29 May 2024

Finite Element, Petrographic, and Mechanical Analyses of Field-Cored Concrete Fairlead Beam Anchor Rods from Luke Air Force Base

Abstract: The fairlead beam is used to accomplish installation of the Barrier Arresting Kit 12 energy absorber for setback aircraft arresting system (AAS) installations at permanent operating facilities. Typical fairlead beams are affixed to a Portland cement concrete (PCC) foundation pad by a series of anchor assemblies made up of steel anchor rods set in grout inside galvanized pipe sleeves. US Air Force Civil Engineering Center (AFCEC) subject matter experts have identified a pattern of premature failures in these steel anchor assemblies when they are nondestructively inspected during AAS overhauls. The US Army Engineer Research and Development Center was tasked by AFCEC to investigate potential reasons for these premature failures. This report outlines methods and results of a finite element analysis of the anchorage, a visual and petrographic analysis of field-cored PCC anchor rods from Luke Air Force Base, and a mechanical analysis of specimens taken from the anchor rods within the PCC cores. Multiple modes of PCC distress were observed, and corrosion was evident in and around the anchor assemblies. Mechanical testing of specimens from the anchor rods indicated that an inferior grade of steel was used to fabricate these particular assemblies. Finally, observed deviations from design intention are discussed.

31 Jan 2024

Verification of Current Los Angeles (LA) Abrasion Test Criterion for Aggregate Degradation in Airfield Asphalt Pavements

Abstract: Low-quality mineral aggregates can potentially lead to production, construction, and long-term performance-related problems in asphalt concrete pavements. Therefore, effective qualification criteria for mineral aggregates are paramount. This study was performed to investigate the effectiveness of the Los Angeles abrasion (LAA) test to assess the abrasion resistance of coarse aggregates commonly used in airfield asphalt paving. The LAA test acceptance criteria currently specified by state departments of transportation were examined and compared to the current Department of Defense criterion. Additionally, recent experiences during a forensic evaluation to identify potential sources of excessive presence of foreign object debris on an airfield runway are also briefly discussed in this report. The LAA test and associated acceptance criterion in Unified Facilities Guide Specification (UFGS) 32 12 15.13 were evaluated by testing 24 aggregate sources from various US locations. Also, the Micro-Deval abrasion test was performed as a surrogate abrasion resistance test. Sufficient evidence was not found to suggest adjustments to current LAA test criterion or to recommend the use of an alternative abrasion test. The current UFGS specifications should be improved to provide a more thorough aggregate testing protocol and detailed guidelines regarding aggregate sampling and testing frequency during design and construction of asphalt pavements.

29 Sep 2023

Microbial Activity in Dust-Contaminated Antarctic Snow

Abstract: During weather events, particles can accumulate on the snow near the Pegasus ice and Phoenix compacted-snow Runways at the US McMurdo Station in Antarctica. The deposited particles melt into the surface, initially forming steep-sided holes, which can widen into patches of weak and rotten snow and ice. These changes negatively impact the ice and snow runways and snow roads trafficked by vehicles. To understand the importance of microbes on this process, we examined deposited dust particles and their microbial communities in snow samples collected near the runways. Snow samples were analyzed at the Cold Regions Research and Engineering Laboratory where we performed a respiration study to measure the microbial activity during a simulated melt, isolated microorganisms, examined particle-size distribution, and performed 16S rRNA gene sequencing. We measured higher levels of carbon dioxide production from a sample containing more dust than from a sample containing less dust, a finding consistent with viable dust-associated microbial communities. Additionally, eleven microorganisms were isolated and cultured from snow samples containing dust particles. While wind patterns and satellite images suggest that the deposited particles originate from nearby Black Island, comparisons of the particle size and chemical composition were inconclusive.

11 Oct 2022

A Review of Airfield Pavement Drainage Guidance

Abstract: Inadequate drainage conditions may lead to airfield pavement deterioration. A thorough review of existing pavement drainage guidance and literature was necessary to identify key drainage considerations such as surface drainage infrastructure, pavement drainage layer thickness, use of geotextiles, and performance in freeze–thaw climates. Existing airport drainage guidance is provided by the Unified Facilities Criteria (UFC), the Federal Aviation Administration (FAA), and the Tri-Service Pavements Working Group (TSPWG). Pavement drainage guidance is buried within regulations for pavement de-sign and can, at times, be split awkwardly to accommodate pavement guidance that is split between rigid and flexible designs. Most airfield pavement guidance has been adapted from guidance for highway design. Most guidance is also strength based, with little to no attention paid to material erodibility (a potential cause of pavement deterioration). This review also found very little reference to repairing, rather than completely replacing, damaged subsurface drainage layers. Further research is needed to assess the use of geofabrics and moisture in freeze–thaw conditions on drainage layers and surface structures. With further research, the retrofit and repair of existing subpavement systems might become a more economical solution to drainage-caused pavement deterioration issues than complete reconstruction.

11 Aug 2020

PUBLICATION NOTICE: Development of Expedient Ultra-High Molecular Weight Aircraft Arresting System Panel Installation Procedures

Abstract: The US Army Engineer Research and Development Center conducted an evaluation of different procedures to install ultra-high molecular weight polyethylene panels beneath pendant-based aircraft arresting systems (AAS). Currently employed techniques were modified or new techniques were developed to increase productivity and installation accuracy, aid in system constructability, and reduce logistical concerns when compared to AAS requirements and pavement repair guidance. Procedures for both asphalt concrete and portland cement concrete surfaced runway pavement were evaluated. The field evaluation was conducted from July to August 2013 at the Silver Flag Training Site, Tyndall Air Force Base, FL. The evaluation consisted of timing various procedures using a six- to eight-man installation crew. Equipment and supplies currently in Air Force inventories were preferred, but outside items were not prohibited if performance gains could be achieved and the new items were deployable using typical military cargo aircraft. Required work tasks were organized and grouped together to efficiently complete the panel installation work within multiple short-term runway closure windows without any long-term closures greater than 12 hours to allow for aircraft operations during the installation process. This report summarizes the timed field trials and the pertinent conclusions based on the results. Recommendations for implementation including additional equipment, supplies, and personnel needs are provided.