30 Oct 2025

Thermomechanical Material Characterization of Polyethylene Terephthalate Glycol Carbon Fiber 30% for Large-Format Additive Manufacturing of Polymer Structures

Abstract: Large-format additive manufacturing (LFAM) is used to print large-scale polymer structures. An understanding of the thermal and mechanical properties of polymers suitable for large-scale extrusion is needed for de-sign and production capabilities. An in-house-built LFAM printer was used to print polyethylene terephthalate glycol with 30% short carbon fiber (PETG CF30%) samples for thermomechanical characterization. Thermogravimetric analysis confirmed the samples had 30% carbon fiber by weight. X-ray microscopy and porosity studies found 25% porosity for undried material and 1.63% porosity for dry material. Differential scanning calorimetry showed a glass transition temperature (Tg) of 66°C, while dynamic mechanical analysis found Tg to be 82°C. The rheology indicated that PETG CF30% is a good printing material at 220°C–250°C. Bending experiments showed an average of 48.5 megapascals (MPa) for flexural strength, while tensile experiments found an average tensile strength of 25.0 MPa at room temperature. Comparison with the literature demonstrated that the 3D-printed PETG CF30% had a high Young’s modulus and was of similar tensile strength. For design purposes, prints from LFAM should be considered from a bead–layer–part standpoint. For testing purposes, both material choice and print parameters should be considered, especially when considering large layer heights.

30 Oct 2025

Full-Scale Evaluation of Multi-Axial, Multi-Aperture Shape Geogrids in Flexible Pavement Applications

Abstract: The US Army Engineer Research and Development Center (ERDC) con-structed a full-scale pavement test section to evaluate the performance of three recently developed multi-axial, multi-aperture shape geogrids, referred to as HX5.5, NX750, and NX-Dev, in asphalt-surfaced highway applications. The test section consisted of a 4.2 in. thick and a 3.8 in. thick hot-mix asphalt layer placed over a 6 in. thick and 4 in. thick crushed aggregate layer, respectively. Underlying the crushed aggregate layer was a 2 ft thick clay subgrade that had a 6% California Bearing Ratio. Simulated truck traffic was applied using ERDC’s heavy vehicle simulator–transportation with a dual-wheel tandem axle truck gear. Rutting performance and instrumentation response data were monitored at multiple traffic intervals. Observed rutting in the geogrid test items was approximately one-third of that in the unstabilized item, in which was a meaningful performance improvement. Instrumentation response data indicated that the geogrid inclusion pro-vided a stiffening effect that altered the anticipated pavement response. An analytical investigation showed that traditional layered elastic analysis techniques did not adequately describe the pavement response with geogrid inclusion. A robust model that included material nonlinearity and a geogrid interface model provided a closer approximation to the measured subsurface response.

29 Oct 2025

Beneficial Use of Contaminated Sediments: A Review of Technical, Policy, and Regulatory Needs

Abstract: This special report summarizes key results from the March 2024 Sediment Management Working Group (SMWG) Contaminated Sediment Beneficial Use Workshop sponsored by US Army Engineer Research and Development Center’s (ERDC’s) Advanced Materials and Substances of Emerging Environmental Concern (AMSEEC) center, a multilaboratory research collaborative reviewing solutions to environmental challenges, and the Dredging Operations Environmental Research (DOER) Program, the navigational dredging research arm of ERDC. The workshop focused on potential avenues for treatment and management of contaminated sediments to support expanded beneficial use (BU) opportunities. AMSEEC, with support from DOER, sponsored four pilot studies to advance the technical aspects of the workshop program and partnered with the SMWG, an industry consortium, to organize the workshop in Washington, DC. The workshop was attended by more than 75 practitioners and relevant stakeholders to review these pilot studies and the challenges of advancing treatment and management of contaminated sediment to support BU. This special report summarizes and prioritizes technical, regulatory, and policy needs to enable expanded BU opportunities for contaminated sediments.

