Modeling the Structural Effects of Rust in Concrete Cover

Vast governmental budgets are spent annually to face corrosion problems of steel reinforcement in concrete bridges attributable to the extensive use of deicing salts. Corrosion controls the lifetime of a bridge, which has two distinct periods. During the first period, chlorides diffuse through the cover. When sufficient chlorides are formed at the rebars, corrosion initiates. This marks the start of the second period, during which rust with higher volume to bare steel is produced. The rust puts pressure on the cover, which finally leads to cover spalling. In this paper, a model is developed to determine the time span of the second period. The model includes a volume compatibility condition that allows for the proper introduction of compaction of all materials that contribute to cover spalling, including the rust. A new condition for marking failure of the cover is also established, based on fracture mechanics and strain energies. Finally, a new formula is proposed for the rate of rust production, which allows for the constant rust production at early and nonlinear diffusion dependant rates at latter stages of corrosion. DOI: 10.1061/(ASCE)EM.1943-7889.0000215. © 2011 American Society of Civil Engineers.

[1]  B. Martín‐Pérez.  Service life modelling of R.C. highway structures exposed to chlorides , 1999 .

[2]  Zdenek P. Bazant,et al.  PHYSICAL MODEL FOR STEEL CORROSION IN CONCRETE SEA STRUCTURES­ THEORY , 1979 .

[3]  Z. Suo,et al.  Mixed mode cracking in layered materials , 1991 .

[4]  Stavroula J. Pantazopoulou,et al.  Modeling Cover-Cracking due to Reinforcement Corrosion in RC Structures , 2001 .

[5]  Ralejs Tepfers,et al.  Cracking of concrete cover along anchored deformed reinforcing bars , 1979 .

[6]  Cruz Alonso,et al.  Cover cracking as a function of bar corrosion: Part I-Experimental test , 1993 .

[7]  Cruz Alonso,et al.  Cover cracking as a function of rebar corrosion: Part 2—Numerical model , 1993 .

[8]  Quang Thanh Nguyen,et al.  Fracture of concrete caused by the reinforcement corrosion products , 2006 .

[9]  Paththini Marakkala Mithila Achintha,et al.  Fracture analysis of debonding mechanism for FRP plates , 2010 .

[10]  Khaled Soudki,et al.  A model for prediction of time from corrosion initiation to corrosion cracking , 2007 .

[11]  Masayasu Ohtsu,et al.  Analysis of crack propagation and crackinitiation due to corrosion of reinforcement , 1997 .

[12]  R. Melchers.  Modeling of Marine Immersion Corrosion for Mild and Low-Alloy Steels—Part 1: Phenomenological Model , 2003 .

[13]  X. H. Wang,et al.  Modelling effects of corrosion on cover cracking and bond in reinforced concrete , 2004 .

[14]  Michael D.A. Thomas,et al.  A study of the effect of chloride binding on service life predictions , 2000 .

[15]  Cj Burgoyne.  Does FRP have an economic future , 2004 .

[16]  Ioannis Balafas.  Fibre-reinforced-polymers versus steel in concrete bridges: structural design and economic viability , 2004 .

[17]  Youping Liu,et al.  Modeling the Time-to Corrosion Cracking of the Cover Concrete in Chloride Contaminated Reinforced Concrete Structures , 1996 .

[18]  T. Uomoto,et al.  Behavior of Concrete Beams and Columns in Marine Environment When Corrosion of Reinforcing Bars Takes Place , 1988, SP-109: Concrete in Marine Environment.

[19]  K. Tuutti,et al.  Service Life of Structures with Regard to Corrosion of Embedded Steel , 1980 .

[20]  Robert E. Melchers,et al.  Early corrosion of mild steel in seawater , 2005 .

[21]  C. Burgoyne,et al.  Fracture Mechanics of Plate Debonding , 2008 .

[22]  Kapilesh Bhargava,et al.  Analytical model for time to cover cracking in RC structures due to rebar corrosion , 2006 .

[23]  Z. Bažant.  Closure of "Physical Model for Steel Corrosion in Concrete Sea Structures—Application" , 1980 .

[24]  S. J. Williamson,et al.  Pressure required to cause cover cracking of concrete due to reinforcement corrosion , 2000 .

[25]  Cruz Alonso,et al.  Comparison of rates of general corrosion and maximum pitting penetration on concrete embedded steel reinforcement , 1995 .

[26]  Cj Burgoyne,et al.  Environmental effects on cover cracking due to corrosion , 2010 .

[27]  Richard E. Weyers,et al.  MODELING THE TIME-TO-CORROSION CRACKING IN CHLORIDE CONTAMINATED REINFORCED CONCRETE STRUCTURES , 1998 .

[28]  Weiliang Jin,et al.  Modeling the Amount of Steel Corrosion at the Cracking of Concrete Cover , 2006 .

[29]  T. Liu,et al.  Modeling the Dynamic Corrosion Process in Chloride Contaminated Concrete Structures , 1998 .

[30]  Sudhir Misra,et al.  Corrosion products of reinforcing bars embedded in concrete , 1993 .

[31]  S. Timoshenko.  Strength of materials : part II : advanced theory and problems / by S. Timoshenko , 1983 .

[32]  R. Weyers.  SERVICE LIFE MODEL FOR CONCRETE STRUCTURES IN CHLORIDE LADEN ENVIRONMENTS , 1998 .

[33]  Robert E. Melchers,et al.  Mathematical modelling of the diffusion controlled phase in marine immersion corrosion of mild steel , 2003 .