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Laboratory test methods to uniquely characterize the presence and contribution of sbs modifiers on the cracking performance of asphalt mixtures

Title: Laboratory test methods to uniquely characterize the presence and contribution of sbs modifiers on the cracking performance of asphalt mixtures
Author(s): B. Kim, R. Roque, B. Birgisson, J. Kim
Paper category : conference
Book title: Fifth International RILEM Conference on Reflective Cracking in Pavements
Editor(s): C. Petit, I.L. Al-Qadi and A. Millien
Print-ISBN: 2-912143-47-0
e-ISBN: 2912143764
Publisher: RILEM Publications SARL
Publication year: 2004
Pages: 139 - 146
Total Pages: 8
Nb references: 6
Language: English

Abstract: Laboratory investigations have been conducted to identify the effects of Styrene Butadiene Styrene (SBS) modification on the cracking resistance and healing characteristics of asphalt mixtures. The focus of these efforts has been to identify the primary properties and characteristics associated with SBS modified mixtures that have superior cracking performance. Identification of these properties and characteristics could provide materials engineers with the tools needed to optimize mixture cracking performance as well as to uniquely identify the presence of modifiers for proper control. Results of fracture, creep, healing, and strength tests at multiple loading rates performed on modified and unmodified mixtures showed that the benefit of SBS modifiers to mixture cracking resistance was primarily derived from a reduced rate of micro-damage accumulation. This was reflected in a lower m-value, without a reduction in the fracture energy limit or healing rates. It was also observed that SBS modifiers had a negligible effect on the short loading time (elastic) stiffness of the mixtures. It was concluded that the key to characterizing the effects of SBS modifier on the cracking resistance of asphalt mixture is in the evaluation of the combined effects of creep (m-value) and failure limits. More specifically, it was shown that the benefits of the SBS modifier were identified by using creep properties and failure limits obtained from Superpave IDT tests, in the HMA fracture mechanics model developed at the University of Florida. However, it was also determined that determination of creep properties and failure limits alone did not uniquely characterize the presence of the SBS modifier, which is necessary for mixture control. A residual dissipated energy parameter, which is determined by analyzing the post-peak response of Superpave IDT tests, was identified for this purpose. Higher levels of residual dissipated energy appear to be uniquely associated with the presence and benefit of SBS modifiers and may provide a quick way to make relative comparisons of cracking performance suitable for SBS-modified mixtures and perhaps other modifiers.

Online publication: 2004-04-15
Publication type : full_text
Public price (Euros): 0.00

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