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AGGREGATE ABRASION VALUE MACHINE - AAV - Dorry Abrasion Machine

AGGREGATE ABRASION VALUE MACHINE


AAV - Dorry Abrasion Machine

BS 812 Pt 113 1990



See also
Polished Stone Value

SPECIFICATION:
The machine is used to determine the resistance of aggregate to wear by abrasion

The test measures resistance of aggregates to surface wear by abrasion. Inadequate abrasion resistance of road-surfacing aggregates means an early loss of the texture depth required to maintain high-speed skidding resistance. Relevant British Standard BS 812 : Part 3 : 1990 Relevant European Standard EN 1097/8 : Part 8 Dorry Abrasion Test This was specified in an earlier version of BS 812, which was superseded in 1951 by the current AAV test. However, the name Dorry continues in common use, for this equipment - (after 40years!)

Test Procedure

Two specimens are pressed against the surface of a steel disc rotating in a horizontal plane, with a force of 0.365 newtons per sq. centimetre.

Sand, fed by hoppers, is used as an abrasive. After 500 disc revolutions the amount of material abraded is measured by calculation of the weight loss of the aggregate.

The percentage loss in mass of chippings as known as the 'Aggregate Abrasion Value' (AAV), and ranges from about 1 for hard flints to over 16 for aggregates normally considered too soft for use in road surfacings. Related Test The PSV test (Polished Stone Value) requires an AAV determination when PSV is greater than 60.

A robust welded steel fabrication carry a steel lap wheel, mounted on a precision ground steel shaft, located in sealed ball bearings, driven from a grease filled totally enclosed reduction gearbox and driven by a v.belt drive calibrated to ensure correct speed of rotation from a resilient mounted electric motor.

Twin specimens manufactured in steel moulds are located on the lap wheel and loaded to a specified weight. Abrasive material is fed on to the lap wheel from adjustable hoppers and after passing under the specimen is removed from the surface of the lap wheel and collected by rotating blades to a collecting hopper for re-cycling.

A predetermined counter is fitted as standard.


TECHNICAL SPECIFICATION: BS812. Pt. 113. 1990.

 STANDARD ACCESSORIES: 2 No. - Specimen Moulds
 2 No. - Flat Plates
 2 No. - Trays

 FINISH: Powder coated and stove enamel. Details electro plated.

 STANDARD ELECTRICAL
 SUPPLY: 220/240v 1Ph 50HZ (Alternatives available).

 PHYSICAL DIMENSIONS: Width 80 cms
 Depth 70 cms
Height 110 cms

 SHIPPING SPECIFICATION: Gross Weight 190 kgs