Consolidation Test - Soil Properties: Testing, Measurement, and Evaluation - page 285

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CHAPTER TWENTY

Consolidation Test
(Referenced Document: ASTM D 2435)

Consolidation Test

When structures are built on saturated soil, the load is presumed to
be carried initially by incompressible water within the soil. Because of
additional load on the soil, water will tend to be extruded from voids in
the soil, causing a reduction in void volume and settlement of a struc-
ture. In soils of high permeability (coarse-grained soils), this process
requires a short time interval for completion, with the result that almost
all of the settlement has occurred by the time construction is complete.
However, in soils of low permeability (fine-grained soils, particularly
clayey soils), the process requires a long time interval for completion,
with the result that strain occurs very slowly. Thus, settlement takes
place slowly and continues over a long period of time.
The phenomenon of compression due to very slow extrusion of wa-
ter from the voids in a fine-grained soil as a result of increased loading
(such as the weight of a structure on a soil) is known as consolidation .
Associated settlement is referred to as consolidation settlement . It is
important to be able to predict both the rate and magnitude of the con-
solidation settlement of structures. Actual prediction (calculation) of
consolidation settlement, however, is beyond the scope of this topic;
as this is a laboratory manual, its purpose is to cover laboratory proce-
dures necessary to obtain results that are needed to estimate the rate
and magnitude of settlement of structures on clayey soils.
The method presented in this chapter covers procedures for
determining the magnitude and rate of consolidation of soil when it is

INTRODUCTION

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