RAB anchors

What is a RAB anchor?

RAB stands for Repair Anchor for Bubbledeck Slab Floors. This specially developed anchor system is designed to safely and durably repair structural problems in bubbledeck slab floors. Development of the RAB anchor gained momentum following the collapse of the parking garage at Eindhoven Airport during the construction phase. An investigation revealed that a design flaw in the application of bubbledeck slab floors was the cause of the incident.

Because bubbledeck slab floors have been widely used in the Netherlands, many buildings had to be structurally recalculated in accordance with stricter safety standards. If the load on a floor exceeds a critical limit, immediate safety measures are required until the floor structure has been permanently reinforced.

What is a BubbleDeck slab floor?

A bubbledeck slab floor is a commonly used precast flooring system in residential construction, non-residential construction, and parking garages. The floor consists of precast concrete elements in which the bottom reinforcement and main reinforcement have already been installed at the factory.

So-called lattice beams extend upward from these elements. These hold hollow plastic spheres in place, which serve as weight-reducing elements. The thicker the floor, the larger the diameter of these spheres.

Advantages of BubbleDeck slab floors

Bubbledeck slab floors offer several advantages:

  • Large spans possible
  • Fewer supporting columns needed
  • Fast construction time
  • Weight of the structure itself
  • Suitable for both residential and commercial buildings

The floor panels are connected to one another using special connecting rods. These rods ensure that transverse tensile forces are safely transferred between the various precast panels.

After systems such as plumbing, electrical wiring, and HVAC have been installed, a concrete screed is poured over the floor. The floor must remain fully supported until this concrete layer has fully hardened.

What went wrong with BubbleDeck slab floors?

Switch to self-compacting concrete

During the production process, precast flooring was adapted by using self-compacting concrete. This meant the concrete no longer needed to be compacted using vibratory rods, which made the production process faster and more efficient.

In addition, it was decided to omit the outer vertical reinforcement at the edges of the floors. This reinforcement frequently caused problems during the transport and hoisting of the precast elements.

Origin of the constructive problem

These changes created a dangerous situation in practice:

  1. The tie rods were laid on a very smooth layer of self-compacting concrete.
  2. Due to the absence of the outer lattice girders, there was insufficient connection between the precast floor and the subsequently poured topping layer.

This resulted in insufficient bonding between the two concrete layers. The tie bars could no longer effectively transfer the tensile forces, causing the poured concrete layer to detach from the precast lower layer under load.

This phenomenon is also called delamination or the “peeling off” of the print layer.

Please note: In particular, buildings constructed between approximately 1995 and 2017 can run the risk of structural problems with bubbledeck slab floors.

The solution: the RAB anchor system

Using the RAB anchor system, the structural integrity of the floor can be restored without completely replacing the floor structure.

Inspection and scanning

Before the repair begins, a concrete scanner will be used to identify:

  • Existing rebar
  • Tie rods
  • Plastic spheres

and the exact position thereof.

This allows the anchors to be placed with extreme precision without damaging the existing structure.

How does a RAB anchor work?

The RAB anchor is installed to the left and right of critical floor joints, directly next to the existing tie bars. This re-establishes a structural connection between the poured pressure layer and the precast floor.

The required quantity of anchors and their dimensions depend on:

  • Floor thickness
  • Load
  • Structural requirements
  • Floor span

Benefits of RAB anchors

Safe Repair of Existing Structures

RAB anchors make it possible to safely reinforce existing bubbledeck slab floors without the need for large-scale demolition work.

Minimal disruption

As the repair work is largely carried out from below, buildings often remain partially occupied during the works.

Structurally Verifiable Reinforcement

Pre-tensioning and testing each anchor individually ensures a quality assurance process that can be verified immediately.

Sustainable solution

The system ensures a long-lasting structural connection between the precast floor and the load-bearing layer.

Applications of RAB anchors

RAB anchors are used in applications including:

Car parks

Apartment complexes

Office buildings

Hospitals

Schools

Civil engineering

Distribution centres

Why Constructive Oversight is Essential

Following nationwide studies on bubbledeck slab floors, it has become clear that structural safety should never be underestimated. Regular inspections and timely reinforcement are essential to prevent risks to occupants and buildings.

The RAB anchor system offers a reliable and technically sound solution for repairing and reinforcing bubbledeck slab floors.

Available on request

RAB anchors are a specialist product. Please contact us for technical advice, specifications, and pricing information.

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