The Advanced Corrosion Control For Concrete Structure Durability
Introduction to Vappro-CRI
Concrete structures such as bridges, buildings, elevated highways, tunnels, parking garages, offshore oil platforms, piers and dam walls all contain reinforcing steel (rebar). The principal cause of degradation of steel reinforced structures is corrosion damage to the rebar embedded in the concrete.
Reinforcing steel used in precast concrete is made largely of iron, is unstable in nature, it becomes unstable when exposed to corrosive agents such as salt, carbonation, and even air. Iron, as we commonly recognize it, is not generally found in nature because of its instability.
It takes a great deal of energy to produce iron from its ore, and even then it is so unstable that it must be coated to keep it from reverting back to its ore forms (hematite, magnetite, and limonite).
The two most common causes of reinforcement corrosion are (i) localized breakdown of the passive film on the steel by chloride ions and (ii) general breakdown of passivity by neutralization of the concrete, predominantly by reaction with atmospheric carbon dioxide. Sound concrete is an ideal environment for steel but the increased use of deicing salts and the increased concentration of carbon dioxide in modern environments principally due to industrial pollution, has resulted in corrosion of the rebar becoming the primary cause of failure of this material. The scale of this problem has reached alarming proportions in various parts of the world.
Magnitude of the Rebar Corrosion Problems
According to a 1997 report, of the 581,862 bridges in and off the U.S.A. federal-aid system, about 101,518 bridges were rated as structurally deficient. Most of these bridges were not in danger of collapse, but they were likely to be load posted so that overweight trucks will be required to take a longer alternative route.
The estimated cost to eliminate all backlog bridge deficiencies (including structurally and functionally) was approximately $78 billions, and it could increase to as much as $112 billions, depending on the number of years it takes to meet the objective. The average annual cost, through year 2011, for just maintaining the overall bridge conditions, i.e., the total number and the distribution of structurally and functionally deficient bridges, was estimated to be $5.2 billions. While corrosion of the reinforcing steel was not the sole cause of all structural deficiencies, it was a significant contributor and has therefore becomes a matter of major concern.
In view of the above, Vappro-CRI products have been developed by Magna to combat corrosion, rehabilitate and repair concrete structures.
Vappro-CRI products are now available as follows:
Vappro-CRI 4000 Series- CST Concrete Surface Treatment
Vappro-CRI 6000 Series- VRC Vappro Rebar Coating
Vappro-CRI 7000 Series- CRP Concrete Repair Products
Vappro-CRI 8000 Series- CAT Concrete Additive Treatment
How Vappro-CRI Works