The Auckland region in particular is experiencing a paucity of readily available quality aggregate to sustain the much needed infrastructure development planned for the region. The other locally available aggregate resource is greywacke, a collective term that includes argillite which the industry perceives to have a particularly high swelling clay content. Since swelling clays are a major source of poor aggregate performance, contract specifications for supply of basecourse aggregate for Auckland roads are often overwritten with the statement that it shall include no argillite, thus effectively ruling out greywacke quarries. In response to this, current research is focused on determining the nature of the swelling clays in aggregate source rocks and the affect they have on the material properties of aggregates, the intention being to determine acceptable boundaries for mineral content instead of ruling out greywacke en masse as a potential source of quality aggregate. (a) For the covering entry of this conference, please see ITRD abstract no. E212706.
Abstract