Predicting the durability of basic crystalline rocks for use as road construction materials

Abstract

One of the major construction materials for high-quality pavement layers in roads in South Africa is the basic crystalline group of rocks, which outcrop locally and/or regionally over at least 60% of South Africa. Problems related to the in-service deterioration of road aggregates produced from these materials, despite their conforming to the necessary specifications at the time, have been experienced in South Africa and internationally for many years. An investigation was carried in which 12 materials were collected from various areas of southern Africa and tested using a range of standard and non-standard tests. Based on the results obtained and a review of the test methods and variation of results, a range of tests and tentative specification limits have been proposed for assessing and predicting the durability of these materials obtained by crushing unweathered material sources