Study On The Mechanism Of Recycled Concrete Powder Modified Asphalt Mortar And Its Interfacial Adhesion Performance With Recycled Aggregate

The recycled concrete powde as an additional product in the production process of construction waste recycled aggregate,the recycling research is not enough.In this paper,recycle concrete powder（RCP）was used as asphalt filler,and research was carried out on the mechanism of RCP modified asphalt mortar and its interfacial adhesion properties with recycled aggregates,in order to realize the application of different particle sizes of construction waste crushed aggregates and powders in asphalt concrete.For this purpose,the following studies were conducted and the following conclusions were drawn.（1）The microscopic morphology,particle size distribution,specific surface area,porosity and chemical composition of two fillers,RCP and limestone mineral powder（LSP）,were compared and analyzed.The results showed that the surface of RCP was rougher than that of LSP,and the overall particle size was smaller than that of LSP,while the specific surface area,pore size distribution and pore capacity were much larger than those of LSP;the main composition of LSP was calcite（Ca CO₃,88.3%）,while RCP was mainly composed of calcite（Ca CO₃,37.1%）,quartz（Si O₂,26.3%）and various silicate minerals.（2）The performance of asphalt mortar with different filler-to-asphalt ratios and RCP replacement ratios were tested,and the effects of filler-to-asphalt ratios and RCP replacement ratios on the performance of asphalt mortar were analyzed.The results showed that the softening point and rutting resistance factor of asphalt mortar increased with the increase of filler-to-asphalt ratios and RCP replacement ratios,while the penetration and ductility decreased.RCP was more effective than LSP in improving the high-temperature performance of asphalt mortar,but had a negative impact on the low-temperature performance.（3）The interaction mechanism between asphalt and RCP was analyzed by Environmental Scanning Electron Microscope（ESEM）and Fourier Transform Infrared Spectrometer（FTIR）,and the degree of interaction was evaluated by two models and gray correlation analysis.The results showed that the interaction was enhanced by the increase of filler-to-asphalt ratio and RCP replacement ratio,and the filler-to-asphalt ratio had a greater effect on the interaction between filler and asphalt than the RCP;no significant chemical interaction occurred between RCP and LSP and asphalt,but mainly physical adsorption;the Palierne C model was not applicable to evaluate the interaction between RCP and asphalt here.（4）The adhesion performance of the interface between asphalt mortar and recycled aggregate was comprehensively evaluated by water boiling method,pixel analysis method,BBS test and surface free energy method,and the effect of surface roughness of recycled aggregate on the adhesion of asphalt mortar was investigated based on BBS test.The results show that:the increase of filler-to-asphalt ratio and RCP replacement ratio will reduce the adhesion performance of asphalt mortar and recycled aggregate;with the increase of roughness of recycled aggregate,the adhesion strength of interface will increase accordingly,and the roughness and adhesion strength are linearly correlated,and the influence coefficient of roughness is in the range of 1.92～2.72.