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Raw Materials Study at Chicago O’Hare International Airport

by Francis B. Nelson III Leslie J. Struble. Raw Materials Study at Chicago O’Hare International Airport. July 14, 2005. Overview. Materials Update Alkali Silica Reaction (ASR) Update Potassium Acetate Deicer Proposal. Illinois Material Surveys. Aggregates

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Raw Materials Study at Chicago O’Hare International Airport

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  1. by Francis B. Nelson III Leslie J. Struble Raw Materials Study at Chicago O’Hare International Airport July 14, 2005

  2. Overview • Materials Update • Alkali Silica Reaction (ASR) Update • Potassium Acetate Deicer Proposal

  3. Illinois Material Surveys • Aggregates • Approved Aggregate Sources graph • Freeze-Thaw Rating graph • ASR Expansion Rating (Draft) graph • Cements • Qualified Cement Plants database • Graph of Cement Plant Alkali Levels • Mineral Admixtures • Fly Ash database • Other Materials database

  4. Surrounding States DOTs • All have similar specifications for materials and concrete pavements • All have testing programs similar to Illinois DOT Bureau of Materials to approve material producers • None have F/T rating list, but all do testing • Only Minnesota has an ASR test, but does not have specification

  5. ASR Update • Attended IDOT Working Group Meeting on May 24, 2005 at District 1 HQ • IDOT has provided: • Draft Special provision • Draft List of fine aggregate suppliers • Recommendations to OMP • UIUC Testing

  6. IDOT Working Group Meeting • Slowly introduce a statewide specification • Special provision on job specific basis (Dan Ryan Project) • Only District 4 (Peoria) showing evidence in pavements of ASR currently • Other districts have reactive aggregates • Draft List of Fine Aggregate Producers • Proposed Four Categories of Aggregate Reactivity • According to ASTM C 1260 Test Results • Less than 0.1% (innocuous), 0.1% - 0.2% (potentially innocuous), 0.2% - 0.3% (potentially deleterious), Greater than 0.3% (deleterious) • Future Work for IDOT • Blended Cements • Blended Sands (manufactured with natural) • Ternary Mixes • Next Meeting on October 26, 2005

  7. Recommendations • Two categories of expansion rather than three (<0.1% and >0.1%) • No maximum alkali content for cements (due to potassium in deicer) • Allow contractors to use ASTM C 1567 to make a combination of aggregate, cement, and mineral admixture that yields expansion less than 0.1%

  8. UIUC Testing • Aggregates selected from Chicago market • 5 natural sands and 1 manufactured sand • Compare results with IDOT for same sources • Chart showing tests completed • Additional tests underway using Pyrex glass and Ottawa sand

  9. Remaining Work • Complete ASR tests • Pyrex Glass • Ottawa Sand • Produce Tech Notes • Alkali Silica Reaction Recommendations • FAA P-501 Specification Modifications • Produce Final Report • Test Mineral Admixtures (Year 2) • Test for potential combinations to mitigate against reactive aggregates, use ASTM C 1567 test method. • Use fine aggregates previously tested and combine with mitigating materials, such as fly ash and slag, to test for decreased expansion.

  10. by Leslie J. Struble Francis B. Nelson III Impact of Potassium Acetate Deicing Chemicals on ASR of Candidate OMP Concrete Materials

  11. Overview • Background • Tasks • Schedule • Deliverables • Budget

  12. Background on Potassium Acetate Deicer • Non-chloride based deicer • Non-toxic, Biodegradable and less corrosive • Lowers freezing temperature (-76o F) • Also anti-icing agent (prevents freezing) • Avoid use with non air entrained concrete, galvanized metals, and non-watertight electrical systems

  13. Tasks • Conduct literature review on deicing chemicals and potential reaction with concrete materials. • Select representative fine aggregates to test for ASR reaction with the potassium acetate chemical. • Survey/test deicing chemicals for alkali concentration in solution. • Test selected samples for alkali-silica reaction using standard tests for aggregates modified to simulate potassium acetate solutions. • Obtain concrete cores from field samples of representative pavements that have used potassium acetate as a deicer. • Test the cores for alkali concentration. Examine cores for possible alkali-silica reaction and possible surface scaling. • Based on test results, recommend materials for OMP pavements. • Write final report at end of project and Technical Notes as necessary throughout the study.

  14. Schedule

  15. Deliverables • Tech notes • Final report with recommendations

  16. Budget • $40,000 • One grad student • One month faculty salary

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