Prediction of Soaked CBR value From Index Properties and Compaction Characteristic of Subgrade Soils
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Date
2019-10
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
The subgrade provides the foundation for the pavement material and should be well compacted to
utilize its full strength. The subgrade strength is related to the CBR value of soil. The CBR test is
laborious and time consuming and must always be performed on remolded soil samples. The CBR
values depend on the type of soil as well as other soil properties. Hence, it is important to
develop correlations between CBR and index properties for the subgrade soils.
In this research work, an attempt has been made to establish a correlation of CBR values as
function of different index properties and compaction characteristics of soil specific to JinkaMendir
design
and
build
road
project
subgrade
soils.
In
order
to
achieve
the
intended
correlations,
a
series
of
laboratory
tests
have
been
conducted
on
forty
one
soil
samples.
Based
on
the
laboratory
test
results,
the
collected
soil
samples
are
categorized
into
two
groups,
namely
coarse-grained
and
fine-grained
soils.
Accordingly,
twenty
five
of
the
soil
samples
are
classified
as
coarse-grained
soils
and
the
remaining
sixteen
soil
samples
are
classified
as
fine-grained
soils.
This
research
work
was
done
on
twenty
three
coarse-grained
soils
and
fourteen
fine-grained
soils
with
two
control tests for both of the coarse-grained and fine-grained soils. For
this research work, statistical software (SPSS) was employed to investigate the significance of
individual independent variables.
Using multiple linear regression analyses, good correlations were obtained between soaked CBR and
index properties test results for coarse-grained and fine-grained soils with coefficient of
determinations of 0.866 and 0.931 respectively. After validating the developed correlation with
control test results, it was noted that the correlations of CBR values with soil index properties are
more applicable for preliminary characterizing of the strength of subgrade soils.
Description
Keywords
Soaked CBR, Subgrade Soils, Compaction