Research On The Method Of Field Rapid Testing Of Concrete Impermeability

The impermeability of concrete is closely related to the durability of concrete,and the test methods for concrete impermeability have also been widely studied at home and abroad.At present,the testing methods for concrete impermeability commonly used in laboratories include electric flux method,NEL method,and RCM method.And the methods for on-site inspection include ISAT method,Figg drilling method,PERMIT method,etc.Although there are many testing methods,laboratory testing methods used for actual engineering require core coring,it is a large damage to the structure and takes longer.And the existing on-site inspection methods also have certain deficiencies in the operation and the accuracy of results,and there is still a lack of relevant standards for on-site inspection of concrete impermeability in China.Considering about the above problems,this passage is based on the chloride ion penetration test and a method that can be used to detect the impermeability of concrete in the field is designed.The chloride ion was penetrated to the concrete structure on the site,and the resistance value of the concrete before and after the penetration was measured to evaluate the impermeability of the concrete.This passage mainly uses the digital multimeter with high stability to measure the concrete surface resistance value after the chloride ion solution infiltration,the resistance value tends to be stable in 45 minutes.The final stable resistance value increases with the fly ash quantity and the strength grade,and the resistance value of the concrete with different mix ratios has obvious difference.This shows that there is a good correlation between the results and the impermeability of concrete.Besides,the influence of the maximum diameter of gravel on the test results was studied,when the maximum diameter of gravel is 26.5mm,the results obtained by 7.5cm hole spacing are more accurate.Th e measured resistance is compared with the commonly used electric flux method,and the linear correlation coefficient is 0.92,which shows that the method is accurate for the evaluation of Impermeability.Finally,in order to avoid the penetration of chlorine ions into concrete structures in situ testing,the same test was carried out using sodium hydroxide solution,comparing the test results with the results obtained by using sodium chloride solution,the linear correlation coefficient reached 0.98,which proved that sodium hydroxide solution could be used to evaluate the impermeability of the concrete in the field.According to the research,it is feasible to evaluate the impermeability of concrete by using the stability of concrete resistance after infiltration of sodium hydroxide solution.This method has the advantages of high testing efficiency,portable equipment,less damage to structure,and has great application value.