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Category: Publications: Geotechnical and Structures Laboratory (GSL)
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  • Characterization of Pigmented Microbial Isolates for Use in Material Applications

    Abstract: Organisms (i.e., plants and microorganisms) contain pigments that allow them to adapt and thrive under stressful conditions, such as elevated ultraviolet radiation. The pigments elicit characteristic spectral responses when measured by active and passive sensors. This research study focused on characterizing the spectral response of three organisms and how they compared to background spectral signatures of a complex environment. Specifically, spectra were collected from a fungus, a plant, and two pigmented bacteria, one of which is an extremophile bacterium. The samples were measured using Fourier transform infrared spectroscopy and discriminated using chemometric means. A top-down examination of the spectral data revealed that organisms could be discriminated from one another through principal component analysis (PCA). Furthermore, there was a strong distinction between the plant and the pigmented microorganisms. Spectral differences resulting in samples with the highest variance from the natural background were identified using PCA loading plots. The outcome of this work is a spectral library of pigmented biological candidates for coatings applications.
  • Old River Control Complex (ORCC) Low Sill: A Literature Synthesis

    Abstract: The US Army Corps of Engineers (USACE), New Orleans District (MVN), tasked the US Army Engineer and Research Development Center (ERDC) with assessing the condition of a grouted scour hole located at the southeast wall of the Old River Low Sill Structure (ORLSS) at the Old River Control Complex (ORCC) using noninvasive techniques, such as geophysical surveys and physical models. This special report (SR) combines a scientific literature synthesis of previous research with further geologic interpretation as a first step in the overall task assigned by MVN. The results discussed in this SR will be used to inform the interpretation of geophysical surveys, construction of physical models, and input for the slope stability analyses.
  • Suggested Updates for the Inclusion of Guidance on Ultra-High Performance Concrete to USACE Engineering Manual 1110-2-2000, Standard Practice for Concrete for Civil Works Structures

    Abstract: Ultra-high performance concrete (UHPC) is a relatively modern class of concrete with properties that include very high compressive strengths, increased tensile strengths, very low permeability, and superior durability compared to conventional, normal-strength concrete. As research of this material continues to progress, its applications under both military and civil works categories expand. However, mixture and structural design guidance using UHPC is limited, particularly in the United States. This special report provides an overview of UHPC as initial guidance for the US Army Corps of Engineers (USACE) so that the material may be more easily utilized in civil works infrastructure. The information contained in this report is based on years of experience researching and developing UHPC at the US Army Engineer Research and Development Center (ERDC) and is intended to be a basis for the incorporation of this material class into USACE Engineer Manual (EM) 1110-2-2000, Standard Practice for Concrete for Civil Works Structures, when it is next updated.
  • State-of-Practice on the Mechanical Properties of Metals for Armor-Plating

    Abstract: This report presents a review of quasi-static and dynamic properties of various iron, titanium, nickel, cobalt, and aluminum metals. The physical and mechanical properties of these materials are crucial for developing composite armoring systems vital for protecting critical bridges from terrorist attacks. When the wide range of properties these materials encompass is considered, it is possible to exploit the optimal properties of metal alloys though proper placement within the armoring system, governed by desired protective mechanism and environmental exposure conditions.
  • Numerical Modeling of Mesoscale Infrasound Propagation in the Arctic

    Abstract: The impacts of characteristic weather events and seasonal patterns on infrasound propagation in the Arctic region are simulated numerically. The methodology utilizes wide-angle parabolic equation methods for a windy atmosphere with inputs provided by radiosonde observations and a high-resolution reanalysis of Arctic weather. The calculations involve horizontal distances up to 200 km for which interactions with the troposphere and lower stratosphere dominate. Among the events examined are two sudden stratospheric warmings, which are found to weaken upward refraction by temperature gradients while creating strongly asymmetric refraction from disturbances to the circumpolar winds. Also examined are polar low events, which are found to enhance negative temperature gradients in the troposphere and thus lead to strong upward refraction. Smaller-scale and topographically driven phenomena, such as low-level jets, katabatic winds, and surface-based temperature inversions, are found to create frequent surface-based ducting out to 100 km. The simulations suggest that horizontal variations in the atmospheric profiles, in response to changing topography and surface property transitions, such as ice boundaries, play an important role in the propagation.
  • Evaluation of a Prototype Integrated Pavement Screed for Screeding Asphalt or Concrete Crater Repairs

