Quantitative Study On The Correlation Between Concrete Pressure And Sound Velocity

With the continuous development of the current social and economic situation,buildings are also increasing.In many building materials,the most widely used one is concrete.It can be used to ensure the stability of the entire building to some extent,so it is widely used.In addition to occupy a large place in the construction of concrete,concrete also plays an irreplaceable role in the field of highway engineering,bridge engineering,tunnel engineering and water conservancy.With such a large amount of concrete,more and more attention has been paid to its quality and extent of damage.The reason for the destruction of concrete is the development of its internal cracks,so the process of crack propagation is particularly important in determining the damage of concrete.After the concrete is pressed,the test piece is cut off and observed its geometric properties of the crack on the interface with an electron microscope.This is the current method of obtaining load-deformation curves.In addition,cut the test piece and dye cracks,then observe the nature of the crack use the microscope and then determine the stage of the concrete damage.This is also a way to detect the development of concrete cracks.These methods are intuitive and accurate,through the microscope can directly see the stage of crack development.However,this test method will cause some damage to the test object,and cut off the concrete will consume much time and will intensive much labor.In the detection of concrete internal structure and its various mechanical properties,Non-destructive testing is a method that uses the highest frequency and the best detection results.This method can quickly determine the location of the internal damageof the concrete and the measurement of the defect,and the method of use is also relatively simple.At present,non-destructive testing technology plays a significant role in the field of reinforced concrete structural inspection with its unique advantages.It plays an irreplaceable role in structural diagnosis,post-maintenance and damage repair of concrete.Among the various non-destructive testing technologies,one of the most important methods is ultrasonic testing(Ultrasonic Method).Ultrasonic detection method is also called ultrasonic method.It uses the transducer to emit ultra-high sound waves,then the ultrasonic wave penetrates the test piece.Finally,test and analyze the ultrasonic wave carrying the internal information of the test piece to obtain the internal quality of the test sample.In 2001,the issuance of the "Ultrasonic Method for Testing Concrete Defects Technical Regulations"(CECS21:2000)played a major role in promoting the use of ultrasonic methods.It has been more and more widely used to determine the internal damage of concrete structures by measuring the speed of sound.There is a certain correlation between sound velocity and pressure.The expansion of concrete cracks under stress can be tested by the speed of ultrasonic propagation in the test block.It can be thought that if the ultrasonic method is used to measure the propagation speed of the ultrasonic wave under the pressure state of the test block,the relationship between the load and the wave velocity can be obtained,and then the damage evolution rule under load can be obtained.The research object of this paper is four concrete pieces with different intensities.After curing to the standard strength,the pieces are placed under the press and pressurized continuously until the blocks are damaged.In this process,the ultrasonic probe is used to test the concrete pieces.Combined with the previous load-deformation curve,and finally obtain the concrete test block pressure-velocity curve,and then obtain the wave velocity variation of concrete in different stages of internal cracks.According to the final fit image,we can obtain the stage of concrete internal crack under certain speed of wave velocity.