Unconfined Compression Test ~ this test can be used to establish
the shear strength of a non-fissured cohesive soil sample using
portable apparatus either on site or in a laboratory. The 75 mm
long¾38 mm diameter soil sample is placed in the apparatus and
loaded in compression until failure occurs by shearing or lateral
bulging. For accurate reading of the trace on the recording chart a
transparent viewfoil is placed over the trace on the chart.
Typical Results ~ showing compression strengths of clays:-
Very soft clay † less than 25 kN/m^2
Soft clay † 25 to 50 kN/m^2
Medium clay † 50 to 100 kN/m^2
Stiff clay † 100 to 200 kN/m^2
Very stiff clay † 200 to 400 kN/m^2
Hard clay † more than 400 kN/m^2
NB. The shear strength of clay soils is only half of the compression
strength values given above.
Soil Assessment and Testing