Improved Test Methods and Practices for Characterizing Steel Corrosion Potential of Earthen Materials

Electrochemical properties of earthen materials—resistivity (conductivity), pH, organic content, and salt content (e.g., chlorides, sulfates, and phosphates)—are used to characterize the potential for corrosion of buried or embedded steel elements. These elements are often incorporated into transportation-related construction projects within retaining walls, earth embankments, bridge foundations, abutments, and approaches. Electrochemical properties are typically evaluated using the current AASHTO standard methods T 288 through T 291. These methods are based upon procedures originally developed and applied to agronomy. They neither consider the different characteristics of materials used in transportation-related construction nor distinguish issues inherent to particular applications. For example, the moisture contents of mechanically stabilized earth (MSE) fills during service cannot exceed 100 percent saturation, which is not adequately addressed in AASHTO T 288. Moreover, current test standards do not accommodate the coarse sand, gravel, and aggregate fill types commonly used in construction. Construction practices and knowledge of in-ground corrosion have evolved since the 1990s, such that the limitations of the current AASHTO test methods must be recognized. Suitable alternatives must be developed and implemented. There are many transportation projects for which these limitations create issues such as project delays, the necessity of using more expensive sources of backfill, lower quality of the finished product, etc. Research is needed to address the limitations of the current AASHTO test methods used to measure the electrochemical properties of earthen materials surrounding buried or embedded steel elements. The research should identify alternative test methods that are more appropriate for particular applications (e.g., MSE walls). The alternative test methods developed should be used for assessing corrosion potential for different applications and should result in recommendations for updating the current AASHTO standards for the design and construction of highway structures. OBJECTIVE The objective of this research is to develop new or improved laboratory and field test methods to measure the electrochemical properties of earthen materials surrounding buried or embedded steel elements. The methods shall be representative of field conditions, and provide acceptable calibration, repeatability, and reproducibility. The research shall review existing test methods that measure the electrochemical properties of earthen materials surrounding buried or embedded steel elements. It shall identify alternatives that enhance or extend the ability to characterize the corrosiveness of earthen materials for a wider range of field conditions than those addressed by AASHTO T 288 through T 291, including, but not limited to: particle size; sample size and frequency; in situ water properties, including electrical conductivity; identification of appropriate test endpoint (elimination of slurry state endpoint); and alternate methodologies to those in current test methods.  

Language

  • English

Project

  • Status: Active
  • Funding: $400000
  • Contract Numbers:

    Project 21-11

  • Sponsor Organizations:

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590

    American Association of State Highway & Transportation Officials (AASHTO)

    444 North Capitol Street, NW, Suite 225
    Washington, DC  United States  20001

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Project Managers:

    Harrigan, Edward

  • Performing Organizations:

    McMahon & Mann Consulting Engineers, P.C.

    ,    
  • Principal Investigators:

    Fishman, Kenneth

  • Start Date: 20160705
  • Expected Completion Date: 20191231
  • Actual Completion Date: 0
  • Source Data: RiP Project 40227

Subject/Index Terms

Filing Info

  • Accession Number: 01572342
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 21-11
  • Files: TRB, RiP
  • Created Date: Aug 6 2015 1:00AM