Rolling dynamic compaction for haul road construction and maintenance - an update

The construction and management of haul roads remains a critical element in the efficient operation of all mines. Significant effort has been applied to design practices, extending the use of design charts and computer programs. Attention has been paid to the pavement materials and material properties, based on decades of geotechnical data and experience. Opportunities still exist for improvements to be realised in compaction protocols, particularly in the use of rolling dynamic compaction (RDC). RDC involves the delivery of a dynamic compactive effort using non-circular towed compactors, which are designed to deliver a combination of potential energy of a falling weight and kinetic energy mobilised due to the relatively high towing speed. The objectives include the proof-rolling and preparation of subgrade areas, exposing soft spots and weak zones and often establishing a sufficiently competent raft layer, as well as deep lift compaction offering cost-efficient construction of ramps and haul road pavements with programming benefits. The ability to compact deeper lifts allows fill particles to be larger without inhibiting the compaction process, which increases the sustainability of the process through reducing the constraints on the fill materials by allowing a larger maximum particle size. Case studies are cited where RDC has been trialled on several mine sites and many mines have benefited from the use of the technology. The continued attention to improving haul road construction will result in less road maintenance, less vehicle damage and improved truck tyre life, and RDC offers a method of contributing to these improvements. The compaction energy of RDC offers more leniency in moisture conditioning where adequate compaction densities can be achieved with much lower water addition than conventional laboratory optimum moisture content. When applied to coarse surface layer materials RDC will generate sufficient fines to provide a high-friction tyre-friendly low-maintenance finish on haul road surfaces.Derek Avalle, Brendan Scott and James Miedeck