Bentonite expansion cord is a material that is used to seal "cold" joints in the construction of structures that will be in contact with water.

Here's how it works:

Bentonite: Bentonite is a type of clay that has the ability to absorb water and expand upon contact with it. This property makes it an ideal material for creating waterproofing systems.

Expansion on Contact with Water: When bentonite cord is in contact with water, it begins to absorb it and expand. This causes the cord to fill the space around the seam or joint, creating an airtight barrier against water penetration.

Sealing seams: In construction, such cords are used to fill “cold” seams - that is, seams that do not pass through the entire thickness of concrete or other building material, but are formed during the assembly of the structure. These can be seams between concrete blocks, slabs and other structural elements.

Continuous or intermittent contact with water: Such structures may be under water permanently or intermittently, for example in the case of swimming pools, dams, underground structures, etc. Sealing cold seams prevents water penetration and maintains the integrity of the structure.

The use of bentonite water-reactive expanding cord is an effective way to provide waterproofing and protect building structures from moisture.