Consolidation Test - Soil Properties: Testing, Measurement, and Evaluation - page 292

The actual step-by-step procedure is as follows (ASTM D 2435-04 [1]):
(1) Preparation of the porous disks and other apparatus will depend
on the specimen being tested. The consolidometer must be assem-
bled in such a manner as to prevent a change in water content of the
specimen. Dry porous disks and filters must be used with dry, highly
expansive soils and may be used for all other soils. Damp disks may
be used for partially saturated soils. Saturated disks may be used
when the specimen is saturated and known to have a low affinity for
water. Assemble the ring with specimen, porous disks, filter disks
(when needed) and consolidometer. If the specimen will not be inun-
dated shortly after application of the seating load [see (2)], enclose
the consolidometer in a loose fitting plastic or rubber membrane to
prevent change in specimen volume due to evaporation.
Note 4 —In order to meet the stated objectives of this test
method, the specimen must not be allowed to swell in excess of
its initial height prior to being loaded beyond its preconsolida-
tion pressure. Detailed procedures for the determination of
one-dimensional swell or settlement potential of cohesive soils
is covered by ASTM Test Method D 4546.
(2) Place the consolidometer in the loading device and apply a seat-
ing pressure of 5 kPa (100 lb/ft 2 ). Immediately after application of
the seating load, adjust the deformation indicator and record the ini-
tial zero reading, d 0 . If necessary, add additional load to keep the
specimen from swelling. Conversely, if it is anticipated that a load of
5 kPa (100 lb/ft 2 ) will cause significant consolidation of the specimen,
reduce the seating pressure to 2 or 3 kPa (about 50 lb/ft 2 ) or less.
(3) If the test is performed on an intact specimen that was either
saturated under field conditions or obtained below the water table,
inundate shortly after application of the seating load. As inunda-
tion and specimen wetting occur, increase the load as required to
prevent swelling. Record the load required to prevent swelling and
the resulting deformation reading. If specimen inundation is to be
delayed to simulate specific conditions, then inundation must occur
at a pressure that is sufficiently large to prevent swell. In such
cases, apply the required load and inundate the specimen. Take
time deformation readings during the inundation period as speci-
fied in (5). In such cases, note in the test report the pressure at in-
undation and the resulting changes in height.
(4) The specimen is to be subjected to increments of constant total
stress. The duration of each increment shall conform to guidelines
specified in (5). The specific loading schedule will depend on the
purpose of the test, but should conform to the following guidelines.
If the slope and shape of a virgin compression curve or determina-
tion of the preconsolidation pressure is required, the final pressure
shall be equal to or greater than four times the preconsolidation