FACT: Kaspar Winkler first used watertight concrete in the Gotthard Tunnel under the Swiss Alps.

How can watertight concrete help a project?

Concrete is a highly adaptable and durable construction material. It can be manipulated into a wide range of design requirements.

The addition of watertight admixtures such as Sika 1+, Sika Watertight Concrete Powder or Sika WT-200P reduce the permeability and enhance the durability of the concrete.

Developed to protect structures from water ingress, the water to concrete ratio is reduced whilst producing a highly workable concrete to aid placing and compaction. The remaining capillary pores are blocked using the hydrophobic or crystalline material contained within the watertight concrete admixture.

Whether it’s used to complement a waterproofing system or in isolation. The benefits of the watertight concrete include:

  • Time saved at design and construction stages as the need for external membranes with their complex detailing and installation is eliminated
  • Cost-effective in comparison with membranes and other systems.
  • Delivers maximum usable area to the occupier
  • Quality backed by Sika warranty, BBA certificate and a 60 years track record.

What you need to know about Watertight Concrete

In order to minimise the risk of shrinkage cracking, pouring should be limited to a 3:1 aspect ratio (width to height) and slab pour to a maximum of 400m², if square-shaped.

BS8102:2009 regulations recommend that structural and waterproofing design should be considered at the earliest stages and communication with the manufacturer maintained throughout.

Using CAD details to aid design in the project will keep all elements of the plan in order.

The CAD detail for Sika® Watertight Concrete Main Section – WTC01 can be found here.

Is Sika watertight concrete suitable for large-scale projects?

No matter the size of the project, a Sika Watertight Concrete admixture will adapt to the needs of the design. There is no surprise that the Sika Watertight Concrete System is now the most widely used system of its type in the UK.

Watertight Concrete graphic

Continuity of waterproofing

No matter how good your watertight concrete is, unless you seal the construction and movement joints correctly you are wasting your time. All joints must be sealed with a suitable waterbar, such as SikaSwell hydrophilic strip, Sika Metal waterbar, Sika PVC Waterbars of Sika Fuko reinjectable hose.

Sealing box-outs and penetrations

For larger box-out areas, such as those greater than 500mm x 500m, SikaSwell hydrophilic strip can be affixed to the outer perimeter and around the cast-in penetrations for a watertight seal, before filling with Sika Watertight Concrete. Smaller box-outs and core drilled penetrations can be filled using Sika Monotop 130 Seal.

Watertight Concrete graphic 2
Find out more about our Watertight Concrete Systems