Research On Semi-circular Bending Test For Asphalt Mixtures

When the stress in pavement structure which is caused by the load and some natural factors such as the changes of temperature is greater than the tensile strength of materials,the pavement structure will be cracked.So the tensile strength is one of the main parameter in pavement structure design.At present, the tensile strength is determined by using indirect tensile strength test and bending beam test as the standard test methord in our country.Semi-circular bending test is a process that adding a concentrated load at the mid-point of the semi-circular arch until the given size semi-cylindrical specimen failures. By using the failure loading the tensile strength is calculated. Compare indirect tensile strength test and bending beam test,the semi-circular bending test has bigger advantages. first,the preparation of specimen and the procedure of test are very simple,furthermore,the stress in the specimen is more close to that in pavement structure. Semi-circular bending test is analyzed by using the software of ANSYS and the comparison of each test:(1)The expressions of tensile strength at the middle point on the lower sueface of the semi-cylindrical specimen is advised by using the plane assumption in material mechanics, and the correctness of the expressions can be proved by giving numerical simulation to the semi-circular bending.(2)Calculate the stiffness of asphalt mixtures by testing the vertical displacement at the bottom of the central beam specimen. Regard the stiffness as the parameter of modular which is required in numerical simulation to the semi-circular bending test, and the simulation was given. Then, make sure that the bending beam test and the semi-circular bending test have a coherence in mensurating the stiffness of asphalt mixtures by comparing the tensile strain at the bottom of the central specimen,which is get by the numerical simulation and the semi-circular bending test.(3)A steady result of tensile strength in semi-circular bending test will be get by Comparing the indirect tensile strength,beam bending tensile strength,and semi-circular bending tensile strength which are gained by the tests in the same asphalt mixtures.Finally, a standard methord of semi-circular bending test is established according to the canonical method of indirect tensile strength and semi-circular bending tests.