Abstract: lt was assumed that the quality and long term stability of new asphalt revetments could be improved by achieving higher compaction densities. The task of the Committee was to verify this assumption and determine under what conditions the improvement could be achieved. Bituminous binders and structures are Iiable to be damaged not only by mechanical influences but also by chemical, physical or biological factors (atmospheric oxygen, sea water, ultraviolet radiation, oil, algae etc.). The principal phenomena which may occur are: a. Oxidation as a result of which oxygen present in the air or dissolved in the water combines chemically with the bituminous binder causing it to harden and become brittle. b. Stripping: differences in surface tension cause the binder to be displaced by water; the adhesion between the bituminous binder and mineral aggregate is reduced or completely eliminated as aresult. The extent to which these phenomena occur depends in large measure on the surface exposed to such attack, i.e. on the accessibility of the interior of the asphalt structure to water and air. This accessibility can be limited by reducing the voids content through adequate compaction of the asphalt mix. The Committee studied ways of achieving the greatest density and hence maximum long-term stability. The following factors were considered: composition, processing and compacting techniques, compacting conditions, structural aspects such as layer thickness and slope gradient, and finally the subsoil characteristics. Durability as such being difficult to measure, the density (voids content) of the processed asphalt mix was taken as the principal criterion of quality or long-term stability of the asphalt structure.
Publication Year: 1977
Publication Date: 1977-01-01
Language: en
Type: article
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