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Cement emulsified asphalt composite binder (simplified as CEACB) is a type of composite binder existed in cement and asphalt mortar (simplified as CA mortar). The effects of freeze-thaw cycles on the dynamic mechanical properties of CEACB were analyzed based on viscoelastic mechanical model and dynamic frequency scanning test. The effects of freeze-thaw cycles, temperatures and mix proportions on the viscoelastic behavior of CEACB were analyzed. This study demonstrates that, as freeze-thaw cycles increasing, constitutive equation parameters E1 and η1 decrease, and r tends to increase. The ability of CEACB to resist elastic deformation and viscous flow is reduced, and CEACB shows a tendency of softening. With asphalt to cement ratio (A/C) increasing and temperature rising, both E1 and η1 decrease, while r increases, and CEACB tends to be like viscous material. As freeze-thaw cycles increasing, the pore content of CEACB increases. Freeze-thaw causes obvious structural damage and viscoelastic mechanical properties of CEACB were changed.

Cement emulsified asphalt repair material (simplified as CEA repair material) is a composite material formed by hardening of cement and cementation of emulsified asphalt. The aging performance and fatigue performance of CEA repair material will affect the repair effect of cracks. In this paper, the effect of aging on fatigue performance of CEA repair material was studied through the fatigue tests after aging. The fatigue equation and the fatigue damage evolution equation considering the aging effect were established. The effects of aging time, stress ratio and material ratio on the fatigue performance of CEA repair material were analyzed. As the aging time increases, the fatigue life of CEA repair material decreases, and the sensitivity of fatigue life to the change of stress ratio decreases. The increase of cement content can reduce the aging degree of asphalt and slow down the aging speed of asphalt. The increase of cement content can also improve the stability of fatigue performance of CEA repair material. The effect of stress ratio on fatigue life is related to aging time and material ratio. As the aging time increases, the phase angle decreases and the energy dissipation decreases. Increasing the amount of cement can improve the stability of fatigue performance of CEA repair material, but it reduces the fatigue life of CEA repair material. The material design of CEA repair material should comprehensively consider the aging resistance and fatigue performance, and rationally determine the amount of cement and emulsified asphalt.

In order to study the viscoelastic-plastic damage of cement asphalt composite binder (simplified as CACB) and the relationship between plastic damage and viscoelastic damage, a viscoelastic-plastic constitutive model (VE-P model) was constructed, and the viscoelastic-plastic damage process of CACB was analyzed. Effects of material composition and microstructure on viscoelastic-plastic damage were studied. During creep test, with the increase of stress ratio, the proportion of plastic strain and unrecoverable strain increases, and the ability of CACB to resist deformation and deformation recovery decreases. Stress ratio has different effects on elastic damage, viscous damage, delayed elastic damage and plastic damage. Temperature has little effect on elastic damage and delayed elastic damage, but has a greater effect on plastic damage. With the increase of initial plastic damage, the damage of elasticity, viscosity and delayed elasticity intensified. When A/C = 0.8, CACB can form a more reasonable microstructure, the mechanical properties of CACB are least affected by damage, and its mechanical properties are more stable. The research results in this paper provide a theoretical basis for CACB’s material design and performance evaluation.

Cement asphalt composite binder (simplified as CACB) is a type of composite cementitious material formed by cement, emulsified asphalt and various admixtures. It is mainly used in the ballastless slab track structure of high-speed railway at present. Freeze-thaw cycles can cause damage of CACB mechanical properties and affect the mechanical properties of high-speed railway ballastless slab track. In order to study effects of freeze-thaw cycles on mechanical properties of CACB and evolution process of freeze-thaw damage, creep and creep recovery tests were carried out after freeze-thaw test. Basing on Revised Kelvin Burgers (simplified as RKB) viscoelastic mechanical model, creep compliance and creep recovery compliance equation were deduced. Damage variables which represent elastic damage, viscous damage and viscoelastic damage of CACB under freeze-thaw cycles were established. Deformation resistance and deformation recovery ability of CACB were weakened by freeze-thaw cycles and the hysteresis of mechanical response increased. With the increase of freeze-thaw cycles, CACB presents a tendency of softening, and the viscoelastic damage stages of CACB are divided into synchronous damage stage and differential damage stage. The material ratio of CACB and microstructure of hardening system have important influence on the evolution of viscoelastic damage and damage difference.

Cement emulsified asphalt composite binder (simplified as CEACB) is a kind of viscoelastic material composed by cement, emulsified asphalt and various admixtures. Fatigue damage caused by dynamic loading affects the viscoelastic properties of CEACB. In this paper, evolution process of fatigue damage was analyzed by fatigue test. Based on the four-element model with five parameters and creep damage evolution equation, CEACB creep equation, single damage creep equation and double damage creep equation were established, and the effect of fatigue damage on the creep behavior of CEACB was analyzed. The damage rate of CEACB increases with the increase of stress level. With the increase of asphalt content, the sensitivity of fatigue properties change with stress level increases. With the increase of fatigue damage, instantaneous elastic deformation and creep rate increase in steady creep stage during creep process. The ability of CEACB to resist deformation is reduced by fatigue damage, and CEACB shows a tendency of softening. The damage of elastic and viscous properties of CEACB are different.

As a grouting material, the flow ability and uniformity of fresh cement asphalt emulsion mortar (hereinafter abbreviated as CA mortar) are governed by its rheological properties. The rheological properties of fresh cement asphalt paste were investigated, in which influencing factors, such as type of asphalt emulsion, superplasticizer dosage, and water to cement ratio, were discussed. Results indicate that CA paste with plain asphalt emulsion has too low yield stress to resist segregation, while it has good yield stress when employing asphalt emulsion modified by viscosity modifying agent. Superplasticizer can reduce the initial yield stress and plastic viscosity, however, its water-reducing effect is not obvious for the water-reducing effect of emulsifier in asphalt emulsion. The stability of asphalt emulsion affects the growth rate of plastic viscosity of CA paste, and superplasticizer dosage affects the growth rate of yield stress, which both affects the retention ability of good fluidity. Therefore, a well stable asphalt emulsion modified with viscosity modifying agent, and high superplasticizer dosage (1% recommended in here) are preferred to produce CA mortar.

Cement asphalt mortar (CA mortar) is a key material of non-ballasted track structure. In order to solve the problem that cement hardens slowly in CA mortar, the retarding effect of emulsifier on cement hydration was studied by measurement of cement setting time, hydration heat and X-ray diffraction analysis. Results show that emulsifier has significant retarding effect on cement hydration, which is relevant to the types of emulsifier and its dosages. The retarding effect increases with the increment of the mass ratio of emulsifier to cement. Significant differences in the setting time, cement hydration rate, hydration heat and the content of Ca(OH)2 are detected utilizing different types of emulsifier. Emulsifier with excessive retarding effect on cement not only abort cement hydration in early age, but also cause a loss in the later hydration heat and content of cement hydrates. Therefore, suitable emulsifier with little retarding effect on cement hydration and its appropriate dosage are recommended when producing asphalt emulsion for CA mortar.