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Soil Types

Learn more about different types of soil and what impact they can have on your home’s foundation.

Whether you’re building a commercial building or a single-family home, you’re going to do all the construction on some type of soil. The underlying soil needs to be strong to support your structure. Sadly, some homeowners overlook this aspect and then have foundation problems. 

Various types of soils such as backfill, native layers, or man-moved soils have different properties that make them suitable for construction or not. Here, we will shed more light on three types of soils and their physical properties. 

1. Man-Moved Soils 

This is any soil that’s dug up and transported to another location for various uses including construction. Some highly-populated areas are hard to develop as they lack stable soil. In such cases, builders have to do mass excavation, disposal, and refilling before they can erect buildings. Man-moved soil will come in handy for this purpose. 

Man-moved soils fall into any of these three categories. 

Hydraulic Fills:  Before building on low-lying land, contractors will first raise the ground using hydraulic fill. These soils can be layered with organic materials and waste. Most of these soils are dredged from lakes or seas during land reclamation. 

Dumped Fills: Here, we have loamy and silty soils. Two fantastic soils that make excellent landfill. Both have a small composition of gravel and stones. Dumped soils are highly variable and can be re-engineered. 

Engineered Fills: This refers to granular material or any subgrade soil that’s compacted and used as backfill. Because they’re dense, these soils can support the foundation of heavy structures. 

2. Backfill Soil 

Backfill is any soil that’s used to fill the holes or trenches that have been dug around the foundation. After construction, builders can reuse the excavated soils or get refill materials from elsewhere. The backfill soil is then compacted to strengthen the soil and stabilize the foundation. Here are three common backfilling materials. 

Coarse-Grained Soil:  It’s a mixture of sand, gravel, and fine material with low plasticity. This type of soil is compact and good for backfilling and supporting a newly built foundation. 

Commercial By-Products: Fly ash and furnace slag are two by-products that can act as backfill. During wall construction, builders also use them as additives for sticky clay soils. The suitability of by-products depends on their natural attributes and engineering characteristics. 

Fine Graded Soil: Here, we have sand, silt, and various clay soils with tiny particles measuring 0.075 mm in diameter. Sand, silt, and various clay soils fall into this category. Inorganic clays join this list too. These soils have low to medium plasticity, which makes them good backfills. 

3. Native Soil Layers 

This refers to soils that exist naturally on the ground or are modified. In areas with good drainage, builders will use the on-site soil as backfill. 

Modified native soils are infused with sand, peat, compost, or ceramic soils. This helps improve their drainage and stabilize the foundation, on which a building rests. 

Native soils are abundant and cheap. The decision to use them or get alternative materials depends on the prevailing weather, site activity, and soil conditions. 

Other Soil Sub-Categories 

Let’s look at other soil sub-categories. 

Rock Soil: This type lies several feet below the ground and is stable. When underpinning, contractors will drive piers down to the rock strata. 

Clay Soil: One of the shrink-swell types of soil, clay has fine particles that get sticky in wet conditions. Because they heave and contract, these soils aren’t good for building a foundation on top of. 

Shale: Rich in clay, shale is a flaky rock that shrinks and swells when it comes to contact with water. 

Sandy Soil: While it doesn’t shrink or swell, sandy soil is easily washed away. 

Loam Soil: It has a balanced mix of silt and sand. Loam retains some moisture and drains well, which makes it good for growing crops. 

Your foundation is a fundamental part of any construction. When it’s built on stable and well-drained soil, it will remain strong and immovable. But if it rests on weak soils, it’s going to fall apart. 

For more information on how you can restore your sunken foundation or strengthen it, contact Complete Basement Systems to request a free inspection and repair quote. We’re happy to examine your foundation and recommend the appropriate underpinning solution. 

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