Consolidation Test - Soil Properties: Testing, Measurement, and Evaluation - page 286

restrained laterally and drained axially while subjected to incremen-
tally applied, controlled-stress loading. Two alternative procedures are
provided. Test Method A is performed with constant load increment
duration of 24 h, or multiples thereof. Time-deformation readings
are required on a minimum of two load increments. In Test Method B ,
time-deformation readings are required on all load increments. Succes-
sive load increments are applied after 100% primary consolidation is
reached, or at constant time increments as described in Test Method A.
The determination of the rate and magnitude of consolidation of soil
when it is subjected to controlled-strain loading is covered by ASTM
Test Method D 4186.
The test method is most commonly performed on undisturbed sam-
ples of fine-grained soils naturally sedimented in water; however, the
basic test procedure is applicable as well to specimens of compacted soils
and undisturbed samples of soils formed by other processes, such as
weathering or chemical alteration. Evaluation techniques specified in
this test method are generally applicable to soils naturally sedimented
in water. Tests performed on other soils such as compacted and residual
(weathered or chemically altered) soils may require special evaluation
techniques.
It is the responsibility of the agency requesting this test to specify
the magnitude and sequence of each load increment, including the
location of a rebound cycle, if required and, for Test Method A, the load
increments for which time-deformation readings are desired.
In this test method, a soil specimen is restrained laterally and loaded
axially with total stress increments. Each stress increment is maintained
until excess pore water pressures are completely dissipated. During the
consolidation process, measurements are made of change in the specimen
height, and these data are used to determine the relationship between the
effective stress and void ratio or strain and the rate at which consolida-
tion can occur by evaluating the coefficient of consolidation. [1]

Load device: a suitable device for applying vertical loads to a
specimen (see Figures 20-1 and 20-2)
Consolidometer: a standardized device to hold the sample in a ring
that is either fixed to the base or floating. The consolidometer must
also provide a means of submerging the sample, applying a verti-
cal load, and measuring the change in thickness of the sample
(Figures 20-1 and 20-2).
Porous stone
Moisture room
Specimen ring with cutting edge attached (minimum specimen
diameter: 50 mm [2.00 in.]; minimum initial specimen height:
12 mm [0.5 in.], but not less than ten times the maximum particle
diameter; minimum specimen diameter-to-height ratio: 2.5; to min-
imize the effects of friction between the specimen's sides and the
ring, the use of greater diameter-to-height ratios is recommended,
with ratios greater than four being preferable.)

APPARATUS AND
SUPPLIES