Experimental Study of Crack Characteristics of Self-Compacting Rubberized Concrete under Four-Point Bending Based on Acoustic Emission Technique

Four-point bending tests of self-compacting concrete with different rubber contents were conducted, and the acoustic emission (AE) technique was used to monitor the fracture process. The evolution law of rise angle (RA), average frequency (AF), and AE intensity was analyzed, and the Gaussian mixture model (GMM) was used for clustering analysis of crack mode in different loading stages. The results clarify that the safe regions of self-compacting rubberized concrete (SCRC) were proposed based on AE intensity. Both the slope of the cumulative RA-AF curve and the average value of RA and AF had a quantitative relationship with rubber content. Rubber content had little effect on crack mode. The failure process of SCRC with rubber contents of 0%-30% was dominated by the tensile crack mode, and the maximum proportion of shear cracks appeared in the postpeak loading stage (40%-20%), which can be considered as warning value of concrete bending failure. The results can provide a theoretical reference for the early warning of SCRC failure.