26 Jun 2025

Preliminary Study for Rapid Ground Stabilization

Abstract: The Army has a need to rapidly repair heavily damaged low-volume roads. This report describes the literature review, laboratory study, and preliminary technology evaluation for potential rapid road rehabilitation materials and equipment. The objective was to identify and evaluate equipment, materials, and techniques for rapid road repair. This phase of the study focuses on rapid stabilizers that, when added to native soil, could improve bearing capacity. Lightweight equipment and attachments were assessed for their ability to effectively excavate and place geomaterials. Several commercial soil stabilizers were identified that could meet strength requirements. Equipment attachments for a compact track loader were deemed most suitable for executing rapid repairs.

25 Jun 2025

Bioconcentration, Maternal Transfer, and Toxicokinetics of PFOS in a Multi-Generational Zebrafish Exposure

Abstract: To enable risk characterization of perfluorooctane sulfonic acid in extended chronic and multi-generational exposures, we assessed PFOS bioconcentration in zebrafish exposed continuously to environmentally-relevant PFOS concentrations through 180 days postfertilization in parental and first filial generation fish. Exposures included five replicate tanks per treatment where whole-body PFOS concentrations were measured. Perfluorooctane sulfonic acid accumulation reached an apparent steady state at ≤ 14 dpf where whole-body wet-weight concentrations remained constant through 180 dpf in the P and F1 generations. The median bioconcentration factor of 934 L/kg was observed for all PFOS exposures with a range from 255 to 2,136 L/kg which varied with PFOS exposure concentration and sex of adult fish. Maternal transfer of PFOS was observed from P females to F1 eggs where maternal whole-body and egg PFOS burdens were equivalent, suggesting PFOS transfer to eggs was not a depuration pathway. Finally, a toxicokinetic model was developed that reliably reproduced PFOS whole-body burdens across all exposure durations spanning the P and F1 generations, providing a tool for PFOS bioaccumulation predictions relevant for risk assessment of acute, chronic, and multi-generational exposures.

25 Jun 2025

Evaluating the Influence of Flexural Strength on Rigid Pavement Performance Under Simulated Aircraft Traffic

Abstract: A full-scale airfield pavement test section was constructed and trafficked by ERDC to investigate the impact of substandard flexural strength portland cement concrete on pavement structural support requirements under simulated aircraft loading conditions. The substandard pavements were representative of ones encountered in remote locations where there may be a lack of locally available competent materials, standard construction equipment, or a skilled labor force. The test section consisted of two PCC surface thicknesses constructed with a standard airfield flexural strength PCC mixture and a low flexural strength PCC mixture and a dowelled and non-dowelled joint. The test items were trafficked with a dual-wheel P-8 aircraft test gear mounted on a heavy-vehicle simulator. The outcomes of the tests showed a significant reduction in PCC pavement cracking performance resulting from the reduction in flexural strength. Instrumentation response data were analyzed to corroborate observed surface cracking. The field data were compared to DoD pavement design and evaluation procedures, and it found current procedures underpredicted observed performance in excess of 90 percent. These estimations may be overly conservative and may exceed a level of conservatism appropriate in a remote environment. The observed conservatism was attributed to simplifying assumptions and empirical correlations made in early development.

24 Jun 2025

A Field Sampling and Analysis Protocol for Assessing Occupational Exposure and Risk from Military Munition Storage Magazines

Abstract: An occupational health study was conducted inside reinforced-concrete earth-covered munitions storage magazines at Fort Wingate Depot Activity. HEPA vacuuming of bulk dust and wipe sample verification post-vacuuming was used. In Phase 1, no explosives detections exceeded site-specific screening criteria. In Phase 2, no exceedances were noted for detected explosives with criterion. Using structure/ reactivity characteristics within the explosives category, surrogates were assigned to the six explosives without occupational health screening criteria. Based upon structural similarities within the analysis category, assignments of surrogates to explosives without criteria did not adversely impact the conclusions. In Phase 1, lead was detected in bulk dust in all igloos, and all exceeded the applicable criterion for commercial/industrial workers. In Phase 2, all lead detections in wipe samples were below the wipe screening criteria. Results indicated the ECM interiors posed no unacceptable dermal occupational risk for explosives or lead residues following bulk dust removal. HEPA filter vacuuming of interior bulk dust in ECMs at FWDA reduced occupational risk/hazard for exposure via inhalation and dermal contact under worst-case exposure conditions. Both phases of sampling are widely applicable, provided the site-specific assumptions made for this study are evaluated for suitability to another specific application and adjusted if needed.

24 Jun 2025

Graphene-Coated Sand for Enhanced Water Reuse: Impact on Water Quality and Chemicals of Emerging Concern

Abstract: This paper investigates the potential of graphene-coated sand as an advanced filtration medium for improving water quality and mitigating chemicals of emerging concern in treated municipal wastewater, aiming to enhance water reuse. The study utilizes three types of sand coated with graphene to assess the impact of surface morphology, particle shape, and chemical composition on coating and filtration efficiency. Additionally, sand coated with graphene and activated graphene coated sand were both tested to understand the effect of coating and activation on the filtration process. The materials were characterized using digital microscopy, Raman spectroscopy, scanning electron microscopy, and X-ray diffraction analysis. The material’s efficiency in removing turbidity, nutrients, chemical oxygen demand, bacteria, and specific CECs was studied. Our findings indicate that GCS significantly improves water quality parameters, with notable efficiency in removing turbidity, COD, and bacterial contaminants. The study also highlights the material’s capacity to remove challenging CECs like Sulfamethoxazole and Diphenhydramine, showcasing its potential as a sustainable solution for water reuse applications. This research contributes to the field by providing a comprehensive evaluation of GCS in water treatment, suggesting its potential for removing CECs from treated municipal wastewater.

