Study On Preparation And Application Of C50 High Performance Concrete For Bridges In High Temperature

At present,the development of expressways is getting faster and faster,and the bridges with complex structures and large spans are more and more.Therefore,the concrete used for highway bridges has received more and more attention.High-performance concrete has good workability and high strength.It has excellent durability,can adapt to harsh environmental climate,reduce engineering cost,extend the service life of buildings,meet the requirements of saving resources and energy consumption,and has become the material of choice for highway bridge concrete.In this paper,the high-temperature engineering environment,high-performance concrete mix design and optimization,combined with the influence of specific parameters on the mechanical properties,work performance and durability of concrete,the related research on high-performance concrete for highway bridgesThe main work and achievements of the paper are as follows:(1)Through experiments to study the effects of different raw materials on the performance of concrete,and then optimize the concrete mix ratio through the selection of cement varieties,crushed stone and slag powder.And analyzed the influence of water-binder ratio,sand ratio,slag powder content on the workability,compressive strength and elastic modulus of C50 high performance concrete.The results show that when the water-binder ratio was 0.32,the sand ratio was 40%,and the slag powder content was 20%.The workability,elastic modulus and compressive strength of concrete are optimized to meet the performance requirements and reduce costs.(2)The paper studied the effect of compounding parameters on the properties of concrete.Three polycarboxylate superplasticizers were designed,of which PC-A wassuitable for ordinary concrete with lower technical requirements;PC-B was suitable for slump,moderate expansion,but high requirements for preservation and appearance,and demoulding Short-term T-beam concrete;PC-C was suitable for pumping concrete with higher requirements for initial and time-dependent conditions.(3)Through experiments to study the effect of slag powder content on the durability of C50 concrete.It mainly included crack resistance,water permeability resistance,chloride ion penetration resistance,early shrinkage rate and carbonation resistance of concrete.The results showed that the incorporation of slag powder can effectively improve the internal structure of concrete,reduced the early shrinkage of concrete,and improved the erosion resistance of concrete against external environment.When the slag powder content was 20%,the concrete had the best durability against cracking and water penetration resistance.(4)The paper studied the application of C50 high performance concrete for highways under high temperature conditions from several aspects such as engineering overview,C50 high performance prestressed T-beam concrete and high pier concrete performance test and T beam and high pier quality control technology.Mainly through the use of multi-dosing technology to reduce hydration heat,strict control of raw material quality,production and on-site control and maintenance,etc.,to avoid C50high-performance concrete cracking under high temperature conditions and other problems.Finally,through the actual production application tracking,the application of C50 high-performance concrete in prestressed T-beams and high piers under high temperature conditions has achieved good results in all aspects.