The Failure Process Of Concrete In Different Erosion Environment Based On Industrial CT Technology

As the economy of China is developing rapidly, the construction of infrastructureis also expanding. Concrete, as one of the most important materials, is used almost inevery field. Because of the vast territory of China, the natural conditions are totallydifferent in many districts, which leads to the condition that the concrete is to beconfronted with different erosion environments. Though researches based on x-ray CThave started many years ago both at home and abroad, most focus on the failureprocess in loading conditions. There is almost no research on the failure process ofdifferent outside erosion environments.This thesis intends to use the X-ray CT technology to study the failure process ofconcrete in freezing-thawing or drying-wetting cycle and sulfate condition. The aim ofthis test is to find the connection between the change of internal pore andmacroeconomic performance indicators.Studies have shown that the number and volume of pores carry out polarizationand mutations phenomenon during the freezing-thawing cycles: the number and totalvolume of those pores whose volumes are smaller than0.5mm~3and larger than20mm~3will have a major change and those pores whose volumes are between0.5mm~3and20mm~3almost have no change. The total number and volume of internal pores have amutation phenomenon in30th freezing-thawing cycle.In this thesis, gray correlation theory is used in the analysis of correlationbetween the changes of different factors. The Tangs Correlation Coefficient derivedfrom Grey theory shows that it is relevant between the changes of several factors andrelative dynamic elastic modulus. Those pores whose volumes are smaller than0.05mm~3and larger than20mm~3almost have the same variation. The change of the0.01-0.05mm~3pores whose diameter are within60mm is in accordance with that of therelative dynamic modulus and the correlation coefficient has reached0.8871.Drying-wetting cycles and salt erosion interact with each other, which have acertain impact on the internal pore structure. The higher the concentration, the moreobvious the impact on. The drying-wetting cycle can change the concrete porestructure to some extent and allows the sulfate an easier access into the concrete.What’s more, the drying-wetting cycle may also produce the salting phenomenon, accelerating the destruction of the concrete.According to the Tangs Correlation Coefficient, the total volume of the poresmaller than20mm~3is in consistent change with the relative dynamic modulus.