The work presented here is a study on the measurement and prediction of the rutting resistance of previously rutted asphalt mixes rehabilitated with a layer of micro-surfacing manufactured with virgin and recycled aggregates at different stages of aging. The experimental procedure Rutting Resistance consisted of rutting tests on hot mix asphalt slabs already degraded and repaired with virgin and recycled micro-surfacing. Then, the evolution of the behavior of micro-surfacing cast on the hot mix asphalt slabs is observed according to loading cycles of the pavement rutting tester MLPC. Before rutting tests, slabs are subjected to 24 hours at 50°C and aged for 2 days and 5 days at 85°C in the oven. The results showed rutting percentages of 6.3% for hot mix asphalt slabs aged for 2 days and 7.2% for 5 days. These hot mix slabs repaired with virgin micro-surfacing have rutting percentage of about 9.2 % for 2 days of aging and 6.5% for 5 days of aging. While, the HMA slabs repaired with recycled micro-surfacing have rutting percentage of about 8.1% for 2 days of aging and 5.9% for 5 days of aging. These results allowed the development of a prediction model based essentially on three predictor variables including cycle number, rutting state and percentage of water in the micro-surfacing material. The developed model shows a strong correlation between the predicted rutting values and the rutting values measured with the MLPC rut tester. Thermal aging in oven has a positive impact on the resistance to permanent deformation of new asphalt mixes and those rehabilitated with micro-surfacing. The parameters of rutting state and contribution water are significant in the rutting prediction model, while the cycle number remains a non-significant parameter in the model but determinant.
Pavement maintenance can be considered as a method using a long-term preservation strategy that improves pavement performance with an integrated and cost-effective set of practices that extend pavement life, improve safety and meet expectations of motorists [1] . Due to the various deterioration, it is important that the road infrastructure management agencies use the best method of maintenance at the best time [2] . Among the existing techniques of maintenance, a popular one is micro-surfacing. It has been argued that this technique presented a solution to correct slight defects related to small radius rutting [3] . However, it must be applied in several layers. Robati et al. [3] have shown that micro-surfacing with a coarse particle size are less susceptible to rutting than micro-surfacing manufactured with a fine particle size. Studies realized by Robati et al. [4] have also demonstrated that micro-surfacing mixtures formulated with 100% RAP meet the specifications of the ISSA TB 147 (Multilayer Loaded Wheel Test [5] ), while micro-surfacing manufactured with RAS shows a decrease resistance to rutting if the percentage of RAS exceeds 10%. Recent research has been carried out in order to compare the performances of two types of cold surface coatings, namely micro-surfacing and slurry seal and their ability to correct defects caused by the rutting phenomenon [6] . For both materials, degradation caused by abrasion, or the loss of aggregates was observed for both types of treatments after 3 years of service. It is important to state that even if the micro-surfacing can be used to rehabilitate defective pavement with small radius ruts, they cannot correct large radius, exceeding a few decimeters, deformation [7] .
In this study, we evaluated the effectiveness of the micro-surfacing type III material to repair the rutting deformation on the pavement. To do this, we evaluated the rutting resistance of a 0 – 10 mm hot mix asphalt (HMA), named ESG-10, before rehabilitating it with micro-surfacing. The objective is to evaluate the rutting resistance of HMA with and without micro-surfacing and different curing and aging conditions, and to model the rutting resistance of a HMA rehabilitated with micro-surfacing.
In this paper, we discuss the results of a rut resistance measurement study carried out with the MLPC rut tester on the HMA slabs considered separately and the HMA slabs coated with virgin micro-surfacing and others with micro-surfacing formulated with RAP (50% of the aggregates by weight). To simulate the site conditions, it should be noted that hot-mix asphalt plates alone, before being coated with micro-surfacing, undergo a rutting test (30,000 cycles).
This work was carried out with two different materials, a reference micro-surfacing made with virgin aggregates, and a recycled micro-surfacing, under well-defined curing and aging conditions.