14 Apr 2023

A 10-Year Monthly Climatology of Wind Direction: Case-Study Assessment

Abstract: A 10-year monthly climatology of wind direction in compass degrees is developed utilizing datasets from the National Oceanic Atmospheric Administration, Climate Forecast System. Data retrieval methodologies, numerical techniques, and scientific analysis packages to develop the climatology are explored. The report describes the transformation of input data in Gridded Binary format to the Geographic Tagged Image File Format to support geospatial analyses. The specific data sources, software tools, and data-verification techniques are outlined.

13 Apr 2023

Advanced Cementitious Materials for Blast Protection

Abstract: Advanced cementitious materials, commonly referred to as ultra-high performance concretes (UHPCs), are developing rapidly and show promise for civil infrastructure and protective construction applications. Structures exposed to blasts experience strain rates on the order of 102 s-1 or more. While a great deal of research has been published on the durability and the static properties of UHPC, there is less information on its dynamic properties. The purpose of this report is to (1) compile existing dynamic property data—including compressive strength, tensile strength, elastic modulus, and energy absorption—for six proprietary and research UHPCs and (2) implement a single-degree-of-freedom (SDOF) model for axisymmetric UHPC panels under blast loading as a means of comparing the UHPCs. Although simplified, the model allows identification of key material properties and promising materials for physical testing. Model results indicate that tensile strength has the greatest effect on panel deflection, with unit weight and elastic modulus having a moderate effect. CEMTECmultiscale® deflected least in the simulation. Lafarge Ductal®, a commonly available UHPC in North America, performed in the middle of the five UHPCs considered.

13 Apr 2023

Historic Architecture and Landscape Inventory for Gordon Lakes Golf Club, Fort Gordon, Georgia

The US Congress codified the National Historic Preservation Act of 1966 (NHPA), through establishing the National Register of Historic Places (NRHP). The NHPA requires federal agencies to address their cultural resources, which are defined as any prehistoric or historic district, site, building, structure, or object. Section 110 of the NHPA requires federal agencies to inventory and evaluate their cultural resources, and Section 106 requires them to determine the effect of federal undertakings on those potentially eligible for the NRHP. Fort Gordon is located in northeast Georgia, directly west of Augusta-Richmond. It was first established as Camp Gordon during WWII for infantry and armor training. It has been known as Fort Gordon since 1956. This report provides historic context and recommends eligibility determinations for 24 buildings, structures, and landscapes associated with the Gordon Lakes Golf Club constructed between 1975 and 2009. The report recommends two Real Property landscapes (the Golf Driving Range and 18-Hole Golf Course including Gordon Lake) and one structure (Gordon Lake Dam) are eligible for the NRHP. The other 21 buildings and structures are recommended Not Eligible. Consulting with the Georgia State Historic Preservation Officer, this work fulfills Section 110 requirements for these buildings, structures, and landscapes.

6 Apr 2023

Naval Expeditionary Runway Construction Criteria: P-8 Poseidon Pavement Requirements

Abstract: A full-scale airfield pavement test section was constructed and trafficked by the US Army Engineer Research and Development Center to determine minimum rigid and flexible pavement thickness requirements to support contingency operations of the P-8 Poseidon aircraft. Additionally, airfield damage repair solutions were tested to evaluate the compatibility of those solutions with the P-8 Poseidon. The test items consisted of various material thickness and strengths to yield a range of operations to failure allowing development of performance predictions at a relatively lower number of design operations than are considered in traditional sustainment pavement design scenarios. Test items were trafficked with a dual-wheel P-8 test gear on a heavy-vehicle simulator. Flexible pavement rutting, rigid pavement cracking and spalling, instrumentation response, and falling-weight deflectometer data were monitored at select traffic intervals. The results of the trafficking tests indicated that existing design predictions were generally overconservative. Thus, minimum pavement layer thickness recommendations were made to support a minimum level of contingency operations. The results of full-scale flexible pavement experiment were utilized to support an analytical modeling effort to extend flexible pavement thickness recommendations beyond those evaluated.

6 Apr 2023

Eelgrass Functions, Services, and Considerations for Compensatory Mitigation

Abstract: Coastal-marine eelgrass habitat is a critical resource within New England and throughout the world. Eelgrass habitat provides functions and services including providing structure, biogeochemical cycling, erosion reduction, habitation provision, and water quality improvement. Declines in eelgrass distribution are often due to anthropogenic processes impacting temperature and water quality. Declines in distribution and abundance highlight the importance of protecting the existing eelgrass, improving environmental conditions allowing for ecosystem restoration, and identifying viable in-kind and out-of-kind compensatory mitigation measures. Considering the limited availability of New England sites for in-kind compensatory mitigation, additional approaches for out-of-kind compensatory mitigation should be considered. These include (1) creation of alternative plant or kelp habitat, (2) using a multi-pronged, multi-habitat and structure approach, (3) contributing to the development of water quality improvement initiatives to encourage current eelgrass bed expansion over time, (4) reduce physical impacts to eelgrass habitat, (5) and identifying locations for future eelgrass habitat suitability based on climate predictions and investing to create future compensatory mitigation habitat in these locations.