29 Oct 2025

A Multigenerational Exposure of the Zebrafish (Danio rerio) to PFOS

Abstract: The ecological risk of PFOS in extended chronic and multigenerational exposures was quantified through survival, growth, reproduction, and vitellogenin (egg yolk protein precursor) responses as well as PFOS bioconcentration in zebrafish (Danio rerio). Fish were exposed to environmentally relevant PFOS concentrations through 180 days postfertilization (dpf) in the parental (P) and first filial (F1) generations and 16 dpf in the second filial (F2) generation. Survival decreased significantly in P and F2 generation exposures, but not F1, at the highest PFOS treatment. Significant adverse effects on body weight and length occurred predominantly at highest exposure treatment. Finally, PFOS had no significant effects on P or F1 egg production and survival or whole-body vitellogenin levels in P or F1 male fish. The present investigation indicated a threshold for ecologically relevant adverse effects in zebrafish at 119 μg/L (standard deviation [S.D.] 23 μg/L, n = 10) for survival and 87 μg/L (S.D. 48 μg/L, n = 19) for all statistically significant negative effects observed. Importantly, males had significantly increased PFOS accumulation and bioconcentration factors versus females in both P and F1 generations. PFOS transfer to eggs was not a depuration pathway. Finally, a toxicokinetic model was developed to reliably predict PFOS whole-body burdens.

24 Oct 2025

Hydraulic Evaluation of the Proposed Brandon Road Lock Flushing System

Abstract: The Great Lakes Mississippi River Interbasin Study is a US Army Corps of Engineers effort focused on stopping the migration of aquatic nuisance species (ANS) from the Mississippi River to the Great Lakes. Brandon Road Lock and Dam (BRLD) has been chosen as the location to stop this northward migration. The study described in this report focuses on the performance of a proposed lock flushing system intended to reduce the risk of ANS from passing northward through BRLD. This system is a modification of the existing filling/emptying (F/E) system and must perform as both a lock flushing system and the F/E system. This study focuses on determining the performance of the flushing system and the F/E system to establish flushing and F/E operating parameters for safe lock operation. The results presented include qualitative descriptions and quantitative measurements of the flushing and F/E systems’ hydraulic performance. Finally, this study investigates commercial barge tows entering and exiting the lock chamber to determine the effects such barge tow movement has on both the barge tow and the vessel-generated currents. This report provides recommendations for flushing system and F/E system operation and commercial barge traffic considerations during flushing.

20 Oct 2025

Tensile Strength of Native Boreal Forest Plant Species

Abstract: Plant roots influence the engineering properties of soil, such as erodibility and strength. Plant roots’ contribution to soil shear strength is of particular importance in Arctic and subarctic environments where the shallow subsurface experiences a decrease in shear strength due to permafrost thaw, subsidence, and wildfires. This paper presents the testing method, sample collection and specimen preparation, and tensile strength testing results for laboratory- and greenhouse-grown boreal forest plants to compare root tensile strengths among plant species and functional groups, including deciduous shrubs and trees, evergreen trees, forbs, graminoids, and grasses using a universal testing machine and a modified triaxial device. The results illustrate that root tensile strength increases as root diameter decreases (as a power function). The root diameters successfully tested ranged from 0.063 mm (grasses) to 8.72 mm (deciduous shrubs) across all functional groups. When compared across functional groups and root diameters for each species, grass roots exhibited the highest tensile strength for root diameters less than 0.8 mm, deciduous tree roots displayed the largest tensile strength for root diameters greater than 0.8 mm, and forbs were consistently the weakest, supporting the conclusion that a diverse spread of functional groups is most effective for slope stabilization.

17 Oct 2025

Northeast Florida Regional Sediment Management: A Guide to Using Dredged Material for Estuarine Restoration

