Determining Moisture-Unit Weight Relations of Soil (Compaction Test) - Soil Properties: Testing, Measurement, and Evaluation - page 176

removal of the assembled mold, collar, and base plate after
compaction is completed.

(4.3) Compact the specimen in three layers. After compaction, each
layer should be approximately equal in thickness. Prior to com-
paction, place the loose soil into the mold and spread into a layer
of uniform thickness. Lightly tamp the soil prior to compaction
until it is not in a fluffy or loose state, using either the manual
compaction rammer or a 2-in. (5-mm) diameter cylinder. Following
compaction of each of the first two layers, any soil adjacent to the
mold walls that has not been compacted or extends above the
compacted surface shall be trimmed. The trimmed soil may be in-
cluded with the additional soil for the next layer. A knife or other
suitable device may be used. The total amount of soil used shall be
such that the third compacted layer slightly extends into the col-
lar, but does not exceed 1 ⁄ 4 in. (6 mm) above the top of the mold. If
the third layer does extend above the top of the mold by more than
1

⁄ 4 in. (6 mm), the specimen shall be discarded. The specimen shall
be discarded when the last blow of the rammer for the third layer
results in the bottom of the rammer extending below the top of the
compaction mold.

(4.4) Compact each layer with 25 blows for the 4-in. (101.6-mm)
mold or with 56 blows for the 6-in. (152.4-mm) mold.

Note 2 —When compacting specimens wetter than optimum
water content, uneven compacted surfaces can occur and
operator judgment is required as to the average height of the
specimen.

(4.5) In operating the manual rammer, take care to avoid lifting the
guide sleeve during the rammer upstroke. Hold the guide sleeve
steady and within 5° of vertical. Apply the blows at a uniform rate
of approximately 25 blows/min and in such a manner as to provide
complete, uniform coverage of the specimen surface.

(4.6) Following compaction of the last layer, remove the collar and
base plate from the mold, except as noted in (4.7). A knife may be
used to trim the soil adjacent to the collar to loosen the soil from
the collar before removal to avoid disrupting the soil below the top
of the mold.

(4.7) Carefully trim the compacted specimen even with the top of
the mold by means of the straightedge scraped across the top of the
mold to form a plane surface even with the top of the mold. Initial
trimming of the specimen above the top of the mold with a knife
may prevent the soil from tearing below the top of the mold. Fill any
holes in the top surface with unused or trimmed soil from the spec-
imen, press in with the fingers, and again scrape the straightedge
across the top of the mold. Repeat the appropriate preceding oper-
ations on the bottom of the specimen when the mold volume was