increasing load repetition, the plastic strain decreases after
each repetition of load. After about 100 to 200 cycles of
repetitions, the strain is almost all recoverable as shown in
Fig 1.
Fig 1: Elastic and plastic responses under repeated loads [2].
The indirect tension test is most common repeated
load test to measure the resilient modulus of bituminous
paving mixes due to its simplicity. It is standardized under
the American society of Testing and Materials (ASTM
D4123) [3]. The test involves preparing a compacted
cylindrical bituminous mix specimen subjected to
diametrical repeated loading. The test method recommends
that the resilient modulus (MR) be measured by applying
stresses with magnitudes in the range of 10 to 50% of the
indirect tensile strength of the specimens. In these tests,
compressive load with haversine or any other suitable
waveform is applied in the vertical diametric plane of
cylindrical specimen through a loading strip, and the
resulting horizontal recoverable deformation is measured.
The resilient modulus is computed from following equation: