Effect Of Fly Ash On The Performance Of Concrete Contracture During Construction And Safety Control Analysis

Studies about performances of concrete structures during construction provide research foundation for security during construction, and safety and durability during usage. As the most widely used mineral admixture in modern concrete, fly ash can reduce energy and resource consumption, lower production costs, reduce the load from fly ash emissions to the environment, it also can improve the physical and mechanical properties, especially significantly improve the creep deformation of concrete performance. Performances of concrete at early age, structural characteristics and reliability have played important roles in domestic and foreign studies about structures during construction. In this paper, effect of fly ash on the concrete compressive strength, elastic modulus and early shrinkage during construction have been studied. On the basis of concrete performance test, through the loaded concrete, influence of proportions of fly ash, compression age and compression age have been studied by deformation and compression strength. Analyze the safety of concrete structure during construction by the reliability of concrete structure.The basic laws revealed by experimental studies are as follows:① Fly ash can increase the slump of concrete, reduce the loss of slump and improve the workability of concrete. Fly ash can reduce the early concrete compressive strength and elastic modulus, slightly increase the later strength of concrete growth rate; With the proportions of fly ash increasing, concrete compressive strength and elastic modulus decreased; When the proportions of fly ash higher than 20%, the 3d compressive strength fell by 35%, the late compressive strength of 28 d fell by 28%, cannot meet the requirement of concrete engineering standards.② Fly ash can reduce the early shrinkage before the setting and hardening of concrete. As the proportions of fly ash increased from 10% to 40%, the 10 h shrinkage reduced 15.4%, 30.7%, 38.4% and 15.4% respectively.③ At the same proportions of fly ash(10%) and compression magnitude(0.4 fc, p(7)), the earlier age of compression concrete, the greater amount of deformation of fly ash concrete, the greater deformation and the lower axial compressive strength will be. The deformation of C30 concrete increased by 300%, and the axial compressive strength loss by 17% in 3 days.④ At the same proportions of fly ash(10%) and loading age(7d), the greater compression magnitude is, the greater amount of deformation of fly ash concrete will be. The deformation of concrete increased by 700%, the axial compressive strength loss by 20.8% under the stress of 0.6 fc,p(7).⑤ The higher the proportions of fly ash, the earlier compression age and the greater compression stress, and the lower importance coefficient of concrete structure are, the higher deflection of concrete structure are,the harder the safety control of concrete structures during construction will be.