Recycled concrete aggregate/municipal glass blends as a low-carbon resource material for footpaths

Construction and Demolition (C&D) materials comprising recycled concrete aggregate (RCA), fine recycled glass (FRG) and a blend comprising 85% RCA with 15% FRG (85RCA/15FRG) were evaluated for their viability as footpath base layers. The geotechnical laboratory evaluation assessed the performance of the C&D materials in footpath bases and included particle size distribution, particle density, water absorption, pH, organic content, modified Proctor compaction, Los Angeles Abrasion and California bearing ratio (CBR) tests. Total concentrations and Australian standard leaching procedure tests were performed on several heavy metals to assess the leaching potentials of contaminants released from the recycled materials. Following the completion of the geotechnical and environmental laboratory evaluation, a footpath was constructed to demonstrate the performance of the 85RCA/15FRG blend as a footpath base material. Field tests comprising nuclear gauges for density and moisture measurements and Clegg hammer tests for field CBR measurements were undertaken to assess the performance of the base materials in the field. The 85RCA/15FRG blend was found to be an optimum one in the laboratory and field evaluation works, as the blend provided adequate bearing strength and furthermore enhanced the workability of RCA, through the introduction of glass fines. Energy savings assessment demonstrated that the use of 85RCA/15FRG blend as footpath base material furthermore has the potential for saving embodied energy. This research indicates that this low carbon concept, utilizing RCA and FRG blends as base materials, is a viable alternative engineering material for future footpaths.