Study On Frost Resistance Design And Measures Of Concrete In Qinghai Tibet Plateau

In order to improve the frost resistance of concrete at high altitude(early frost resistance and frost resistance durability),this paper mainly studies the following aspects:(1)This paper analyzes the influence of different factors of concrete freezing thawing damage degree,influence of typical climatic characteristics of frost resistance design of concrete on the basis of the special climate and environment in plateau area;then,through the collation of the Qinghai Tibet Plateau weather station meteorological data,statistical regression obtained concrete in Qinghai Tibet plateau annual number of freeze-thaw formula,and so on the Tibetan Plateau in different regions of the concrete structure durability design division,puts forward the corresponding design level of antifreeze recommended value,lays the foundation for the design of frost resistant concrete in Qinghai Tibet plateau.(2)To simulate the low pressure environment in the plateau area by reducing the mixing pressure,the air content,the pore structure parameters and the bubble stability of the air entraining concrete with the addition of 4 kinds of common air entraining agents were measured.The results showed that the fresh air entraining concrete containing gas decreases linearly with the ambient pressure decreased,when the pressure is reduced to 50 kPa when the air content of concrete is reduced about 20%~52%;meanwhile,the hardened concrete under low pressure mixing of hardened concrete pore structure parameters to the overall inferior to the atmospheric conditions of stirring,and the bubbles have poor stability.Based on this,the concrete preventive measures to improve the frost resistance of Qinghai Tibet Plateau concrete are put forward.At the same time,this part of the study also provides an experimental basis for determining the air content of concrete with different frost resistance in the design of frost resistance.(3)This paper through the establishment of durability index and material parameters of concrete(water cement ratio,air content and the spacing factor)function relationship between the combined influence of air entraining air content of concrete freeze-thaw environment zoning and low pressure environment the Qinghai Tibetan Plateau,to optimize the existing antifreeze concrete design specification,finally puts forward the design method of plateau frost resistance concrete.This research has important theoretical significance and practical value to improve the durability of concrete frost plateau early frost damage and prevention of concrete.