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.

16 Jun 2025

Enhancing Resilience: Integrating Future Flood Modeling and Socio-Economic Analysis in the Face of Climate Change Impacts

Abstract: As climate change intensifies, floods will become more severe in some areas with geographic variation, necessitating governments implementing systems providing information for climate adaptation. We aimed to develop a methodology identifying areas at an increased risk. In this study, 100-year recurrence interval flood extents and depths were estimated using an ensemble of six independent Coupled Model Intercomparison Project Phase 6 climate models for a past and future period under the highest-emissions climate scenario. The flood inundation results were related to social vulnerability for two study areas in the Mississippi River Basin. To identify at-risk areas, the relationship between the spatial distribution of flood depths and vulnerability was assessed. Finally, an analysis of current and future damages on infrastructure from flooding on residential housing to determine whether damages correlated with higher vulnerability areas. Results show flood extents and depths are increasing in the future, ranging from an increase of 6 to 76 km2 in extent. A statistically significant relationship between spatial clusters of flooding and of vulnerability was found. Overall, a framework was established to holistically understand the hydrologic and socioeconomic impacts of climate change, and a methodology was developed for allocating resources at the local scale.

16 Jun 2025

Evaluation of Tekcrete Fast for Airfield Pavement Repairs

Abstract: Tekcrete Fast is a deployable, high-strength cementitious product with rapid bonding force that was initially developed to provide stability for structures damaged by seismic activity and explosives. The product was evaluated by researchers at the US Army Engineer Research and Development Center for its ability to execute necessary force projection and resilient infrastructure repairs for the US military without major negative impacts to the mission. Full-scale testing of the rapidly emplaced calcium-sulfoaluminate (CSA) concrete product was completed to identify the sustainability and strength of the material with military aircraft traffic. The CSA concrete mixture was designed for dry-mix shotcrete applications and adapted to be placed conventionally (cast-in-place) using a portable skid steer concrete mixer. This report presents a technical evaluation of the field performance of full-depth concrete repairs conducted using the cast-in-place Tekcrete Fast material in a portable concrete mixer. Passes-to-failure rates for each repair were determined using an F-15E load cart. Results indicated that Tekcrete Fast meets the military’s criteria for being an expedient pavement repair solution.

16 Jun 2025

Development of Innovative Cyanophage-Based Biotechnology for Harmful Cyanobacterial Blooms Mitigation: Interim Progress Report

Abstract: Freshwater harmful cyanobacteria blooms (HCBs) are caused by toxin-producing cyanobacteria. Current efforts to prevent and mitigate HCBs include physical and chemical treatments, as well as manipulating the nutrient input and biological ecosystem of impacted water bodies. However, the development of remediation technologies lags behind the increasing frequency, prevalence, and severity of HCBs and their associated adverse health effects and socioeconomic losses. It is difficult to control the side effects of these remediation technologies due to their interactions with nontarget species, including microbes, plants, and animals. This project proposed the use of cyanophages, an abundant natural resource, to control HCBs in a target-specific manner. Here, the results of Year 1 of this effort are reported. Environmental field samples were collected, processed, and characterized morphologically and molecularly. Assays were refined for isolating and characterizing lytic environmental cyanophages. Cryopreservation methods were tested on pure cyanobacteria cultures, while well-characterized cyanophages were used to verify methods to retain infectivity for over 1 year. Methods to induce lysogenic phages to enter their lytic cycle were also explored. The goal was to develop a novel cyanophage-based biotechnology for HCBs mitigation by turning field-collected cyanophages into genetically modified (GM) or non-GM biocontrol agents to disrupt HCBs.

13 Jun 2025

User Guidelines on Catchment Post-Wildfire Hydrological Modeling

Abstract: Wildfires significantly alter watershed hydrology by increasing runoff due to reduced infiltration from soil-water repellency. To predict long-term wildfire impacts, a coupled framework was developed to simulate postfire changes in soil hydraulic properties, infiltration, and hydrological response. This framework integrates Wildfire-Induced Soil Hydraulic (WISH) Factors with a Soil-Moisture Threshold (SMT) formulation in the Green and Ampt infiltration model, representing reduced infiltration due to water repellency. Postfire inputs, including burn severity, soil type, and land use, are formatted for the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model to ensure realistic hydrological simulations. The approach was applied to the 41.7 km² Upper Arroyo Seco watershed in northeast Los Angeles County, where 95% of the area was burned during the August 2009 Station Fire. Hydrological simulations effectively captured increased water repellency and excess runoff following postfire rainfall, demonstrating the model’s ability to represent wildfire-induced watershed changes and improve postfire hydrological assessments.

13 Jun 2025

Enhanced Route Reconnaissance—Generation 1

Abstract: The movement of soldiers and materiel across battlespace is critical to a successful military operation. Knowledge of the road network condition ensures safe and successful vehicle maneuver. This research focused on remote assessment of poor-quality paved road networks for vehicle maneuver using data products derived from three-dimensional point clouds. Point clouds were generated from lidar sensors deployed from ground and airborne platforms to enable engineering analysis of the pavement surface. A series of algorithms developed to extract roughness, grade, radius of curvature, and width along the road network ensured storage of information for graphical display. A vehicle speed lookup table was calculated by conducting computer simulations using the NATO Reference Mobility Model over a range of road parameters. The lookup table enabled determination of the maximum allowable speed for a given vehicle type associated with the extracted road parameters. A graphical interface, developed for displaying the percentage speed reduction as either red, amber, or green squares along the road network, provided visual assessments of road condition. This report summarizes developing a software suite to calculate and visualize speed reduction over a road network as a function of route geometry, condition, and vehicle type. The interface developed can aid in critical logistical decisions that influence the success of military maneuver operations.

12 Jun 2025

Evaluation of Commercial Cementitious Rapid-Setting Materials and Testing Protocol for Repairing Airfield Spalls: Material Testing Results for 2023 and 2024

Abstract: The Pavement Repair Material Certification Program assists the US Air Force Civil Engineer Center by executing independent testing on select proprietary commercial cementitious products used to repair partial-depth spalls in airfield concrete pavements. Selecting cementitious rapid-setting repair products can be difficult for military personnel because of the high number of commercially available products. Too often, 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 permitted products. Under the program, approximately four to six repair products are tested annually. This report presents the laboratory test methods and results for cementitious rapid-setting repair products tested at the US Army Engineer Research and Development Center in 2023 and 2024. These test methods and results were evaluated for their ability to assess a material’s suitability for airfield spall repairs. No products were identified as compatible with partial-depth airfield pavement concrete spall repairs.