The PSV of an aggregate is a measure of the resistance of an aggregate to polishing. The value is established by subjecting the aggregate to a standard polishing process, and then testing the aggregate with the Portable Skid Resistance Tester to determine its PSV.
The testing procedure and description of the process is set out in, BS 812 : Part 114 & ASTM E 303-98 (Reapproved 2008)
Research at the UK Road Research Laboratory showed a significant relationship between polishing of aggregates used in road surfaces and skid resistance. Tests were devised using an Accelerated Polishing Machine and a friction measuring device, a Skid- Tester, to determine a Polished Stone Value.
These developments have resulted in a simple and inexpensive procedure to determine in advance of a road being built what its resistance to skidding will be.
Our Accelerated Polishing Machine was first made 25 years ago, and we were deeply involved both in the development in the machine and of the test procedures based on it. More than 1000 of these machines have been supplied throughout the world to Materials Laboratories, Consulting Engineers and Research Institutions.
The Skid Tester was first made to a design of the UK Road Research Laboratory. We now offer this machine. Customers may now purchase the two machines required to carry out PSV calculations from the same company, which is also able to provide a full range of spares and technical advice and support.
Calculation of Polished Stone Value
The Polished Stone Value of aggregate gives a measure of resistance to the polishing action of vehicle tyres under conditions similar to those occurring on the surface of a road.
The action of road vehicle tyres on road surfaces results in polishing of the top, exposed aggregate surface, and its state of polish is one of the main factors affecting the resistance to skidding.
Resistance to this polishing action is determined principally by the inherent qualities of the aggregate itself. A later section of this memorandum gives some information about the polishing resistant qualities of different sources of aggregate.
The actual relationship between PSV and skidding resistance wilI vary with traffic conditions,type of surfacing and other factors. All factors together with reproducibility of the test should be taken into account when drawing up specifications for road works which include test limits for PSV.
The PSV test is carried out in two stages - accelerated polishing of test specimens followed by measurement of their state of polish by a friction test.
Description of the PSV Test
Full details are given in BS812Part1 14:1989. A copy of this document is essential to understand and carry out the test.
Four curved test specimens are prepared from each sample undergoing test. Each consists of 35 to 50 representative chippings of carefully controlled size supported in a rigid matrix.
Fourteen specimens are clamped around the periphery of the 'road wheel' and subjected to two phases of polishing by wheels with rubber tyres. The first phase is of abrasion by a corn emery for three hours, followed by three hours of polishing with an emery flour. Two of the fourteen samples are of Control stone.
The degree of polish of the specimens is then measured by means of the portable skid resistance tester (using a special narrow slider, shorter test length and supplementary scale) under carefully controlled conditions. Control specimens are used to condition and check the slider before the test; also a pair of control specimens is included in each test run of fourteen specimens to check the entire procedure and to allow for adjustment of the result to compensate for minor variations in the polishing and or friction testing. Results are expressed as 'polished stone values' (PSVs), the mean of the four test specimens of each aggregate.
International Use of the PSV Test - BS 812
This British Standard has been adopted and used widely throughout the world. It is the only test with available equipment to calculate PSVs.
The Permanent International Association of Road Congresses PIARC in conjunction with RILEM and the American Society for Testing Materials (ASTM), recommend the use of BS 812 to determine Polish Stone Values.
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Aggregate Stone Explained Videoby phoenixhomeservices545 views
I carry-out this test in a UKAS accredited Laboratory in England. We used to perfrom this test in accordance with BS 812:114 but have now switched to BS EN 1097-8:2009. The only subtle difference is that the specimens have to be made using 36-46 particles instead of 35-50.
cw090 1 month ago
the result was in line with European standard?
Richaroocc 2 months ago