The Bubbles Formation Mechanisms And Its Control Technology During The Grouting Process Of Crts-ii Cement And Asphalt Emulsion Mortar

Ballastless slab track is the development direction of high-speed railway; of which, cement and asphalt emulsion mortar (abbreviated as CAM) is the key supporting technology. However, the bubbles would form on the surface of CAM, which influence the interfacial properties of CAM with slab track during the grouting process of CRTS-II CAM. This has limited the development of CRTS-II slab track high speed railway. Focused on this problem, this paper studied the formation mechanisms and control technology of bubbles during the grouting process of CAM. This is meaningful for the improvement of CAM grouting quality and high-speed railways drive safety.The simulation platform of CAM grouting process was established according to the characteristics of slab track in high speed railway. The Fluent Software and finite element analysis was employed to investigate the influence of exhaust holes set, grouting process parameters of CAM on the water-gas-solid phases flow field. The formation mechanisms of bubbles were studied and the CAM flow pattern control technology and exhaust holes set methods were invented.The Matlab analysis method was employed to simulate the interfacial bubble distribution. The influence of bubbles areas and distribution on the interfacial properties of CAM with concrete was studied. The relationship between bubbles area and interfacial adhesion force was studied. The key control parameters to control the harmful holes percentage and sizes were proposed to control the grouting quality.The nondestructive testing technology of ultrasonic wave testing was employed to monitor the bubbles defects in the interface between CAM and concrete. The relationship between ultrasonic wave testing, concrete depth and bubbles sizes were investigated and the methods to test the harmful bubbles were invented.Based on the CAM construction of Shi-Wu passenger dedicated line, the grouting technology of CAM was summarized according to the analysis of CAM grouting process, off board tests. Over20,000m3CAM was grouted under our instruction. The random check results indicated that, the CAM was fulfilled and CAM had a nice and even section. There are seldom harmful bubbles larger than10mm on the surface of CAM, and the total bubble percentage was less than0.2%.The CAM quality met the standards requirements and the quality was quite good.