Experimental Study On On-site Detection Method Of Compressive Strength Of High-strength Self-compacting Concrete

Among various high-strength concretes,high-strength self-compacting concrete has good fluidity,cohesion,and segregation resistance.It can pass through the complex bundled steel bars by its own weight,and can be filled into every corner of the model without vibration,which is suitable for projects with large size and difficult construction.However,the existing researches on high-strength self-compacting concrete mostly focus on its configuration field,but when it comes to the on-site compressive strength test,the method of retaining cube test blocks is still using.However,this method cannot fully reflect the actual working strength of concrete.When the concrete structure is lost or there is doubt about the strength of the completed concrete structure,the method of leaving the test block cannot be realized.Therefore,it is necessary to advance the research on the field testing of high-strength self-compacting concrete.In this paper,the rebound method,the ultrasonic rebound comprehensive method,pre-loading method,post-loading method,core drilling method are used to test the self-compacting concrete with strength class of C50,C60,C70,C80,C90,C100.The test results were compared with the values of the indented test block compressive strength.The strength curve and strength formula of the five methods are obtained through experiments,the accuracy is high,and all parameters meet the requirements of relevant specifications.The conclusion that the traditional strength testing method is still applicable to high-strength self-compacting concrete is provided,which provides guidance for future engineering quality acceptance.Secondly,considering the factors that may affect the detection results of the five methods in actual operation,this paper starts from the factors that have the greatest influence on various methods,the authors explored the effects of carbonization depth on the extraction method,the concrete age on the ultrasonic rebound method,the anchorage depth on the pull-out method,the core diameter for core drilling method.At the same time,the accuracy of the test results was explored to further standardize the actual operation method of the on-site detection method.Finally,based on the respective principles and limitations of the rebound method and the pull-out method,the rebound method was combined with the pre-loading method and the post-loading method,respectively,to propose the rebound-pre-loading method and rebound-post-loading method,the correlation between concrete strength-extraction force-rebound value was obtained.Various regression models were established,and the corresponding strength measurement surfaces and formulas were derived,and compared with a single detection method.It is concluded that this method is more accurate and reliable.