Rear loading pull-out method;  pull-out resistance;  concrete strength;  Detection

Through the extraction and coring tests of commercial concrete components with a strength range of 20~70 MPa for four ages, the pulling force and compressive strength of concrete were measured. According to the results of 4 sets of tests, the mathematical correlation model was determined, and the mathematical relationship between the pulling force of concrete and the compressive strength of concrete was established, and the correlation and error range of the obtained curve conformed to the requirements of the formulation curve specified in the specification. The test results show that the post-loading extraction method is used to detect commercial concrete and high-strength concrete, and it is suggested that the curve be used as the local strength measurement curve of the post-loading pull-out method of commercial concrete (including concrete above C38) in Zhengzhou.