The Mix Ratio Design And Construction Temperature Control Technology Of High-performance, Large-volume And High-strength Concrete For Super-large Section Tunnels

The massive high-performance concrete has been successfully applied in engineering,but there was rarely reported of the comprehensive construction technology of high-performance mass high-strength concrete for super-large tunnel and the construction literature for solving the problem of high-performance mass high-strength concrete for super-large tunnel.In this paper,the comprehensive construction technology of high-performance large-volume and high-strength concrete in a super-large tunnel is taken as the research object,and the environment,design and specification requirements of the project are investigated.Starting from the mix design,the cooling water pipe cooling method is adopted in the process.It basically solves the problem of hydration adiabatic temperature rise and the temperature crack in the construction of high-performance large-volume high-strength concrete in super large tunnel,ensuring the quality of national key projects.The main conclusions are as follows:1.The durability and the hydration heat of concrete should be solved in the mix proportion design of mass high performance concrete.By referring to the domestic and international engineering examples of high-performance concrete mix ratio,considering the environment and raw materials in the project site,the technical measures of low water binder ratio,low dosage of cementitious materials,large amount of high quality fly ash and minerals,and high efficiency retarded polycarboxylic water reducer are put forward.2.The mix ratio parameters of high-performance and large-volume high-strength corrosion-resistant concrete are obtained through orthogonal design and range factor analysis,mixture performance test,mechanical property test,durability test,on-site concrete construction temperature measurement.The dosage of cementitious material is 510Kg/m3,the dosage of fly ash is 25%of the total cementitious material,the dosage of mineral powder is 9%of the total cementitious material,the water binder ratio is 0.29,the sand rate is 38%,and the dosage of retarded polycarboxylic water reducer is 1.0%.3.Compared with the previous concrete mix proportion,the mix proportion of 34%high-quality fly ash and mineral powder not only reduces the cement dosage,improves the working performance of concrete and meets the design requirements,but also reduces the temperature peak value of hydration adiabatic temperature rise of concrete from 91.5? to 64.3?.4.The final setting time of concrete is delayed for 6 hours after adding 1.0%retarded polycarboxylic superplasticizer.Combined with temperature monitoring,it is found that the peak value of adiabatic temperature rise of concrete is reduced by 11%;the peak time is delayed for 20 hours,which reduces the possibility of concrete cracking.5.The effect of retarded polycarboxylic superplasticizer,mineral admixture content and condensation pipe water passage method on the hydration adiabatic temperature rise of large volume and high performance concrete was studied by means of setting condensation circulating water and outer geotextile "heat storage and maintenance" technical measures.The results of data monitoring shows that the use of mineral admixtures instead of 34%of the total amount of cementitious materials;the condensate circulation pipe plum-shaped arrangement,multiple inlets and the timely exchange of water heads successfully reduced the internal hydration adiabatic temperature rise peak of concrete,avoiding the risk of concrete cracking.