24 Jun 2025

Analytical Solutions for Coupled Hydromechanical Modeling of Lateral Earth Pressures in Unsaturated Soils

Abstract: Lateral earth pressures in unsaturated soils undergo variations with changes in suction due to infiltration. The infiltration-induced alterations in the pressure head present a coupled hydromechanical problem, where interactions between solids and fluids influence the outcomes. However, existing analytical solutions for determining lateral earth pressures in unsaturated soils do not consider the effects of hydromechanical modeling. This paper presents analytical solutions for coupled hydromechanical modeling of lateral earth pressures in unsaturated soils. For this purpose, an analytical solution for coupled hydromechanical modeling of one-dimensional (vertical) infiltration is integrated into effective stress-based formulations for at-rest, active, and passive earth pressures of unsaturated soils. The solutions are presented for two cases: with and without a consequential drop in groundwater levels during infiltration. The results are verified by comparing them against those obtained from the finite difference method. The findings demonstrate significant differences between coupled and uncoupled results for pressure head and lateral earth pressures for fine-grained soils (characterized by small Gardner’s coefficients) and during transient (short time) conditions. The comparison of analytical and numerical results was very close for both cases and thus illustrates that the Laplace Transform is an accurate and robust method for determining analytical solutions for this problem.

18 Jun 2025

Evaluation of Commercial Cementitious Rapid-Setting Materials and Testing Protocol for Repairing Airfield Spalls

Abstract: The Pavement Repair Material Certification Program assists the US Air Force Civil Engineer Center by executing independent testing on select commercial cementitious proprietary products to repair partial-depth spalls in airfield concrete pavements. The selection of cementitious rapid-setting repair products can be difficult for military personnel considering the number of commercially available proprietary products. Too often, many product manufacturers highlight product strengths while masking undesirable properties. The purpose of this research was to evaluate selected commercially manufactured cementitious products through a series of laboratory testing protocols. These protocols were established to aid airfield managers and repair teams in selecting optimal airfield pavement spall repair materials by maintaining a database of approved products. Under the program, approximately four to six repair products are tested annually. This report presents the laboratory test methods and results of cementitious rapid-setting repair products tested at the US Army Engineer Research and Development Center from 2018 to 2022. The report also evaluates the overall test methods for assessing a material’s suitability for airfield spall repairs. Using the laboratory evaluation, eight products were identified as compatible for partial-depth airfield pavement concrete spall repairs.

17 Jun 2025

Evaluating Permanganate Oxidizable Carbon (POXC)’s Potential for Differentiating Carbon Pools in Wetland Soils

Abstract: Soil carbon (C) storage is a globally important ecosystem service with potential to contribute to climate change mitigation. Wetlands are heavily researched for this. Most studies focus on total C quantification; there is limited methods that evaluate differences in C stability and vulnerability to mineralization within the C pool. Permanganate oxidizable C (POXC) is a well-established soil health indicator shown to be sensitive to changing conditions or management regimes and may prove equally informative. This research quantified POXC in six diverse wetland soils, then evaluated the relationship between POXC and basic soil C properties, microbial indicators, and physical and chemical fractionation metrics. POXC averaged ~ 37 times greater in wetlands than upland agricultural soils, but was less robust in differentiating between individual wetlands than total C or organic matter content. Rather, the ratio of POXC to soil organic C may be a more informative metric for evaluating the proportion of slightly processed C in wetland soils. Significant correlations were found between POXC and almost all soil properties measured, suggesting POXC could be a rapid, reliable, and economical proxy for other analyses. Overall, POXC shows potential for providing novel information about wetland soil C stability, but requires additional research.

16 Jun 2025

Entropy-Based Guidance of Deep Neural Networks for Accelerated Convergence and Improved Performance

Abstract: Neural networks have dramatically increased our capacity to learn from large, high-dimensional datasets across innumerable disciplines. However, their decisions are not easily interpretable, their computational costs are high, and building and training them are not straightforward processes. To add structure to these efforts, we derive new mathematical results to efficiently measure the changes in entropy as fully-connected and convolutional neural networks process data. By measuring the change in entropy as networks process data effectively, patterns critical to a well-performing network can be visualized and identified. Entropy-based loss terms are developed to improve dense and convolutional model accuracy and efficiency by promoting the ideal entropy patterns. Experiments in image compression, image classification, and image segmentation on benchmark datasets demonstrate these losses guide neural networks to learn rich latent data representations in fewer dimensions, converge in fewer training epochs, and achieve higher accuracy.

16 Jun 2025

Estuarine Dams and Weirs: Global Analysis and Synthesis

Abstract: Estuarine dams and weirs are constructed in estuaries for blocking the salt intrusion, securing freshwater, and stabilizing upstream water levels. While they can provide many social benefits, they also alter physical and sedimentary processes. To address this, we perform and extensive remote sensing and literature analysis. Remote sensing was conducted based on a global river database of 1531 rivers representing the largest rivers cumulatively draining 85 % of the landmass discharging into the global ocean. It was found that 9.7 % of global estuaries and deltas are currently affected by estuarine dams or weirs acting as the upstream limit of salt, tide, or storm surge intrusion. Most estuarine dams and weirs are located at x = 0–100 km inland from the mouth and their discharge intervals can be continuous. They are found most in river mouths which are wave-dominated followed by tide-dominated and then river-dominated. They can cause significant changes to the quantity and timing of freshwater discharge, tides, stratification, turbidity, sedimentation, oxygen conditions, phytoplankton blooms, and fish migration. We propose a conceptual model for physical and geomorphological change in mixed wave- and river-dominated and tide-dominated estuaries with estuarine dams.