O’Hare Modernization Program2.2 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• Suitability in combination with other materials
– Admixtures• Suitability in combination with other materials
• Provide database of properties • Make recommendations concerning materials
Aggregates
• Geometric properties– Size distribution
• Physical properties– Adsorption capacity– Hardness
• Durability – Freezing and thawing– Alkali-silica reaction– Alkali-carbonate reaction
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
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
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
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
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
IDOT Experience with Chicago Quarries
• Extensive database of quarries with approved sources
• Freeze/thaw performance, excellent durability
• ASR performance, low expansion
Work Done during Fall 2004
• Reviewed IDOT aggregate database
• Learned IDOT F/T testing procedure
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
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