What You Need to Know About Expansive Soil

Expansive soil, also known as bentonite clay soil, is a prevalent problem in the Denver Metro Area. The soil's expansive nature can cause significant damage to foundations, resulting in costly repairs. Understanding the causes and effects of expansive soil can help homeowners and builders take preventive measures to avoid foundation damage.

Causes of Expansive Soil in Denver Metro Area

Expansive soil in the Denver Metro Area is primarily caused by the presence of bentonite. Bentonite is a type of clay mineral composed primarily of smectite, a group of minerals with a layered structure. The layered structure of smectite minerals makes them ideal for water absorption and swelling, giving bentonite its unique properties. Bentonite is typically formed from the weathering of volcanic ash deposits, where it is rich in smectite minerals.

The mineral composition of bentonite can vary, but the most common types are sodium bentonite and calcium bentonite. Sodium bentonite has a high swelling capacity, making it ideal for use in sealing ponds, landfill liners, and oil and gas drilling. Calcium bentonite, on the other hand, has a lower swelling capacity, but it has excellent adsorption properties, making it suitable for use in animal feed, cosmetics, and pharmaceuticals.

Bentonite has several physical and chemical properties that make it unique. Its ability to absorb water and swell up to several times its original size makes it an excellent natural sealant, capable of preventing water leakage in various applications.

Clay soils containing bentonite are known for their high plasticity and ability to absorb water, leading to significant changes in volume and swelling when exposed to moisture.

Other factors that contribute to the expansive soil problem in the Denver Metro Area include:

Climate: Denver's semi-arid climate with low precipitation levels and high-temperature fluctuations causes the soil to dry out quickly, leading to increased shrinkage and cracking.

Poor drainage: Poor drainage in the area can result in water accumulation around the foundation, leading to increased soil moisture levels and subsequent swelling.

Building practices: Poor building practices, such as improper grading, compaction, and inadequate foundation design, can exacerbate the effects of expansive soil.

Effects of Expansive Soil on Foundations

Expansive soil can cause significant damage to foundations, leading to costly repairs. The effects of expansive soil on foundations include:

Foundation movement: When expansive soil swells, it exerts pressure on the foundation, causing it to move and crack.

Basement flooding: Expansive soil can cause the basement to flood due to the increased water pressure around the foundation.

Wall cracks: Expansive soil can cause the walls to crack and bow, leading to potential structural damage.

Preventive Measures

Preventive measures can be taken to minimize the effects of expansive soil in the Denver Metro Area. Here are some of the most effective methods:

Soil stabilization: Stabilizing the soil with additives such as lime or fly ash can reduce the soil's swelling potential.

Proper drainage: Ensuring proper drainage around the foundation can prevent water accumulation and minimize the soil's moisture content.

Foundation design: Proper foundation design, including proper sizing and depth, can help prevent foundation movement.

Moisture barrier: Installing a moisture barrier around the foundation can prevent the soil's moisture content from reaching the foundation.

Expansive soil is a prevalent problem in the Denver Metro Area, and its effects on foundations can be severe. Proper prevention measures can help minimize the soil's effects and protect the foundation from damage. Homeowners and builders should be aware of the causes and effects of expansive soil and take proactive measures to ensure their foundation's stability and longevity.