Sealing of Bulkhead and Adjacent Patio, Virginia Beach, Virginia
Fadi Debbas, PE, ABC Consulting, Inc., Norfolk, VA, www.abcnorfolk.com
The joints between deepwater concrete precast bulkhead panels were not sealed. The adjacent patio settled, causing rainwater to run behind the bulkhead and erode the backfill sand through the unsealed joints. The problem was self-perpetuating, in that the more material eroded from behind the bulkhead, the more the patio slabs settled, directing more water behind the bulkhead, causing more erosion.
In addition to the settled slabs and voids behind the top of the bulkhead, there were weep holes near the low low tide line which had lost their screens. This allowed tidal changes to erode additional backfill material out from behind the panels.
The material selected had to effectively seal the unsealed joints from behind. As the voids behind the bulkhead were up to 30 inches deep, the material had to be capable of installation in deep lifts.
High density polyurethane grouting to fill the voids, seal the joints in the bulkhead wall, raise the patio slabs and plug the weep holes.
CJGeo polyurethane grouting crews successfully sealed the joints in the precast panels, filled the large voids adjacent to the bulkhead and corrected settlement. Weep hole plugging was completed at low low tide when the winds were right, yet still in a wet environment.