Correlation Study Of Pumping Concrete Strength And Ultrasonic Rate And Low Strain Wave Velocity Pile In Haikou

With the height and shape increasing of the building, a large amount of pumping concrete was used in high-rise buildings, how to effectively monitor and control of pumping concrete quality is an important issue in construction engineering technology.Traditional method of the structural concrete quality detection mostly based on the cube sampling selected according to the the regulation, or other test method such as use cube sampling by drilling.Traditional detection methods can only take the structure's minority,a small amount of sampling lack of representativeness for large buildings, therefore,ultrasonic and low strain detection methods, such as high efficiency.In recent years, the concrete ultrasonic testing and pile low strain test was widely applied to practical application. So far there has been little research on the wave velocity of ultrasonic and low strain detection technology in haikou region, it has seriously influenced the accuracy and reliability of concrete nondestructive testing.On the one hand, There are fewer studies relative to the establishment of local strength curve, the applicability of the strength curve of "technical specification for testing concrete strength by ultrasonic-rebound combined method" also has not yet been tested in Haikou area; On the other hand , the value of wave velocity in pile low strain detection often according to the experience,and there is a certain error.Haikou, which is subtropical monsoon climate,high humidity and salt content in the air, and pumping concrete raw material has its particularity. The correlation between the wave velocity of ultrasonic and low strain with concrete strength has a significant difference with raw materials and environmental conditions changed., It can significantly improve the quality of concrete nondestructive testing precision to carry out research on the the correlation correlation between the wave velocity of ultrasonic and low strain with concrete strength in haikou.This article mainly launches the research from the following several aspects:(1) Test and verify the applicability of the strength curve of "technical specification for testing concrete strength by ultrasonic-rebound combined method" to Haikou area.Choosing common concrete strength grade from C30 to C40 for validation test,comparative analysis on relative error of the measured compressive strength with conversion strength, the calculation results show that the strength curve of "technical specification for testing concrete strength by ultrasonic-rebound combined method" is not applicable to Haikou area.(2) Taking the pumping concrete of Haikou as the research object, choosing the common materials of Haikou to design concrete mixture ratio, we produce strength grade from C15 to C50 and at the size of 150mm × 150mm × 150mm concrete standard test block, measuring the ultrasonic velocity and the compressive strength under different ages.The experiment data were comparatively analyzed to reveal the correlation between the wave velocity of ultrasonic with pumping concrete strength in Haikou: concrete strength and ultrasonic velocity is nonlinear relationship, and ultrasonic sound velocity is more sensitive to the change of compression strength of the intermediate and low strength concrete. Compared with different age concrete, there is better correlation between the ultrasonic sound velocity with compression strength of concrete at same age, and the fitting effect of f-v is well. Therefore, the district supersonic strength detection curve of pumping concrete of Haikou is respectively established for 7 day ages and 28 day ages. Engineering validation data show that the district supersonic strength detection curve has good applicability in Haikou area.(3) This paper establishes the correlation between the ultrasonic wave velocity with low strain wave velocity based on stress wave theory, and establishes the correlation between low strain wave velocity with concrete compressive strength of Haikou. This article put forward two methods of calculating low strain wave velocity: ? Calculating the low strain wave velocity according to the mathematical relationship between the low strain wave velocity with ultrasonic wave velocity after measuring the ultrasonic wave velocity of the same condition curing standard test cube. ? Based on supersonic strength detection regression equation, inversely calculating ultrasonic wave velocity through the compressive strength of cubic pile concrete, then convert low strain wave velocity.