Study On The Thickness And Defect Of Concrete Slab Based On Impact Echo Method

It is of significance for maintenance and strengthening the reinforced concrete structures to study the influential factors that affects the impact echo scanning system testing the concrete structures.With the thickness of plates,the size and depth of defects being the variables,the precision of concrete slabs is measured in different condition.Laboratory test is verified and complemented by numerical simulation.Two models called Shen Hou Bi and Kong Hou Bi are built,through the spectrum analysis of laboratory test,to make an error correction of the results.The experimental results show that,for a given thickness,size and depth,as the size of defects increases and the depth of defects shallows,the precision of the results decreases.In some fields(10~30cm),as the thickness increases,the precision decreases;When the thickness is 30 cm,the error is minimum.In some fields(30~50cm),as the thickness increases,the precision increases.It is found from the experimental data that Shen Hou Bi has a square relation with the ratio of the frequency of defect and the reference frequency of the slab.A regression formula of Shen Hou Bi is given and preliminarily verified with experimental results and numerical simulation results.Through the model of Shen Hou Bi,a more accurate relation between the depth and the thickness of slab is obtained.