表面处理对再生骨料-沥青混合料路用性能的影响

Effect of Surface Treatment on Road Performance of Recycled Aggregate-Asphalt Mixture

为了提高混凝土再生骨料(RCA)的利用率,本文提出利用硫酸氢钠和氢氧化钙饱和溶液结合超声波和有机硅防水剂对RCA进行离子沉积处理的方法(MIP)。分析MIP处理对RCA的微观形貌、物理性能,以及沥青混合料油石比和路用性能的影响。研究结果表明,MIP处理后的RCA表面均匀且孔隙内沉积大量石膏、氢氧化钙和钙矾石等胶凝材料,压碎指标、磨耗值和吸水率显著降低;MIP处理可显著降低RCA-沥青混合料的最佳油石比,提高界面黏附性、水稳定性和高温稳定性;MIP处理后的混凝土再生骨料可取代60%(质量分数)的原生粗骨料,生产具有优良路用性能和较低最佳油石比的沥青混合料。

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.