Unconfined Compression (UC) Test

Procedure

Test standard

ASTM 2166-06

Test procedure

1) Measure the diameter of the top of the specimen at three location 120° apart, similar take three

measurements at the bottom. Record the average on the datasheet.

2) Measure the length of the specimen at three locations 120° apart. Record the average on the

datasheet.

3) Place the specimen in the loading device so that is centered on the bottom plate

4) Adjust the loading device carefully so that the upper platen just makes contact with the specimen.

Zero the deformation and load dials to zero.

5) Apply the load so that the device produces an axial strain at a rate of 0,5% to 2% per minute.

Record load, deformation, and time values at sufficient intervals to define the shape of the stress-

strain curve (usually 10-15 points are sufficient).

6) Keep applying the load until the load values decreases with increasing strain, or until 15% strain is

reached.

7) Draw a sketch to depict the sample failure.

8) Remove the sample from the compression device and obtain two samples for water content

determination. Determine water content using

a. conventional oven method (>20g); 24 hrs at 105 deg.

b. microwave oven method (>100 g); 3 min. at high power, thereafter 1 min intervals

Unconfined Compression (UC) Test

Data sheet

Sample No. ___________________________ Project No. _________________________

Location _____________________________ Boring No. _________________________

Depth of Sample ________________ _______ Date of Test _________________________

Description of Soil _______________________________________________________________________

Tested by ___________________________________

Specimen data

Type of specimen □ Undisturbed □ Remoulded □ Reconstituted

Shape of specimen □ Cylindrical □ Prismatic

Diameter of specimen, D0 __________ g

Initial area of specimen, A0 __________ cm2

Initial height of specimen, H0 __________ cm

Height to diameter ratio __________

Volume of specimen, __________ cm3

Mass of specimen, mt __________ g

Wet unit weight of specimen __________ g/cm3 __________ kg/m3 Specific weight __________ kN/m3

Water content of specimen, w = mw/ms __________ %

Can no. __________ Can no. __________

Mass of can __________ g Mass of can __________ g

Mass of wet soil + can __________ g Mass of wet soil + can __________ g

Mass of wet soil + can __________ g Mass of wet soil + can __________ g

Mass of dry soil + can __________ g Mass of dry soil + can __________ g

Mass of water, mw __________ g Mass of water, mw __________ g

Mass of dry soil, ms __________ g Mass of dry soil, ms __________ g

Water content, w = mw/ms __________ % Water content, w = mw/ms __________ %

Unit dry weight of specimen __________ g/cm3 __________ kg/m3 Specific weight __________ kN/m3

Compression data

Proving ring No. _____________ Proving ring calibration __________ kN/mm

Elaspsed time (min.)

Deformation dial reading,

H (mm)

Unit strain,

(%)

H/H0

Cross-sectional area,

A’ (cm2)

A0/(1-)

Proving ring dial reading (mm)

Applied axial load, P (kN)

Axial stress,

’a (kPa)

P/A’

Strain rate __________ %/min Unconfined compressive strength, qu __________ kPa

Cohesion, c = qu/2 ___________ kPa

Sketch of specimen after failure

Plot of results

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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Axi

al s

tres

s,

' a[k

Pa]

Axial strain, [%]