Fibre optic sensing measurement of static surface load distribution on road base layer

Road base layer has a unique way to distribute the stresses. Unlike a concrete layer which relies on its flexural strength, the road base layer transmit its working load by grain-to-grain contact. Many aspects will affect this load transfer system, for example, the aggregate type, shape, and strength. In this research, the fibre optic sensing was used to obtain the strains of the load under the road base layer. By knowing the strains under the road base layer, then the load distribution characteristic on the road base layer can be obtained. Two samples were tested in this research. Sample A was a road base layer constructed from natural crushed aggregate (NCA), and sample B was constructed from recycled concrete aggregate (RCA). The dimensions of the samples are 1 m x 1 m with 200 mm of thickness. A gradual static load was applied on the road base layer surface and the fibre optic sensing will measure the strains at the bottom of the road base layer. A software simulation also conducted as a comparison for the mechanical test. The result shows that the distribution area of road base layer from RCA is smaller than road base layer from NCA which means it distributes less stress than road base layer from NCA. It means that NCA has a better grain-to-grain action compare to RCA.