The Use of Recycled Construction Materials in the Manufacture of Road Building Materials

摘要

It has been estimated that in the Sydney area 1.2 million t of asphalt and concrete is available annually for recycling compared to a combined annual production of 9 million t of new materials. This paper describes a laboratory study that was initiated to assess the feasibility of producing a road base complying with the State Road Authority Specification for unbound pavement material using locally available crushed concrete and reclaimed asphalt pavement (RAP) material. Two blends were produced in a stabilization and blending plant using specialized procedures to ensure removal of contaminants. Trials were performed on these blends under heavy traffic in a quarry access road with thick asphalt surfacing in 1997 to assess handling and construction aspects. A further trial was established in 1999 on a main road to gauge the effect of rutting of each blend with a thin wearing surface. Both trials have been continuously monitored and are performing satisfactorily. The manufacturing, construction, and monitoring of these trials are discussed in the paper. The field trials have shown that handling and compaction characteristics of the two recycled materials blends are superior to the control that was a conventional crushed rock road base. Under heavy traffic both trial sections have performed well with no failures reported to date. A selected formation material has been developed as an alternative to sandstone using RAP and crushed bricks. This product is nonplastic with a soaked California Bearing Ratio (CBR) of a minimum of 30%. The benefits and use of this material in construction are discussed, presenting not only the laboratory results but also its field performance as a shoulder material and as a layer over the subgrade.