Flexural behaviour evaluation on foamed bitumen stabilised pavement beams using fibre optic sensors

The paper aims to evaluate the effectiveness of both distributed fibre optics sensors (DFOs), and fibre Bragg grating sensors (FBGs) to acquire an accurate measurement of the flexural strain of foamed bitumen stabilised (FBS) beams and to assess the material behaviour under both static and dynamic loading conditions. The beams were equipped with DFOs, FBGs and a linear variable differential transformer (LVDT) to perform the static and dynamic flexural tests using a four-point bending apparatus. The initial plastic flexural strain progression of both top and bottom faces of the beam specimen under different test conditions, including different load pulse shapes and rest periods were evaluated. The results revealed that both haversine-upward and haversine-downward pulse shapes lead to a significant amount of plastic flexural strain compared to that evolved through sinusoidal pulse shapes. However, the plastic flexural strain under haversine pulse shapes can be minimised by introducing a rest period at certain cycle intervals. Further, the flexural strain profile captured by DFOs during the static and dynamic flexural tests indicated the capacity of DFOs to detect cracks initiation and propagation.