Active Filler's Effect on in-situ Performances of Foam Bitumen Recycled Mixtures

Cold recycling is one of the most employed rehabilitation techniques for asphalt pavements and it is becoming more and more important as saving of emissions becomes a priority in the reduction of the greenhouse effect. The main advantages of asphalt cold recycling techniques are the use of reclaimed materials and the lack of need to heat the aggregates to make the mixtures. This paper describe the in situ performance over time of different foam bitumen stabilized mixtures made with different blend of fillers (cement, lime and mineral filler), monitored during the first year from construction. Results are part of a more extensive research program aimed to investigate the effects of using lime as active filler in cold recycled mixtures. Mixtures have been placed on a specifically designed trial section which is part of a constructing road in Italy, close to Florence. Short term bearing capacity, immediately after construction, has been evaluated by means of LWD (Lightweight tests) while in the mid-term performance FWD tests have been performed after 24 hours, 14 days, 28 days and 9 months from construction. Up until mid-2014 tests road was not yet opened to traffic than the mixtures experienced only construction traffic loads. Results obtained positively support the use of lime as active filler in the foamed bitumen stabilized material and allow to underline the effect of different blend of filler in the material behavior. FWD tests are scheduled to be repeated every 6 months in order to monitor the stiffness evolution of the mixtures and evaluate the nature of traffic damage.