Uses of Bentonite in Construction

Bentonite has been widely used in the construction industry for decades. It is formed from the weathering of volcanic ash and is known for its high colloidal properties, making it an excellent material in many construction applications. In this article, we will dive into the properties of bentonite, its uses in the construction industry, and how to safely handle/apply bentonite products. 

Properties of Bentonite

Bentonite is a unique and versatile clay mineral that is composed primarily of montmorillonite, a soft, swelling clay mineral. Some of the key properties of bentonite include:

1. Swelling Capacity: Bentonite has a high swelling capacity (5-15 times its dry volume) due to the presence of montmorillonite, which allows it to absorb and retain water or other liquids. 
2. Plasticity: Bentonite is highly plastic and can be molded into a variety of shapes without cracking or breaking.
3. Adsorption Capacity: Bentonite also has a high adsorption capacity, which means it can attract and hold onto other molecules or particles. This makes it useful in a variety of applications, including water treatment, where it can be used to remove impurities from water.
4. Viscosity: Bentonite is highly viscous (ave. η 23,400 mPa·s ± 120.4 mPa·s). It can form a thick, sticky gel when mixed with water. 
5. Thermal Stability: Bentonite is thermally stable and can withstand high temperatures without losing its properties. This makes bentonite a suitable material in the production of refractories.
6. Ion Exchange Capacity: Bentonite has a high ion exchange capacity, which means it can easily exchange cations with other ions in a solution. Such property allows bentonite to be used in the production of catalysts and as a soil amendment.
7. Low Permeability: Bentonite is highly impermeable and can act as an excellent barrier to the movement of water and other liquids. 

Uses of Bentonite in Construction

Thanks to its unique properties, bentonite has a number of applications in the construction industry. Here are some of the most common uses of bentonite in construction:

1. Waterproofing: Bentonite is an excellent material for waterproofing applications, such as filling voids and cracks, and lining underground structures. When mixed with water, bentonite forms a gel-like substance that can effectively prevent water from seeping through. Bentonite membrane sheets are also widely used in foundation waterproofing. 
2. Drilling: Bentonite is a popular drilling mud. The bentonite mud helps to cool the drill bit, suspend the cuttings, and prevent collapse of the borehole. Bentonite slurries are also used to support excavation works during drilling operations.
3. Grouting: Bentonite is commonly used in grouting applications, where it is mixed with water to form a slurry that is pumped into soil or rock formations. The slurry fills gaps and voids, effectively stabilizing the ground and preventing seepage.
4. Soil Stabilization: Bentonite can be used to stabilize soil in construction applications, such as road construction and foundation works. The bentonite slurry is mixed with the soil to improve its stability and prevent soil erosion.
5. Concrete Additive: Bentonite can be used as an additive in concrete to improve its strength, durability, and workability. Bentonite is added to concrete mixtures to reduce shrinkage, improve adhesion, and increase the resistance to chemical attack.
6. Retention Pond Lining: Bentonite makes effective pond liners, where it prevents water or leachate from seeping into the ground, such as in the construction of retention ponds and landfills.