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Liang F.,China University of Petroleum - East China | Liang F.,Highway Maintenance Technology Key Laboratory for Transportation Industry | Jian L.,CPECC East China Design Branch | Jianming W.,China University of Petroleum - East China | And 2 more authors.
China Petroleum Processing and Petrochemical Technology | Year: 2014

In this paper, in order to investigate the viscoelasticity of asphalt binder at the softening point temperature, more than 30 different asphalt binders were selected and tested by dynamic rheological scan method using a dynamic shear rheometer (DSR). The softening points and the rheological parameters of the asphalt samples were measured and analyzed. The results indicated that at the softening point temperature the neat asphalt and the SBS modified asphalt showed two different rheological states. The neat asphalt binders had a majority of viscous components in viscoelastic composition, with the phase angles being mostly higher than 80°. The SBS modified binders had lower phase angles, with their elasticity still retained. Meanwhile, the Shapiro-Wilk normality test showed that at a confidence level of 0.05, at whatever aging state, the neat asphalt had a stable complex modulus corresponding to the softening point, which was 13.034 kPa at a standard deviation of 2.105 kPa under the same test condition. The softening point of neat asphalt binder can be calculated via the equivalent modulus rule. It is found out that there is a good relationship between the calculated and the measured softening points. And it is suggested that more data are needed to validate this finding.

Fan L.,Highway Maintenance Technology Key Laboratory for Transportation Industry | Fan L.,Transportation Institute | Hu J.,Highway Maintenance Technology Key Laboratory for Transportation Industry | Hu J.,Transportation Institute | And 3 more authors.
Wuhan Ligong Daxue Xuebao (Jiaotong Kexue Yu Gongcheng Ban)/Journal of Wuhan University of Technology (Transportation Science and Engineering) | Year: 2015

Dynamic shear rheometer was used to evaluate rheological performance of asphalts mixed with three warm-mixing additives, and the final result showed that different chemical compositions in warm-mixing additives decide different rheological performance of asphalts. Sasobit and Leadcap can provide neat asphalt with an apparent modulus increase and influence asphalt viscoelasticity because of recrystallization behaviors; but asphalt-min additive has no this effect in a content range of 6~8%, only slightly influence viscoelasticity in lower temperature. Fatigue indexes from time sweep test show that, because of the difference of chemical composition and molecular, Leadcap and Sasobit can improve fatigue performance of neat asphalt, but asphalt-min additive cannot provide this effect. ©, 2015, Wuhan University of Technology. All right reserved.

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