NDT (Non-Destructive Testing )

 Vacuum Repair

 Ongoing Condition Assessment

Non Destructive Testing
Balvac's turnkey solution begins with testing to identify the type and extent of defects and the overall quality of the element to be repaired. A proper analysis of the structural and architectural condition leads to a superior project outcome as it determines the appropriate method and materials to be used.

Impact Echo, the non-destructive evaluation of concrete and masonry, is one of the state-of-the art technologies used by Balvac to achieve the goal of proper analysis. It was developed in 1983 by the National Institute of Sciences and Technology and further developed at the School of Engineering at Cornell University, New York. Impact echo is based on impact generated stress waves of low frequencies that propagate through the test element and are reflected by internal defects and external stress free boundaries. As effective and advanced as this technology is, it is not considered a rapid method of analysis, but this is more than compensated for by its accuracy. Impact echo analysis requires a great deal of experience and knowledge of concrete and masonry structures and stress wave theory. The transient resonance and the spectral patterns produced are determined by the geometry of the element being tested. Therefore, it is imperative that the technician is familiar with the characteristic solid response of the various types of geometric elements.

Impact echo, while the principal tool of non-destructive testing, is only one of the many instruments and test procedures used by Balvac technicians for structural evaluation. Along with non-destructive testing, Balvac also provides consulting services for the co-ordination and analysis of laboratory testing such as compressive strength, petrographic examination, alkali aggregate reaction (AAR) and alkali silica reaction (ASR) pre-tests.

Vacuum Repair
The use of vacuum processes instead of positive pressure for the repair of concrete, masonry and stone construction falls into three main areas.

1. Vacuum injection of individual discrete cracks.
2. Vacuum flushing to partially impregnate closely spaced cracks on horizontal and vertical surfaces.
3. Vacuum re-bonding and void filling to re-bond vertical and horizontal delaminations and cavitations.

In addition to these three repair options, there are other variations, such as the Balvac Nitrovac System, vacuum grouting and the Balvac Waterstop System. The Balvac Nitrovac System is used to dry out interconnecting cracks and voids. Vacuum grouting is used to fill formed areas for material replacement. The Balvac Waterstop System is used prior to vacuum injection to prevent water or air being drawn into the void during the process.

Ongoing Condition Assessment
Balvac provides an ongoing service to its vacuum repair clients as a part of the firm's commitment to providing complete and lasting solutions and as a mark of best practice with regard to quality control. In addition, Balvac has a long-standing relationship with engineers and architects providing services to develop and conduct visual and non-destructive structural condition assessment and evaluation. These services include analysis of existing hardened concrete, newly repaired and restored concrete and quality control of current construction and restoration.