Development of a hollow cylinder tensile tester to obtain mechanical properties of bituminous paving mixtures

A novel hollow cylinder tensile (HCT) test device was developed that can be used to determine fundamental tensile characteristics of brittle materials, such as asphaltic paving mixtures. These properties include tensile strength, creep compliance, and dynamic modulus at low and intermediate temperatures. Theoretical and experimental results showed that the HCT mode provides a favorable method for imparting tensile stresses to brittle materials with minimum stress concentrations. The method took average properties over the entire inner wall of the specimen, thus, offering excellent resolution and gage length-to-particle ratio in the direction of measurement. Finite element-based conversion factors were presented that allowed strains and stresses to be precisely obtained from test measurements. Test arrangements with partially loaded cavity walls and/or tests carried out on eccentrically-cored specimens required the use of the finite element formulas. A second linear variable differential transformer can be added to the HCT to obtain Poisson's ratio, but the added complexity was not justified for most applications. However, hoop stress and tensile strength was independent of Poisson's ratio. Preliminary tests confirmed the accuracy of the HCT mode using calibration cylinders and tests on asphalt concrete specimens gave promising results. The method can be used in quality control/quality assurance of hot-mix asphalt construction, and has potential application as a supplement volumetric mixture design, such as Superpave level I mix design.