The strength of EACRM (emulsified asphalt cold recycled mixture) is closely related to the properties and proportion of raw materials. In this paper, the strength formation mechanism of EACRM was first studied through microscopic analysis, and the influence regular of aggregate gradation, emulsified asphalt, water consumption, cement consumption, and other factors on its strength was analyzed through a series of laboratory tests. The analysis results show that the asphalt binder plays the role of cementing material in cement emulsified asphalt mortar. The combination of cement and emulsified asphalt is a physical combination. The hydration product not only increases the viscosity of asphalt cement, but also makes the surface of asphalt cement become uneven, which increases the adhesion area with the aggregate. Therefore, the microstructure of the interface between mortar and aggregate is improved. The bonding force of the interface and the mechanical properties of concrete are improved. Due to the influence of recycled asphalt pavement (RAP) materials, the excessive amount of emulsified asphalt and cement are not conducive to improve the strength of cold recycled mixture. Through experiments, the optimal amount of emulsified asphalt and cement is determined as 2.9% and 1.5%, respectively, for the RAP materials. At the same time, improving the performance of emulsified asphalt and adding quicklime and organic activator are also helpful to improve the strength of a cold recycled mixture.

Based on an analysis of the cold regeneration mechanism of emulsified asphalt, the emulsified asphalt binders and cement were applied to prepare the cold recycled mixtures, and the main technical performances of the designed mixtures were evaluated, including high-temperature stability, water stability, and fatigue characteristics. A high content of 65% recycled asphalt pavement (RAP) material was used with some new aggregates and mineral powders, and the optimal emulsified asphalt binder and cement dosages were determined as 2.9% and 1.5% respectively. The technical performance test results show that: (1) The well-designed emulsified asphalt cold recycled mixtures have good high-temperature stability and water stability, and can meet the requirements of the road base layer and the lower layer. (2) When the stress level is lower, the fatigue performance of mixtures with lower emulsified asphalt binder dosage and lower cement content is better, but when the stress level is higher, the high dosage of emulsified asphalt binder is more favorable, while the cement content has little effect on the fatigue property. (3) The emulsified asphalt cold recycled mixtures have relatively poor fatigue resistance, and their fatigue life is significantly lower than that of the hot mixed asphalt mixtures.

By applying early disturbance to the concrete, the influence of the disturbance on the macroscopic mechanical properties of basalt fiber concrete during the period from the initial setting to the final setting is explored, and the influence mechanism is revealed. Also, the influence of this disturbance on the process of sulfate erosion of concrete is evaluated by the sulfate erosion test and by the ultrasonic data acquisition of its damage process. The experimental results show that the flexural strength of basalt fiber concrete is increased after the concrete has been disturbed in the early stage of condensation but is decreased in the middle stage of condensation and is not affected in the later stage. When the condensation and hardening processes are disturbed, damage is caused inside the concrete, which is greater with the increase in the condensation degree until the penetration resistance reaches about 15 MPa, which then is more and more reduced. The durability of basalt fiber concrete is reduced by disturbance, which has a significant effect on it when the penetration resistance is between 7 MPa and 16 MPa.

In this paper, the basic composition and performance evaluation of the recycled asphalt pavement (RAP) materials were firstly analyzed, and two methods were proposed to evaluate strength characteristics of RAP materials, including a triaxial method for the residual strength and the mortar cementing method for the strength of RAP lump. Then, the cold recycling technology was applied on RAP materials with emulsified asphalt by using vibratory compaction and heavy-duty compaction methods (Proctor compaction method), and the results showed that the maximum dry density obtained by heavy-duty compaction was closer to the actual situation. Finally, the effects of wetting water, emulsified asphalt dosage and curing conditions on the performance of the specimens were investigated. It was found that when the emulsified asphalt was mixed uniformly, whether or not to add the wetting water have almost no effect on the strength of the molded specimens. When the matrix asphalt content of the emulsified asphalt was 30%~60%, the water could be directly added to the cold recycling mixture. The intensity of accelerated curing for two days at 40 • C was approximately equal to that of natural curing for three days, while that of accelerated curing for three days at 40 • C was approximately equal to that of natural curing for seven days, which provided a basis for the short-term laboratory test. emulsion content, aggregate properties, coating and adhesion tests. Strength testing mainly refer to the indirect tensile strength test, in addition to resistance, moisture-induced damage sensitivity test and rutting test [7]. A. Widayanti et al. used SEM imaging technology to observe the morphology and surface texture of the RAP materials [8]. Also, Y. N. Li et al. evaluated the effects of emulsified asphalt and cement on the porosity, indirect tensile strength, tensile strength ratio, dynamic stability and mechanical properties of RAP materials [9]. X. Zhang made an in-depth research on the RAP materials treatment process from four aspects: Method of recycling RAP materials, selection of crushing equipment, old material screening process, storing and testing [10]. F. Ye et al. researched the layered aging regulation of asphalt stratification on the surface of RAP materials [11]. T. Ma et al. researched the effects of aging properties in asphalt on the performance of 48 RAP materials by measuring the low temperature performance of mortar with bending beam 49 rheometer (BBR) [12].However, there has not been a uniform conclusion on the research of RAP materials compaction methods abroad. Some of the compaction methods are mainly selected according to different design methods of recycling asphalt mixtures. Generally, the Marshall compaction method is used to mold specimens for the Marshall design method. The kneading method is used for Hveem method. The gyratory compaction method is used for Superpave design method, which is more popular in the U.S. and Sweden [13][14][15].H. Y. Wei et al. used the method of vibration compaction specimens and de...

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Pavement structure directly affects the performance of the road, and the high altitude and low temperature of the Qinghai Tibet Plateau has a great influence on the pavement structure. Based on the investigation of Qinghai Tibet highway, Sichuan Tibet highway line five, summarizes the existing pavement structure types; through a comparative analysis of the pavement analysis of disease type and reason and jade high speed test of four new pavement test road. The research results show that: the four kinds of test road are better than the existing traditional semi-rigid base pavement structure in which ATB+2% cement stabilized crushed stone base of the composite structure of the overall economic performance and performance optimization.

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