RAP recovered binder has no visible traces of solvent in it (bubble formation on heating). Is it necessary or mandatory to do the RTFO ageing before testing its Rheology, Physical and Chemical Properties.
Regards
Irrespective of whether it is virgin asphalt binder or RAP extracted asphalt binder, I believe that Short Term Aging (STA) is needed before proceeding for further characterization.
I could sense that your confusion is due to RAP asphalt binder which is already aged and will further age to an extent during the extraction process. Therefore, why is STA needed?
We know that STA is required to simulate aging to asphalt binder during the construction process. Even if someone has used RAP, the blending with the virgin asphaltic mix is needed which takes place in a heated condition.
Of course, exclusively separate heating of asphalt binder in case of RAP does not take place in real field condition unlike in the case of virgin Hot Mix Asphalt (HMA). Rather, the binder of RAP gets soften when RAP mixture is heated. Even during this stage, binder associated with RAP mixture is bound to undergo a certain degree of aging. Subsequently, transportation and compaction process is completed which is also associated with aging.
Finally, think RTFO as a protocol needed for simulating STA. Irrespective of what kind of asphalt binder (aged or unaged) one have used, this process needs to be followed (if at all it has gone through a different process which causes short term aging) for its simulation in the laboratory.
At the same time, I must point out that how far the laboratory simulation of extracted binder using RTFO is appropriate is not clear and hence it is a matter of investigation.
Irrespective of whether it is virgin asphalt binder or RAP extracted asphalt binder, I believe that Short Term Aging (STA) is needed before proceeding for further characterization.
I could sense that your confusion is due to RAP asphalt binder which is already aged and will further age to an extent during the extraction process. Therefore, why is STA needed?
We know that STA is required to simulate aging to asphalt binder during the construction process. Even if someone has used RAP, the blending with the virgin asphaltic mix is needed which takes place in a heated condition.
Of course, exclusively separate heating of asphalt binder in case of RAP does not take place in real field condition unlike in the case of virgin Hot Mix Asphalt (HMA). Rather, the binder of RAP gets soften when RAP mixture is heated. Even during this stage, binder associated with RAP mixture is bound to undergo a certain degree of aging. Subsequently, transportation and compaction process is completed which is also associated with aging.
Finally, think RTFO as a protocol needed for simulating STA. Irrespective of what kind of asphalt binder (aged or unaged) one have used, this process needs to be followed (if at all it has gone through a different process which causes short term aging) for its simulation in the laboratory.
At the same time, I must point out that how far the laboratory simulation of extracted binder using RTFO is appropriate is not clear and hence it is a matter of investigation.
it is recommended to perform RTFOT on extracted binder...so that any traces of the solven present in the binder could be evaporated...
Dear Prabin sir, I am totally satisfied with your answer. Yes RTFO ageing of RAP recovered binder is necessary. And your last line that it is a matter of further investigation that is RTFO ageing really impact/ change the ageing of already aged RAP binder. Because, this question come from the background that it takes days and a lot energy to recover that amount of recovered RAP binder. And that's why I putted this question, but yest I agree that it is necessary to do the RTFO ageing.
I am obliged by your answer.
Great Regards
Ankit
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