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Cement and emulsified asphalt (CA) mortar is a critical viscoelastic component of ballastless track systems, exhibiting pronounced temperature sensitivity. However, accurately predicting the mechanical responses of CA mortar due to temperature fluctuations remains a challenge. This work proposes a novel variable-order fractional Maxwell (VOFM) model to investigate the viscoelastic properties of CA mortar under temperature variations. The VOFM model is numerically solved using a time-varying coefficient ladder (TVL) model. The VOFM model is validated by comparing with both numerical integration methods and experimental data. The basic properties of the VOFM model, the viscoelastic responses of CA mortar under varying temperatures and alternating stress are systematically investigated. The results show that the mechanical properties of VOFM model agree with the FM model when time-dependent parameters of the VOFM model correspond to that of the FM model. Moreover, high temperatures have a promoting effect on the deformation of CA mortar under both alternating and constant stress conditions. The peak amplitude of CA mortar strain under practical varying temperature and stress loading correlates with the trend of temperature changes. • A VOFM model predicts CA mortar's viscoelasticity under temperature variations. • The VOFM model is numerically solved by a time-varying coefficient ladder model. • The VOFM model is validated with numerical methods and experimental data. • High temperatures have a promoting effect on the deformation of CA mortar. • The strain of CA mortar shows a positive correlation with temperature fluctuations. [ABSTRACT FROM AUTHOR]

Cement-asphalt mortar (CA mortar) is an inorganic-organic composite, which combines both advantages of the mechanical property of cement and flexibility of asphalt. Therefore, it has been widely applied in high-speed railway and used as a kind of semi-flexible pavement material. Cement hydration process can affect the rheological property of fresh cement-asphalt paste as well as the mechanical and durability properties of the hardened cement-asphalt paste. Whereas, the interaction of emulsifier and cement particles will significantly affect the hydration process. Hence, the influence of emulsifier on cement hydration was investigated though measuring of setting time, hydration heat, ions concentration and electrical resistivity. It is indicated that the cement hydration process was retarded with the addition of emulsifier according to the results of the setting time and the hydration heat, and meanwhile, the hydration process was delayed gradually with the increasing dosage of emulsifier. The mechanism of the retardation effect can be attributed to the occupation of emulsifier at the active sites of cement particles, therefore, the delaying of cement hydration was further confirmed by the results of the lower ions concentration of the paste mixed with emulsifier. More specifically, for the cement mixed with emulsifier, a protective layer formed around the cement particles and this protective layer hindered the releasing of ions. As is well known, electrical resistivity is an indicator parameter which can indicate the cement hydration process and the formation of micro-structure effectively, thus, the variation law of the electrical resistivity can also reflect well the retardation effect of emulsifier on cement hydration. [ABSTRACT FROM AUTHOR]

Abstract: In order to find a new test method to investigate the relationship between the compositions and fluidity of the cement and emulsified asphalt mortar (CA mortar), the conductivity and the fluidity properties of the fresh CA mortar with different mixtures were studied by analysis of the relationships among the liquid fraction, the “J” type funnel flowing time and the conductivity. Results showed that (1) the electrical conductivity was linear relationship to the liquid volume fraction of the slurry, but markedly influenced by thickening agent, (2) there exist apparent relationship between the flowing time of fresh CA mortar through “J” type funnel and liquid volume fraction, also and electrical conductivity, (3) the difference of the density showed good linear relationship with the difference of the electrical conductivity caused by the segregation. [Copyright &y& Elsevier]

Cement asphalt mortar (CA mortar) is the key component in slab track and serves as the elastic shock absorber. The prominent presence of asphalt renders the mechanical properties of CA mortar susceptible to temperature variation. In this paper, the compressive strength of CA mortar was investigated at different temperatures (0, 20, 40, and 60°C [32, 68, 104, and 140°F]) and a temperature stability coefficient (TSC) was put forward to indicate this temperature dependence. Influences of asphalt emulsioncement ratio (A/C), and addition of the silica fume (SF) and crumb rubber (CR) on the temperature stability of compressive strength of CA mortar were also explored. Results indicate that the compressive strength of CA mortar decreases with higher temperature. The addition of SF and CR mitigates the temperature dependency to some extent. [ABSTRACT FROM AUTHOR]

Asphalt emulsion is an important component in the preparation of cement asphalt mortar. In the work reported here, different emulsifiers and basic asphalts were used to manufacture emulsions and their properties were investigated. Results indicate that a diamine-based emulsifier renders asphalt emulsion that exhibits better compatibility with cement; lower density and higher ductility basic asphalt; and that styrene-butadiene-styrene modifiers are more appropriate in the manufacturing of emulsion. [ABSTRACT FROM AUTHOR]