11 Aug 2025

Cracking Performance Characterisation of Aramid Fiber-Reinforced Asphalt Mixtures Using Digital Image Correlation

Abstract: Conventional index-based testing of asphalt mixtures cannot accurately capture local deformation in a sample, limiting the usage of standard test measurements. The non-contact-based measurements proved effective to capture local deformation fields. This study aimed to capture the fatigue and thermal cracking behaviour of fiber-reinforced asphalt mixture by utilising digital image correlation (DIC). One binder (PG76-22), a diabase aggregate and three fibers (polyolefin/ aramid fibers (PFA) at 0.05% dosage and Sasobit-coated aramid fibers at 0.01% and 0.02% dosage) were used to prepare a total of four mixtures (one control and three FRAM). All these mixtures were produced at a local batch plant following manufacturer-recommended mixing methods. DIC analysis was performed for three-point bending beam (3PB) and disk shape compact tension (DCT) tests at intermediate temperature (25°C) and low temperatures of −12°C and −18°C. Based on index values from DCT and 3PB, the thermal and fatigue cracking performance enhancement was not significant. However, DIC analysis showed that, regardless of testing temperature, the crack propagated in a random pattern for FRAM, whereas the crack followed a relatively straight path for the control mix. Finally, based on DIC strain contours, FRAM mixtures exhibit distributed strain over a larger area compared to the control mix.

11 Aug 2025

3D Printing of Ultra-High-Performance Concrete: Shape Stability for Various Printing Systems

Abstract: Attention is on concrete 3D printing for its potential in structure optimization, life-cycle extension, emission reduction, and cost savings. Previous studies tailor a mix to a specific printing system and evaluate printability based on measurements of pumpability, extrudability, and buildability. For this investigation, an experimental program was conducted using various printing systems on a nano-modified UHPC mix. A medium-scale gantry and a large-scale ABB robotic arm were utilized, piston-type extruder and an auger system were employed, various nozzles, including circular and rectangular designs, were tested, and a cavity and Thom-Katt pump were used. Results indicated the shape stability of the UHPC mix is influenced by the printing system. Furthermore, the use of a circular nozzle demonstrated different shape stabilities when the extrusion system was changed from a piston-type extruder to an auger system. Additionally, the method of material pumping to the extrusion system was found to be critical for shape stability of printed layers. The mix failed to maintain its shape post-extrusion when using the cavity pump, which was attributed to higher strain rates imposed on material during the pumping process. This issue was not observed when the piston-type pump was used.

7 Aug 2025

C-Band Radar Measurements in a Snow-Covered Boreal Forest Environment

Abstract: Sled-based side-looking C-band radar profiles were collected around Fairbanks, Alaska, in March 2023 during the NASA SnowEx campaign to improve the conceptual understanding of C-band radar wave interactions with snow in a boreal forest environment. Seven transects with different vegetation and ground conditions were studied. Significant volume scattering from snow was observed in this shallow snowpack, indicating sensitivity at lower snow depths (SDs) which are common in high-latitude snowpacks. Manual removal of the snowpack decreased the backscatter by more than 2 dB in all polarizations, with a larger decrease in the cross-polarization, supporting the potential use of Sentinel-1 to retrieve SD.

7 Aug 2025

Financing Natural Infrastructure: Lightning Point, Alabama

Purpose: This technical note explores the restoration of Lightning Point, an award-winning natural infrastructure project led by The Nature Conservancy (TNC) in coastal Alabama. The story of Lightning Point provides an exemplar case study of successful coordination of cross-sector partnerships and the use of ecosystem services valuation to attract project funding.

7 Aug 2025

Continued Development of Methods for the Determination of Legacy and Insensitive Munitions from Environmental Matrices: Addition of Four Degradation Products and One Internal Standard to Previously Developed 29-Analyte Method

Abstract: To continue improving separation methods of explosive analytes and their degradation products, chromatographic methods from Environmental Protection Agency (EPA) 8330B, Strategic Environmental Research and Development Program (SERDP) 2722, and Environmental Sensors for Explosives were modified to include the separation of four additional analytes and one internal standard so that a total of 36 analytes could be resolved on a single column. Four degradation compounds, 3-amino-1,2,4-triazol-5-one (ATO); 1 methyl-3-nitroguandine (MeNQ); 2 methoxy-5-nitroaniline (MENA); and 4 methoxy-3-nitroaniline (iMENA) were added to the analytical method. The internal standard, 3,5-dinitrotoluene, was also added to the method to extend its application. Additionally, an analytical method on gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS) were explored for the analytes of interest.

