Strengthening the attached old cement mortar of recycled aggregate (RA) is a common approach to enhance the RA properties. In this study, four representative chemical enhancing‐technologies were chosen. Through the analysis of physical properties, mechanical properties, and shape indexes, the changes of performance before and after strengthening were tested, so as to grasp the influence of chemical enhancing‐technologies on the performance of RA. The results indicated that the chemical strengthening methods had obvious influence on the physical properties of RA, such as density and water absorption. Due to the different chemical enhancing mechanism, the influence trend and range were varied. The mechanical properties of RA such as crushing value and abrasion value were obviously improved by chemical enhancement. However, chemical enhancement had an effect on the shape of RA, which will slightly reduce the angularity index and sphericity index. The texture index of RA with C‐3 and C‐7 decreased sharply, but texture index increased after abrasion, and the discrepancy of aggregate texture index of different enhancing methods is significantly reduced. The microanalysis exhibited that the aggregate surface structure with C‐3 and H was large, but there were a lot of fine structures on the aggregate surface with C‐7 and N‐P. Different chemical enhancing methods have different effects on the mechanical performance and microstructure of RA, but it should be noted that the fluctuation of RA performance tends to increase.

In order to understand the influence of the vibration mixing method on the performance of cement-stabilized aggregate mixture (CSAM), in this study, an unconfined compressive strength test, drying shrinkage test and the influence of gradation characteristics on compressive strength were used to systematically analyze the performance of CSAM based on vibration mixing. At the same time, the influence mechanism of vibration mixing on the interface transition zone of cement aggregate was analyzed by use of a scanning electron microscope (SEM), and the influence of the mixing method on cement dispersion uniformity was studied by the ethylene diamine tetraacetic acid (EDTA) titration method. The results show that 7 days of unconfined compressive strength and crack resistance of the CSAM with vibration mixing is better than those of the ordinary mixing, and the aggregate grade has a great influence on the compressive strength of the CSAM. Vibration mixing can improve the micro-water-cement ratio uniformity of CSAM and significantly improve the bonding condition of the interface transition zone between cement paste and aggregate, thus enhancing the structural compactness of CSAM. The dispersion uniformity of cement under the vibration mixing is better than that of ordinary mixing.

To develop a color antiwearing wear layer based on epoxy resin adhesives, the effect of single formula composition on the properties of adhesives was analyzed through drawing strength tests, shear strength tests, and bending strength tests. It was found that when the mass ratio of the epoxy resin curing agent and the dosage of the toughening agent increased, the bonding performance and toughness of the adhesive firstly increased and then decreased. With the increase of the mass ratio of phenolic aldehyde amine to polyamide, the bonding performance and toughness of the adhesive were improved, but the effect was significantly reduced when the ratio was more than 2. With the increase of diluent content, the bonding performance and toughness of the adhesive were reduced. Based on response surface optimization, the optimum formulation was recommended. The content of the mass ratio of the epoxy resin to the curing agent and mass ratio of curing agent phenolic amine to polyamide, toughening agent content, and diluent content was determined to be 2.971%, 1.887%, 2.455%, and 1.000%, respectively. And, the dosage of each material was consistent with the effect of the dosage of a single formula on the properties of adhesives. The performance of the color antiwearing thin layer was tested by the adhesion test and antiwearing durability test. It was found that temperature had a significant effect on the adhesion, the adhesion of the thin layer was significantly reduced at low temperature, and the sensitivity to impact load was enhanced, while the adhesion and sensitivity to impact load were effectively improved at more than 20°C. At the same time, the antiwearing of the thin layer decreased rapidly at the initial stage under the reciprocating load but tended to be stable when the load exceeds 500 times.