Cold in-place recycling for a base layer of an Italian high-traffic highway

Cold in-place recycling (CIR) has increasing interest worldwide due to the large economic and environmental benefits deriving from reduction of atmospheric emissions, preservation of natural resources, no hauling of the material to the recycling plant and back to the jobsite. However, a unique protocol for the structural rehabilitation of highly trafficked highways based on CIR has not been still developed, discouraging their application in the upper layers of the pavement (base layer). This paper describes a case study where a cold recycled asphalt base (CRAB), containing 100% of reclaimed asphalt treated with polymer-modified bitumen emulsion and cement, has been applied in the reconstruction of the SS268 divided highway in southern Italy. The technical approach followed in this project included the preliminary execution of falling weight deflectometer tests to estimate the subgrade stiffness, the design of the pavement structure through a mechanistic-empirical procedure, the mix design of the CRAB and the validation of the construction procedure and mix properties in a trial section. This paper aims to provide a protocol for the design and construction of CIR mixtures, allowing their use as base layer for the highways interested by a high traffic.