INSTALLATION | Keystone Standard & Compac Units
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STEP FOUR: Install and compact backfill and corefill material.
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| Fill in all voids — in and between Keystone units — using 1/2" to 3/4" (13 - 20 mm) crushed stone or clean, well-draining granular fill. Place drain zone behind the units as required to achieve total 2 ft. (0.6 m) depth of drainage zone from unit face. Peagravel should not be used. Compact material in unit cavities appropriately to eliminate settling. Next, if economical, use existing soils for backfill behind the gravel drainage zone. (Heavy clays or organic soils are not recommended due to water-holding properties.) In some situations poor site soils will cause higher reinforcement costs, so economics of using import soils should be reviewed. Compact soils to a minimum of 95% Standard Proctor compaction, placing fill in 8" (200 mm) lifts on a course-by-course basis or as specified by a Professional Engineer. (Use only walk-behind mechanical compaction equipment within 3' [1 m] behind the units to avoid localized overstress.) Sweep off any pebbles or debris so the next. Keystone units rest evenly upon the layer below. |
