In 1972 a full-scale experiment was begun on A33 Winchester By-pass to compare the road performance of rolled-asphalt wearing-courses with the results of three laboratory design procedures. Eight wearing-courses were investigated, each containing a different sand fine-aggregate. The results after seven years of service show that, although the properties of rolled-asphalt are tolerant of variations in binder content, good performance can be obtained by designing the mix using laboratory mechanical tests. Marshall Tests and Wheel-tracking Tests on complete rolled asphalt mixtures gave the best overall assessment of an optimum binder content, together with a direct measure of the resistance to deformation. These tests generally gave a better assessment of the optimum binder content than did the design method specified in Section 3 of BS 594:1973 using the mortar only. (A)

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