Page 21 - HIGHWAY ENGINEERING LABORATORY_FLIP BUILDER

Page :
WORK INSTRUCTION
Edition :
Checking No.
POLISHED STONE VALUE (PSV)
CIVIL ENGINEERING (Reference Standard: BS812 Effective Date:
Part1 14:1989)
JKA/ DCC30112/ 2021 Amendment Date:

1.0 OBJECTIVE OF EXPERIMENT :

To determining the polished-stone value (PSV) of an aggregate.

2.0 SUMMARY OF THEORY :
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 will 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.

The actual relationship between PSV and skidding resistance will vary with the
traffic conditions, type of surfacing and other factors. All factors together with the
reproducibility of the test should be taken into account when drawing up specifications

for road-works which include test limits for PSV. The test is in two parts.
a) First part. Samples of stone are subjected to a polishing action in an accelerated
polishing machine.

b) Second part. The state of polish reached by each sample is measured by means of a
friction test and is expressed as a laboratory-determined PSV.
In order to evaluate the effects of different grades of calcined bauxite on the polishing

behaviour, six types of calcined bauxite, including grades 90, 85, 80, 75, 70, and 65, were
used in this study. The main chemical composition of calcined bauxite was tested
with X-ray fluorescence analysis and is shown in Table 1. As coarse aggregates

commonly

Higway Engineering Laboratory page 8