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 lining 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. Potential for corrosion may occur at metal railings causing estimated life span to be cut in half in certain situations.
In Situ Measurement of Chloride Content
The 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. The samples can be tested on site by adding an extraction fluid to the samples 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 best type and extent of 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 of the 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.
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 buildings condition.
Click here to contact our building consultants for more information or call our office at (416) 298-8448.