Waterstops Information

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Waterstops are static seals installed between joints of a concrete structures to prevent the passage of water or other fluids. The waterstop is embedded in the concrete or across and/or along the joint. In order to select the right waterstop for the application there are several things to consider. These include, the structure type, joint type, joint movement type, chemical containment requirements, and the method for securing the waterstop in position (hog rings, grommets, etc.)

waterstop

Image Credit: GreenStreak | Waterproof Magazine

 

 

History of Waterstops

 

Concrete waterstops rose to prominence as concrete use became the standard choice in commercial and residential construction in the mid-20th century. After concrete bridges started dotting the map in the early 1900s and the Hoover and Grand Coulee dams were built from concrete in the 1930s, it took hold as the most used material in new construction. Due to the porous joints created when dispensing concrete in sections, the need for waterstops was immediately apparent. PVC was the predominant choice for waterstops by the 1940s and continued for decades. While PVC is still the most common waterstop material, more advanced and better-performing waterstops have quickly caught on in recent years.

 

Types

 

Waterstops are available in two categories—movement and non-movement. Concrete joints allowing movement of adjoined concrete sections utilize dilation joints with expansion characteristics. Movement and non-movement waterstop types include:

 

  • Mechanical waterstops, which are embedded across and along concrete joints to create a diaphragm
  • Hydrophilic waterstops get installed along the joint and expand when exposed to water, thereby creating a compression seal
  • Crystalline waterstops are rolled or sprayed on between pours of concrete and act similarly to hydrophilic waterstops by producing microscopic crystals that grow large enough to seal a joint in the presence of water
  • Mastic waterstops, applied in and along concrete joints with a primer adhesive
  • Fuko injection waterstops are designed to operate like a hose and provide a conduit to inject joints with a type of injection resin 

How Waterstops Work

 

Waterstops are embedded into concrete or installed along joints, creating a barrier in the vulnerable areas that prevents the passage of water or other liquids. The waterstop helps inhibit the passage of liquid in a variety of ways depending on the material used. Some waterstop materials are hydrophobic, creating a diaphragm that repels water and other liquids. Others are hydrophilic, expanding when in contact with water so that the compression generated by the expansion forms a seal. The primary composition of materials in waterstops are constructed to interlock with concrete and designed to accommodate any lateral or transverse movement that could cause a joint to open or misalign.

 

Features

 

Waterstops utilize techniques during installation that force seals to embed into the concrete. In some applications, it is necessary to repel water and liquids entirely. Special circumstances require the prevention of liquids from moving beyond the barrier created by the waterstop. This feature is associated with needing to keep solvents, hot petroleum oils and chemicals from making its way past the seal itself. Additional features include alternative physical forms such as strips. A strip is capable of covering a vast area when purchased in large rolls or pastes.

 

Applications

 

Waterstops are essential for construction projects where concrete is used to retain water or exclude it. These types of applications in residential, commercial and industrial construction include:

 

  • Dams and water reservoirs
  • Canals, locks, aqueducts and culverts
  • Bridges and tunnels
  • Water and wastewater treatment facilities
  • Sludge ponds
  • Containment structures surrounding oil, chemical and other types of refineries
  • Storage tanks, both above and underground, for liquids like fuel or chemicals
  • Basements and concrete foundations for homes and other buildings 

Specifications

 

Specifications are made available in the following four areas:

 

  • Structure type
  • Joint type application
  • Joint movement requirements
  • Chemical containment requirements 

Materials

 

While PVC has been and remains the predominant material used in waterstops, most often in residential applications, there are a wide variety of waterstop materials now in use. Specific applications demand materials such as:

 

  • PVC
  • Metals like copper and stainless steel
  • Natural rubber, SBR rubber and neoprene rubber
  • Bentonite clay (a hydrophilic substance)
  • Thermoplastics — TPV and TPER
  • Regular and high-density polyethylene
  • Swelling paste materials made from polyurethane 

Selecting Waterstops

 

The type of liquid needing retention or exclusion is one primary factor necessary for choosing the appropriate waterstop. In addition, the joint type requiring the seal is the other critical factor. Together these two characteristics are applied to the functional aspect of the concrete itself. Concrete joints with movement need a mechanical waterstop such as PVC, rubber, neoprene, stainless steel or copper.

 

Standards

 

DIN 18187 - Sealing of Joints in Concrete with Waterstops

DIN 7865-1 - Elastomeric - Waterstops for Sealing Joints in Concrete - Part 1

 

 

Resources

Waterstops for Concrete