Laboratory Investigation and Neural Networks Modeling of Deicer Ingress into Portland Cement Concrete and its Corrosion Implications

Abstract

By exposing reinforced concrete samples to four common chloride-based deicers, the corrosive effect of chloride-based deicers on rebars and dowel bars was systematically investigated. The experiments were designed in such a way that the effect of deicers on reinforced concrete can be characterized in an accelerated manner, by either ponding the concrete samples with deicer solutions at room temperature, or incorporating pressurized ingress, wet-dry cycling and temperature cycling into the test regime. The chloride ingress over time was monitored using a custom-made chloride sensor embedded in each concrete sample. Also periodically measured were the open circuit potentials (OCPs) of the top bar in concrete. Once the chloride sensor detected the arrival of sufficient chlorides near the top bar and the OCP data indicated the possible initiation of top bar corrosion, the corrosion rates of rebars and dowel bars are characterized by macrocell current and corrosion current density derived from electrochemical impedance measurements. From a modeling perspective, artificial neural networks (ANNs) were used to achieve better understanding of the complex cause-and-effect relationships inherent in the deicer/concrete/bar systems and were successful in finding meaningful, logical results from the noisy data associated with the deicer ponding experiments. According to the ANN modeling, corrosion inhibitor (and possibly other additives in the inhibited CaCl 2 and MgCl 2 deicers) did slow down the ingress of chloride into concrete (indicated by more positive 105 Brought to you by | Purdue University Libraries Authenticated Download Date | 5/26/15 11:42 PM Volume 28, Nos. 3 & 4, 2010 Laboratory Investigation and Neural Networks Modeling chloride sensor potentials),, reduce the pitting risk of rebars and dowel bars in concrete (indicated by more positive OCP values) and reduce their corrosion rate in concrete (indicated by reduced macrocell current and corrosion current density of top bar). For both concrete mixes and both types of deicer ponding, the overall risk of deicers to reinforced concrete was in the order of: non-inhibited NaCl > inhibited NaCl > inhibited CaCl 2 deicer > inhibited MgCl2 deicer. While the corrosion inhibitors in deicer products provide some benefits in delaying the corrosion initiation of rebars and dowel bars in concrete, such benefits seem to diminish once the active corrosion of the bars is initiated. In other words, the inhibitors showed little benefits in repassivating the actively corroding bars in concrete or in stifling the corrosion propagation.

Effectiveness of Liquid Agricultural By-Products and Solid Complex Chlorides for Snow and Ice Control

“…Chloride salts are effective over a wide range of temperatures [3], and their baseline performance and corrosivity have been recently reported [4]. The last two decades have seen increased use of chloride based deicers and continued concerns over their deteriorating effects on motor vehicles [5,6], transportation infrastructure [7,8] and the environment [9]. KAc is more expensive than chloride salts but generally considered to be non-corrosive to carbon steel and more benign on surrounding soils and ecosystems [10].…”

Modelling of Behavior for Inhibition Corrosion of Bronze Using Artificial Neural Network (ANN)

“…Some works have already demonstrated the efficiency of these models in corrosion systems using different conditions. For example, in the prediction of corrosion inhibition in pipeline steel [ 16 , 17 , 18 ], the resistance of dental metallic [ 19 ], to determine inhibitor efficiency applied in aluminium [ 20 ], and others [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ].…”

Effect of Electrical Injection of Corrosion Inhibitor on the Corrosion of Steel Rebar in Chloride-Contaminated Repair Mortar

“…Chloride, often originated from marine environments [2] or deicing applications [3], can initiate the rebar corrosion once its concentration exceeds a threshold level. The threshold chloride contents in published literature are scattered over a wide range of values, attributable to the variability in measurement methods and the numerous factors that affect steel corrosion in concrete, such as the pH of concrete pore solution, the electrochemical potential of the steel, and the physical condition of the steel/concrete interface [4][5][6].…”