A paper in the NZ Journal of Forestry discusses improving forest road surfaces by using good gravel aggregate.
This professional paper, titled “Aggregate Gradation – Getting the Road Surface Right”, authored by Simon Fairbrother, was published in the New Zealand Journal of Forestry, February 2011 (Vol. 55 No.4). The paper discusses the high costs of importing suitable aggregate material for forest road construction, with the result that forest managers often tend to use inferior material that is closer to the construction site to reduce this cost.
The article discusses the difference between public low volume roads and forest roads with regard to the surfacing layers used. Forest roads are unsealed and can be damaged through the capillary action of water. Aggregate gradation standards are discussed, with specific reference to New Zealand standards. Reference is made to the Centre for Dirt and Gravel Roads at Pennsylvania State University (USA), which suggested different standards for unsealed roads compared to what was used in the past.
The paper then discussed the results of analysis that took place on various quarries and gravel pits found near forest land in New Zealand. The results showed that in general the materials were poorly graded. The material was generally too coarse and had too few fines. The consequences of using this poor aggregate were explained. The decision regarding which aggregate to use should be well planned to ensure that surfacing money is well spent.
Please access the paper for a more complete account of the research. Source: http://www.nzjf.org/