Application Of Nano Modified High Durability Concrete In The Qinghai Tibet Plateau

Cement based materials in harsh environment durability problems of Qinghai Tibet Plateau is directly related to the construction of the plateau area of service life, safety and quality of construction cost, this paper carried out the research from the micro scale, the research of nano CaC03 doped by mercury porosimetry, scanning electron microscopy and other test methods into the characteristics of concrete research scale and distribution structure tiny pores, and simulate the different curing conditions in Qinghai Tibet region, the compressive strength and durability of cement concrete test strength, abrasion resistance and other characteristics of comprehensive evaluation of materials, with the introduction of nano porous material by spraying, using nano crystalline materials on the surface of concrete spray penetration, in its theory on the basis of the research, combined with the application in the engineering field, the analysis of research on the nano modified, in order to improve the concrete in Qinghai area Lay the theoretical foundation of durability.The results of this study show that:（1） Different curing conditions have an important effect on the microstructure of concrete, dry conditions of low temperature, the reaction rate of cement hydration water. Material production is reduced, the influence of microstructure of concrete hydration products morphology, performance for the disorder lap, compactness, structure, loose formation of large pores; standard curing condition, concrete suitable curing temperature and humidity, the hydration reaction of cement, hydration products with calcium silicate gel as the main structure the overall morphology of dense, compact, dry curing conditions, high temperature, low humidity, water evaporates quickly, the water evaporates, leaving a lot of micro pore structure. The concept of structure shows that the porosity is large, the structure is loose, the compressive strength is low;（2） after dispersion of nano CaCO₃, in full hydration process of cement to participate actively in the secondary water process, according to the SEM picture shows, nano calcium carbonate content is 2.2%, cement paste with nano CaCO₃ crystal, nano materials and the surrounding crystal key combine well, around the cement stone structure compact.（3） pore structure analysis found that dosage is 2% of nano CaCO₃ compared with not adding nanometer CaCO₃, harmless pores and less harmful pores increase, while harmful hole and multi harm pore reduced, dosage is 4% of the concrete pore size distribution shows, harmless pores increase in the number, but less harm hole and a reference group difference is not big, and reduction of harmful pore 8%, harm pore number is decreased by 7%;（4） in early maintenance（forming 2d） and maintenance（forming 14d）. After Sprayed Nanostructured permeable crystallization agent of concrete compressive strength, is not sprayed specimen can be increased significantly（up to a maximum of 40 per cent increase in）; even if they don’t do any maintenance treatment, nano penetration crystallization agent processing after the compressive strength of concrete can still be increased by 30%.（5） in the early maintenance（forming 2d） and maintenance（forming 14d）, passing through the nanometer penetration crystallization agent processing after the concrete water absorption rate, compared with no spraying of the specimen can be decreased significantly（up to a maximum of 67% lower）, namely, the concrete density increased, even if they don’t do any maintenance treatment, nano penetration crystallization agent processing after the compressive strength of concrete can still improve more than 7.8%;（6） both in the early maintenance（forming 2d） and maintenance（forming 14d）, passing through the nanometer permeable crystallization agent spraying concrete anti abrasion strength, is not sprayed specimen can be increased significantly（up to a maximum of 75% higher）; even if they don’t do any maintenance treatment, nano surface treatment agent spraying processing after the compressive strength of concrete can still be increased by more than 50%.