C40 Self-compact Concrete In Ballastless Research On The Application Of Orbital Plate Engineering

In recent years,with the rapid development of China's high-speed railway,ballastless track has gradually replaced ballastless track.At present,CRTS III ballastless track slab is widely used in high-speed railway track laying.CRTS III ballastless track slab is used in the track of the new airport line project of Beijing Rail Transit.Because of the tight binding of steel bars in the filling layer and the narrow working space of concrete,the auxiliary vibration tamping construction cannot be realized,so the vibration-free tamping C40 self-compacting concrete is needed.Self-compacting concrete has excellent self-filling performance,anti-segregation performance and clearance passing ability,which can realize vibration-free tamping construction of filling layer.Through indoor and field simulation experiments,this paper discusses the effects of the cement ratio and sand ratio of C40 self-compacted concrete used in Beijing rail transit engineering on the performance of concrete.The test results show that when the water-binder ratio is 0.35,the comprehensive price ratio of concrete is the highest,and the strength assurance rate is about 145%;when the water consumption is 188 kg,the concrete has the best working performance and fluidity;when the sand ratio is 54%,the comprehensive performance of concrete,such as T500,expansion,J ring height difference and strength,is the best;raw materials with 50% of natural sand and 50% of manufactured sand,are the best in each particle grade of concrete.Material filled with each other has the best encapsulation,good working performance,more compact internal structure of concrete,and the strength of concrete has also been improved;silica fume and water reducing agent mixed with bio-glue are the most ideal state of concrete and are conducive to production control.After the indoor test,the concrete performance meets the requirements of the standard.After several simulated tests on the construction site,the concrete performance is good,and the construction mix ratio is finally determined.The single dosage of concrete raw materials determined is: 282 kg cement,460 kg natural sand,460 kg machine-made sand,784 kg crushed stone,91 kg fly ash,91 kg granulated blast furnace slag powder,48 kg expansive agent,25 kg silica fume,13.46 kg water reducer.At the same time,the control points of the self-compacting concrete in the production,pouring and maintenance process are also explored.At last,the results of three field simulation tests on concrete performance are stable,which meet the technical requirements applied to the actual project,and finally applied to the Beijing New Airport Line Project.