In-laboratory compaction procedure for cold recycled mixes with bituminous emulsions

► A new compaction procedure for cold recycling mixes has been designed. ► It produces test specimens with a density close to 100% of the worksite density. ► This procedure will improve the job mix formula finally applied. The cold in-place recycling (CIR) of asphalt pavements is a technique for pavement rehabilitation that uses 100% of the milled or reclaimed asphalt pavement (RAP) from a deteriorated road surface at ambient temperature, and which does not heat any of the mix components. Consequently, CIR has the advantage of reducing gas emissions into the atmosphere. It also cuts fuel consumption since there is no need to transport RAP to an asphalt plant or to convey the mix from the plant to the paving site for spreading and compaction. Nevertheless, one of the weaknesses of this technique is the design of the job mix formula since the densities of laboratory test specimens are generally higher than the densities of the samples obtained at the worksite. As a solution for this problem, we designed an in-laboratory compaction procedure capable of manufacturing test specimens, whose density closely approximated the density of the material at the worksite. For the purposes of our research, we selected three CIR roadwork projects carried out in 2009 in southern Spain. These sites provided the RAP and the emulsion for the laboratory work in our study. It was thus possible to validate the compaction method designed in our research by comparing the dynamic modulus values of pavement cores extracted at the worksite with the values of cores taken from the laboratory specimens. The results obtained validate the new compaction procedure designed in this study.