Concrete Pipe & Box Culvert Installation - Shaw Precast Solutions

When trench shields are removed take care notto disturb the installed boxes. Restraining the boxmay be necessary to hold it in place. If any voidsare created in the side fill material they should befilled and compacted.Once the envelope of backfill material is placedand properly compacted, the remainder of the fillor backfill should be placed and compacted to preventsettlement at the surface. Compaction andequipment loads should not exceed the pipe designstrength. Several types of compaction equipmentare available and certain types are best for particulartypes of soils. The steel wheeled roller is bestsuited for compacting coarse aggregate such asslag, coarse gravel and graded rock aggregates.The sheepsfoot roller is best for cohesive clays orsilts, but is not suitable for use on granular soils.Specially designed rubber tired rollers, which provideboth static weight and kneading action, are applicableto many soils from clays to sand.Regardless of the type of compaction equipmentused, the backfill or fill material should be consistentwith density requirements of the particular installationspecified.MINIMUM COVER FORCONSTRUCTION LOADSIf construction equipment is going to travel overinstalled box sections, compacted backfill shouldbe placed to a minimum of 3 ft. (1 m) over the topof the box section unless the box has been specificallydesigned for the anticipated constructionloads. Above all, the loads applied to the box sectionshould not exceed those specified by the designer.In an embankment installation, the minimumamount of backfill should extend one box sectionAmerican Concrete Pipe Association • www.concrete-pipe.org 77