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Foundation heave is a serious structural issue that should be fixed as soon as it is diagnosed. The first step involves the identification of the cause of heaving. This enables the engineers in implementing the appropriate solutions.
One of the major causes of foundation heave is the soil saturation underneath the foundation. In this case, the source of water should be determined and eliminated to halt further heaving. Next, a proper repair or rehabilitation method should be specified and executed based on the severity of the foundation damage.
If the damage is minor, small repair work, such as concrete grinding of the outdoor slab, is adequate. However, if the damage is severe, extensive and costly repair will be needed, for instance, ground injection to stabilize soil under the foundation and repair of the foundation structure.
Sources of Water
There are several water sources that can lead to foundation heave of a structure:
- Leakage of underground pipes
- Clogged drains
- Broken sprinkler lines
- Faulty gutter and leader systems
- Tree roots and pressure from adjacent structures.
How to Repair Foundation Heave?
1. Control Moisture
Since the prime reason for foundation heave is moisture, controlling the water around the structure is the best way to tackle foundation heave. This will avoid water pooling around the building, which can be achieved through rain gutters, proper drainage, and appropriate grading around the perimeter of the structure.
2. Repair Methods
Sometimes, foundation heave is solved by eliminating adjacent water sources, such as repairing leaked plums. This is a simple solution that does not work all the time. The foundation heave can lead to severe damages, and requires extensive and costly repair work.
Stabilizing the soil underneath the foundation by polymer injection is another technique to tackle foundation heave. It resists the infiltration of water into the soil.
For outdoor concrete elements like outdoor slabs with a minor heave, grinding of the concrete surface can be used to repair the slab. However, the water source or the cause of the heave still needs to be eliminated.
If foundation heave damages the foundation severely, extensive repair should be considered to prevent detrimental effects of heaving. The foundation repair methods include:
- Pier systems
- Wall anchors
- Helical tieback anchors
- Plate anchors
- Carbon fiber wall supports
Pier systems such as helical piers, slab piers, and push piers can be used to repair foundation heave. The differences between these piers lies in their load-carrying capacity and placement. The pier system can support and even lift foundation slabs.
Helical piers are considered the best approach to secure buildings against foundation heave. They are locked together, so the upward movement of structures due to heaving is prevented. Push piers are not locked together but rather fit into one another. So, they may become unlinked due to uplift pressure. Figure-1 through Figure-4 explain the placement of piers.
The foundation heave is the foundation's upward movement due to expansive soaked soil.
1. Leakage of underground pipes
2. Clogged drains
3. Broken sprinkler lines
4. Faulty gutter and leader systems
5. Heaving may occur due to tree roots and pressure from adjacent structures.
Since the prime reason for foundation heave is moisture, controlling the water around the structure is the best option to tackle foundation heave. This will avoid water pooling around the building, which can be achieved through rain gutters, proper drainage, and proper grading around the perimeter of the structure.
1. Stabilization of the soil underneath the foundation by polymer injection
2. Grinding of the concrete surface
3. Pier systems
4. Wall anchors
5. Helical tieback anchors
6. Plate anchors
7. Carbon fiber wall supports