AS 1141.41:2017 pdf free download.Methods for sampling and testing aggregates Method 41: Polished aggregate friction value—Horizontal bed machine.
3.4 Reference specimens
Specimens incorporating reference material prepared in accordance with Appendix A.
NOTE: One unused reference specimen is included in each test run and is polished and tested at the same time as the test specimens. Its function is to indicate whether the polishing and testing procedures have been correctly carried out.
3.5 Test specimens
Specimens incorporating aggregate prepared from a material for which the PAFV is
required.
4 APPARATUS
The following apparatus is required:
(a) Horizontal bed polishing machine (See Figures 1 and 2) rigidly mounted on a firm level base, and comprised and constructed as follows:
(i) Specimen bed an electrically driven circular specimen bed of about 700 mm in diameter, revolving at 33 r/rnin to 35 r/min, and with provision for accurately positioning the nine specimens.
(ii) Solid rubber-tvred wheels Replaceable rubber-tyred wheels not exceeding
225 mm in diameter, 35 mm to 37 mm wide with a Shore A rubber hardness
60 ±5. Two sets of four rubber-tyred wheels are required for each polishing run,
one set for use with the silicon carbide grit and the other set with the aluminium
oxide powder. Any tyre shall be discarded if it shows signs of irregular wear, or
its hardness falls outside of the above limits, or the diameter becomes less than
210 mm.
Each wheel shall be capable of being brought to bear on the surface of the specimens mounted on the specimen bed with a total force of 155 ±5 N.
NOTE: The total force of 155 ±5 N for each wheel is normally achieved by means of appropriate weights attached to each wheel mount. The actual applied force should be verified either by calculation or direct measurement.
The wheels shall be located such as to give a polishing track of 110 mm minimum width and a length of 130 mm across the face of the specimens.
Each wheel is toed in at an angle of 5 degrees to the tangent of the circular tracks at the centre of the contact area between wheel and specimen, so as to provide a side-slipping action as the specimen bed revolves.
(iii) Grit feeder Abrasive grit feeder and water feed control for delivering abrasive and water to the surface of the specimens in front of the inner track wheel.
(b) Clock or tuning device for periods of 2 h preferably with an alarm.
(c) Mould To make specimens for the horizontal bed polishing machine consisting of the following components:
(I) A specimen moulding frame of steel strip about 3 mm thick by 25 mm wide, in the shape of a truncated wedge, about 200 mm at the wide end, 90 mm at the narrow end, 1 80 mm long and 25 mm deep.
(ii) A base plate of glass or metal on which the moulding frame is placed during the preparation of the test specimens.
(iii) A mounting plate of aluminium of similar shape to the moulding frame but of longer dimensions to allow for bolt holes for attaching the test specimens to the specimen bed of the polishing machine.AS 1141.41 pdf download.