Question:

We have a number of penetrations through a below grade wall. The penetrations are for electrical and mechanical conduits and pipes. There is the possibility of the exterior of the wall being flooded with water due to ice and snow melt. The cored holes for the conduits and pipes are larger in diameter than the conduits and pipes. What can we fill the annular spaces with to prevent water from leaking into the interior mechanical space?

Answer:

I am not going to address the tightness or waterproof properties of the conduits or pipes, themselves. I am going to assume the fittings and joints are snug and tight enough to prevent taking on water.

I am going to try to answer the annular void filling problem. The process I am going to promote is called "dry packing." The grout I am going to recommend is "Premier" grout by L&M.

Find a safe way to access both sides of the wall. Your information to me included the fact the wall is four feet thick. This is a long ways to ram or pack a grout. "Premier" grout has the unique properties to permit such travel and packing by packing or ramming.

Once your crew has accessed the wall from both sides, rod the annular space with a very stiff wire or shop made device, to clean the space, it is best if the rod or wire pass all the way through the wall and be worked in a sawing motion. Again, keep safety paramount. Your crew members are separated by four feet of concrete and someone could get poked or stuck with the rod or wire.

Once the annular space is clean and clear, pack one side with rags or foam rope and force water into the cored holes annular space from the other side. This is part of the presoaking process. Block the end the water was poured into and allow the cored holes to water soak over night.

The next day, mix up the "Premier," let it dwell in the bucket until it achieves its unique soft set. Scoop up trowels full of the "Premier" and with a long rod, pack it into place. Start on the bottom of the cored hole and work your way around the conduit or pipe until you are at the top. Work both sides together, and only pack from one side of the wall. The dead end of the wall has been blocked off with wood or some strong forming material. The "Premier" is intended to be rammed tight against this dead end form. Continue filling and packing until the void is filled.

The best trick I ever saw was a crew using a ripped PVC pipe as a feed trough to the ram rod. The "Premier" was scooped into the PVC trough and then the rodding process carried the stiff grout into the core hole interior.

The process is labor intensive, but it is a good way to grout and fill those wall penetrations and turn that ice and snow melt away.