Field investigation results of narrow-trench compaction methods with granular materials are presented. To determine what levels of compaction energy would produce target densities of at least 95 percent of standard Proctor, thus minimizing shoulder settlement above pavement edge drain trenches, a 200 mm (8 in) wide trench was excavated to four different depths: 300, 600, 900, and 1200 mm (12, 24, 36, and 48 in). Fine filter aggregate was backfilled above a 75 mm (3 in) inside diameter corrugated polyethylene pipe. Four compaction methods were evaluated: (a) one and two passes with a relatively low-energy modified plate compactor, (b) one and two passes with a high-energy vibratory wheel compactor, (c) one pass with a front-end loader tire, and (d) flooding with water. Sand cone densities and dynamic cone penetrometer tests were taken in each test section to determine how well the backfill was compacted. The high-energy wheel performed the best, producing satisfactory compaction to 300 mm (12 in) with one pass and to 600 mm (24 in) with two passes. Dynamic cone penetrometer testing generally correlated well with percent of Proctor compaction data, thus showing promise for evaluating compaction in narrow, granular-backfilled trenches. (A)
Samenvatting