Surface dressing is an application of a thin film of bituminous binder followed by a coat of aggregates of single size, rolled into position. Surface dressing is done in one course (single coat) or two courses (two coats). Normally, the first coat is the heavier of the two. The second coat, which is lighter, is applied after the binder in the first coat works up around the cover aggregates, a process which takes up about 3-4 weeks. The quantity of binder and aggregates is as given in Table 5. The binder is a penetration grade bitumen 80/100 heated to 163-175oC or a cold application emulsion.
Table : Binder and Aggregates for Surface Dressing (Per 10 m2)
The construction consists of spraying the binder by means of a mechanical sprayer, spreading the aggregates manually or by a mechanical spreader, and rolling the aggregates to a firm position. Rolling should proceed from the edges to the centre. Traffic is disallowed for the first 24 hours so that the binder hardens.