The Commercial Sector:

Nottingham One Basement Car Park

Structural Waterproofing

Project case study for a basement car park in Nottingham

structural waterproofing

A national main contractor contacted Restek regarding a solution to issues with water ingress in a lower basement car park in Nottingham. The initial site inspection identified that water ingress was a result of numerous issues and a tailored solution would be required to address each issue.

Water ingress was identified between the cast concrete slab, the column bases, junctions between the sheet piles and areas of the slab due to fractures. Additional tests were then carried out in areas that were showing the highest levels of deterioration, to help determine the best approach to sealing the basement car park.

The concrete slab was also showing signs of micro cracking due to polyurethane injections, carried out in the past by another contractor. Restek therefore had to propose a solution to both waterproof the existing slab and address the damage left by the previous contractor.

Pumps were installed to reduce the water pressure. This meant we could concentrate our efforts on locating the main points of the water ingress. The Restek team accurately marked out areas for the specifically designed injection grid pattern and commenced drilling. When drilling the concrete slab, the drill bit penetrated through the concrete at relative ease and came to a stop at the rebar, suggesting a serious de-bonding of the slab at around 65mm depth. The likely cause of this could usually be water opening up channels along the rebar, thus causing the slab to de-bond.

We first encapsulated the rebar by injecting a specialist resin to seal, bond and stabilise the slab with our pressure injection system, to stop any further channels being created. Once the rebar was encapsulated, we installed high pressure bore packers in pre-drilled holes and mechanically fixed them in place, before connecting our specialist pumps.

The Restek team injected the resin to permeate through the fine cracks and pores in the concrete, ensuring the binding of the concrete and rebar back together, thus renewing the slab back to its original design specification. Once the injection process was complete, the resin provided a watertight seal to the concrete, preventing any further decay from water ingress and frost.

Materials & Equipment:

Our mechanical packers serve as connection pieces between the injection device and the building component for the injection of various types of resins. Depending on the necessary pressure, the nature of the building component and the injection material, different versions of the packers can be specified.

A high-grade, low viscosity PU injection resin was used to stem the flow of water ingress so that a secondary injection could be carried out through our structural waterproofing injection system. The Restek team used a flexible seal at junctions where minor movements were expected.

Finally, a structural resin with a controlled expansion was used with a compressive strength of approximately 65n/mm² and a bending/tensile strength of approximately 85m/mm².

Restek’s Unique Approach 

Restek’s approach of designing tailored solutions together with our value engineering capabilities for projects ensure every part of the scheme brief from client’s expectations through to budget and programme requirements are met.

We are unique in our whole project approach as we look to engage with clients and main contractor very early (ECI) allowing Restek to value engineer a specific project solution using a variety of products and application techniques, to not only meet but exceed the client’s requirements.