Questions and comments poured in from the enthusiastic audience. Can this restoration process be used on my office building and parking garage? Will this process restore the structural integrity of my foundations and walls? How much money can I save? What is the down time?

Questions like these are common as owners, property managers, and maintenance personnel explore the use of vacuum injection and impregnation technology. You can use this process to improve the load carrying capacity and extend the useful life of your concrete structures. It costs less than conventional restoration (i.e., removal and replacement of deteriorated components) and in comparison has fewer impacts to building use and facility operations.

In many cases it is also a better investment than conventional restoration. When restoration failures are analyzed in a forensic environment, they have been found to actually contribute to or accelerate the deterioration process. This is because, unless fracture mechanics and material compatibility are properly analyzed, restoration can turn out to be nothing more than a short term fix.

The Problem
Can we prevent the cracking to begin with? Unfortunately, no. In the case of concrete, cracking occurs even as it sets. We can only design for and somewhat control or delay it.

Once concrete, stone, or masonry does crack, it sets the stage for a series of physical changes that will eventually reduce its load-carrying capacity. The propagation of cracks can then lead to a number of failures such as:

• Spalling on exposed faces of concrete,
• Delaminating of concrete around reinforcement bars, and
• Debonding of concrete overlays and the creation of voids underneath.

Many property owners have learned that they can avoid these problems or mitigate an ongoing condition with preemptive maintenance, aimed at correcting a problem before expensive reconstruction is needed. They are finding that preemptive maintenance using vacuum injection and resin impregnation is a superior solution to crack repair and restoration.

Vacuum injection/impregnation is the only method to seal the internal network of voids and micro-cracks that other crack and seal systems cannot reach. As a result, concrete deterioration is arrested. Since the path for moisture and air to reach reinforcing steel is sealed, the opportunity for continued corrosion is mitigated. The structural resins that are used will bond to the concrete and steel to restore structural integrity.

The useful life of the structure is extended because the symptom (the crack) is treated AND the cause (loss of load-carrying capacity) is addressed.

The Process
Your first step in fixing a problem is to identify cause of disrepair. This is crucial in determining the materials and method of repair to be use(See article on ‘Getting Started on Preventive Maintenance). Once you have gone through this process and determined that vacuum injection is your preferred repair technique, here is the general repair procedure:

• Inspect, clean, and vacuum the surface.
• Install resin injection ports.
• Apply a surface seal over the area to be repaired.
• Create a vacuum over the sealed area.
• Evacuate and dry the moisture from the crack network.
• Maintain vacuum and release resin through injection ports.
• Pause while resin absorbs and wicks into the micro-cracks.
• Complete the injection process.
• Move to the next repair section.

Summary
The vacuum injection/impregnation process is a tool that you need to consider when your buildings, decks, retaining walls, and floor slabs need repair. It is a cost-effective alternative to conventional repair techniques. Refer to the case study on Page 3 for a sample project.

Vacuum injection meets stringent design requirements for restoring structural integrity, architectural performance, and historical preservation. It has been accepted, specified, and embraced for buildings and façade repairs by design professionals, government agencies, property managers, and building owners.

For more information, contact Joe Logan, P.E. at 585-334-1310, x 251 or by e-mail at jlogan@fisherassoc.com