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O’Hare Modernization Program 2.2 Raw Materials

O’Hare Modernization Program 2.2 Raw Materials. Leslie J. Struble Francis B. Nelson. Kickoff Meeting, October 28, 2004. Proposed Objectives . Assess and test suitability of materials Aggregates Properties required for mix design Properties required for durability Cementitious materials

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O’Hare Modernization Program 2.2 Raw Materials

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  1. O’Hare Modernization Program2.2 Raw Materials Leslie J. Struble Francis B. Nelson Kickoff Meeting, October 28, 2004

  2. Proposed Objectives • Assess and test suitability of materials • Aggregates • Properties required for mix design • Properties required for durability • Cementitious materials • Suitability in combination with other materials • Admixtures • Suitability in combination with other materials • Provide database of properties • Make recommendations concerning materials

  3. Aggregates • Geometric properties • Size distribution • Physical properties • Adsorption capacity • Hardness • Durability • Freezing and thawing • Alkali-silica reaction • Alkali-carbonate reaction

  4. Testing Procedures • Gradation • ASTM C136 • ASTM C33 • Adsorption Capacity • Bulk Density • ASTM C29 • Abrasion Resistance • ASTM C535 • Analysis • X-ray fluoresence • X-ray diffraction • Optical Microscopy

  5. Freezing and Thawing • Freezing when saturated causes expansion and cracking (D-cracking) • Expansion affected by • Porosity • Permeability • Degree of saturation • Size • Mitigation • No mitigation is possible, avoid susceptible aggregate

  6. Testing Procedures • ASTM C 666 • Procedure A – freeze and thaw in water • Procedure B – freeze in air, thaw in water • Measure ultrasonic resonance frequency • IDOT Modified Method • Procedure B using length change

  7. Alkali-Silica Reaction • Chemical reaction • Alkalies in cement and silica in aggregate • Reaction forms a gel that adsorbs water and expands • Expansion causes severe cracking • Mitigation • Mineral admixtures • Low-alkali cement Micrograph courtesy of D. Cong, WJE

  8. Testing Procedures • Petrographic analysis • ASTM C289 • Quick chemical method (24 hours), useful for quality control • ASTM C1260 • Accelerated mortar-bar method (16 days) • ASTM C1293 • Concrete test (1 year), most reliable

  9. IDOT Experience with Chicago Quarries • Extensive database of quarries with approved sources • Freeze/thaw performance, excellent durability • ASR performance, low expansion

  10. Work Done during Fall 2004 • Reviewed IDOT aggregate database • Learned IDOT F/T testing procedure

  11. Work Planned for 2004-05 • Select 5 quarries based on IDOT database to avoid deterioration due to F/T, ASR • Measure properties needed for mix design • Test aggregates for F/T, ASR • If ASR possible, select and test cements and mineral admixtures • If F/T possible, reject quarry

  12. Possible Work in Year 2 • If aggregate alkali-reactive, identify suitable cements and mineral admixtures • Based on recommended mix proportions, identify suitable cements and chemical admixtures • Test cement-admixture combinations for performance, robustness

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