Theory and methodology for testing asphalt mixtures’ tensile strength by four-point bending

Tensile strength is a crucial parameter for assessing the pavement performance of asphalt mixtures. However, the methods currently commonly used to test the tensile strength of asphalt mixtures usually encounter issues related to operational convenience and testing theory, which significantly impact the accuracy and ease of conducting tensile strength tests. Therefore, this paper proposed a novel testing theory and methodology that utilizes the actual tensile stress–strain relationship of asphalt mixtures and the measured neutral axis height of asphalt mixture bending beams of four-point bending test to determine the tensile strength of the mixture. Furthermore, a series of four-point bending beam tests and direct tension tests at various loading rates were conducted to validate this method. The results demonstrated that this method effectively overcomes the limitations of conventional testing method, and the tensile strength determined by this approach is aligned well with that obtained from direct tension tests, their percent error is only -30%~20%. Additionally, this method better reflects the tensile performance of the mixture over a broad section of the beam, ensuring representative and reliable test results.