Resistance of bituminous mixtures to fatigue-induced cracking is one of the main factors that influence pavement service life. Knowledge of the rigidity modulus of bituminous mixtures allows appropriate choices that increase this resistance. Design methods for bituminous mixtures, on which the modulus value depends, are evolving rapidly, requiring development of a new method for determining the modulus.
Develop a test method allowing measurement of the fatigue strength of bituminous mixtures and determine their modulus, particularly based on binder characteristics. Establish criteria for meeting minimum fatigue strength requirements.
A Strategic Highway Research Program (SHRP) instrument for measuring fatigue, is used to determine the test criteria, such as temperature, applied load and testing load frequency. Bituminous mixtures are subjected to rotary shear machine and wheel-tracking rutting tests, water resistance and thermal shrinkage tests. Tests on aggregates concern their angularity and shape.