Application of non-destructive testing method in strength testing of large-size rock-filled concrete test silo
[Objective]The conventional mechanical property test method for concrete do not apply to rock-filled concrete,and it remains to be verified whether the shrinkage test can apply to rock-filled concrete.At present,non-destructive testing method have been widely used for concrete strength determination,but their applicability to large-size rock-filled concrete remains to be investigated.[Methods]The large-size rock-filled concrete test silo was taken as the object of study,and the combined rebound and ultrasonic rebound method were used to carry out on-site non-destructive testing of the test silos at different ages and measur-ing distances and to calculate their compressive strengths.[Results]The test result show that the strength presumptions obtained using the rebound method are relatively concentrated,and the overall strength of the test silo at the age of 90 d reaches the design strength.But,it is small compared with the result of other studies and tests.After the test result of 90 d age substitute into the conversion formula of concrete compressive strength in the national unified test area,the maximum coefficient of variation of strength calculated reaches 48.22％,with a high degree of dispersion.After the range exceeds 2 400 mm,the waveforms of the three ages of the rock-filled concrete C15 test silo are gentle,and the wave velocity is a wide range of distribution,ranging from 994 m/s to 4 391 m/s.the sound velocity above 3.82 km/s in the C15-test silo at 180 d accounts for a large proportion,65.12％.the strength result obtained by using the ultrasonic rebound synthesis method continue to increase with the 60～180 days age period.[Conclusion]The result show:The rebound method is not suitable for the strength determination of rock-filled concrete;The conversion formula for the compressive strength of concrete in the nationally harmonized survey area does not apply to rock-filled concrete,the ultrasonic rebound synthesis method should establish a specially rock-filled concrete curve formula,and it is not recommended to use this method when the range is more than 2 400 mm It can provide a reference for applying non-destructive testing in engineering rock-filled concrete and avoid unnecessary testing.
万方数据
维普
