When performing the asphalt mixture design in the laboratory, according to relative specifiction that didn't be mentioned the curing time how long should follow it, especially for RAP that was used in the mixture design. Anyone knows any methods or requirement to cure the mixture for fresh mixture and RAP mixture?
Hi Mr. Lal,
If your question refers to hot mix asphalt (HMA), it is normally cured in the Marshall mold for 24 hours after compaction.
If your question is referring to cold mix asphalt design, the fresh mixture after compaction should be cured in mold for 24 hours followed by curing at 38 degrees celsius for additional 24 hours. You can refer MS-14 for cold mix asphalt design
Curing of cold mix asphalt is a complex question, not being clear the equivalence between the artificial curing in the lab and the actual curing in real conditions. For example, Ruckel et al., (1983) proposed that a 3-days curing at 40C would be equivalent to 1 month in real conditions, what contrasts with the definition of the Asphalt Academy (Kekwick, 2005) where it is suggested that this same curing process is equivalent to 6 months in a real road. A curing process of 3 days at 60C is equivalent to the real curing produced for a time between 23 and 200 days according to Acott (1980, cited by Jenkins, 2000) but other authors, such as Maccarrone (1994) estimated the same equivalence to 1 year.
In addition, authors, such as Hugener et al., 2014 stated that curing processes at more than 40C could produce internal pressure and differential stress between the wet and dry parts of the sample, damaging the specimens.
In Spain, the Bitumen Emulsion Technical Association recommends through their technical reports a 3-days curing time at 50C. This is the process I have personally chosen for my research.
Kekwick SV (2005). Best practice. Bitumen emulsion and foamed bitumen materials laboratory processing. Proceedings of the 24th Southern African transport conference, SATC. South Africa
Jenkins KH (2000). Mix design considerations for cold and half-warm bituminous mixes with emphasis on foamed bitumen. Doctoral Dissertation. University of Stellenbosh, South Africa
Maccarrone S (1994). Cold asphalt systems as an alternative to hot mix. Proceedings of the 9th AAPA international Asphalt conference. Australia
Hugener M, Partl MN, Morant M (2014). Cold asphalt recycling with 100% reclaimed asphalt pavement and vegetable oil-based rejuvenators. Road Materials and Pavement Design 15(2), 239-258
Technical Association of Bituminous Emulsions (ATEB). Gravel-emulsion specifications. ATEB (http://www.ateb.es/pdf/PLI_GRAVA.pdf)
2 hours at 135C for HMA and 2 hours at 116C for WMA. There is a recent report on the topic that concludes with these recommendations.
http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_815.pdf
Dear all
Thanks for yours help to send lots of resources for me.
Thank you very much indeed.
Best regards
Chiahung Lai
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