8. Calculation
8.1 Calculate the axial strain,
e
1
, to the nearest 0.1 %, for a
given applied load, as follows:
e
1
5 DL/L
0
where:
DL = length change of specimen as read from deformation
indicator, mm (in.), and
L
0
= initial length of test specimen, mm (in).
8.2 Calculate the average cross-sectional area, A, for a given
applied load, as follows:
A
5 A
0
/
~1 2 e
1
!
where:
A
0
= initial average cross-sectional area of the specimen,
mm
2
(in.
2
), and
e
1
= axial strain for the given load, %.
8.3 Calculate the compressive stress,
s
c
, to three significant
figures, or nearest 1 kPa (0.01 ton/ft
2
), for a given applied
load, as follows:
s
c
5 ~P/A!
where:
P
= given applied load, kPa (ton/ft
2
),
A
= corresponding
average
cross-sectional
area
mm
2
(in.
2
).
8.4 Graph—If desired, a graph showing the relationship
between compressive stress (ordinate) and axial strain (ab-
scissa) may be plotted. Select the maximum value of compres-
sive stress, or the compressive stress at 15 % axial strain,
whichever is secured first, and report as the unconfined
compressive strength, q
u
. Whenever it is considered necessary
for proper interpretation, include the graph of the stress-strain
data as part of the data reported.
8.5 If the undisturbed and remolded compressive strengths
are remolded, determine the sensitivity, S
T
, is calculated as
follows:
S
T
5
q
u
~undisturbed specimen!
q
u
~remolded specimen!
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