    Abstract: Finishing, or screeding, the hot mix asphalt or rapid-setting concrete surface of a crater repair is important for rapid airfield damage recovery (RADR) since it determines the aircraft ride surface quality. The objective of RADR repairs is to expediently produce a flush repair, defined as ±0.75 in. of the surrounding pavement surface, with minimal logistical and personnel burden. Multiple screeds were previously evaluated; the most recent project proposed a prototype design of a telehandler-operated integrated screed for both small and large repairs using asphalt or concrete. This project’s objective was to finalize the prototype design and fabricate and test the prototype RADR screed. The prototype RADR screed was successful for small repairs (8.5×8.5 ft). Large repairs (30×30 ft) were generally successful with modest repair quality criteria (RQC) issues being the only notable deficiencies. Large concrete repair RQC issues were attributed to plastic formwork movement, and large asphalt repair RQC issues were attributed to compaction issues or improper roll-down factors. Methods to mitigate these factors were investigated but should be further evaluated. Overall, the RADR screed was successful from technical perspectives but, functionally, is 600-800 lb overweight. Weight reduction should be considered before entering production.
  • Stability Analysis of Old River Low Sill Structure

    Abstract: An updated stability analysis was performed on the Old River Low Sill Structure due to a change in the operating conditions from historic river sedimentation. Sedimentation of the Mississippi River channel since the 1973 spring flood has caused higher river stages at lower discharges. Numerical methods used included nonlinear analysis of pile group stability, seepage analyses, and limit equilibrium methods. The structure’s foundation was compromised during the 1973 flood, and emergency repairs were conducted to prevent scouring and undermining of the foundation by the flood scour. Rehabilitation included the reconstruction of a failed wing wall on the left abutment, rock and riprap fill in the forebay channel, and emergency grouting to fill the scour hole beneath the structure. An operating restriction was emplaced to limit the differential head across the structure due to flood damage. Taking these conditions into account, results from an updated analysis showed that full headwater uplift caused increased tension in the piles, while the increased body load caused increased compressive loads in the piles. Review of piezometric monitoring and the seepage analyses showed that full headwater uplift is unlikely, indicating the foundation grouting adequately sealed the scour hole beneath the structure. Analysis results exhibited lower magnitude compression and tension loads in the piles with design load cases compared to previous analyses. Recommendations from these analyses indicate that increased monitoring and additional investigation may support increasing the differential head limitation.
  • Legacy Datums and Changes in Benchmark Elevation through Time at the Old River Control Structure, Louisiana

    Abstract: Vertical datums used in the study area at the Old River Control Structure in southern Louisiana have involved Memphis Datum, Mean Gulf Level, Mean Sea Level, Mean Sea Level Datum of 1929, National Geodetic Vertical Datum of 1929, and the North American Vertical Datum of 1988. The focus of this study was to examine historic benchmarks in the study area to determine the magnitude of elevation changes associated with the different legacy datums that have been used by the US Army Corps of Engineers. Comparison of elevation values across these legacy datums has involved examining historic hydrographic surveys, compiling a list of known benchmarks from these surveys, and comparing their elevation values against publications involving spirit-leveling surveys from the Lower Mississippi Valley and the National Geodetic Survey database for benchmarks. This study describes the history of legacy datums, floodplain geology at the Old River Control Structure, potential subsidence impacts affecting the benchmarks, methods for identification and tracking benchmarks, and the results obtained from this study.
  • The Old River, Mississippi River, Atchafalaya River, and Red River (OMAR) Technical Assessment

    NOTE: The Old River, Mississippi River, Atchafalaya River, and Red River (OMAR) Technical Assessment is a 9-volume series of reports that was produced under the direction of the Mississippi River Geomorphology & Potamology Program. An abstract from the main report, Volume 1, is listed below, along with the individual volume titles and links to the relevant reports. ABSTRACT: This is the main report of Old River, Mississippi River, Atchafalaya River, and Red River (OMAR) Technical Assessment. The primary objective of the OMAR Technical Assessment was to conduct a comprehensive evaluation that aimed to understand the impacts of former and potential changes to the system in the vicinity of the Old River Control Complex (ORCC) over time, the water and sediment delivery regime at the ORCC, and the effects to the river system surrounding the ORCC. Scenarios evaluated in this technical assessment were designed to investigate potential system responses to a wide range of possible operational alternatives and identify knowledge gaps in current understanding of system behavior. This report summarizes and synthesizes the individual reports detailing the investigations into specific aspects of the ORCC and the surrounding region.
  • Effects of Impure Water Sources on Early-Age Properties of Calcium Sulfoaluminate Cements for Rapid Airfield Damage Recovery

    Abstract: In austere environments with limited access to clean water, it is advantageous to use nonpotable water for construction (i.e., mixing water for concrete.) In rapid-response situations such as rapid airfield damage recovery (RADR), the use of calcium sulfoaluminate (CSA) cements is beneficial for expedient pavement repairs because of their rapid strength gain characteristics. However, the hydration products formed by CSA cements are substantially different from those formed by ordinary portland cement and might react differently to impurities that water sources may contain. A laboratory study component investigated the application of various salts and impure sources of mixing water with commercially available CSA cement-based products. A field component studied the application of naturally occurring impure water sources for RADR. Recommendations are made for implementation of impure mixing water for RADR using commercially available flowable fill and concrete products made with CSA cement.