When faced with inadequate soil strength to support the required load for new construction or other land uses, ground improvement columns provide an effective way to bolster weak soil and reduce the effects of settling over time. However, not all types of ground improvement columns are equal, and selecting the right one is critical to meeting project requirements.
The Two Types of Ground Improvement Columns
Assessing the stability of underlying soil during the design phase of a construction project is an instrumental step if you want to construct a stable, reliable structure while mitigating the chance of foundation failure later on. Many project timelines fail to account for this factor until later stages of the project when ground improvement options are more limited in scope or may lead to broader project delays. That’s why it’s critical to assess the strength of ground soil prior to the design phase of the project, so as project requirements are clarified, your team can align ground improvement planning with the intended use of the land.
For sites with inadequate soil strength, ground improvement columns are one of the most commonly employed strategies to immediately improve the shear strength of the soil while providing a reliable solution designed to withstand decades of settling and shifting soil. During the preliminary project planning phases, you need to first assess soil strength at the site. From there, you can decide if ground improvement columns are the right option for your project. If they are, you next need to understand the critical differences between the two primary types of ground improvement columns—aggregate piers and rigid inclusion piers.
Aggregate Piers
An aggregate pier (AP) is also commonly known as a vibro stone column (VSC). The process starts by drilling a deep hole at the designated pier location to a specified depth (most commonly between 5 to 20 feet). An aggregate (usually either recycled concrete or crushed stone) is then added to the hole, and repeated vibrational energy is used to compact the aggregate until the hole is filled, increasing load capacity and shear resistance of the soil.
Rigid Inclusion Piers
Rigid inclusion piers are similar to aggregate piers, but instead of using an aggregate to support soft soil, they rely on unreinforced, grouted, or concrete columns. One of the most common types of rigid inclusion piers is termed vibro concrete columns (VCCs), the key distinction being that VCCs use a vibrating probe to displace soil and place the column. Rigid inclusions also increase ground load capacity and shear resistance but are better suited to much softer soil.
CNC Foundations: The First Choice in Ground Improvement
Whether you need help determining which ground improvement solution is right for your requirements or you’re trying to decide between rigid inclusion or aggregate piers, the experts at CNC Foundations are ready to answer your questions and get your next project started with a free consultation. Schedule yours today.
Not ready to get your next project started? Read about how we installed vibratory stone columns for a multifamily building project in St. Paul.