Study On Mix Proportion Design And Construction Technology Of Slab Concrete For Crts Ⅱ Slabstructure

The ballastless slab track of CRTSII with the advantages of running smoothlyand comfortably under a high-speed, is most widely applied in China currently. Theconcrete of ballastless slab track of CRTSII is the key material of the slab trackstructure, its performance directly affects the durability and security of the trackstructure, the preparation and construction of this kind of track structure is one of thecore technology. In this research the optimization design was used, combined withthe concrete curing process matching breakthrough the concrete curing conditions in16h to reach the technical bottleneck of stripping strength in48MPa, and a completeset of ballastless slab track of CRTSII production technology of concrete constructionwas gotten, to promote our country’s high-speed railway construction anddevelopment, and perfect the system of the high-speed railway construction whichhave a great significance.The main works and the innovations of this paper are as follows:The mix proportion was optimized using the P.II42.5Portland cement, S95mineral powder, class II fly ash, poly carboxylic acid of high efficiency waterreducing agent and high-quality aggregates with the water/cement ratio of0.27-0.29,sand coarse aggregate ratio of34%-38%, fly ash mineral powder compositecompatibility (mineral powder: fly ash=50%:50%) content under the condition of10%-15%. Based on which, a ballastless slab track of CRTSII concrete with thecompressive strength mare than48MPa after16h was achieved.The concrete was cured under four stages of stop, heating and constanttemperature and cooling. The temperature concrete into the mold, templatestemperature were adjusted according to the climate change, concrete hydrationprocess was controlled, the early strength was improved, and at the same time, the topcuring temperature≯55℃, warming and cooling rate≯15℃/h wascontrolled to prevent the concrete crack and ensure the quality of track plateproduction.The durability of slab track concrete was studied，and the influencing factors ofprimary and secondary for electric flux respectively are as follows：water-binder ratio, fly ash, air content, the dosage of admixture content. The resistance to sulfatecorrosion coefficient of concrete increases gradually, the fly ash content increasedfrom0%to40%. And after the content of fly ash reached40%-50%, the corrosionresistant coefficient decreased, and sulfate attack resistance reduced. Mineral powder-fly ash composites improved the performance of freezing-thawing resisting andcorrosion resistance helpfully.The CRTSII track slab production and maintenance process in system wasobtained combining with the development of early strength and high durability.According to the CRTSII type track slab concrete construction technology conditions,the appropriate track slab concrete construction technology was put forward. On thisbasis, the theoretical mix proportion was transferred to a construction mix proportionaccording to the Beijing-Shanghai high-speed railway to four blocks of civilengineering material characteristics. This technology is applied in civil engineering infour sets of the Beijing-Shanghai high-speed railway about45000pieces of trackplate, and150000m3of concrete precast production. The production cost of concreteis greatly reduced with high quality, safety, and little time, which creates a economicbenefits of more than5million RMB.