Cold recycling of lime-fly ash stabilized macadam mixtures as pavement bases and subbases

The cold recycling technology has been increasingly used to rehabilitate semi-rigid pavement bases and subbases in China due to the focus of the sustainable development. This paper presents the mechanical and pavement performances of cold recycled lime-fly ash stabilized macadam (LFSM) mixtures using Portland cement as the stabilizing material. The unconfined compressive strength, indirect tensile strength, frost resistance, dry shrinkage (DS) resistance, and temperature shrinkage (TS) resistance of different cold recycled mixtures (CRMs) with three cement contents, two reclaimed materials (RM) sources, and two aggregate gradations were measured, respectively. The locally recommended criteria for RM properties were proposed based on performance correlations between RMs and CRMs. It is found that the gradation optimization by adding appropriate amount of the coarse virgin aggregate (VA) can greatly improve the mechanical strength and pavement performances of CRMs. CRMs with the clean RM do not show significantly worse DS and TS resistance than cement stabilized macadam mixtures with 100% of the VA. The CRM strength is highly affected by the RM strength and angularity. Field investigations confirm the feasibility and application potentials of the cold recycled LFSM layer as pavement bases and subbases.