Preparation Technique for Prestressed Concrete Beam Used in Ballastless Track

With running speed of train increasing, the ballastless track including integral and consolidated road bed was taken as the model of track structures of high speed railway. High stability, symmetrical stiffness, high geometric regularity and uniform, good durability and low maintenance rate were merits of ballastless track, so ballastless track becames preferential selective track model in high speed railway. In this paper, the preparation technique that how to control creep deformation of prestressed concrete components used in track structures of high speed railway was introduced. In order to understand influence factors of concrete composition on creep deformation of prestressed concrete beam used in high speed railway ballastless track, creep rules of C 50 concrete with ultrafine fly ash and C 50 ordinary portland concrete were tested by parallel experimental methods, the influence of composition, curing system and loading age on creep behavior being investigated, and the corresponding mechanisms were discussed. The results indicate that creep of concrete with ultrafine fly ash is lower than that of ordinary Portland concrete in the same conditions. Compared with crushed pebble, crushed limestone can better reduce the specific creep of concrete with ultrafine fly ash, but the influence of types of coarse aggregate on specific creep of ordinary Portland concrete was inapparent. Curing system has great influence on the specific creep of concrete with ultrafine fly ash. Under steam curing condition, the specific creep of concrete with ultrafine fly ash is lower than that under moist curing condition. Addition of ultra-fine fly ash into concrete can remarkably improve microstructure and reduce dry creep. The creep deformation of C 50 concrete with ultrafine fly ash becomes stable after concrete is loaded 60∼90 days whether loading age is 10 days or 28 days.