Waterstops or Waterbar
Waterstops or waterbars are flexible tape like elements of a concrete structure that prevent the passage of water through concrete joints. Concrete joints are most liable to seepage. They are designed as fluid tight diaphragm embedded in or running along the joints. The join is as watertight as the waterbar that join them.
For sizeable concrete structures like retaining walls, basements, reservoirs and tunnels joints are inevitable. It can be construction or expansion joints or both. Joints in direct contact with water need the protection of a waterbar. They are hydrophilic or impervious strips cast into the concrete at the joints to prevent the passage of water.
Waterstops placed centrally provide efficient barrier to penetration of water from either face of slab or a wall. It should be carefully fixed in the formwork before concreting. On the other hand externally placed waterbars are easy to fix by nailing through “outboard” flange. These prevent passage of water from outside of the structure. External waterstops are usually used in piled wall basement construction.
The primary functions of a waterbar is to act as a waterproofing seal in the joint. It allow movement of two sections independently of each other without restraint (free of tension). PVC waterstops are always be joined by welding by heating and never by lapping. Waterbars are supplied in rolls.
Applications of Waterstops or Waterbars
Waterstops used in construction industry provides waterproofing. Waterbar is used in water and transportation industry to improve the quality of construction. Common structural applications are in:
- Water and sewage disposal projects.
- Liquid containments.
- Dams, channels, tunnels and tanks.
- Box culverts and locks.
- Primary and secondary containments structures.
- Bridges and decks abutments.
- Wall and slabs.
- Basements and foundations
Types of Waterstop
Depending on the application and availability of products, following major types of waterstops can be used in construction. Fosroc and Sika are most common suppliers of waterbar. Selection of the right waterstop depends on the type of structure, level of exposure and construction method. Water stops are available in different shapes and materials.
Based on type of material, water stops can be classified into following:
This is the most common type. It features a high tensile strength, high resistance to acids, diesel oil, chlorinated water and other chemical liquids. They do no discolor the concrete nor does any electrolytic action occurs with the surrounding reinforcement. It has excellent inherent elasticity and impermeability. PVC waterstop is rather easy to install by tethering the outer flanges to adjacent a reinforcing bars.
This is made of high density polyethylene material. It is strong, durable and exhibits high resistance to temperature change. It is not prone to swelling action and is resistant to oxidants as well as reducing accents. HDPE waterstops can find its applications in primary and secondary containment structures, sewage treatment facilities and chemical plants.
This is made of an alloy of rubber and plastic. TVP waterstops are easy to butt-weld. It exhibits excellent dynamic fatigue resistance, high elasticity, and high resistance to long term temperature change. Moreover, TVP is environment friendly and has superior weather and UV resistance.
This type of waterstop has excellent high movement accommodation, adjusts for subsidence and seismic movements, and is shown to withstand high hydrostatic head. Its application is ideal for high movement joints.
Watch the video below to understand how waterbars prevent water leakage
What are waterstops?
The waterstops are hydrophilic or impervious strips cast into the concrete at the joints to prevent the passage of water.