Effect of curing regime on mechanical characteristics of cold recycled bituminous mixes

The curing process in bituminous mixes plays a vital role during the early-stage strength development of cold in-place recycling technology. Curing temperature and curing period (collectively termed as curing regime) are the critical factors governing the curing process. Inadequate curing of cold recycled (CR) bituminous mixes can result in distresses as well as premature failure. The present study evaluated the influence of the curing regime on the mechanical characteristics of CR-Bituminous mixes stabilized with foam and emulsion bitumen (CR-Foam and CR-Emulsion) respectively. The moisture loss pattern in both CR-Foam and CR-Emulsion mixes was monitored over a curing period of 14 days and at three temperatures of 25, 40 and 60 degrees C. Results of the research showed that moisture loss was rapid during the 24 h and then the rate of moisture loss decreased eventually becoming constant approximately after 7 to 10 days. An increase in curing temperature accelerated the moisture loss in the initial days of curing resulting in better mechanical characteristics whereas the increase in humidity delayed the strength development process even after a prolonged curing period of 7 days. Both the CR-Mixes were found to have similar resilient modulus values for the same residual moisture content indicating the impact of curing temperature. In terms of performance, CREmulsion mixes showed superior cracking resistance than CR-Foam mixes as indicated by the Cracking Tolerance Index.