Page 17 - HIGHWAY ENGINEERING LABORATORY_FLIP BUILDER

1. Aggregate Impact Test Machine according to the British Standard 812: Part
112 1990.

2. BS Sieves of aperture sizes (14 mm, 10mm, 2.36 mm)
3. Cylindrical metal measure with an internal diameter of 75 mm and an internal

depth of 50 mm.
4. A straight metal tamping rod, 10 mm diameter, 230 mm long rounded at one
end.

5. A balance of capacity not less than 500 g and accurate to 0.1 g.

6. A bristle Brush.
7. A set of tray.

4.0 DETAILED PROCEDURE : AGGREGATE IMPACT VALUE

REFERENCE
WORK PROCESS
DOCUMENT
i. The apparatus consists of a steel test mould with a falling

hammer as shown in Figure 1. The hammer slides freely between
vertical guides so arranged that the lower part of the hammer is
above and concentric with the mould.

ii. The material used is aggregate passing a 14 mm sieve and
retained on a 10 mm sieve. It shall be clean and dry (washed if

necessary) but it must not be dried for longer 4 hours nor at a
temperature higher than 110 °C. Otherwise certain aggregates
may be damaged. Weight a clean cylindrical metal container
and denote it as W1.

iii. Fill up the cylindrical metal container with aggregates in three
(3) similar layers. Each layer shall be tamped 25 times with a 10
mm rounded end tamping rod by allowing the tamping rod to

fall freely from a height of about 50 mm above the surface of
the aggregate and the blows being evenly distributed over the
surface.

iv. Remove, by rolling the tamping rod across and in contact with
the top of the container, any aggregate which impedes its

progress. Aggregate being added to fill any obvious
depressions.

Higway Engineering Laboratory page 4