01154899

Component

At the bottom of an asphalt layer strain signals look more like a haversine than a sine when a load is passing. Therefore using haversine signals in four point bending (4PB) tests would be more realistic. However, asphalt is a viscous-elastic material and in contrast with the road there is no elastic subgrade in the fatigue test to push the specimen back to its original position after the load is gone. 4PB tests with constant haversine deflections will immediately change into tests with constant sine deflections, performed on a bended beam. Apart from the observed sine force, permanent strain and deflection are observed when the load is removed. Two fatigue tests were carried out, a constant sine deflection (strain amplitude 225 ƒÝm/m) and a constant haversine deflection (peak-peak strain value 225 ƒÝm/m). Instead of comparable fatigue lives, the difference is too high, leading to the conviction that the later test is a sinusoidal fatigue test with 112.5 strain amplitude on a bended beam. Due to the viscous-elastic character it is not possible to perform continuous fatigue tests where both the load and deflection signals maintain haversine shapes. This might be possible if the asphalt beam is glued on an elastic beam and rest periods between the haversine signals are applied. The elastic part of the composite beam avoids the evolution of permanent deformation. Due to rest periods the stress response in the asphalt due to the offset component in the haversine load might be present in the stress signal.

01147878

10-0485

English

13p

2010

Transportation Research Board 89th Annual Meeting

DVD

Figures (10) ; Photos (2) ; References (17)

Asphalt; Asphalt pavements; Bituminous materials; Deflection; Elasticity (Mechanics); Fatigue (Mechanics); Field tests; Pavement layers; Pavements; Strain (Mechanics)

Highways; Materials; Pavements; I31: Bituminous Binders and Materials

Transportation Research Board Annual Meeting 2010 Paper #10-0485

TRIS, TRB

Jan 25 2010 10:15AM