High performance grout and water stop for storm water system

The Challenge

FP McCann manufactures, supplies and delivers precast concrete to the UK’s building and civil engineering sectors. They approached Pozament, Tarmac’s specialist construction products brand to help them waterproof a pioneering new storm water management system they’d developed.

The first of its kind, StormStore™ is a bespoke, precast concrete system that offers an alternative to using plastic tanks. Storm water management systems are heavily regulated and undergo rigorous performance testing at the development stage.

FP McCann faced a major challenge. They needed to specify the correct materials and joint details that would make the tanks 100% watertight.

Our Solution

One of the first things we did was test the permeability of our construction grouts against the pre-cast concrete FP McCann were using.

Our tests revealed that our High Flow Construction Grout was the most suitable material for the base grout and column base reinforcement because it:

• Allows minimal water flow
• Provides a high level flow – this grout has high flow characteristics to achieve penetration and leveling with no bleed
• Acts as a secondary base, thanks to its high strength
• Wouldn’t shrink – it offers zero shrinkage when placed at 0.22 water/solid ratio

We also recommended Hydrotite should be used on all of the waterproof joints to provide a fully watertight seal. Hydrotite is a hydrophilic water stop that offers exceptional durability and water sealing capacity due to the fact it expands when it comes into contact with water.

The next area we focused on were the columns, Flowing Repair Concrete was recommended for use on the column base plates in order to meet the design life of the project.

Cemthix Installation Mortar was then chosen to provide a strong bond between the vertical joints of the precast wall units. Using this product also enabled greater control to be achieved when grouting these areas.

In addition to recommending the best waterproofing products, we carried out additional tests on our materials to guarantee their suitability. We also provided the client with laboratory demonstrations, gave them a tour of our plant and held regular meetings with them to ensure all parties were kept fully up to speed as the system progressed.

FP McCann successfully installed its first StormStore™ system at a waste-to-energy plant in Leeds in June 2016 and is currently seeking planning permission for more StormStore™ projects throughout the UK.