MARGINAL AGGREGATE PAVEMENT TRIALS - QUARRY ROAD, DRURY

The BC16B test strips at Quarry Road, Drury were constructed as a full scale test of the performance of a range of marginal (lower quality than that normally required for top quality aggretates in NRB M/4 specification) aggregates. The test strips were constructed as a 150 mm overlay on top of an existing road pavement, and were sealed with a chip seal wearing surface. The aggregates included in the test consisted of two different gradings of greywacke aggregates from four different quarries and andesite aggregate from a fifth. The strips were laid down between June and October, 1974, and final evaluation and testing was carried out in 1979. The test strips were subjected to heavy traffic originating from the large quarry which is serviced by this road. The performance of the test strips was evaluated by a variety of methods, including laboratory tests on materials at the start and end of the trial, Benkelman beam measurements of deflections at regular intervals over the period of the test, and visual observation of the strips. Amongst the conclusions from this study are the following: (1) changes in aggregate properties, including both grading and plasticity, occurred with time during the life of the test strips; (2) stability of these aggregates was unsatisfactory when water contents were excessively high; (3) the Benkelman beam is a good tool for indicating the performance of a pavement over a period of time. (Author/TRRL)