Akira NOMOTO
Study on Fatigue Resistance Estimate of Recycled Asphalt Mixture by Rheological Property of Old Binder
Osamu TAKAHASHI , Takeshi NAKAMURA
In generally, old asphalts attached to pavement wastes have deteriorated, it need to be evaluated and recovered the properties for reuse as recycled aggregates. Penetration test is a common as binder property evaluation test, it evaluate the consistency of the binder. Since asphalt binder becomes brittle with the progress of deterioration, it can evaluate the extent of degradation by penetration test.
However, several asphalt binder has appeared in recent years which have a different rheological properties as modified asphalts, it became difficult to evaluate extent of degradation of these asphalt binder by penetration test comprehensively. Therefore, it is needed to provide a new evaluation test and index which can be used on several asphalt binders which have different rheological properties.
Our laboratory provides the Force Ductility Test (FDT) as solution. FD value calculated from the FDT results, has a high correlation between the fatigue number and the total dissipated energy obtained from Bending fatigue tests of the asphalt mixture, in the case of dense-graded asphalt mixture which has continuously grade.
In this study, we aimed to apply these research results to evaluate the fatigue resistance of the recycled asphalt mixture, and suggest new recycled asphalt mixture design method with using FDT results.
Mixed degraded binder and new binder imitate the state of binder in recycled asphalt mixture, it is confirmed to have high correlation between FD value of mixed binder and total dissipated energy of recycled asphalt mixture. Moreover, FD value of mixed binder is to remain linearly with changes in the mixing ratio, and it can be estimated by FD value of new binder, FD value of degradation binder, and their mixing ratio.
Therefore, the fatigue resistance of the recycled asphalt mixture can be estimate from FD value of new binder, FD value of degradation binder, and their mixing ratio.
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