Development of a New Test Specimen with Tapered Cross-Section for Use in Uniaxial Fatigue Testing of Hot Mix Asphalt.

Abstract

Despite recent developments, two primary challenges associated with fatigue testing of asphalt concrete cylinders remain: end failures and applicability to in-situ samples. End failures, or failure regions developing outside the strain gauge length, occur frequently and significantly reduce the value of the test. Samples cored from the field are often made up of several construction lifts ranging from 38 – 150 mm, rendering it incompatible with standard test cylinder dimensions. This study proposes a modified specimen geometry for use in fatigue testing of asphalt concrete mixtures which addresses these two challenges. The proposed configuration is a prismatic specimen which can be sliced horizontally from a cylinder with a diameter of 150 mm. The dimensions of the specimen are 110 mm long by 100 mm wide with variable thickness. The specimen width is tapered along the longitudinal axis to encourage middle failures. Constant crosshead fatigue tests are performed on test specimens as a proof of concept.