Humboldt H-4340 Sand Equivalent Test Set with Case - Manual (Page 7)

If a cast is formed that permits careful handling without breaking, the correct
moisture range has been obtained. If the material is too dry, the cast will
crumble and it will be necessary to add water and remix retest until the material
forms a cast. If the material shows any free water it is too wet to test and must
be drained and air-dried, mixing if frequently to ensure uniformity. This overly
wet material will form a good cast when checked initially, so the drying process
should continue until a squeeze check on the drying material gives a cast which
is more fragile and delicate to handle than the original. If the "as received"
moisture content is within the limits described above, the same may be run
immediately. If the moisture content is altered to meet these limits, the sample
should be put in a pan, covered with a lid or with a damp towel that does not
touch the material, and allowed to stand for a minimum of 15 minutes.
D. After the minimum curing time, remix for 1 minute without water. When
thoroughly mixed, form the material into a cone with a trowel.
E. Take the tin measure in one hand and push it directly through the base of the
pile while holding the free hand firmly against the pile opposite the measure.
F. As the can travels through the pile and emerges, hold enough hand pressure to
cause the material to fill the can to over-flowing. Press firmly with the palm of
the hand, compacting the material until it consolidates in the can. The excess
material should be struck off level with the top of the can, moving the edge of
the trowel in a sawing motion across the brim.
G. To obtain additional test specimens. repeat the procedures in steps D through F
above.
Preparation of Apparatus
1. Fit the siphon assembly to a 1 gal (3.8 litre) bottle of working calcium chloride
solution. Place the bottle on a shelf 3 ft ± 1 in. (914 ± 25 mm) above the work
surface.
NOTE 6: Instead of the 1 gal (3.8 litre) bottle, a glass or plastic vat having a larger
capacity may be used provided the liquid level of the working solution is maintained
between 36 and 45 in. (914 and 117 mm) above the work surface.
2. Start the siphon by blowing into the top of the solution bottle through a short piece
of tubing while the pinch clamp is open.
3. When using either the mechanical or the manually operated sand equivalent shaker,
fasten the apparatus to a firm and level mount.
NOTE 7: If only a few sand equivalent tests are to be performed at one location , it is
possible to hold the manually operated shaker by hand on a firm mount.
Procedure
1. Siphon 4 ± 0.1 in. (101.6 ± 2.54 mm) (indicated on the graduated cylinder) of
working calcium chloride solution into the plastic cylinder.
2. Pour one of the test specimens into the plastic cylinder using the funnel to avoid
spillage.
3. Tap the bottom of the cylinder sharply on the heel of the hand several times to
release air bubbles and to promote thorough wetting of the specimen.