5 Apr 2023

4D Printing Structures for Extreme Temperatures Using Metakaolin Based Geopolymers

Abstract: Geopolymers (GPs) are a class of amorphous, aluminosilicate-based ceramics that cure at room temperature. GPs are formed by mixing an aluminosilicate source, which is metakaolin in this case, with an alkali activator solution, which can be either sodium or potassium water glass. GPs have attracted interest for use in structural applications over the past few decades because they have superior mechanical properties to ordinary Portland cement (OPC). Additionally, they can tolerate much higher temperatures and produce a fraction of the CO₂ compared to OPC. This project aims to develop geopolymer composites for 4D printing (the fourth dimension being time) and test their mechanical properties. Rheology and the effects of curing in ambient conditions will be evaluated for fresh geopolymer. Freeze-thaw resistance will be evaluated on potentially printable composites for extreme temperature resistance, etc.

4 Apr 2023

Character-Defining Features of the Buffalo South Mole (South Pier), NY

The US Congress codified the National Historic Preservation Act of 1966 (NHPA), the nation’s most effective cultural resources legislation to date, mostly through establishing the National Register of Historic Places (NRHP). The NHPA requires federal agencies to address their cultural resources, which are defined as any prehistoric or historic district, site, building, structure, or object. The precursor to the Corps of Engineers erected the mole (a.k.a., the south pier) in the early 1820s at the entrance to the Buffalo harbor. The area on top of and surrounding the mole was modified through the past two hundred years, many of the character-defining features remain including the stone retaining walls, talus, stairs, and lighthouse identified in plans and drawings from the period of construction. Notably lost is the stone tow path, or banquette, and the stone incline on the south side of the mole is no longer visible. The researchers recommend a period of significance of c. 1820 through 1972 (50 years) since the mole has continued its original use of keeping the entrance to the Buffalo River open for freight and recreational boating traffic through the present day.

28 Mar 2023

Exploration of Two Polymer Nanocomposite Structure-Property Relationships Facilitated by Molecular Dynamics Simulation and Multiscale Modeling

Abstract: Polyamide 6 (PA6) is a semi-crystalline thermoplastic used in many engineering applications due to good strength, stiffness, mechanical damping, wear/abrasion resistance, and excellent performance-to-cost ratio. In this report, two structure-property relationships were explored. First, carbon nanotubes (CNT) and graphene (G) were used as reinforcement molecules in simulated and experimentally prepared PA6 matrices to improve the overall mechanical properties. Molecular dynamics (MD) simulations with INTERFACE and reactive INTERFACE force fields (IFF and IFF-R) were used to predict bulk and Young's moduli of amorphous PA6-CNT/G nanocomposites as a function of CNT/G loading. The predicted values of Young's modulus agree moderately well with the experimental values. Second, the effect of crystallinity and crystal form (α/γ) on mechanical properties of semi-crystalline PA6 was investigated via a multiscale simulation approach. The National Aeronautics and Space Administration, Glenn Research Center's micromechanics software was used to facilitate the multiscale modeling. The inputs to the multiscale model were the elastic moduli of amorphous PA6 as predicted via MD and calculated stiffness matrices from the literature of the PA6 α and γ crystal forms. The predicted Young's and shear moduli compared well with experiment.

28 Mar 2023

Waste Management and Landfill Facilities Assessment Using Unmanned Aircraft Systems

Abstract: Finite and decreasing landfill space on Army installations is a significant concern. Efficient waste management is essential for achieving resiliency and extending the lifespan of remaining landfills. The purpose of this demonstration was to conduct independent performance tests of small unmanned aircraft systems (sUAS) and their utility for providing landfill assessments in remote areas where physical presence is either dangerous or inefficient. An active, near capacity construction and demolition (C&D) landfill at Fort Gordon, Georgia, was identified for the demonstration. The flights, data requirements, and outputs generated by the sUAS flyovers were analyzed for efficacy in detecting cell capacity and subsidence. Each flight took 1–2 hours for mobilization, ground marker placement, flight, and postflight analysis. Volumetric and topographic surveys were analyzed in less time than is typical for traditional surveying methods. After initial setup of ground markers and rectification, sUAS flights save a significant amount of time. However, skilled individuals are required for flights and for processing and maintaining data. The technology is widely relevant to the Army, is commercially available, and offers an average of 30% cost savings in terms of manpower, repeatability, and equipment. The use of sUAS technology is recommended for monitoring and surveying Army landfills.

27 Mar 2023

Evaluation of 11 Properties at Fort Hunter Liggett, California for Eligibility to the National Register

Abstract: The US Congress codified the National Historic Preservation Act of 1966 (NHPA), the nation’s most effective cultural resources legislation to date, mostly through establishing the National Register of Historic Places (NRHP). The NHPA requires federal agencies to address their cultural resources, which are defined as any prehistoric or historic district, site, building, structure, or object. Section 110 of the NHPA requires federal agencies to inventory and evaluate their cultural resources, and Section 106 requires them to determine the effect of federal undertakings on those potentially eligible for the NRHP. Fort Hunter Liggett is in Central California, entirely within Monterey County. It was first established as the Hunter Liggett Military Reservation in 1941. The post was renamed Fort Hunter Liggett in 1975. This report provides a determination of eligibility for nine properties (Buildings 172, 179, 196, 197, 291, 2199, 723, and 914 and facilities 0301BS and radio-controlled aerial target [RCAT]) constructed between 1956 and 1972 and recommends that none are eligible under the NRHP and the California Register of Historic Resources (CRHR) criteria. Two other properties (Buildings 177 and 178) were found to be covered by the Unaccompanied Personnel Housing (UPH) Program Comment of 2006. In consultation with the California State Historic Preservation Officer (CASHPO), this work fulfills Section 110 requirements for these buildings.