Builders

Every commercial builder knows that expansive soils beneath a building foundation or floor slab must be addressed. Normally this is accounted for by removal of expansive soil and replacement with a non-expansive fill. This is a proven method for solving the problem but it can be expensive, especially if done properly. Of course, another costly solution would be drilled piers with void forms to accommodate the expected expansion of the remaining clay.

We have noticed that large numbers of homebuilders in Oklahoma do not provide a foundation system adequate for the home. This was pointed out in a short newsletter published by the Oklahoma Professional Engineering Society. Foundations have been found to be inadequate in a number of areas such as non-expansive fill placement, weak pier and grade beam systems, shallow piers, etc. Many builders seem to think that merely installing non-expansive fill such as sand, gravel, or sandy loam below the slab and to the depth of the grade beam will provide the stability they need. Since most foundations in Oklahoma have grade beams that are only 18-24" below grade to prevent frost heave, means that most, if not all, grade beams are too shallow to avoid seasonal wet to dry fluctuations in soil moisture. While unstable moisture has no impact on non-expansive fills, expansive clay soils in Oklahoma can only be guaranteed to swell or shrink during our wide swings in seasonal moisture. For a grade beam system to remain stable in Oklahoma, it would either have to be 15 feet deep or be supported on piers that penetrate to the same depth. Most homes and many light commercial structures do not use such deep grade beams or foundations. Think about how much the cost of a home or light commercial structure would rise if all of the native soil down to a depth of 15 feet was required or if commercial construction practices had to be incorporated into the design of the foundation!

Another solution commonly applied is through the use of post-tensioned slabs. While this method is an approved reinforcement method it has to be designed and installed in accordance with the Post Tensioned Institute (PTI). None of the residential installations that we have obverved over the years comply with this standard. If they did meet the PTI standards the builder would find that other than saving a bit of steel rebar there would be no benefits to post tension designs. They would still need to install intermediate grade beams to make the slab rigid enough to withstand the bending forces due to the clay movement.

Bottom Line: Post tensioning is just another method to reinforce concrete !!

This where Condor SS can solve several problems for the builder. Condor SS can easily be injected into the soil to a depth of 10+ feet and stabilize all of the clay within the injection zone. This give you a non-expansive platform to build upon that will remain not only as stable but possibly more stable than imported fill. The injection can be made for both single building and multiple building sites.

Condor SS can actually increase the seasonal strength of the clay soil. It does this by stabilizing the possible moisture content in the clay soil. Instead of the compressive strength of clay diminishing during wet conditions, it can retain useful strength.