Complex shear modulus test using a DSR

This test method determines again the complex modulus (G ) and the phase angle (8), but using torsion rectangular geometry on a DSR to prismatic specimens. The test is specified by ASTM D 7552 (2009). 

According to the specification, the test is applicable to bituminous mixtures having complex shear modulus values greater than 1 x 10 Pa when tested over a range of temperatures from 10°C to 76°C at frequencies of 0.01 to 25 Hz and strains of 0.001% to 0.1%. 

Because of the geometry of the specimens tested, the test is not applicable to open-graded asphalts or stone mastic asphalts (SMAs). It is appropriate for dense-graded mixtures with 19 mm or smaller nominal maximum aggregate size. 

Prismatic specimens nominally 49 2 mm in length, 12 2 mm in width and 9 1.5 mm in thickness are cut from cylindrical specimens 150 mm in diameter, compacted in the laboratory (Marshall or gyratory compaction) or cored from the field. 

During testing, one of the fixtures is rotated with respect to the other at a pre-selected% strain (usually 0.01%) and a range of 10 frequencies at the selected temperatures. The frequency ranges from 10 to 0.01 Hz. 

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