Abstract
In order to solve the problems of the sudden loss of fluidity and low expansion rate of CAM I (cement asphalt mortar type I) in a construction site with high environmental temperature, this paper studies the effect of temperature on the fluidity, expansion ratio and pH value of CAM I. The mechanism of action was analyzed by IR (infrared spectrometry), SEM (scanning electron microscopy) and other test methods. The results showed that a high temperature accelerates aluminate formation in cement paste. Aluminate adsorbs emulsifiers leading to demulsification of emulsified asphalt, and wrapped on the surface of cement particles, this causes CAM I to lose its fluidity rapidly. The aluminum powder gasification reaction is inhibited, resulting in an abnormal change in the expansion ratio. Based on findings, the application of an appropriate amount of superplasticizers can effectively improve the workability and expansion characteristics of CAM I at a high temperature.
Highlights
The ballastless slab track structure is an advanced track structure which is used widely in high speed railway in countries, such as Germany, Japan and China, due to its advantages of high stability, high durability and low maintenance compared to ballasted track structure
Layer varies due to differences of slab track structure and the type of CAM I used [1,2,3,4,5].Studies showed that the environmental temperature has a serious impact on the quality of CAM I perfusion in a construction site
The CAM I paste in the mixing will lose fluidity instantaneously, and causes the phenomenon of demulsification and flocculation (Figure 1)
Summary
The ballastless slab track structure is an advanced track structure which is used widely in high speed railway in countries, such as Germany, Japan and China, due to its advantages of high stability, high durability and low maintenance compared to ballasted track structure. Two main forms of ballastless slab track (CRTS I and CRTS II) are used in China, and there are some differences in slab structures, the cement asphalt mortar (short for CAM I) layer is present in both slab tracks. CAM I is an interlayer injected in between the track and the bottom plate of the high-speed railway ballastless slab track. Insufficient expansion of CAM I results in gaps between the filling layer and the track slab (depth > 40 mm) (Figure 2). These problems have seriously delayed the construction progressions and threatened the safety of high-speed trains, so need to be resolved
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