Effect of Supplementary Cementitious Materials (SCMs) and waste products on Critical Chloride Threshold, CT, of Concrete

Chloride-induced corrosion of reinforcing steel is one of the most significant durability challenges facing concrete infrastructure, especially for bridges, pavements, and marine or deicing-salt exposed structures. A critical parameter controlling corrosion initiation is the critical chloride threshold (CT), yet existing test methods produce inconsistent values and do not fully reflect the behavior of modern concrete mixtures containing supplementary cementitious materials (SCMs) or waste-derived additives. As transportation agencies adopt newer binder systems such as Type IL cement and increase the use of SCMs, the need for reliable, practical, and reproducible CT measurement techniques has become increasingly important for service-life design. This project addresses these needs by evaluating how Class C fly ash, Class F fly ash, and metakaolin, each applied at two replacement levels with Type IL cement, affect the CT of reinforced concrete. The study employs the newly developed OCcrit test method, which measures CT directly on mortar specimens under controlled electrochemical conditions. OCcrit offers improved reproducibility and more realistic assessment of steel–concrete interactions compared to traditional embedded-bar or potentiometric techniques, making it a promising method for future durability evaluations. In parallel, the project will investigate a second approach to CT measurement using cyclic polarization. While this method has previously been applied only to steel samples immersed in simulated concrete pore solutions, results have not aligned with OCcrit values which is believed to be due to the absence of true concrete environments. Leveraging a high capacity potentiostat, this research will apply cyclic polarization directly to mortar samples for the first time, enabling a meaningful comparison with OCcrit and helping determine whether the method can be adapted into a practical tool for corrosion threshold assessment. Finally, the project will examine the role of waste-derived materials by assessing the influence of acid- and base-pretreated ground tire rubber (GTR) on CT. Previous studies showed that untreated GTR can affect corrosion initiation, but the mechanisms remain unclear. By evaluating chemically surface modified GTR using the OCcrit method, the project will clarify how surface treatments alter particle–matrix interactions, pore solution characteristics, and overall corrosion behavior. The combined findings will provide transportation agencies with more accurate data and improved testing methods for designing durable, long-lasting concrete infrastructure exposed to chloride environments. The proposed research directly aligns with CHDT’s core mission to enhance the durability and service life of transportation infrastructure through innovative materials and techniques. CHDT emphasizes the development of sustainable, performance-driven construction materials, particularly the reuse of recycled and waste materials such as rubber and industrial by-products, to improve structural longevity and reduce maintenance costs. By evaluating how SCMs and treated GTR influence corrosion resistance and by advancing CT testing methods, this project extends CHDT’s ongoing portfolio of work on freeze-thaw durability, corrosion mitigation, and the beneficial use of waste materials in concrete pavements.

• Record URL:
  • https://transportation.umkc.edu/project/effect-of-supplementary-cementitious-materials-scms-and-waste-products-on-critical-chloride-threshold-ct-of-concrete

Language

• English

Project

• Status: Active
• Funding: $105,725.00
• Contract Numbers:

  69A3552348335

• Sponsor Organizations:

  Department of Transportation

  Intelligent Transportation Systems Joint Program Office
  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Managing Organizations:

  Office of the Assistant Secretary for Research and Technology

  University Transportation Centers Program
  Department of Transportation
  Washington, DC  United States  20590
• Performing Organizations:

  Center for Healthy and Durable Transportation

  University of Missouri Kansas City
  Kansas City, Missouri  United States  64110
• Principal Investigators:

  Halmen, Ceki

• Start Date: 20260101
• Expected Completion Date: 20261231
• Actual Completion Date: 0
• USDOT Program: University Transportation Centers

Subject/Index Terms

• TRT Terms: Admixtures; Cement; Chloride content; Concrete; Crumb rubber; Fly ash; Wastes
• Subject Areas: Bridges and other structures; Highways; Materials;

Filing Info

• Accession Number: 01986489
• Record Type: Research project
• Source Agency: Center for Healthy and Durable Transportation
• Contract Numbers: 69A3552348335
• Files: UTC, RIP
• Created Date: Apr 21 2026 1:35PM