Hydrophilic waterstop made of high quality sodium bentonite and butyl rubber for the preventive sealing of construction joints and as a system component for bentonite mats. BENTOSWELL retains its shape after 3 wet and dry cycles (MFPA certified). However, at some point there will be some wash-out. The advantage of this phenomenon is that concrete voids/cracks are filled. BENTOSWELL has a good resistance to a wide range of chemicals.