|
|
Auckland University has been working with the AQA and Roading NZ to set up an inventory of aggregates around the country. Our aggregate resources are finite and non-renewable and demand for them is increasing every year. Currently, every living soul in the country consumes around 11 tonnes a year and high quality resources are either very limited or have been exhausted. The roading industry is a significant consumer of aggregate and currently needs around 24 million tonnes a year of top material. New Zealand is, geologically, a young and active country and the properties (textures, grain size, mineralogy) of our aggregate resource vary dramatically from region to region. Consequently, a wide range of different rock types is used as aggregate and with a poor understanding of their properties and long-term performance. In the past, bad planning has sterilized many aggregate resources adjacent to areas of demand – increasing transport costs for construction and infrastructure projects, and this is compounded by our ‘risk aversion’ culture with over specification of aggregate. It is for these reasons this inventory project was initiated by the ‘pavements committee’ of Roading NZ as a joint University of Auckland geology/civil engineering project with the AQA, and funded by Foundation for Research Science and Technology. With your help, the ‘geological inventory of New Zealand aggregates’ project will answer a lot of questions on the relationship between geological materials and their performance potential as aggregates. The project has two parts. The first is to survey and classify aggregate resources in terms of their ‘source properties’ and provide understanding of causes of performance variations. This will not only provide a reference for the industry, but enhance awareness among producers and consumers of the (geographic) availability of different aggregate types for a better understanding of their potential. The project spans a couple of year with the first stage, involving a classification of North Island resources, almost completed. The results of this first stage will be presented in draft report that should have been circulated to industry members by now. Philippa Black from the department of geology at Auckland University says the final reports will be presented a web-based publication with free access, and a link to it on the AQA website. Some aspects will also be presented and published at various industry conferences, she adds. “In the report of the North Island aggregate resources, many of the aggregate property tests commonly used to specify aggregates have been reviewed in order to reveal what the tests are actually measuring – often not what people think what the tests are measuring!” Over the next few years a similar data collection process will be undertaken for the South Island. Black says quarry operators can get involved in the project by contacting her (pm.black@auckland.ac.nz) and she will visit them over the next 10 months to collect samples of their source material (quarries are not identified in the project). “I will also ask them about their aggregate, how it varies within the quarry or gravel pit, how it is processed, how it is being used, and the general range of test properties achieved by the various grades of aggregate they produce,” she says. “This helps me understand the aggregate and source rock properties.” One of the motivations of the project was to better understand the properties of what are often called marginal aggregates and encourage more use of them, says Black. “The project should allow both the producers and consumers of aggregate to see aggregate properties in a regional context – that is to compare like with like, rather than, as is often the case, making comparisons with another aggregate in another region produced from a quarry or pit exploiting a totally different rock type.” Quarry industry input into the study is via a project advisory committee made up of members of the AQA and other industries with an invested interest in the work. Wider industry feedback and discussion on the project will be solicited at a 90 minute industry workshop that has been slotted in at the combined Transport Agency and New Zealand Institute of Highway Technology conference being held in Rotorua this year – November 1-3. The results of the first stage of the project will be presented at this workshop and industry input will be taken in as to the research methodology and task needed to complete the project. The workshop is scheduled in on the afternoon of the third and last day when an overview of the Geology Inventory and Performance of NZ Aggregates Research Project will be discussed with Douglas Wilson from the University of Auckland.
Q&M Vol.6 No.5 October-November 2009 All articles on this website are copyright to Contrafed Publishing Co. Ltd. |