Abstract: Splitting tensile tests were conducted on concrete with different gradations (two gradations, three gradations, and four gradations) under different strain rates (10^-5/s, 10^-4/s, 10^-3/s, 10^-2/s). The splitting tensile strength and axial strain of concrete were analyzed, and the energy release characteristics and damage regularity of mass concrete in the whole process of splitting tensile damage were researched through collected real-time acoustic emission data. Results show that with the strain rate increasing, the splitting tensile strength of concrete displays a trend of increasing. Singularity in the variation of splitting tensile strength is larger when the gradation of concrete is higher. The process of splitting tensile failure does not have the characteristics of a typical three-stage: stage without cracks, stage with cracks, and stage of failure. The acoustic emission signal is weak in the early stage of loading, but rises sharply when the material reaches peak stress. Acoustic emission data can truly reflect the process of concrete splitting tensile failure.

Key words: concrete gradation, strain rate, splitting tensile, acoustic emission, peak strain, energy count