There is an increasing environmental drive to reduce quarrying of geological stone and, at the same time, to reduce the volume of waste and by-product materials going to dump or low-value uses. Road construction consumes vast quantities of bulk material so seems a natural place to use alternative materials such as ash, slag, foundry sand, glass cullet, crumbed tyre rubber, etc. Engineers are then tasked with the job of making these materials work. They must deliver a serviceable pavement to the normal expectations of the user and, at the same time, must not generate any pollution of the environment into which they have been placed. Andrew Dawson summarised several studies, which have looked at the means of economically improving residues so as to make them mechanically suitable as lower pavement layers and also reported on the leaching behaviour of these materials in simulated road-environment conditions. Particular issues addressed were the means of assessment, mix design, quality control, time-related behaviour and water quality.
Engineers Australia members participating in AGS technical sessions can record attendance on their personal CPD logs. Members should refer to Engineers Australia CPD policy for details on CPD types, requirements and auditing guidelines.