Segmented concrete piles, also known as pressed concrete piles, have been used for many years around the country--especially in Texas. They were originally designed for foundation repair in Texas due to the expansive nature of the clay soils located in many parts of the state. People were looking for an alternative to poured in place concrete pilings, hence the precast concrete segments. This solution became very popular and migrated throughout Texas and other southern state regions due to fantastic marketing and cheap pricing. Just now has the other shoe fallen.
With unprecedented lawsuits and educated engineers, the trend is flowing away from these stacked concrete pilings for foundation repairs. Instead of the soils being blamed for continued movement of homes, people are now blaming foundation repair contractors that use this process for their never ending foundation problems. The engineering community has become aware of these issues, and many engineers are now demanding that any foundation repair system to be installed needs to be driven below the upper active regions of the soils down to a load bearing stratum that is not affected by fluctuating moisture levels. This issue can be easily seen in areas with expansive clay soils. As the hot summer sun dries the clay soils, the concrete press piles cannot penetrate past the active soil layers like steel push piers can. The number one issue with these cabled or stacked concrete piles is the method and the depth that they are driven.
First, a red flag should be raised anytime a car jack (bottle jack) is used to lift a structure. Car jacks are fine for cars or trailers but should never be used in foundation repairs. Their capacities are very limited along with the fact that there is no way of determining the pressure that they are exerting on the home. In the installation of pressed concrete piles, car jacks are used to drive the concrete cylinders into the soil. Car jacks have a very small saddle that contacts the footing hence placing a much localized force on the concrete foundation. Many times footings will crack or crumble due to this method of foundation repair.
Next, the flat bottom 6” diameter concrete cylinders are pushed against the soil causing shallow drive depths. Picture in your mind the amount of force required to press a concrete cylinder into your front yard. Now picture, in your mind, that you are using a 1” diameter metal shaft to accomplish this task. The 1” shaft is using your footing to press the cylinder through the soil, obviously not a good situation. Not only are the 6” cylinders not going to drive very deep but the duress that is being placed on the footing is unacceptable.
Every foundation repair contractor worth his weight in salt calculates the weight of the structure before prescribing a method of repair. This information is necessary for driving pier sections along with lifting structures when there is a means of controlling hydraulic flow and pressure. Without being able to control flow or pressure, as with car jacks, foundation repair becomes a guessing game. Proper depth and soil conditions cannot be met when the structures weight and strength are not calculated.