characterization of the stone texture, as auxiliary elements for the wear forecast of the applied materials.