Polished Stone Value | PSV

The Polished Stone Value (PSV, in french Coefficient de Polissage Accéléré CPA) indicates the resistance of aggregates to polishing under traffic.
The sample undergoes a double polishing by two abrasive powders made up of Corundum (one being coarse, the other rather fine), aluminous silicate, with a hardness just lower than that of diamond (9/10 on the hardness scale of Mohs). The residual roughness of each polished mosaic, saturated with water, is measured using a friction pendulum (S.R.T pendulum) which indicates the loss of kinetic energy.
Each wheel intended to be polished comprises six distinct samples, ie 12 pads, to which are added two so-called reference pads (CPA aggregate = 52.5, constant value). Each wheel undergoes two 3-hour polishing cycles, one with coarse emery, the other with fine emery. Friction measurement on each pad. The latter is repeated 5 times and only the average of the last three values is retained.
The final result is the average S of the four test specimens (2 per wheel) compared to the average C of the four reference test specimens.

EN 1097-8