Characteristics and evaluation of recycled crushed rock in railway subgrade applications

M. A. Rahman and M. Ambrose

The present research represents several laboratory experiments to evaluate the characteristics of recycled crushed rock (RCR) in railway sub-grade applications. Excessive amounts of construction and demolition (C&D) materials have gone to landfill every year and therefore it is necessary to recycle and reuse to reduce the carbon footprint generated throughout the world. A great way to reuse these materials is to put into operation for new construction projects. Although several recycled materials have been used recently in construction industry, little knowledge and research has been undertaken on RCR, which is generated from construction and housing industries. The RCR has previously been used as a structural element of highway pavements and has shown positive results, where very limited and undefined parameters are available. Laboratory test includes sieve analysis, California bearing ratio (CBR), compaction, Atterberg limit and Repeated Load Triaxial (RLT) tests were carried out on specimens sourced locally in Victoria. This research also investigates the resilient moduli (MR) and permanent deformation characteristics of RCR using RLT equipment to gain a thorough and definite understanding of how the material reacts under cyclic loading due to heavy and continuous cyclic loads on the railway track. A finite element modelling was also developed using laboratory experimental results to compare the permanent deformation obtained from the laboratory and numerical modelling. The physical properties, geotechnical properties and finite element modelling shows that the results were satisfied with the Australian standards and Australian Rail Track Cooperation (ARTC) guidelines for the application in railway systems as sub-grade materials.