Study on road performance of recycled aggregate asphalt mixture under water-temperature coupling effect

Abstract To investigate the damage law of recycled aggregate asphalt mixtures under diverse water-temperature combinations and to enhance the working life of asphalt pavement, the article conducts a comparative study on the road performance of recycled aggregate asphalt mixtures under diverse water-temperature combinations. The optimum asphalt-aggregate ratio of recycled aggregate asphalt mixture was determined based on Marshall test; through the investigation of the actual water temperature conditions and traffic load, to determine the indoor test conditions under diverse water-temperature combinations; using indoor testing to analyze the road performance of recycled aggregate asphalt mixtures under diverse water-temperature combinations, to reveal the diverse water-temperature combinations of recycled aggregate asphalt mixtures of the damage law; with the help of scanning electron microscope and industrial CT test, analyze the micro-morphology and fine structure characteristics of recycled aggregate asphalt mixtures under diverse water-temperature combinations from the micro and fine viewpoints. The results indicate that the optimum oil-stone ratio of recycled aggregate asphalt mixture is 5.1%. High-temperature water bath indoor test conditions in the 60℃ constant temperature water bath box heat preservation for 10 days; freeze-thaw cycle indoor test conditions for the first specimen into the -18℃ refrigerator freezing 17.7h, and then put the specimen into the 60℃ constant temperature water bath box heat preservation 8.7h; dynamic water flushing indoor test conditions in the temperature of 35℃, the pressure for the role of the 200kPa, dynamic water flushing 2h. Asphalt mixture road performance with the increase of high temperature water bath time is a downward trend, in the high temperature water bath 15d when the mixture dynamic stability does not meet the specification requirements; asphalt mixture road performance with the increase in the number of freeze-thaw cycle gradually decreased, when the freeze-thaw cycle after 3 times the role of the mix of the maximum bending tensile strain does not meet the specification requirements; asphalt mixture road performance with the increase in the time of dynamic water flushing showed the first upward and then downward trend, and the road performance of the mixture is optimal when the dynamic water flushing is 2h. The asphalt mixture surface under the action of high temperature water bath 10d has a large area of aggregate exposure; freeze-thaw cycle under the action of one asphalt mixture skeleton structure loose, surface cracks; dynamic water flushing under the action of 2h asphalt mixture surface although there are small holes and cracks defects, but the overall structure of the more dense. Three kinds of water-temperature coupling under the action of the mixture void volume increases, the void ratio rises, there are a large number of specimen internal 0.1mm3 below the tiny voids, and most of these damages occur in the specimen height of 0~10mm, 50mm~60mm range, the long-term water-temperature coupling effect on the mix of high-temperature stability and low-temperature resistance to cracking has a greater impact.