Road-making bitumen products are typically applied in conjunction with a mineral aggregate. The bitumen acts as a binder and the aggregate provides mechanical strength. One way of applying the bitumen phase is as a bitumen-water emulsion that must break in a controlled manner upon laying. The efficiency with which the bitumen emulsion breaks is strongly influenced by the surface characteristics of the aggregate substrate. The current study employs colloid and surface chemistry techniques to investigate the properties of the mineral aggregates commonly used in roadmaking processes, for example slurry surfacing and sprayed sealing. A selection of mineral aggregates, ranging from those found to be too reactive to obtain a satisfactory slurry surfacing mixture to unreactive (those that have been successfully used in slurry surfacing) have been studied. Typical slurry surfacing characterisation techniques, such as the cohesion and mixing tests (determination of break and cure), have been performed on slurry surfacing mixtures using the range of aggregates. The results have been interpreted in terms of the surface characteristics of the aggregates. (a).
Samenvatting