Corrosion Control of Bridges

Corrosion research may be divided into academic and corporate research. According to NACE International, there are 114 professors performing corrosion research with a total annual budget of less than 20 million. 

The methods utilized for corrosion control on bridges are specific to the type of bridge construction and whether its intended use is for new construction or main-tenance/rehabilitation of existing structures. The present discussion is focused on the 

In the present discussion, reinforced concrete and prestressed concrete corrosion control methods are combined. Although prestressed concrete bridges have special concerns such as anchorage in both posttensioned and pretensioned structures and ducts for post-tensioned structures, the general corrosion control methods are applicable to both prestressed and conventional reinforced bridges. 

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Sacrificial anode CP systems have been used for the corrosion control of bridge decks as long as impressed-current anode systems for corrosion control of bridge decks. Two of the earliest field trials (1977) for sacrificial anode systems were the following ... 

Dust control is a major problem in corrosion control by silicone polymers. Dust particles which may bridge, or meerly lay upon conductors will absorb moisture diffusing through the silicone and result in a localized site of corrosion. We found this to be the case in a number of our early saunples. Following the results of this study, all of our encapsulated assemblies will be cleaned and encapsulated in a clean room which is serviced by HEPA filters. 

From the point of view of cost, it is preferable to use stainless steel-clad rebar instead of stainless steel rebar. It is estimated that the use of stainless steel-clad rebar provides an expected life of 50 years. The cost of stainless steel cladding can vary depending on the raw material market prices just like solid stainless steel, but also depends on the cladding manufacturer, cladding thickness, and the chosen grade of stainless steel. With proper quality control, stainless steel-clad rebar promises to be an effective means of control for bridge deterioration because of corrosion of reinforcing steel. 

Salt-induced reinforcing steel corrosion in concrete bridges is a serious problem and an economic burden. Although the positive effect of corrosion protection measures can be seen on individual cases, there are many bridges (thousands) without corrosion control. 

It is useful to note that even the latest corrosion control methods are not likely to prevent all corrosion for the fife of the bridge structure. Therefore, there is a need for repair/rehabilitation of bridge stmctures, and the mitigation of existing corrosion will draw the attention of bridge engineers for years to come. 

Because of the relatively high resistivity of atmospherically exposed concrete substructures, most anodes utilize impressed current to achieve the necessary driving voltages to supply the current required for corrosion control. However, an exception to this is the use of sacrificial zinc anodes for CP of coastal bridges in Florida, which have a relatively low concrete resistance. However, studies continue to examine the use of sacrificial anodes because of the benefit of its low maintenance compared to impressed-current CP systems. Two of these studies are the following ... 

The effort to implement bridge corrosion control maintenance practices, which achieve regulatory requirements and cost efficiency, cannot be successful without the development of reliable task-based cost data for bridge painting tasks. These data depend on many factors such as local labor costs and structural factors such as accessibility to contractor costing rules. 

Technical Alert Criteria for the Cathodic Protection of Reinforced Concrete Bridge Elements. Pre.sents results and recommendations based on the investigation of control criteria used to nrea.sure corrosion rates of steel in a concrete environment. 14 pages. SHRP-S-359, 5... 

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