7 Aug 2025

Thermodynamic Exposure Reductions of PCBs Available to Lumbriculus variegatus in Lake Erie Region Sediments Amended with Activated Carbon

Abstract: A chemical activity-based assessment of PCB bioaccumulation from Lake Erie region sediments was studied using polydimethylsiloxane coated fibers and Dow Corning silicone coated jars. Polymers equilibrated with the sediments were compared to bioaccumulation in blackworms, exposed to the sediments for 28 days. Sediments were from Cleveland Harbor, Ashtabula Harbor, and Buffalo River. Sediment from Ashtabula was amended with activated carbon. Using lipid-polymer partition coefficients, the polymers were able to estimate actual bioaccumulation in worms, with close to a 1:1 relationship and r2 = 0.94. If lipid normalized worm bioaccumulation was compared to equilibrated PDMS concentrations, there was a 20:1 ‘off-set,’ but the relation was still strong. Different doses of AC were mixed into Ashtabula sediment in the laboratory, corresponding to 1 %, 10 %, and 100 % of the native total organic carbon. Based on PCB concentrations in DC silicone, a target AC dose equal to 10 % of the TOC would substantially reduce bioaccumulation of the more hydrophobic PCBs from Ashtabula Harbor dredged material. Widespread AC amendment to surficial sediment of the eastern basin of Lake Erie may reduce the thermodynamic pressure of PCBs from that sediment source and allow for a continued decline in fish tissue concentrations.

5 Aug 2025

Vessel Draft and Velocity Updates for Tybee Island Vessel Wake Analysis

Purpose: This Coastal and Hydraulics Engineering technical note (CHETN) updates the results of a previous study (ERDC/CHL TR-22-21; Bain et al. 2022) and evaluates whether newly available datasets offer greater insight into the relationship between vessel characteristics and wake conditions near Tybee Island, Georgia. Whereas the original study used vessel drafts from the Automatic Identification System (AIS), the present analysis substitutes more accurate draft information from US Customs Foreign Vessel Entrances and Clearances (FVEC) records. In addition, cross-sectionally averaged flow velocities from the US Geological Survey (USGS) gauge at Fort Pulaski, Georgia, are used to update the AIS-reported speed over ground (SOG), yielding the vessels’ speed relative to the water. The combination of these two updates generates a visible improvement in wake forecasting ability. However, the mechanisms underlying drawdown oversteepening and bore formation near the beach remain poorly understood, and further study is recommended to determine the cause of this hazardous behavior.

5 Aug 2025

Determination of Runoff Coefficient and Permeability of Airfield Matting (AM2) Long-Term Placement

Abstract: This report describes a small-scale water infiltration study of airfield mat-ting version 2 (AM2) at a test site on the US Army Engineer Research and Development Center’s Vicksburg, Mississippi, site. Before constructing AM2 runways, engineers must conduct a storm water drainage analysis; but no published study defining the runoff coefficient for AM2 exists. This study evaluated water infiltration of AM2 when subjected to 10-year and 100-year storm conditions from a proposed building site at Tyndall Air Force Base near Panama City, Florida. The allowable grade slopes for AM2 runways range from 1% to 3% in the longitudinal direction and 1% to 5% in the transverse direction. Multiple tests were conducted at various combinations of allowable grade slopes to determine grade slope orientation effects on AM2 runoff behavior. Runoff coefficients generally fell within the range of 0.05 to 0.10 for AM2. The highest runoff coefficients observed were within the range of 0.35 to 0.40 for a 5% transverse grade slope with a 1% longitudinal grade slope. Observation of the water infiltration behavior showed runoff increased with increasing transverse slope and de-creased with increasing longitudinal slope.

4 Aug 2025

Acoustic and Seismic Wave Transmission Throughout the Multidomain Environment: Experimental Design, Methods, and Construction of a Prototypical Littoral Zone

Abstract: The future operational environment is projected to be a multidomain, transparent battlefield in which the Army must be able to act as both a supported and supporting force. An accurate detection and interpretation of acoustic and seismic signals propagating across land-air-water (LAW) interfaces are required to meet future requirements of a fully “transparent” domain. The LAW domains converge at the significant contested littoral zones. Historically, interpreting signals crossing media boundaries has been studied by stovepiping each distinct medium. These fragmented perspectives led to discrepancies in boundary and adjacent media descriptions and media-specific governing physics. No comprehensive physics framework exists to accurately predict how disorderly waveforms freely traverse LAW media boundaries. To understand these complex phenomena, a highly controlled physical experiment was designed and implemented. Repeatable controls were conducted. Epistemic uncertainty was decreased, and high waveform fidelity was maintained in the experimental setup by not interfering with wave transmission or sensor accuracy between controls. This report summarizes the experimental design, implementation, challenges, and repeatability.

29 Jul 2025

Engineering Practice Guide for Floodplain Benching: A Natural Infrastructure Approach for Riverine Systems

Abstract: Floodplain benches are a potential solution for inland river systems where out-of-bank flooding generates unacceptable flood risk and access to riverine floodplains has become restricted over time. Benches are a naturally forming geomorphic feature between the riverbed and a higher floodplain or terrace. In addition to reducing flood risk, benches reduce erosion risk, improve aquatic ecosystems, enhance plant and wildlife diversity, expand recreational opportunities, and may be places of cultural and tribal value. This document informs engineering activities related to site investigation and design of floodplain benches. It is intended to be used by engineers and ecologists to inform the design of floodplain benches in a manner that is consistent with and augments other planning, design, and engineering guidance. A well-designed floodplain bench can improve ecological and biological functions while also reducing flood risk by creating a channel in geomorphic equilibrium with current conditions and resilience to anticipated changes in hydrology and sediment supply rates. This publication is among a series of planned technical reports providing guidance on how to identify, conceptualize, and design natural infrastructure solutions for riverine and coastal systems. It has been produced by the US Army Corps of Engineers (USACE) Engineering With Nature® Program.