How high can Keystone units be stacked before placing unit corefill and backfill?
Keystone recommends adding corefill and backfill after each consecutive course for the Compac units. This insures that all voids are properly filled with rock providing maximum interlocking strength. It also aids in keeping the wall straight and reduces the amount ofwaisted rock. NOTE: Because of the depth and size of open core areas on the Keystone Standard units, Keystone recommends that the standard units can be stacked up to a maximum of 3 units before placing unit corefill and backfill.