Abstract: Regional sediment management is a systems approach using best management practices for more efficient and effective use of sediments in coastal, estuarine, and inland environments. The primary RSM objective for this Northeast Florida study is to determine what opportunities exist to beneficially use dredged material for ecosystem restoration and habitat enhancement. A secondary objective is to ensure more efficient use of federal funds by coordinating dredging schedules for navigation projects with federal, state, and local authorities. This study met these objectives through collaboration with stakeholders on the technical, social, and cultural components required to combine resources to meet common goals. The Federal Standard for navigation projects in Northeast Florida is either upland disposal or disposal at the Jacksonville Ocean Dredged Material Disposal Site. This document describes five beneficial uses of dredged material: (1) thin-layer placement, (2) island creation and restoration, (3) dredged hole filling, (4) shoreline stabilization, and (5) upland beneficial use. Dredged material from navigation projects throughout Northeast Florida was considered, including Fernandina Harbor, Kings Bay Naval Submarine Base, Jacksonville Harbor, St. Augustine Inlet, Ponce De Leon Inlet, and the Atlantic Intracoastal Waterway. For each placement strategy, the document outlines the required sediments, volumes, construction methodologies, and estimated costs.

15 Oct 2025

An Investigation into the Correlation Between Selected Coastal Protection Indices and Percent Residual Dune and Berm Volumes Following Coastal Storms

Abstract: Morphometric indices describe the dimensions of a dune and berm profile and can serve as relative metrics of coastal protection. However, coastal vulnerability to storm damage also depends on storm, wave, sediment, and offshore characteristics. Recently, more elaborate non-morphometric indices have been proposed in an effort to account for these other factors. This study compares the correlation between these morphometric and non-morphometric indices and one measure of coastal protection, the ability of a dune and berm profile to resist storm-induced changes in volume. This study uses a numerical-simulation approach rather than an empirical approach because a sufficiently comprehensive set of observational data does not exist. A randomized sample of dune and berm profiles were generated at eight coastal locations. Using the cross-shore numerical model (CSHORE), storm-induced changes in dune and berm volume were simulated for storms of low to moderate severity. The correlation between the various prestorm indices and the percentage of prestorm dune and berm volume remaining after the storm was calculated at each location. Results show that no single index always exhibits a higher correlation with percent dune and berm volume remaining. However, some indices were far more likely than others to produce higher correlations.

15 Oct 2025

Use of Chirp Sub-bottom Acoustic Profiling to Assess the Integrity of the Submerged Portion of the Jonesville Lock and Dam, Located at Jonesville, Louisiana

Abstract: Jonesville Lock and Dam serves as a critical navigation conduit along the Black River in Louisiana. The structure has previously been impacted by localized scour, leading to concerns regarding the structure’s long-term integrity and an effort to stabilize the structure with targeted fill efforts. Despite these efforts, operators continued to observe localized water and sediment swirls and boils during high-flow events, suggesting that scour is still an ongoing concern. Recent research suggests that shallow acoustic sub-bottom mapping might be able to identify ongoing or historical scour along and underneath concrete structures, and that technique was evaluated at Jonesville. Sub-bottom profiles revealed density anomalies along the inside, eastern wall of the lock structure and underneath both the lock floor and the wall. These anomalies are interpreted to represent an erosional surface created by ephemeral scour events, with subsequent infilling of homogenous, fine-grained sand. The complex geology on which Jonesville is constructed likely contributes to the localized scour observed at this navigation facility.

14 Oct 2025

Literature on the Load Distributions for Effects on Hydraulic Steel Structures: Notes on Existing Literature for Establishing LRFD Load Factors

Abstract: Previous to 1993 Hydraulic Steel Structures (HSS) were designed using Allowable Stress Design (ASD); modern design, has transitioned to Load and Resistance Factor Design (LRFD) method, which targets a probability of a limit state. To implement LRFD, an understanding of the probability distributions of the loads applied to the structure, the resistances of the components of the structure, and the approximate durations and overlapping of these loads must be determined. The loads applied to HSS are dissimilar to loads applied to buildings or roads, so existing distributions cannot be applied to this problem. Any attempts to implement LRFD without these distributions will result in designs that do not target the probability of reaching a limit state. The USACE has adapted LRFD load combinations and factors to encompass the different geometry, force and displacement conditions, and environments present in HSS. This work collects literature for load effects on HSS to determine either probabilistic distributions or what loads sufficiently unknown to necessitate new research. Because the loads the HSS are subject to are dissimilar to other designed structures, these load distributions cannot be taken from them directly. Loads considered are hydrodynamic, barge impacts, debris impacts, ice expansion, seismic, wind, and waves.