The Polished Stone Value (BS 812: Part 3) Gives A Measure Of Resistance Of Road Stone To The Polishing Action Of The Pneumatic Tire. Under Conditions Similar To Those Occurring On The Surface Of The Road Where The Surface Of The Road Consists Largely Of Road Stone, The State Of Polish
2.0 Objective
To Measure The Extent Of Aggregates In Wearing Course That Would Be Polished Under The Traffic Flow.
3.0 Apparatus
a) An accelerated polishing machine, which shall be rigidly mounted on firm, level and resilient base of concrete.
Figure 3.1: Polishing Stone Aggregate Tester
b) Metal moulds for preparation of specimens.
Figure 3.2: Metal Moulds
c) Friction Test.
d) British Standard Sieve.
Figure 3.4: Sieve Size 9.25mm And 7.94mm
e) Materials consisting of no. 36 corn emery and air-floated emery flour.
Figure 3.5: No. 36 Corn Emery Flour
4.0 Methodology
a) Specimens Are Prepared As Shown In The Standard And The Particle Used Shall Pass The 9.52mm And Retained On The 7.94mm British Standard Sieve.
b) Specimen Are Polished Using The Polishing Machine. Temperatures Are Within 27 Degree Celsius During The Polishing Period.
c) Watered And The No. 36 Corn Emery Are Faded Continuously On The Road Wheel Within The Period Of 3 Hours.
d) After 3 Hours, The Machine And The Specimens Are Washed To Remove The Trace Of The Corn Emery.
e) Repeat Step 2 With The Air Floated Emery Flour Replaced No. 36 Corn Emery The Rates Of Feeding Of The Water Are Twice For The Emery Flour.
f) The Specimens Are Stored Facing Downwards Under Water At A Temperature Of 25 Degree Celsius For ½ To 2 Hours.
g) After That, Specimen Are Removed From The Water And Tested On The Friction Tester.
h) The Specimen And The Rubber Slider Are Wetted Before The Frictions Are Done.
i) The Pendulums Are Released From Its Original Position (Horizontal) And Readings
5.0 Result
Polished Stone Value (PSV) (BS 812: Part 3)
| Specimen | Specimen No | Polished – Stone Value     1 2 3 4 5 | Mean |
| 1 | 1 | 49 48 49 47 48 | 48.2 |
| 2 | 2 | 54 55 54 53 54 | 54.0 |
| 3 | 3 | 48 48 49 48 48 | 48.2 |
| 4 | 4 | 53 51 51 50 50 | 51.0 |
| 13 | 13 | 52 52 52 53 53 | 52.4 |
| 14 | 14 | 52 52 52 51 52 | 51.8 |
Mean = 52.1
Polished Stone Value (P.S.V) = S + 52.5 – C
= 50.35 + 52.5 – 52.1
= 50.75
6.0 Discussion
a) Aggregate must need to be the right chosen because need to place in the metal mould nicely.
b) Need so much used of water.
c) Must have 14 specimens to complete wheel of polish stone aggregate tester.
d) Portable skid tester must be balance place to avoid the error measure reading.
7.0 Recommendations
a) Nice not so rounded aggregate have chosen to be place in the metal mould.
b) Water is used in making the specimen and to wet the specimens.
c) Specimens can be from different types of rocks.
d) Portable skid tester has to be balance using air bubble to get the balance portable skid tester.
8.0 Conclusion
From the experiment, we get the value is 50.75 more than the requirement of JKR’s; 40. This specimen are not manage to handle the heavy raining or flood because the skid value are mild and near to 40. The more skid value is better because it’s affecting the resistance of the surface pavement and tire. These relationships are varying with the traffic condition, type of surfacing and other factors. We can conclude this experiment successful because the value are exceeding the JKR’s requirement, <40.
9.0 Reference:
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