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

Polymer modification of bitumen : Advances and challenges

American Society for Testing and Materials

Influence of aging on the evolution of structure, morphology and rheology of base and SBS modified bitumen

Morphology, rheology, and physical properties of polymer-modified asphalt binders

Evaluation of aging behaviors of asphalt binders through different rheological indices

The effect of long-term oxidation on the rheological properties of polymer modified asphalts☆

This project was a comprehensive study directed at developing an improved method of screening asphalt binders for long-term pavement performance. A new dynamic shear rheometer (DSR) function, G'/(eta'/G'), and a new aging procedure should warn of premature asphalt hardening and resulting fatigue cracking. For unmodified asphalts the new DSR function correlated well with ductility (at 15 deg C, 1 cm/min) below 10 cm. The correlation was originally developed for DSR measurements at 15 deg C and 0.005 rad/s. These conditions were time-temperature superposition shifted to 44.7 deg C and 10 rad/s to produce a method that is easily accessible to standard laboratory rheological equipment and methods. The recommended aging procedure uses the pressure aging vessel (PAV) apparatus but takes advantage of the higher average aging rate when the asphalt is aged in thinner films. This change, combined with somewhat longer aging, results in a more rigorous test of durability than the standard PAV method. At the same time, the resulting rankings of aged materials are more representative of rankings that are obtained from aging at atmospheric air pressure and 60 deg C. For modified asphalts, the results were complex. Generally for a given value of the DSR function, the ductility was better than indicated by the unmodified asphalt DSR-ductility correlation. Larger amounts of modifier produced increasing values of ductility for a given function value. This result was very asphalt dependent, however, so no general correlation could be found. As modified binders oxidize, the asphalt hardens and the improvement to ductility imparted by modifiers decreases. After enough aging, the improvement is gone and modified binders perform no better than their aged unmodified counterpart. A critical issue is whether the life extension produced by modifiers is life-cycle cost effective. Long-Term Pavement Performance (LTPP) and SH 21 binders indicate: sealcoats may provide an opportunity for significant and very cost-effective in-place binder rejuvenation; G'/(eta'/G') is an excellent function for tracking pavement aging; pavements can oxidize rather uniformly with depth; brittle binders can be tolerated in stiff pavements; aggregates appear to have little effect on asphalt oxidation reactions; rolling thin-film oven tests plus PAV aging is not severe aging, in the context of pavement life.

Development of a New Method for Assessing Asphalt Binder Durability with Field Validation

Literature reports indicate that the ductility of binders recovered from asphalt pavements correlate with cracking failure. However, ductility measurement is a time and material consuming process, ...

An Investigation of Asphalt Durability: Relationships Between Ductility and Rheological Properties for Unmodified Asphalts

Asphalt binders are complex mixtures of a wide variety of hydrocarbon materials. Added to this complexity in recent years has been modification with a variety of polymer modifiers. Binders used in this study were commercial materials obtained directly from the suppliers. They include diblock poly (styrene-b-butadiene) rubber (SBR), triblock poly (styrene-b-butadiene-b-styrene) (SBS), and high-cure ground tire rubber. A study of the effect of these modifiers on oxidative aging and on changes in physical properties due to aging shows several effects. Modifiers can reduce oxidative aging rates to some degree, but a bigger effect tends to be to reduce the hardening of binders that occurs in response to oxidative aging. This reduction in hardening rate is expected to have a positive effect on pavement performance over time, relative to the performance of base asphalts. Furthermore, the effectiveness of modifiers varies with the base asphalt.

Oxidation and Viscosity Hardening of Polymer-Modified Asphalts

This project was a comprehensive study directed at developing an improved method of screening asphalt binders for long-term pavement performance. A new dynamic shear rheometer (DSR) function which correlates well with ductility was coupled with a new aging procedure in a tentative specification which should guard against failure caused by premature asphalt hardening and consequent fatigue cracking. The correlation was found for unmodified asphalts between ductility (at 15 deg C, 1 cm/min) below 10 cm and the DSR function G'/(eta'/G'). The correlation was originally developed for DSR measurements at 15 deg C and 0.005 rad/s. These conditions were shifted to 43 deg C and 10 rad/s by using time-temperature superposition to produce a method that is easily accessible to standard laboratory rheological equipment and methods. The developed method is not adequate for modified asphalts. The aging procedure that is recommended uses the pressure aging vessel (PAV) apparatus but is modified by taking advantage of the higher average aging rate when the asphalt is aged in thinner films. This, combined with somewhat longer aging, results in more extended binder aging and thus a more rigorous test of durability than the standard PAV method. At the same time, the resulting rankings of aged materials is more representative of rankings that are obtained from aging at atmospheric air pressure and 60 deg C. For modified asphalts, the results were complex. Generally for a given value of the DSR function, the ductility was better than indicated by the DSR function correlation for unmodified asphalts. Larger amounts of modifier produced increasing values of ductility for a given function value. This result was very asphalt dependent, however, so no general correlation could be found. As modified binders oxidize, the asphalt hardens and the improvement to ductility imparted by modifiers decreases. After enough aging, the improvement is gone and modified binders perform no better than their aged unmodified counterpart. A critical issue is whether the life extension produced by modifiers is life-cycle cost effective.

/pdf/development-of-a-new-method-for-assessing-asphalt-binder-15ww8e6l02.pdf

Yonghong Ruan

Papers

The effect of long-term oxidation on the rheological properties of polymer modified asphalts☆

Development of a New Method for Assessing Asphalt Binder Durability with Field Validation

An Investigation of Asphalt Durability: Relationships Between Ductility and Rheological Properties for Unmodified Asphalts

Oxidation and Viscosity Hardening of Polymer-Modified Asphalts

Development of a new method for assessing asphalt binder performance durability