Ministry
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Project title: Determining the Modulus of Rigidity for Different Bituminous Mixtures Used in Québec

File: R275.1

Problem:
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.

Objectives:
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.

Methodology:
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.

General information:

Modality:
Postsecondary

Beginning:  1996-04-01
Ending:  2000-03-31

Departmental funding:  $44 897 
Total cost:  $44 897 

Research report:  Caractérisation de la rigidité et de la résistance à la fatigue des revêtements bitumineux

Final reports are available for loan from the Transports Québec Documentation Centre.

Results and recommandations:
A methodology was developed for characterizing the complex modulus of a mixture using a frequency sweep test and for characterizing the fatigue resistance under constant strain of a mixture. ESG-14, GB-20 and MB-16 mixes were characterized using different asphalts. The type of gradation seems to have little influence on the mechanical behaviour of the mix. A mix designed with a high penetration asphalt (150-200) with polymer additives appears to have a lower complex modulus and better fatigue resistance that an mix designed with "conventional" asphalt. Temperature greatly influences the mechanical behaviour of asphalt mixtures, depending on the type of asphalt.

Principal researcher
Département de génie civil
Université de Sherbrooke
2500, boul. de l'Université
Sherbrooke, Québec