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Airfields and Pavements Research Overview. J. Kent Newman, Phd John Rushing Mariely Mejias Jonathon Griffin Greg Norwood Geotechnical and Structures Laboratory November 9, 2011. US Army Corps of Engineers BUILDING STRONG ®. Outline. Introduction APB Mission and History
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Airfields and Pavements Research Overview • J. Kent Newman, Phd • John Rushing • MarielyMejias • Jonathon Griffin • Greg Norwood Geotechnical and Structures Laboratory November 9, 2011 US Army Corps of Engineers BUILDING STRONG®
Outline • Introduction • APB Mission and History • Selected Research Project Summaries • Flowable Fill for Rapid Pavement Repair • Warm-Mix Asphalt Guide Specifications • Pavement Preservation • Geogrid-Reinforced Pavement Designs
Introduction • APB Mission • Tri-Service (Army, Navy, Air Force) Lead R&D Agency • Design, construction, evaluation, rehabilitation, and maintenance of structural systems for pavements, rails, and other transportation facilities to support DOD infrastructure and global force projection. • Responsibilities - Materials, Design, Models Development, Performance Evaluation and Prediction, Forensic Analyses, Criteria Development, Rehabilitation, and Repair HVS-A
History of Corps Airfields and Pavements Research • HVS-A Testing • AAF Evaluation program • Railroad program • RCC, RMP pavements • Polymer-Modified Asphalts • Design and construction criteria for B-29 • C-5A, B-747 criteria • Vietnam • Unsurfaced criteria 1990 1940 2000 2012 1950 1960 1980 1970 • 3-D finite element modeling • Advanced materials characterization • Rapid Airfield Construction • CBR Design Improvement • Rapid Airfield Repair • AM-X Mat Program • Asphalt Mix Design • Nondestructive testing procedures • PCI • Bomb-damage repair • FRC pavements • Layered-elastic design • Heavy-load (B-52) pavements • Landing mats • Fuel and blast resistant pavements • Airfield evaluations
Flowable Fill for Rapid Pavement Repair • Mixture properties influence performance • Pavements constructed with rapid-setting flowable fill can withstand numerous high load traffic applications • When compared to traditional compacted aggregate, repairs are easily and rapidly completed at reduced in-place cost
Optimized Flowable Fill Placement • Military Problem • Optimized tactics, techniques, and procedures (TTP) are required to increase backfill production rate and reduce the time required to repair damaged airfield pavements. • Objective • To evaluate material, equipment, and process alternatives for increasing efficiency and production rate of rapid-setting flowable fill.
Optimized Flowable Fill Placement • Approach • Field examination of • technologies increasing production rate when employing traditional wet mixed flowable fill • modified dry placement techniques to increase flowable fill performance • Equipment Alternatives • Rapid Material Loader • Ready-Mix Transit Truck • CRATR Simplified Volumetric Mixer • TTP Modification • Front Load Mix Water • Mobile Drum Mixer • Soil Mixing Attachment (CTL) • Handheld Concrete Mixer
Optimized Flowable Fill Placement • Status • 18 trials in concrete pavement completed • 3 trails in asphalt pavement pending • Water front loading TTP modification successfully exhibited during CRATR Cold-Weather Demonstration, Malmstrom AFB, MT • Working with AFRL on evaluation of short-term flowable fill performance under compaction equipment
Warm-Mix Asphalt Guide Specifications • Objective: • Develop specifications for the use of warm-mix asphalt on military airfield pavements. • Scope: • Lab study using 24 mixes: • 3 WMA technologies and RAP • Site visits to verify mix production, construction and performance from field projects. HMA WMA NCAT Test Track
Warm-Mix Asphalt for Airfield Pavements • Current: • Evaluate field performance of WMA mixtures under military aircraft loading • Evaluate lab performance of plant-produced mixtures • Develop a test protocol for product approval
Approach • Accelerated Pavement Testing: • 3 WMA technologies and HMA • F-15 Traffic • Laboratory Evaluation: • 11 WMA technologies and HMA • Plant-produced and lab-produced mixes • Rutting: • APA – 250 psi • APA – 325 psi • Hamburg • Moisture Damage • TSR • Hamburg • Recovered Binder PG grade
Accelerated Pavement Testing 4 in. Asphalt Limestone (100 CBR) 10 in. 10 in. Clay Gravel (30 CBR) 12 ft Subgrade (15 CBR) N Item 3 Item 4 65 ft 130 ft Item 2 Item 1 24 ft • F-15E • HVS • Temperature-controlled: ≈ 40 °C • Failure Criteria: • 1 in. rut depth • 100,000 passes 24 in.
Pavement Preservation Initiatives • Objective • To provide guidance for preventive maintenance on HMA airfield pavements to reduce rate of environmental degradation. • Scope • Conduct long-term evaluation of performance of asphalt surface treatments in airfield pavements while ensuring adequate friction and resistance to FOD generation Wheeler Sack AAF Dover AFB Davis Monthan AFB Lawson AAF Robert Gray AAF Hurlburt Field
Evaluation of Geogrids for Airfield Pavements • OBJECTIVE: • Quantify the performance benefits of geogrid reinforced aggregate bases under aircraft loading • Develop specifications to facilitate selection of geogrid products which will provide acceptable performance benefits, • Develop design guidance with a method of determining the appropriate decrease in base course thickness when geogrid products are used for base reinforcement.
Evaluation of Geogrids for Airfield Pavements • APPROACH: • Full-scale test section • 4-inch HMA surface course • 8 CBR subgrade • Control, 7 different commercially available geogrid products with grid placed at base/subgrade interface • Flexible pavement • 14-inch 100 CBR base course • 9 test items • One item with a repeat geogrid product placed mid depth in the base course layer
Instrumentation Asphalt Strain Gauges Earth Pressure Cells Single Depth Deflectometers Geogrid Strain Gauges Pore Water Pressure Transducers Moisture/Temperature Probe
Evaluation of Geogrids for Airfield Pavements • C-17 single wheel • 48” wander pattern normally distributed • Evaluate rut depth, surface deformations, and instrumentation response at selected traffic intervals • Accelerated Pavement Testing: • Traffic with the HVS-A • 45,000 lb wheel load, 142 psi • Constant pavement temperature of 77° F