http://www.diva-portal.org/smash/get/diva2:711917/FULLTEXT01

Polymer modification of bitumen : Advances and challenges

Performance of Warm Mix Asphalt containing Sasobit®: State-of-the-art

Current asphalt binder specifications lack the ability to characterize asphalt binder damage resistance to fatigue loading. Multiple accelerated testing procedures that attempt to efficiently and accurately characterize the contribution of asphalt binders to mixture fatigue are under investigation. One of these tests, which has received significant acceptance by experts and has been submitted as a draft AASHTO standard, is the linear amplitude sweep (LAS) test. This procedure uses viscoelastic continuum damage mechanics to predict binder fatigue life as a function of strain in the pavement. The LAS test uses cyclic loading with systematically increasing load amplitudes to accelerate damage and provides sufficient data for analysis in less than 30 min. Although results of the current LAS testing protocol are promising, the time and the complex numerical procedures required for the analysis have raised concern. In addition, insufficient damage accumulation was observed when the strain amplitudes proposed in...

Modification and Validation of Linear Amplitude Sweep Test for Binder Fatigue Specification

Modelling the linear viscoelastic rheological properties of bituminous binders

Evaluation of permanent deformation of unmodified and SBS modified asphalt mixtures using dynamic creep test

This report documents the results of a study on the applicability of Superpave specification (AASHTO MP1, "Standard Specification for Performance Graded Asphalt Binder") and protocols developed for asphalt cements to modified asphalt binders. A survey indicated that, although the majority of state agencies intend to increase future use of modified binders, very little is known about the binders' behavior. In addition, there are serious concerns regarding their storage stability, aging, and mixing and compaction temperatures. Using advanced rheological characterization of a selected set of binders and mixtures, it was found that the binder specification parameters in the current AASHTO MP1 are not adequate to rank the modified binders according to their contribution to mixture damage. The concepts of viscous flow and energy dissipation were explored in an effort to derive binder parameters that more effectively relate binder to mixture behavior. Suggested test protocols and specification parameters were developed to integrate the new concepts into a future specification. A direct measure of the glass transition behavior and the use of a design-cooling rate were identified as reliable estimators of the binders' role in thermal cracking. Also, a storage stability test and a particulate additive test were developed and proposed as standard tests. The concept of low shear viscosity was introduced for the determination of laboratory mixing and compaction temperatures to avoid excessive heating and to consider the shear-rate dependency of modified binders. Revisions to the binder grading system are recommended to include a three-level grading scheme. A field validation plan is proposed to test the validity of these concepts and to derive reliable specification criteria and limits.

D I Hanson

Papers

Characterization of modified asphalt binders in superpave mix design