Experimental Study On Compressive Performance Of CA Mortar Of CRTSâ…¡ Subjected To Various Loading Factors

As the major part of the slab track structure, the mechanical properties of cement asphalt mortarlayer are essential to the safety of the railway. The uniaxial compression tests of CA mortar of CRTS Ⅱ ballastless track slab subjected to different temperature, age and loading rats, as well as the static triaxial text of CA mortar under different confining pressures were conducted. The variation of strain-stress relationship, compressive strength, elastic modulus and failure patternswith influencing factors includingtemperature, age, loading rateand confining pressure was analyzed and summarized. The study has provided the references for the behaviors of CA mortar under the complex loading conditions, and established a theoretical foundation for the stress analysis of non-ballast track.The main research results can be concluded as follows:(1)Based on the uniaxial compression tests of CA mortar of CRTS Ⅱ ballastless track slab subjected to different temperature and age, the variation of strain-stress relationship, peak stress, peak strain and failure patterns with influencing factors including temperature and age was analyzed and summarized. The multivariate linear fitting equation of compressive strength of CA mortar related to temperature, age was obtained according to the experimental results. The results showed that, on the whole, within28days, the influence of age on the compressive strength of CA mortar was more significant than the temperature. The age was the main factor to affect the compressive strength development of CA mortar at the beginning of curing period, while with the increase of age, the influence of temperature on the compressive strength increased. For CA mortar of CRTS Ⅱ ballastless track slab, curing in the low temperature was not favorable to the development of compressive strength of CA mortar, and in the late period of curing, the growth of compressive strength of CA mortar slows down in the high temperature environment, and even weakens. Therefore, in the high temperature environment, it is suggested to take necessary measures to cool the CA mortar, and keep the curing temperature around20℃.Through the uniaxial compression tests of CA mortar subjected to different temperature and loading rates, the variation of strain-stress relationship, peak stress, peak strain and failure patterns with influencing factors including temperature and loading rate was analyzed and summarized. The multivariate linear fitting equation of compressive strength of CA mortar related to temperature, loading rate was obtained according to the experimental results. The results showed that, on the whole, after curing period of28days, the influence of loading rate on the compressive strength of CA mortar was more significant than the temperature. With the increase of loading rate, the effect of temperature on the compressive strength gradually enhanced. Therefore, relevant measures should be taken to alleviate the temperature sensitivity of CA mortar. For southern area with high temperaturein summer, it is recommended to use CA mortar with low temperature sensitivity.(3)According to the uniaxial compression test results of CA mortar subjected to different temperature, age and loading rate, the multivariate linear fitting equation of compressive strength of CA mortarrelated to the three relevant factors was obtained. The compressive strength of CA mortar can be determined when the complex loading conditions are known according to the fitting equation, which has provided reference for performance design and control of CA mortar in different climate and working conditions.(4)Through the static triaxial text of CA mortar under different confining pressures,the variation of strain-stress relationship, peak stress, peak strain, elastic modulusand failure patternssubjected to different confining pressure was analyzed and summarized.The results showed that with the increase of confining pressure, thecompressive strength and peak strain of CA mortar increased and had a linear relationship with the confining pressure, while the variation of elastic modulus was insignificant. A model was proposed to describe the deviatoric stress-strain relationship of CA mortar under different confining pressures reasonably.