Effect of Surface Treatment on Road Performance of Recycled Aggregate-Asphalt Mixture
In order to enhance the utilization rate of recycled concrete aggregate(RCA),this paper proposes a method of ionic precipitation(MIP)to treat RCA by using a saturated solution of sodium bisulphate and calcium hydroxide combined with ultrasonic waves and organosilicon hydrophobes.The effects of MIP on the micro-morphology and physical properties of RCA,as well as the oil/stone ratio and road performance of asphalt mixtures,were analyzed.The test results show that the MIP resulted in the surface of RCA covered by a layer of alkaline cementitious materials.Moreover,the pores of RCA are filled with gypsum,calcium hydroxide and ettringite.Consequently,the crushing index,wear value and water absorption rate of RCA are reduced greatly.MIP treatment significantly reduces the optimal asphalt content of RCA-asphalt mixture and enhances interface adhesion,water stability and high-temperature stability.In addition,according to the test results,the replacement of 60%(mass fraction)original coarse aggregates by using of MIP-RCA can construct an asphalt mixture with excellent road performance and a low optimal asphalt content.