Contraction Joints by Using Oxidized Bitumen

The joint is designed to be positioned so that the tip of the central projection is disposed at or slightly above the level of the surface of the layer of concrete formed above the joint.  

A contraction joint sealant for use in forming a layer of concrete is disclosed which comprises a base, a central projection extending from the base having an upper apex section of uniform thickness and a lower triangular section having a cut-out portion to assist in the contraction and expansion of the joint, a plurality of water stops attached to the base, at least one on each side of the central projection, and a plurality of elongated ribs located between the water stops and the central projection. 

The joint is made of a flexible, durable material, and is particularly suitable for use in the preparation of concrete-lined structures for water conveyance systems such as canals or reservoirs. 

The use of the joint prevents a bond from forming in two adjoining concrete panels so that deterioration at the panel interface is reduced, stress in the concrete is relieved, and buckling is prevented.