Engineers Australia

Compaction trial for comparison of impact rolling and conventional rolling techniques for a large earthworks program in The Pilbara

Jessica Dalton


As part of the development of a project site in the Pilbara, a large earthworks program will take place involving the placement of up to six metres of fill above the current ground level. Prior to commencement of bulk production filling, a compaction trial was carried out at the site to compare the effectiveness of impact rolling compaction techniques with conventional compaction techniques. Two different rollers, a 12 tonne impact roller and a 21 tonne single drum vibratory roller, were applied across two prepared fill pads.

Variables considered in the trial included: compactive effort, lift thickness, number of roller passes, and moisture conditioning. Significant geotechnical field and laboratory testing was carried out across the two pads to assess density with depth, prior to compaction and at various stages of compaction. The test methods used included density testing (nuclear density gauge and sand replacement methods) and in situ penetration testing including cone penetration testing (CPT), dynamic cone penetrometer (DCP) and Perth sand penetrometer (PSP). Settlement monitoring was also carried out prior to and following compaction.

This paper presents an overview of the trial methodology and results of the compaction trial in terms of compaction achieved by the impact rolling and conventional methods.