| In according with the severe characteristics of environment in Qinghai-Tibet plateau permafrost region, the basic performance of the concrete to be used in this area was put forward, and the techniques to prepare the concrete was studied. Based on the theory of cement minus-hydrating, the mechanism of concrete early frame-forming and the influence model of early frame-forming on the early anti-freeze and later frost-resistance of concrete, the DZ-1 multi-function composite admixture was developed by orthogonal designed experiment. The performance of High Performance Concrete in Qinghai-Tibet plateau permafrost region(QT-HPC), was investigated in term of physical and mechanical performance, and durability of this type of concrete, which mixed with DZ-1 multi-function admixture in the case of plus-minus changeable temperature of -5℃~20℃ and constant minus temperature of -5℃, and the reasons why the concrete has preeminent long-term performance and durability was analysed.It was found that the multi-function composite admixture could prompt the strength development of concrete in minus temperature, and realize such preeminent performance as early anti-freeze and late frost-resistance of concrete. Air-entraining agent could notably improve the frost-resistance by prompting pores to tiny and distributing pore diameter rationally. Mineral composite could greatly improve the chlor-ion penetration resistance and the sulphate corrosion resistance by filling up the pores in concrete. It was found originally that environment atmosphere could effect the entrained air content of concrete. Under the same circumstance, the entrained air content of concrete tends to be lower when elevation become high. So it is a necessary means to increase the dosage of air-entraining agent in concrete when building structures in high elevation region.Through applying QT-HPC on-the spot, it was proved that the performance of QT-HPC were superior and could fulfill the necessities of constructing. |
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