1. Scope

Keywords

Rationale

Cracking at intermediate temperatures is one of the main distresses in asphalt concrete pavements. Therefore, it is critical to have a reliable test method to evaluate the cracking resistance performance of asphalt mixtures for quality assurance and quality control. The Semi-circular bending (SCB) geometry is a practical, simple, and truly describe the cracking behaviour of asphalt concrete. The SCB test is accepted and used by many researchers and agencies. Currently, the available standard SCB test protocols are only for 150 mm diameter samples, including EN12697-44:2010, AASHTO TP 105-13, ASTM D8044 16, AASHTO TP 124-18. So far, there is no SCB standard test protocols developed for 100 mm diameter. The SCB standard for 100 mm diameter is important because it allows the use of Marshall Hammer Compacted samples to be tested using the SCB. Furthermore, the SCB test on 100 mm diameter can also be used for gyratory compactor samples and cores from asphalt pavement layers. The new SCB test protocol for 100 mm diameter provides more choices for agencies around the world to use the SCB test flexibly with their own available equipment. The research works conducted by the authors (Lu et al. 2019) showed that 100 mm diameter SCB samples produced acceptable and comparable repeatability with the SCB 150 mm diameter. The research work found that fracture stiffness in mode I (KI), fracture energy (Gf), and Cracking Resistance Index (CRI) of both diameters are equal or convertible, depending on the mechanical parameters used. This proposed ASTM standard is designed to standardize a new test protocol to test 100 mm diameter SCB samples. The new test standard can be used as part of the asphalt mixture design, quality control and quality assurance purposes. The users of this test method will be asphalt concrete mix contractors, Departments of Transport, and asphalt pavement consultants. Reference: Lu, D.X., Nguyen, N.H., Saleh, M. and Bui, H.H., 2019. Experimental and numerical investigations of non-standardised semi-circular bending test for asphalt concrete mixtures. International Journal of Pavement Engineering, pp.1-13.