Characterizing the tension-compression asymmetric viscoelasticity of asphalt mixture using the uniaxial tension and compression test

Abstract

• The viscoelasticity of asphalt mixture during loading and unloading is different. • The stress-rate-dominated mode of asymmetric viscoelastic model is more accurate. • The viscoelasticity in loading of tension approaches that in unloading of compression. The asphalt concrete of flexible pavement, although viewed as a linear viscoelastic material in many studies, exhibits tension–compression asymmetric viscoelasticity under practical loading. However, the distinction between tension and compression becomes an inevitable issue once the implementation of the constitutive model is involved. To determine the distinction, two modes of asymmetric viscoelasticity, stress-dominated and stress-rate-dominated, were compared, and the constraints of the two modes were derived based on mechanical theory. Further, the uniaxial tension and compression creep-recovery tests were conducted to characterize and verify the distinction of the asymmetric viscoelasticity. Results show that the viscoelasticity of asphalt mixture in loading and unloading has significant differences, indicating the inaccuracy of the stress-dominated distinction. Based on the stress-rate-dominated hypothesis, it is a substitutable method for the asphalt mixture that is consisted of fine gradation and stiff binder to obtain the tension viscoelasticity by the unloading stage of compression tests. In addition, the method of stress-rate-dominated distinction has advantages of precision when the viscoelastic calculation involves the unloading process, especially the long-period or multicycle calculation.