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52 NOVEMBER 2017 MATERIALS PERFORMANCE NACE INTERNATIONAL: VOL. 56, NO. 11 CHEMICAL TREATMENT S Organofunctional silanes (OS) are increasingly used to protect concrete bridge decks against chloride ingress and resulting corrosion. This article describes the evaluation of OS in mit- igating ongoing corrosion due to chlorides or carbonation. The proce- dure used for determining the mitiga- tion of chloride-induced corrosion is a new test protocol, M-82, developed by the U.S. Bureau of Reclamation in conjunction with the Strategic Devel- opment Council of the American Concrete Institute. The mitigation of carbonation-induced corrosion was determined using a modified version of an ASTM standard. The OS inhibi- tor was effective in mitigating both chloride-induced and carbonation corrosion. For chloride-induced cor- rosion, there was a reduction in addi- tional chloride ingress. S u r f a c e - a p p l i e d o r g a n o f u n c t i o n a l silanes (OS) are increasingly being used to prevent corrosion of steel reinforcing bars (rebar) in concrete that has a high amount of chlorides. 1-4 This article builds upon earlier w ork don e in thi s field . 2-4 Tw o organofunctional silane topical treatments were evaluated to determine their feasibil- ity as a treatment for concrete that has been subjected to chloride ingress and the steel reinforcement was corroding. OS-1 has a corrosion inhibitor as part of its composition, whereas OS-2 has an amine- b a s e d i nhi bitor a d d e d . R e s e a rch w a s conducted by the authors according to the M-82 5 test protocol developed by the U.S. Bureau of Reclamation. 6 This work also describes the use of OS in mitigating carbonation-induced corro- sion—a common problem that o ccurs when carbon dioxide (CO 2 ) or carbon mon- oxide (CO) in the air permeates into con- crete. This results in a lowering of the con- crete's pH caused by the conversion of calcium hydroxide [Ca(OH) 2 ] into calcium carbonate (CaCO 3 ). Steel is not passive at the lower pH (<10), and corrosion can initi- ate even in the absence of chlorides. This form of corrosion usually occurs in con- crete with a higher water-to-cement (w/c) ratio and at lower concrete covers because the rate of CO 2 ingress decreases as con- crete permeability decreases (decreased w/c). The depth of penetration is propor- tional to the square root of time. Experimental Procedure Data from three different test series are presented. The first two test series exam- ined OS-1 and OS-2 by following the M-82 protocol. The third test series was per - formed to determine if the OS-1 treatment mitigates carbonation-induced corrosion when applied soon after carbonation has initiated or after carbonation-induced cor- rosion is already proceeding at a high rate. Organofunctional Silane Corrosion Inhibitor Surface Treatment Protects Concrete n eal S. Ber K e, F na C e and Kri S tin M. a de, Tourney Consulting Group, LLC, Kalamazoo, Michigan, USA Peter K. d e n i C ola and a tri r ungta, Evonik Corp., Piscataway, New Jersey, USA