Research On The Testing Method Of Splitting Tensile With Notch And Its Relationship With Uniaxial Tensile Testing For UHPC

As an indirect test method of tensile strength,the splitting tensile test is suitable for evaluating the tensile performance of ordinary Portland concrete.Because it is convenient to use and the test results are closer to the uniaxial tensile strength than the bending tensile test.Although the splitting tensile test method has been widely used,the test data are not reliable in FRC and ultra-high performance concrete(UHPC)with high volume steel fiber concrete.Due to the good ductility of the material,it is necessary to propose a splitting tensile test method suitable for UHPC.In this study,two specimens with different shapes(cube,cylinder)three notched forms(no notched,30° notched,45° notched)were used to explore a splitting tensile test method suitable for UHPC.The strain and crack evolution of specimens under splitting load were analyzed using extensometer displacement test and digital image correlation(DIC)measurement technique.The influence of different fiber types and fiber mixing on splitting tensile performance were then experimentally measured.This paper discusses the influence of various factors on the splitting tensile test.Combining the strengthcracking opening displacement curve and crack distribution results,a reliable UHPC splitting tensile test method was expressed.The test results show that the strengthcracking opening displacement curve of cubic specimens with 45° notch had the least discrete,and the curve characteristics and crack distribution characteristics were consistent with the existing results.In the second stage,different UHPC mixtures with various ingredients including steel fiber contents,steel fiber types and water-binder ratios were investigated using the notch splitting test method.The digital image correlation(DIC)measurement technique was employed to the strain and damage degree of specimens under notch splitting and uniaxial tensile loads.Meanwhile,the influence of various ingredients on the tensile performance of UHPC and the relationship between notch splitting test and uniaxial tensile test results were analyzed based on DIC measurement.The results show that the tensile strength-cracking opening displacement curves basically had the same trend as that of the uniaxial tensile strength-cracking opening displacement.Their ultimate strength and dissipation energy were the similar at various ingredients.The law of limit strain was basically the same,but the values varied greatly.The cracking strength and cracking strain were different,but the values were close to each other.The law of elastic modulus varied greatly.The relationship between splitting tensile strength and uniaxial tensile strength was established.Moreover,the relationship between splitting tensile strength and compressive strength,and that of uniaxial tensile strength and compressive strength were proposed,which the correlation of splitting tensile strength and uniaxial tensile strength was better than the other two.According to the experimental and analytical results,the test results of splitting test with notch agreed well with that of uniaxial tensile test basically Therefore,simple splitting test with notch is a good measured method to evaluate the tensile performance of UHPC.