Materials Performance

OCT 2016

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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36 OCTOBER 2016 MATERIALS PERFORMANCE NACE INTERNATIONAL: VOL. 55, NO. 10 CHEMICAL TREATMENT A This work documents the effective- ness of an organic corrosion-inhibit- ing admixture for reinforced concrete under chloride exposure conditions. Reinforced concrete samples were exposed in a road salt environment in the Swiss Alps and periodically in- spected over 18 years using a number of test methods. The results illustrate that this corrosion-inhibiting admix- ture can significantly delay corrosion initiation and thus prolong the service life of reinforced concrete structures. A wid A wide variety of types of corrosion- A iety A wide variety of types of corrosion- A of types of corrosion- i n h i b i n h i b i t i n g a d m i x tu re s f o r re i n f o r c e d A n i n h i b i t i n g a d m i x tu re s f o r re i n f o r c e d A d m i x tu re s i n h i b i t i n g a d m i x tu re s f o r re i n f o r c e d A f o r re i n f o r c e d c on c on cre t e are kn ow n . A t e c on cre t e are kn ow n . A kn ow n . c on cre t e are kn ow n . A 1 - 3 Th e s e in clu d e or organic corrosion inhibitors such as formu- A c organic corrosion inhibitors such as formu- A corr organic corrosion inhibitors such as formu- A n organic corrosion inhibitors such as formu- A inhibitors such as formu- lations based on amin es and alkanol- A ns lations based on amin es and alkanol- A base lations based on amin es and alkanol- A n lations based on amin es and alkanol- A amin es and alkanol- amin e s (amino alc o ho l s). It has b e en A lc o ho l s). amin e s (amino alc o ho l s). It has b e en A It has b e en demonstrated in various laboratory inves- A monstrated demonstrated in various laboratory inves- A in demonstrated in various laboratory inves- A ious demonstrated in various laboratory inves- A laboratory inves- tigations A gations tigations A 4-9 that th that these products can prolong A products that these products can prolong A can prolong the the time to corrosion initiation in chloride A time to corrosion the time to corrosion initiation in chloride A initiation the time to corrosion initiation in chloride A in chloride exposure environments, or that they can ra i s e th e c r it i c a l c h l o r i d e th re s h o l d , th ereby decreasing corrosion rates. In recent literature reviews, 1-3 however, it has been emphasized that the vast majority of results stem from short-term laboratory studies, and that long-term documentation on the effectiveness of organic corrosion- inhibiting admixtures under real exposure conditions is lacking. Experimental Procedures Specimens In 1995, L-shaped concrete specimens were cast and installed along a highway in the Swiss Alps (Figure 1). During the winter season, the vertical wall elements are ex- posed to chloride-bearing splash water. These walls are 2.10 m in height, 1.70 m in width, and have a thickness of 200 mm. They are reinforced with two layers of car- bon steel bars (12-mm diameter bars with 200-mm vertical and horizontal spacing). On the front side facing the highway, the cover depth is 15 mm; on the rear side, the cover depth is 30 mm. The front and rear reinforcing steel mats are electrically iso- lated from each other ; however, cable con- nections to each mat from junction boxes mounted on the rear side of the elements permit measurements and electrical inter- connection of the front and back layers of steel reinforcement. The electrical continu- ity between these two layers was estab- lished through the junction boxes to simu- late realistic conditions, apart from the short interruptions that were occasionally needed for certain measurements. Three types of concrete were cast (one L- shaped specimen per concrete type), but only the results of the reference concrete and the concrete containing the commercial corrosion-inhibiting admixture are re- por t ed . B oth concret es contain equal amounts of a superplasticizer and an air- Long-Term Field Performance of an Organic Corrosion Inhibitor for Reinforced Concrete U. m . a ngst and m . Büc H ler Swiss Society for Corrosion Protection (SGK), Zurich, Switzerland J. s c H l U mpf Sika Services AG, Zurich, Switzerland B. m arazzani and m . Bakalli Sika Technology AG, Zurich, Switzerland

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