Let Accent Be Your Early Warning Concrete Corrosion Detection Service
Accent professionals ensure complete and accurate Rapid Chloride Testing, Corrosion Potential Testing and Carbonation Contamination Results for your convenience. At a time when liability claims against building owners are continually rising, ensure you have the most updated information on your building’s condition. Accent Building Sciences Concrete services include:
- Visual Survey
- Non Destructive Testing as well as Destructive Testing as required
- Comprehensive Condition Survey Report
- Design Specifications and Tender documents
- Project Management
We repair any commercial structure such as:
- Commercial office buildings
- Building restoration
- School Repair
- structural maintenance
- Balcony repair
When concrete structures deteriorate, it is extremely costly to repair or replace them. Deterioration is the result of exposed concrete on balconies, improper detailing of the base plates of balcony railings, and a lack of waterproofing. Failure to design, install and maintain the concrete in a manner that takes into consideration the Canadian environment is the primary cause of failure.
The main causes for concrete deterioration can be attributed to chemical or physical reactions. Corrosion of embedded reinforcing steel is one of the most common causes of the premature deterioration of concrete structures. Corrosion may be the result of the presence of chlorides from de-icing salts, seawater, admixtures or aggregates, carbonation from carbon dioxide from the air, or from the active minerals within the concrete.
Concept of Concrete Repair
When a building owner/manager is faced with major repairs/rehabilitation, the issue of Life Cycle Costing is thoroughly examined. It is very important to relate engineering evaluation of the data collected on site and the causes of deterioration to the financial viability of the repair approach.
When to repair
Once problems are clearly identified and objectives have been set, a timetable for repair is established in close consultation with the property owner that is in keeping with the findings of the evaluation.
First and foremost, the contractor must comply with the drawing details and specifications. To further ensure the durability of the repair, repair procedures and selection of the repair materials must be compatible with the substrate.
Protection of Repaired Areas / Slabs
The application of a waterproofing membrane protects the surface from water penetration and seals any cracks that may be present. Both the type of usage and the durability required must be considered when selecting the type of waterproofing membrane to be used.
Other protection methods, such as Galvanic Anodes and other treatments of the anodes and cathodes, are available and have been in use in recent times.
Salt Corrosion – Prevention and Detection
Salt and acid precipitation mix may be a greater cause for corrosion damage than just salt alone. Parking structures and balcony slabs on buildings adjacent to major highways are exposed to a number of environmental and user related conditions causing premature deterioration. If proper testing procedures have not been carried out, the likelihood of spalling, delamination, or rebar corrosion is high. The bond between concrete and steel during initial installation of the concrete may break down and will no longer transfer the necessary tensile strengths needed between the two. Significant salt spray from highway traffic can cause plumes of road salt and moisture to hover above major traffic routes. This can be detrimental to balcony slabs facing highways. The potential for corrosion may occur at metal railings causing the estimated life span to be cut in half in certain situations.
In Situ Measurement of Chloride Content
This test consists of collecting concrete dust samples from the surface of the balcony or garage slab to the approximate depth of the reinforcing steel. The samples are extracted with ¾” concrete bits minimizing damage and simplifying repair. Samples can be tested on site by adding an extraction fluid to them and measuring the voltage through a chloride sensitive membrane electrode. The chloride content, as a percentage of concrete mass, is determined by calibration measurements taken before and after each test.
Corrosion Potential Testing, carried out in accordance with ASTM C876 (Standard Test Method for Half-Cell Potentials of Uncoated Reinforcing Steel in Concrete) can also be used to verify results and help determine the extent of the repair and the best approach to use to complete the repair. This test involves setting up a copper-copper sulphate half-cell and measuring the relative galvanic activity in the reinforced concrete surface. Results are presented as contour maps clearly showing areas of concern.
Pre 1980’s Buildings May Be A Problem
CMHC found that a potential for carbonation in some urban centres was significant enough to warrant further investigation. Balcony concrete proved to be the most susceptible to carbonation. Carbonation depth emerged as a function of the quality of the concrete and possibly its constituents.