Testconsult Ireland has been awarded Irelands first UKAS accreditation for PSV testing ( Polished Stone Value) - to BSEN 1097-8-2000.

The PSV test will determine how quickly a sample of aggregate will become 'polished' or worn smooth, by the repeated passing of tyres. The road surface layer needs to retain its roughness for as long as possible, to provide skid resistance for traffic. The higher the polished stone value (or PSV) the longer the aggregate will remain rough during use in road surfacing.

PSV equipment includes an 'accelerated polishing machine', which is designed to imitate the effect of tyres on a road, and apparatus to test friction. The samples of aggregate are fixed into small moulds using resin, according to a specified method, together with a control sample of known PSV.

Each sample is then subjected to polishing in the accelerated polishing machine, in a prescribed order. After polishing, the friction test is carried out first on the control samples to calibrate the apparatus and then on each test sample in turn.

PSV results are expressed as 'categories', such as PSV 68 , PSV 62 or PSV 56 , etc. The number represents the minimum value for the aggregate. For road surfacing in critical locations a value of at least 62 is often required.

For more information contact Michael Robinson

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