Application Of Ultrasound In Geotechnical Materials Of Highway Engineering

Application Of Ultrasound In Geotechnical Materials Of Highway Engineering

Date:Sep 15, 2020

The ultrasonic method is one of the non-destructive detection methods. The propagation speed of ultrasonic waves in a homogeneous and isotropic elastic medium is related to the density and elastic modulus of the medium. When a material is regarded as an elastomer, its elastic modulus can be determined by ultrasonic waves. [1] The reliability of measuring the elastic modulus of cement mortar by ultrasonic was analyzed. In recent years, whether the geotechnical materials in highway engineering construction, such as semi-rigid materials, polymer modified cement materials, etc. can also be used to determine their elastic modulus by ultrasonic method to reflect their mechanical properties. In the research of cement materials, polymer modified cement materials and other geotechnical materials, the ultrasonic method is used to study the feasibility of analyzing the mechanical properties of materials and others.

 

It can be seen from the ultrasonic waveform diagram that the waveform of the ordinary concrete cube changes significantly after the compression test, but the waveform of the modified concrete after the addition of the polymer changes little, indicating that the addition of the polymer hinders the internal cracks of the concrete And micro-cracked and expanded. With the increase of the stress ratio F / Fmax of the load and the large load, the modified concrete has the tendency to decrease with the increase of the stress ratio F / Fmax of the ordinary concrete, which indicates the propagation trend of micro-cracks.

 

24 Ultrasonic method to study the damage process of emulsion-modified concrete For uniform and dense concrete, the sound intensity of ultrasonic wave passing through the test piece is relatively regular, but after loading, cracks and micro-cracks occur inside the concrete, and with the load Increased cracks and micro-cracks gradually expand, reflecting the change in sound intensity and time from regular to irregular waveforms. At the same time, the ultrasonic waves pass through the test piece's sound to varying degrees.

 

After curing the concrete to 28 days of age, perform axial compression experiments on the cube specimens, dispose the probes at the center of its sides, apply a 3-point force P load to the trabecular specimens, and dispose of the probes at the center of its sides and bottoms When measuring the waveform and sound during the loading process, the measured parameters are: the frequency is 2MHz, the point is flat, and the result is 3. The ultrasonic method can be used to study the mechanical properties of semi-rigid materials and polymer modified cement materials. The application of the ultrasonic method is highway Engineering materials research provides another convenient way.

 

The dynamic elastic modulus measured by ultrasonic of semi-rigid materials has a good correlation with the flexural tensile modulus and flexural tensile strength. The degree of correlation and the regression expression vary with the type of stability


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