Bentonite cord: which one to choose and how to use

Bentonite cord is a special swelling profile that participates in the waterproofing system of concrete structures. It is used both in new construction and in reconstructions and repairs of old structures.

It consists of bentonite clay, which, when in contact with water, tends to swell and increase in volume. Bentonite cord, firmly fills all cracks, seams and voids, forming an impermeable connection from moisture and water. When the water leaves, the bentonite cord returns to its previous size and is ready to swell again at the next contact with water.

Bentonite cord can be of several types and sections:

Bentonite cord of round shape – has a diameter of 22 mm. It is used for sealing holes in concrete that remain after removing the formwork.

• Installation of a round bentonite cord: a protective tube is drilled, which remains in the concrete body after the studs and the formwork itself have been removed, a round bentonite cord is inserted, and sealed on both sides with a repair compound.

Bentonite cord of rectangular cross-section can be of different sizes and is used to seal cold joints in concrete and places of passage of engineering communications (foundations, floor-wall junction, wells, reservoirs, pools, etc.):

• Bentonite cord 5x20 mm is the minimum cross–section, which is used only for sealing places of passage of engineering communications: engineering networks of water supply, sewerage, central heating, etc. Installation of bentonite cord 5x20 mm: wrap around the pipe being laid several times, minted with a repair compound.
• Bentonite cord 10x20 mm – used for sealing cold joints, with a concrete structure thickness from 80 mm to 150 mm.
• Bentonite cord 15x25 mm – used for sealing cold joints, with a concrete structure thickness from 150 mm to 250 mm.
• Bentonite cord 20x30 mm – used for sealing cold joints, with a concrete structure thickness from 250 mm to 400 mm, as well as in structures that are subject to high groundwater pressure or very deep occurrence.

If the thickness of the concrete structure is more than 400 mm, a bentonite cord measuring 20x30 is laid in two contours, on both sides of the insulated seam, at a distance of at least 50 mm from the edge of the concrete.

Installation of bentonite cord 10x20; 15x25; 20x30 mm: lay in the place of the technological seam and fix it with a special mesh or sealant.