Helical Piles vs Concrete Drilled Shafts: Which Is Better For Deep Foundations?

When a deep foundations are required, there are two options available to foundation contractors and structural engineers are helical piles or concrete drilled shafts

Deep foundations are required when the soil upon which the foundation is to be built is unable to carry the load. In the case of a deep foundation, the structure’s load is transmitted to soil deep in the ground to ensure the structure’s stability.

When dealing with expansive soils that are weak or unstable, contractors opt for either helical piles (also known as helical piers or screw anchors) or concrete drilled shafts (sometimes called drilled shafts or bored piles).

So what is the difference between the two, and what makes helical piles the preferred method for deep foundations? 

The Difference Between Helical Piles and Concrete Drilled Shafts

Helical Piles

Another way to refer to a steel helical pile is a displacement pile. This means as a helical pier is driven into the soil, there is little soil disturbance.

Because of their design, there is limited skin friction. Skin friction is the result of friction or adhesion between the pile and the surrounding soil.

This allows the helix plates to reach load-bearing soils, such as clay, stiff sand, and soil above bedrock. Capacity is achieved through end bearing on the helical plates. 

Concrete Drilled Shafts

The big difference between concrete-drilled shafts and helical piles, is that a concrete-drilled shaft is a replacement pile. In this case, soil is removed and the piles are placed into the holes dug or augured out of the earth.

The strength of the soil determines the length of the shaft that is placed into the hole. Generally, you may see either a straight-drilled shaft or a belled shaft.

The straight shaft develops capacity from the shaft-in-end bearing or from friction on the sides of the shaft. A belled shaft does so for the most part due to the belled-in-end bearing. 

What Makes Helical Piles the Preferred Method for Deep Foundations? 

Capacity:

• Steel Helical piles offer known capacity by measuring torque during installation
• Depending on the readings the Installer can change the helical piles by adding or subtracting extensions. 
• Unexpected soil conditions can be taken into account. 
• Concrete drilled shafts only offer estimated capacity

Weather Conditions

• Helical piles can be installed in any weather condition.
• Concrete installation is affected by both freezing and hot conditions, as well as snow and rain. 
• Concrete cure time is affected by weather conditions.

Equipment Considerations

• Both concrete itself, as well as the concrete truck, carry significant weight. 
• A drill is required to create the drilled shaft for concrete drilled shafts. 
• Helical piles are installed with hydraulic equipment that is readily available and less intrusive allowing them to be installed almost anywhere. 

Installation Time & Location 

• Helical piers can be installed with no cure time allowing swift project implementation. 
• Concrete requires approximately 2-4 weeks to cure creating a lengthy project implementation. 
• Deep foundations with helical piers are possible in difficult-to-access areas such as flood plains, swampy areas, and other challenging soil conditions. 

Environmental Effects 

• Steel helical piles are reusable and can be removed and used elsewhere, reducing waste. 
• Less cleanup is required upon installation as compared to concrete. 

ECP Helical Piers for Deep Foundations

ECP Helical Piers are manufactured in the USA using American steel. We are an industry leader in foundation products including helical piers for deep foundation applications.

This includes many civil applications such as boardwalks, new construction foundations, utility applications, and more. Read more about the benefits of helical piers. They are one of several helical foundation products manufactured by ECP.

Contact us today to learn more about our foundation repair products, and to become a partner contractor with ECP. 

Are you a homeowner in need of foundation repair? Visit www.myfoundationrepairs.com