Triaxal cyclic compression test - method

In the triaxial cyclic compression test, the cylindrical specimen is subjected to a confining pressure, c, on which a cyclic axial pressure is superposed. 

The confining pressure may be either dynamic or static. However, the static type is typically used. In both cases, before starting the test, a small pre-loading axial stress, not exceeding 0.02[2Oy + oj in the case of haversinusoidal loading and 0.02[o, + oj in the case of block-pulse loading, is applied. 

The cylindrical specimens should have a minimum diameter of 50 mm and a minimum height of 50 mm, if the nominal maximum aggregate size is 16 mm. Alternatively, the minimum diameter should be 75 mm and the minimum height should be 75 mm, if the nominal maximum aggregate size is 16 mm. It is recommended to use a height-to-diameter ratio of 0.6, if the nominal aggregate size is 16 mm, and 0.8, if the nominal aggregate size is 16 mm. At least two specimens are required to be tested per type of bituminous mixture (CEN EN 12697-25 2005). 

The specimens are produced in the laboratory by using a gyratory or an impact compactor (CENEN 12697-31 2007 or CEN EN 12697-30 2012) or cored from the road or laboratory-compacted slab (CEN EN 12697-27 2000 or CEN EN 12697-33 2007). Specimens are tested not before 2 days after compaction and all specimens are stored at a temperature between 5°C and 25°C. 

The test is conducted at 30°C to 50°C typically, a temperature of 50°C is used for asphalts for surface courses and a temperature of 40°C is used for asphalts for binder and base courses. 

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