Field Trials of Lithium Treatments on PCC

Since 1980 alkali-silica reactivity (ASR) has become an increasingly critical concern with regards to the durability of concrete pavements and structures in South Dakota. The first pavement to exhibit severe ASR was a 38-mile section of I-90 in Lyman County built in 1972. The pavement has continued to deteriorate and become a significant maintenance problem remaining serviceable only due to the presence of the reinforcing. In fact, the worst section is in the process of reconstruction this year. To combat potential problems with ASR in future construction the South Dakota Department of Transportation (SDDOT) adopted the use of Type II, Low Alkali cement in 1983. Contemporary wisdom contended that the use of Portland cement with an equivalent alkali content less than 0.6% would eliminate ASR in concrete even if an aggregate source were deleteriously reactive. Unfortunately, confidence in the assumption has been gradually eroded by the discovery of certain aggregates, mostly volcanic in origin, which undergo ASR even in the presence of a low alkali cement and by the growing awareness of deicing salts as an external source of alkali. Since 1983 numerous pavements statewide have exhibited various degrees of ASR. In addition, Sioux quartzite, the primary coarse aggregate used in eastern South Dakota, has proven to be reactive. The impact of ASR on concrete durability and pavement life and the need to develop strategies to minimize the risk of premature deterioration of PCC pavements prompted further research. Because the use of lithium salts is a recognized method of mitigating potential ASR in new concrete, SDDOT participated in the Strategic Highway Research Program (SHRP) Concrete and Structures ASR Showcase Test and Evaluation Project 34 Mitigation of Potential Alkali-Silica Reactivity Using Lithium. This work involved the construction of new concrete test sections incorporating various lithium admixtures as well as treatment of a series of 500-foot test sections on an ASR affected severely deteriorated pavement with several dosage levels of lithium nitrate and acetate solutions in 1995. Monitoring of these test sections over the last five years has provided strong evidence of the beneficial effects of lithium treatments on ASR in existing pavements. It has also led to the development of strategies designed to monitor in situ changes in pavement properties that reflect a reduction in the magnitude of expansive stresses. A paper detailing these results, which was presented at the 11th International Conference on Alkali-Aggregate Reaction in June 2000, is attached. The work did not directly address determining the optimum point for applying the treatment or evaluating its cost benefit ratio. This research should address these issues. ASR severity is determined through visual inspection of the pavement surface. SDDOT currently identifies pavement distress by driving on the shoulder of the highway at 5 mph and visually rating quarter mile long sections for the pavement management system. The following severity levels are used to evaluate ASR distress in concrete pavements: Low: Cracks are light, with no loose or missing pieces. Medium: Cracks are well defined and some small pieces are loose or missing. High: Cracks form a well-developed pattern with a significant amount of loose or missing material. SDDOT continues to search for methods to mitigate ASR in existing concrete that are cost effective, environmentally sensitive, user-friendly, and effective. With research in this area that examined methacrylate, silane, sealers, and polymers, the SDDOT has identified lithium salts as a product that may meet all of these criteria. Laboratory research has shown that lithium salts are effective in treating ASR affected samples. Unfortunately, there are still unknowns that exist when this technology is applied to existing pavements. These unknowns include when to treat an ASR affected pavement, how deep does the lithium penetrate, how effective is the application, what should the application rate be, how many applications are needed, and how is the effectiveness measured. With the encouragement of the Federal Highway Administration (FHWA), to address these unknowns in a nationwide lithium implementation field trial program, SDDOT has the opportunity to further their own goals and benefit from other state agencies.The objectives of this research project are to: (1) Verify the effectiveness of using lithium nitrate on a pavement that contains reactive aggregate at various levels of ASR severity; (2) Determine the cost benefit of using a topical lithium nitrate treatment for mitigating ASR based on life cycle cost analysis; and (3) Develop detailed guidelines for field application of lithium nitrate for mitigation of ASR in existing concrete pavement.

Language

  • English

Project

  • Status: Active
  • Contract Numbers:

    SD2001-10

  • Sponsor Organizations:

    South Dakota Department of Transportation

    Transportation Building, 700 E Broadway
    Pierre, SD  United States  57501
  • Project Managers:

    Ormesher, Daris

  • Performing Organizations:

    South Dakota Department of Transportation

    Transportation Building, 700 E Broadway
    Pierre, SD  United States  57501
  • Principal Investigators:

    Johnston, Dan

  • Start Date: 20010514
  • Expected Completion Date: 0
  • Actual Completion Date: 20070630
  • Source Data: RiP Project 12567

Subject/Index Terms

Filing Info

  • Accession Number: 01458309
  • Record Type: Research project
  • Source Agency: South Dakota Department of Transportation
  • Contract Numbers: SD2001-10
  • Files: RiP, STATEDOT
  • Created Date: Jan 3 2013 12:40PM