OPTIMUM RATES OF APPLICATION OF SEALING AGGREGATE

The Country Roads Board (CRB) had a worldwide reputation for their standard of sprayed work. This is considered to be partly due to the attention given to the rate and uniformity of the rate of application of the aggregate, aided by having a purpose built spreader to do this. Due to financialconstraints these spreaders were replaced by cheaper simpler box spreaders. This led to a general lowering of the quality of aggregate spreading.About the same time the inconsistent performance of the standard of sealing was of concern to state road authorities, and an AUSTROADS project was approved to investigate this. One of the observations to date is that control of aggregate spreading needs to be improved. From this, and the development work done by VicRoads on improving spreading equipment, it can be concluded that significant gains can be made in terms of service life, road safety and cost of sealing work, by improving the reliability of the design of rates of application of aggregate and being able to spread uniformly and accurately at that rate. (a) For the covering abstract of this conference see IRRD abstract no. 861222.