Study on Frost Resistance of Cast-in-place Bed Slab Manufactured Sand Concrete with Vacuum Dewatering Method
Freeze-thaw damage is the main durability degradation mechanism for cast-in-place bed slab manufactured sand concrete of high-speed railway ballastless track in cold regions.Improving the frost resistance of ballastless track bed slab manufactured sand concrete presents great benefits for the long-term service performance of ballastless track sys-tem.In this paper,the manufactured sand concrete of C40 cast-in-place bed slab was dewatered with a vacuum method at a vacuum degree of 0.06 MPa and 0.08 MPa for 1,3,5 and 10 minutes,respectively to study the frost resistance of vacuum dewatering treated manufactured sand concrete.The influence of vacuum dewatering treatment on manufactured sand concrete was analyzed through the vacuum dewatering rate,surface rebound value and pore structure of the surface concrete.The results show that compared with untreated concrete,the mass of scaling of treated manufactured sand con-crete is reduced by 25.8％～95.5％,with water uptake reduced by 7.9％～77.0％.With the effect of vacuum dewatering process,the actual water cement ratio of the surface concrete is decreased with improved pore structure of the surface concrete and the increased compactness.The relationship model between the mass of scaling of concreteand the vacuum degree and time was established,aiming to provide a technical solution for improving the frost resistance of cast-in-place bed slab manufactured sand concrete in severe cold regions.
ballastless bed slabvacuum dewateringmanufactured sand concreteone-sided freeze-thaw
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