A major contributor to the failure of road pavement materials is the influx of water. For pavement construction, it is desirable to source materials that are stable with respect to likely moisture content changes. However, some pavement materials, particularly the locally won non-standard materials known as marginal materials, can be quite sensitive to water content changes, giving rise to premature pavement distress. Then the designer has the option of either not using such materials or stabilising them to improve their performance. Various chemical, cementitious, and polymeric dry powders are available for such stabilisation. In this paper, the use of hydrophobic polymeric dry powders is discussed. This paper reports preliminary results of a research program into hydrophobic stabilisation. Source material used was alluvial clayey sand from NSW. The results indicate that compaction properties are improved by the hydrophobic additive mixed at 1.5 to 3 per cent dose rates (by weight). Similarly, capillary rise was significantly reduced with the addition of hydrophobe. It was found that the plot of capillary rise against square root of time is close to a straight line, similar to the behaviour observed for cementitiously stabilised materials. Theoretical interpretations were forwarded to claim that the gradient of this curve could be used to examine the efficiency of stabilisation in terms of water ingress. (a) For the covering entry of this conference, please see ITRD abstract no. 0612AR242E.
Abstract