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

The aim of the present work is to study the rheology in the linear viscoelasticity range of polymer-modified bitumens with recycled EVA. In this way, blends of bitumens having two different penetration grades (60/70 and 150/200) and recycled EVA were prepared, ranging from 0 to 9 wt % polymer. Oscillatory shear tests were carried out at different temperatures, from −10 to 75 °C. From them, “empirical” master curves for polymer concentrations up to 7 wt % were obtained in a wide frequency range. Nevertheless, empirical superposition could not be carried out on the system having 9 wt % polymer. This fact suggests that a change in the binder microstructure takes place at this polymer content, although, as shown by optical microscopy, phase inversion (i.e., a continuous polymer-rich phase) is not yet achieved. In addition, MDSC measurements made evident that a significant decrease in the polymer melting point occurs as EVA is blended with bitumen, probably related to smaller polymer crystallites. Bitumen modi...

Linear Viscoelasticity of Recycled EVA-Modified Bitumens

Asphalt binder was modi- fied by low-density polyethylene (LDPE) and ethyl vinyl acetate (EVA) polymers to investigate the structure-property relationships of polymer-modified asphalt (PMA). The PMA was prepared in a high- shear blender at 160 � C. The opti- mum blending time (OBT) for each polymer was determined following a separate investigation. OBT was influenced by Mw, MWD, and polymer structure. The influence of Mw of LDPE and vinyl acetate (VA) content of EVA on PMAs was studied by rheological tools. Poly- mer modification improved the rhe- ological properties of base asphalt. EVA-PMAs were found to be less temperature sensitive than LDPE- modified asphalts. LDPE modifica- tion increased flow activation energy (Ea) but EVA modification de- creased Ea. Both VA content and Mw of LDPE have influenced the storage stability of PMAs. The low- temperature properties of PMAs and short ageing tests were not influ- enced by polymer type. On the other hand, the high-temperature proper- ties of PMAs were strongly influ- enced by Mw of LDPE and VA content of EVA. Overall, EVA with low VA content showed the best temperature resistance to high- temperature deformations, the highest upper service temperature as well as the best storage stability.

https://faculty.kfupm.edu.sa/che/ihussein/RA2005V45.pdf

Influence of M w of LDPE and vinyl acetate content of EVA on the rheology of polymer modified asphalt

This paper shows the state of the art of Mexican asphalt, AC-20 grade, modified by linear styrene−butadiene triblock copolymers (SBS), which include variations in their chemical structures, specifically, total styrene and 1,2-butadiene vinyl contents. The main objective of this work was studying the influence of variation in the 1,2-butadiene vinyl content between 9 to 41% (wt/wt), and also variation in the styrene content between 10 and 45% (wt/wt). Both variables were changed in the structure for the SBS copolymer in order to see the effect on thermal and rheological properties when they are used as asphalt modifiers. The research includes composition characterization and thermal properties of raw and modified asphalt. Analytical characterization of SBS polymers was carried out too by means of differential scanning calorimetry, fluorescence microscopy, and a parallel plate rheometer. Results obtained showed that SBSs with a molecular weight of 200 000 ± 10 000 Daltons get the maximum performance in the ...

Thermomechanical and Rheological Asphalt Modification Using Styrene−Butadiene Triblock Copolymers with Different Microstructure

The effect of ethylene, ethylene acrylate and glycidyl methacrylate (EA) terpolymer, and ethylene butyl acrylate (EBA) copolymer on asphalt modification was in- vestigated at 4, 6 and 8% polymer concentrations. Both melt state rheology and asphalt concrete mix (ACM) were inves- tigated. In the melt state analysis, dynamic shear rheology, storage stability, artificial ageing, and performance grading (PG) were studied. The PG grading of polymer modified asphalt (PMA) is correlated to the elastic properties of the polymers. Both resins improved the rheological properties, reduced the temperature susceptibility, showed better stor- age stability, and increase the upper grading (performance) temperature of the base asphalt. The two polymers showed similar ageing characteristics with little influence on flow activation energy. In asphalt concrete mix analysis, Marshall stability, stripping (durability), resilient modulus, and per- manent deformation tests were performed. Polymer-modi- fied asphalt concrete mix (PMACM) has increased percent retained stability and the resilient modulus when compared with ACM. The elastic modulus of PMA and the resilient modulus of their ACM followed the same trend. Weak in- fluence on water sensitivity was observed, but excellent rutting resistance was obtained for PMACM over ACM. EA (much cheaper than EBA) produced satisfactory properties of PMA and superior ACM properties when blended with the high asphaltenes Arabian asphalt. © 2006 Wiley Periodicals,

https://faculty.kfupm.edu.sa/che/ihussein/japsv2006p3446.pdf

Rheological Investigation of the Influence of Acrylate Polymers on the Modification of Asphalt

The linear viscoelastic properties of one family of base asphalts, unmodified or modified by the simple addition of an elastomer or by further in-situ crosslinking, have been investigated. The time-temperature superposition principle was shown to be valid for the base as well as for the modified asphalts. The addition of the elastomer styrene-butadiene (SB) copolymer increased drastically the storage modulus and the elastic character of the asphalts. The thermal susceptibility of the polymer modified asphalts was considerably reduced and this combined with an increased resistance to deformation (larger complex modulus) suggests much better performances for road applications. The chemically modified asphalt containing 3% SB showed similar viscoelastic properties as the physical blend containing 6% SB.



On a etudie les proprietes viscoelastiques lineaires d'une famille d'asphaltes de base, non modifies ou modifies par simple ajout d'un elastomere ou par reticulation in situ. On montre que le principe de superposition temps-temperature est valable autant pour les asphaltes de base que pour les asphaltes modifies. L'ajout du copolymere elastomere de styrene-butadiene (SB) augmente considerablement le module d'emmagasinage et le caractere elastique des asphaltes. La susceptibilite thermique des asphaltes modifies est grandement reduite ce qui, si l'on tient compte egalement de la resistance accrue a la deformation (module complexe plus grand), suggere de meilleures performances en vue d'applications sur les routes. L'asphalte modifie chimiquement contenant 3% de SB montre des proprietes elastiques comparables au melange physique contenant 6% de SB.

Frank Bonniot

Papers

The viscoelastic properties of polymer‐modified asphalts