Bentorub®+ is a green flexible hydrophilic strip of approx. 25 by 20 mm, made of natural sodium bentonite clay and synthetic rubber. Bentorub®+ is manufactured in lengths of approx. 5 metres. The swelling properties are created by the particle structure of the clay. In contact with water and in confined conditions, Bentorub®+ will swell to approximately 4V and create a waterproofing pressure inside the joint. The expansive clay mass will thus seal these hair line cracks and voids in the joint. The first expansion is de- layed to prevent the strip from reacting too soon with possible rainwater, before or during the installation.