The Groundwork for a Successful Build: Soil Testing for Foundation Construction

Welcome to the world of construction, where the foundation for success is built from the ground up. And by that, we mean the soil beneath our feet.

Whether you’re building a skyscraper or a humble abode, the quality of your foundation is everything, and it all starts with the soil testing.

While soil testing may not be the most glamorous aspect of construction, it’s a vital step that can’t be ignored. Think of it as the foundation of the foundation, the bedrock upon which your building will stand. Without proper soil testing, your construction project is at risk of sinking, cracking, or even collapsing.

But fear not, as we’re here to guide you through the ins and outs of soil testing for foundation construction. In this blog, we’ll cover everything from the types of tests available to the factors that affect soil stability.

If you’re ready to dig deep and learn how to lay the groundwork for a successful build, keep reading!

What’s the Purpose of Soil Compaction?

Soil compaction is the process of increasing the density and strength of soil by reducing its air content. This is typically achieved through the use of heavy equipment, such as rollers or vibratory compactors, which apply pressure to the soil and force out air pockets.

At its core, the purpose of soil compaction serves to create a more stable and supportive foundation for construction projects. Compacted soil is less likely to settle or shift over time, which can prevent damage to the building and ensure that it remains structurally sound for years to come.

Why Is Soil Compaction Testing Important?

While soil compaction is crucial for building a strong foundation, it’s not enough to simply compact the soil and assume that it’s ready for construction. That’s where soil compaction testing comes in handy, as it helps ensure that the soil has been compacted to the appropriate level and has the necessary strength and density to support the weight of the structure.

The process of soil engineering testing involves taking samples of the soil and measuring its density and moisture content. This information is then used to determine whether the soil has been adequately compacted and whether any additional compaction is needed.

If soil testing for foundation construction is not performed, there is a risk that the soil may not be able to support the weight of the building, which could lead to settling, shifting, or even collapse. This could result in costly repairs—or worse—compromise the safety of building occupants.

How to Test Soil Compaction and Density for Foundation Construction

Below are a few tests you can conduct to measure soil characteristics before beginning the process of foundation construction:

Proctor Compaction Test: Proctor Tests are one of the most common methods to test for soil compaction. In this assessment, a soil sample is placed in a cylindrical mold and compacted using a predetermined amount of energy. From there, the density and moisture content of the soil are measured and compared to a standard Proctor curve, which helps determine the optimum moisture content and maximum dry density of the soil in question.
Sand Replacement Test: Sand Replacements typically involve replacing a known volume of soil with sand. Once swapped, you measure the density of the resulting mixture. This application is often used when the soil is too rocky or hard, as traditional testing methods struggle to adequately compact the soil.
California Bearing Ratio Test: This test measures soil strength by comparing the pressure required to penetrate a soil sample to standard materials like crushed stone, gravel, etc. While there’s a variety of applications California Bearing Tests can be used for, it’s most common during road construction.
Plate Load Test: In this test, a steel plate is placed on the soil surface, with a specific load applied to the plate. The deflection of the plate is measured, and this information is used to determine the strength and compaction of the soil.
Dynamic Cone Penetrometer Test: As the name suggests, this test is conducted by driving a metal cone into the soil at a consistent rate of speed. By doing this, you’re able to measure the soil’s resistance to penetration. Using these findings, it’s much easier to determine the strength and stiffness of a soil.
Cone Penetration Test: Similar to the above, this test involves driving a cone into the soil and measuring the resistance to penetration. However, while the data collected is still used to determine the soil’s shear strength, the test itself is far less invasive.
Falling Head Permeability Test: This test measures the rate at which water can pass through a soil sample. To conduct these measurements, soil is placed in a permeameter. Once set, water is allowed to flow through the sample. By gauging the rate of flow, you get a holistic view into the permeability of a soil type.
Pressuremeter Test: This test involves inserting a cylindrical probe into the soil and measuring the pressure required to expand the probe. The data collected from this test is used to determine the soil’s strength and stiffness.
Vane Shear Test: Much like Pressuremeter Tests, this assessment involves inserting a vane into the soil and measuring the torque required to rotate the vane. This data is also used to determine the soil’s shear strength, but it’s not an effective way to measure stiffness.
Flat Plate Dilatometer Test: Lastly, in this test, a flat plate is placed on the soil surface. Once in place, the pressure required to expand the plate is measured. Using this data, you’re able to determine the soil’s shear strength, and, in return—deformation characteristics.

Minimize Risk With Soil Testing for Foundation Construction

There’s no way around it; uncertainty regarding subsurface conditions can bring grave consequences to your new construction project. Luckily, FNA specializes in geotechnical soil investigations so you can be sure you’re building on a strong foundation. Get in touch today, and let’s develop a robust construction plan for your next project.