Development And Application For Non-Destructive Testing Technology In Concrete

At present, Guangzhou faces lots of new, rebuild and reinforced concrete buildings, so how to scientifically detect and evaluate the quality of these buildings has become a major subject. Now, Guangzhou still uses the country strength curve, when testing the concrete strength by rebound method. Practice shows that using the country strength curve have grate errors and go against conducive the quality of the buildings.Guangzhou regional normal materials were used to make concrete cubes which are tested by rebound, pull-out instruments. 320 groups of data, which include seventh ages, from 3d to 180d, ten strength grades, from C15to C60 have been obtained. Analyzing the experimental dates of rebound testing by dualistic linear regression, one power regression and dualistic power and index regression. The mean relative error is respectively 11.7%,10.8%,12.3% and lower 14.0% requirements of national standard; the relative standard deviation is respectively 14.4%,13.2%,14.8% and also lower 17.0% requirements of national standard. In addition, research on the pull-out method which hasn't used in Guangzhou. The thesis theoretically demonstrate the feasibility and advantages of pull-out method. Analyzing the experimental dates of pull-out testing by one linear regression and one power regression. The relative standard deviation is respectively 8.3%,8.5% and lower 12.0% requirements of national standard.The tests indicate that pull-out method not only have high detection precision, but slao have the follow advantages compared with core drilling method widely used in Guangzhou:simpler operation, lower cost, lower damage to structure. The pull-out mehod can be popuplaried .To test the applicability and practicality of respective strength curves, we test the concrete items on site by rebound, pull-out methods. The strength calculated by our obtained regression formulas compared with actual strength and calculate strength by country regression formulas. The results showed that the strength curve of our obtained have high applicability and practicality.Tests have been done using concrete cubes with crushed stones bones, so it is necessary to set up other regional strength curves in the future work with cobble as bone material. The cube ages are all within 180d, so the curves should be modified by higher-cube-age concrete. Cubes are all protected in natural curing, so the curves should be inspected and modified by a lot of engineering practice in real structures.