High-speed Rail Precast Box Girders C50 Concrete Mix Design And Construction Quality Control

High-Performance concrete is a new type of high-tech concrete, which is made under the conditions of a modern concrete technology, choosing high-quality materials, using strict quality management. The construction of high-speed rail and passenger dedicated line require for the concrete has at least 100 years life. In order to achieve the desired service life, the high durability and good performance concrete is essential. In this paper, a set of good high performance concrete mix was successfully made by a large number of comparative tests.This paper carefully studied the box girder production process should pay attention to.The conclusions are the followings:(1) The important condition for high performance concrete is a low water-cement ratio.(2) Because of the high requirements for high strength, the raw materials of high performance concrete should be controlled,for example the maximum size of aggregate should be smaller than 25 mm.(3)After added the fly ash, the anti-permeability of concrete and the resistance to carbonation has increased,but the freezing resistance of concrete has decreased.(4) The strict control of concrete mixing and pumping time can avoid irregular shrinkage cracks.(5) The use of thin layer continuous casting and the control of concrete casting speed can ensure the concrete has no crack.