Acoustic Characteristics Research Of Self-compacting Concrete Under Uniaxial Compression

Self-compacting concrete(SCC)is a kind of high performance concrete material with excellent working performance and wide application prospect.It has strong filling ability and can be compacted by its own gravity.Therefore,the research on SCC is of great significance in engineering practice.However,in practical application,the failure of self-compacting concrete will have a great impact on its structure and working performance.Therefore,it is necessary to adopt reasonable methods to monitor the state of self-compacting concrete,to warn the failure of self-compacting concrete and to explore the failure law of self-compacting concrete.Nondestructive testing technology is a testing method to evaluate the damage of materials and judge the defects of materials without destroying the structure of materials.It is commonly used in the research of concrete materials in recent years.However,there are still many deficiencies in applying this technology to the field of SCC at this stage.Therefore,applying this technology to the field of SCC,evaluating the integrity of concrete structure in the process of failure,and analyzing the failure law of structure can lay a foundation for the application of this technology in the field of SCC.In this paper,acoustic emission and ultrasonic nondestructive testing technology are used to explore the acoustic characteristics of SCC specimens under uniaxial compression on the basis of selecting a suitable ratio to make SCC specimens.The results show that:(1)With the uniaxial compressive strength test,the variation law of AE signal characteristic parameters of some SCC specimens cured for 7 and 28 days is similar to ordinary concrete;(2)With the uniaxial compressive strength test,some SCC specimens cured for 7 and 28 days will have a stationary period like some rock materials during the loading process.The stationary period accounts for about 20% of the entire failure process.At this stage,no acoustic emission events will occur.(3)In the process of failure of SCC specimens,the distribution of positioning points in some areas is more concentrated,and the area where the positioning points gather is in the shape of inverted triangle or landslide,in these areas,the activity of specimens is relatively strong.In the process of failure,most of the cracks on the specimens are cutthrough;(4)After curing the SCC specimens for 7 and 28 days,the average sound time before the failure of each measuring point is lower than the average sound time after the failure,and the average amplitude and sound velocity after the failure are lower than the average value before the failure.After the specimens are broken,the defects of the internal structure will lead to the amplitude anomalies of some measuring points.