Humboldt H-4165 Harvard Miniature Compaction Apparatus - Manual (Page 2)

General
This test determines the relationship between the moisture content of soils and resulting
densities (oven-dry weight per cubic foot) when the soil is compacted in the laboratory
with this apparatus. Selection of the most appropriate number of layers, number of tamps
per layer and tamping force depends on the type of material and the intended use to
which the compacted material will be put. In general, at least five layers and ten tamps
per layer are required to produce homogeneous test specimens.
Unpacking
In shipment, all of the parts are packed carefully to prevent damage. It is suggested that
all packing material be carefully checked to ascertain that no parts are overlooked. The
apparatus consists of the following:
Specimen ejector and collar remover with spacer plate
Mold holder
1/454 cu. ft. (129 m3)-volume mold & collar
Compaction tamper with 20 lb. (9.07kg), 37.5lb. (17kg) & 40lb (18.2kg) spring
Assembly
Very little assembly is required since the collar remover and specimen ejector is shipped
completely assembled. To assemble the mold, place collar on the mold. Set in center of
base plate with top of mold collar fitted into recess in top plate. Tighten knurled nuts.
The tamper is supplied with 20-pound compaction spring in place. To change springs,
remove the two lock nuts and remove insert in lower end by loosening the two set
screws.
Sample Preparation
Air-dry to a slight to slightly damp condition a 2 to 3 lb. sample of soil taken from a
portion of the material passing the No. 4 (4760-micron) sieve. Mix thoroughly to break
up the lumps and insure a homogeneous mixture. Then divide into six to eight portions,
such that each portion contains slightly more than enough material for one test. To each
portion add approximately the required amount of water to obtain the desired range
of moisture contents. After thorough mixing, place each portion in a small glass jar
with tight fitting cover and store overnight or until ready for testing. For soils that mix
readily with water and have low dry strengths, it is satisfactory to add water and mix the
specimen immediately prior to testing. It is important that a compacted specimen not be
remixed and used over again.
Test Procedure
1. With the mold and collar clamped to the base, place the desired amount of loose soil
in the mold. For five layers, two slightly heaping teaspoonfuls will be required for each
layer. Level the surface by pressing lightly with a wood plunger.
2. Insert the tamper in the mold until it is in contact with the surface of the soil and press
down firmly until one feels that the spring is starting to compress. Releasethe force and
shift the tamper to a new position. Each of the first four tamps should be applied in
separate quadrants and adjacent to the mold. The fifth tamp should be in the center,