Auger Cast Grout Piles

Auger Cast Grout Piles

Use this 3-part specification template to specify Auger Cast Grout Piles specification for machine-drilled concrete-filled piers for foundation use.

What is it?

An auger cast grout pile, also known as an auger cast-in-place pile (ACIP) or continuous flight auger (CFA) pile.  Is a type of deep foundation used in construction. These piles are created by drilling into the ground with a hollow-stem auger to the required depth. Once the desired depth is reached, grout (or concrete) is pumped through the hollow stem of the auger as it is gradually withdrawn. Simultaneously, a steel reinforcement cage is inserted into the grout for added structural integrity. Here are the key characteristics and benefits of auger cast grout piles:

1. Method of Installation: The installation process involves drilling into the soil using a continuous flight, hollow-stem auger. The depth and diameter of the piles depend on the specific requirements of the building project and the underlying soil conditions.
2. Grouting Process: As the auger is withdrawn, grout or concrete is pumped through the stem.  Filling the void created by the auger. This process forms a grout or concrete pile in the soil.
3. Reinforcement: To reinforce the pile, a steel rebar cage is typically inserted into the wet concrete or grout. This reinforcement is crucial for enhancing the load-bearing capacity and stability of the pile.
4. Load-Bearing Mechanism: Auger cast grout piles work on both end-bearing and friction principles. They transfer the load from the structure above to the soil below, with the pile end bearing on a solid soil layer and the pile shaft creating friction with the surrounding soil.
5. Applications: These piles are used in areas with deep soft soil layers, where traditional driven piles might be less effective. They are suitable for both residential and commercial construction.  Especially in situations where noise and vibration from pile driving must be minimized.
6. Advantages: Auger cast grout piles are known for causing minimal disturbance to the surrounding soil, making them ideal for urban environments. They are relatively quick to install and are often more cost-effective compared to other deep foundation methods. Their installation produces minimal noise and vibration, which is a significant advantage in sensitive areas.
7. Limitations: The effectiveness of auger cast piles can be limited in very hard soil or rock. They require careful quality control during installation to ensure that the grout fills the pile void completely and that the piles achieve the desired strength and integrity.

In summary, auger cast grout piles are a versatile and efficient deep foundation solution, particularly advantageous in urban settings and soft soil conditions. Their method of installation makes them suitable for projects where minimizing disturbance is a key concern.