IIT Gandhinagar  ajanta@iitgn.ac.in  ap@iitgn.ac.in
Soil Testing Lab

Introduction Experimental Setup Data Analysis Results Theory

Constant Rate of Strain (CRS) Test

Need and Scope:

Determination of the magnitude and rate of consolidation of saturated cohesive soils using continuous controlled strain axial compression. The specimen is restrained laterally and drained axially. The axial force and base excess pressure are measured during the deformation process. Controlled strain compression is typically known as constant rate of strain (CRS) testing (ASTM D4186-06).


Constant rate of strain (CRS) consolidation is performed to determine the compressibility characteristics under a controlled-strain axial compression loading, unlike conventional oedometer test which can apply incremental loading. In this test, the soil specimen is constrained laterally by the consolidation ring; thus, cross sectional area remains constant throughout the test. The specimen is sandwiched axially between top and bottom platens along with top and bottom porous stones. Drainage is provided from the top and excess pore water pressure is measured at the bottom of the soil specimen. Only vertical deformation is allowed during the test. The axial force, axial displacement and base excess pore water pressure are measured during the CRS consolidation test.

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