13 Feb 2026

Morphology-Driven Electromagnetic Shielding Performance of Graphitic Nanoparticles in Segregated Polypropylene Nanocomposites via Electromagnetic Melt Processing

Abstract: Electromagnetic melt-processing has emerged as an innovative and energy-efficient strategy for the structuring of thermoplastic nanocomposites. In this study, polypropylene (PP)-based TPNCs were fabricated using different grades of graphitic carbon nanoparticles to yield electrical conductivity and electromagnetic interference shielding effectiveness. The applied structuring methodology consists of a multiscale processing strategy that combines high-energy ball milling of polymer micro-pellets and CNPs, formulated powder compaction into green bodies, and EM-driven localized heating to produce the TPNCs. This enables the formation of highly segregated, percolated conductive networks at ultra-low filler loadings. The percolation threshold values for green bodies were significantly dependent on CNP morphology, ranging from approximately 0.50 wt% for low-aspect-ratio graphene nanoplatelets to around 1.0 wt% for medium-aspect-ratio carbon nanotubes. Upon EM melt-processing, due to viscoelastic deformation of CNP networks, the resulting threshold values of the structured TPNCs were approximately 0.73 wt%, 0.50 wt%, and 0.74 wt% for low, medium, and high aspect ratios, respectively. High-aspect-ratio CNTs, despite exhibiting greater structural defects, achieved the highest EMI SE of 19.7 dB/mm at 10 wt%, demonstrating that morphology dominates over graphitic crystallinity in governing transport properties and electromagnetic performance. Statistical modeling via response surface methodology confirmed the predictive significance of the CNP morphology and the concentration responses. This work underscores the critical influence of filler architecture and EM-induced structuring in enabling a novel, scalable platform for multifunctional polymer nanocomposites with enhanced electromagnetic shielding capabilities, offering promise for next-generation aerospace, electronics, automotive, and defense applications.

12 Feb 2026

Mechanical Properties and Microstructure of Annealed Ni/CrC-NiCr Metal Matrix Composite Prepared by Cold Sprayed Deposition

Abstract: This study investigates the effects of low (700 ◦C) and high (1000 ◦C) temperature annealing on the micro-structure and mechanical properties of two metal matrix composites consisting of Ni and two separate compositions of CrC-NiCr cold-sprayed onto A-514 structure steel. The mechanical properties, including tensile strength, ductility, interface shear strength, and microhardness, were evaluated after heat treatments. Additionally, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to characterize the microstructure of the annealed deposits. The results showed that annealing significantly enhanced the inter-splat bonding quality between the matrix (nickel) particles. However, higher temperature annealing led to an increase in voids surrounding the cermet particle due to enhanced elemental diffusion. Furthermore, the interparticle bonding between the nickel particles in the matrix and the cermet particle was also improved after annealing. Depending on the composition, the ultimate tensile strength increased by a minimum of 32 %, and the adhesion shear strength improved by over 77 % following annealing at 1000 ◦C. Recrystallization and reduction of the dislocation density in the nickel matrix occurred within the splats during annealing, resulting in increased ductility from less than 0.2 % in the as sprayed condition to more than 6.5 % after annealing. However, a general reduction in hardness was observed after annealing. The interplay between the annealing temperature, microstructural evolution, and mechanical performance demonstrates that the improved bonding directly influenced the mechanical properties, resulting in increased tensile strength, greater ductility, and a shift from brittle to ductile fracture behavior as the micro-structure evolved.

5 Feb 2026

Evaluating Snow Pavement Strength in Remote Cold Environments via California Bearing Ratio (CBR) and Russian Snow Penetrometer (RSP) Combined Testing

Abstract: Accurate assessment of compacted snow strength is critical for ensuring the safety and performance of snow runways in cold environments. The Russian Snow Penetrometer (RSP) is widely used in snow science and engineering due to its simplicity, portability, and capability for rapid field measurements under extreme conditions. Conversely, the California Bearing Ratio (CBR) test remains the benchmark for evaluating the load-bearing capacity of conventional granular materials but is seldom applied to snow because of logistical constraints and the material’s complex mechanical behavior. The relationship between these two pavement evaluation tools remains poorly defined. This work investigates how RSP strength indices relate to CBR measurements to determine whether the RSP can serve as a practical proxy for snow pavement load-bearing capacity. Side-by-side field measurements of snow pavement strength were collected over a 30 h period at two test section locations. Both methods captured temporal strength increases and spatial variability, with consistently higher values at the second site attributed to extended sintering. A moderate linear correlation (R2 = 0.44) between RSP and CBR results supports a quantifiable relationship between the two methods. These findings begin to bridge the gap between conventional pavement testing and snow-specific strength evaluation, demonstrating the potential of the RSP for rapid assessment of snow runways. Continued data collection and analysis will refine this relationship and strengthen its applicability for operational use.

30 Jan 2026

Well-Defined Glycopolymer Chitosan Mimics for Design of Chitosan Nanocomposites

Abstract: Chitosan, a naturally derived polysaccharide with intriguing antimicrobial and polycationic properties, is highly desirable as a biosourced and biodegradable material for biomedical, food packaging, and personal care applications. Its inherent high levels of variability in molecular weight, dispersity, and degree of deacetylation, however, make the establishment of structure− property−processing relationships difficult and limit materials development. In this study, a novel methacrylate-based glycomonomer with saccharide structure similar to that of chitosan was synthesized and copolymerized with methyl methacrylate via reversible addition−fragmentation chain-transfer (RAFT) polymerization to create a series of well-defined chitosan mimics with controlled molecular weights and low dispersity (<1.1). Evaluation of mammalian cytotoxicity and antibacterial activity against Escherichia coli and Staphylococcus aureus revealed performance similar to that of chitosan. The copolymers were used as models to evaluate difficult-to-probe interactions between chitosan and graphene oxide (GO) and elucidate mechanisms of mechanical property improvements observed in chitosan/GO nanocomposite films.

28 Jan 2026

Lightweight Deflectometer (LWD) Evaluation of Low Volume Road Structural Deterioration Under Military Traffic Loads

Abstract: In a combat zone, military vehicles may not have the benefit of traveling on well-constructed pavements, necessitating the use of low volume roads (LVR) to transport personnel and cargo. Military vehicles can cause rapid structural damage to LVRs that are not designed to withstand increased traffic loads. Currently, rapid pavement infrastructure assessment techniques for military personnel are based on qualitative visual inspections which do not provide estimates for structural capacity of the pavement. The objective of this project was to determine whether the lightweight deflectometer (LWD) can be used as a structural evaluation tool for LVRs in contingency operations. This study explored the capability of LWD equipment in evaluating factors that influence flexible pavement structural capacity: load-induced deterioration, soil moisture, and asphalt temperature. Falling-weight-deflectometer (FWD) and LWD tests were performed to measure pavement structural condition. The LWD was shown to be applicable for LVRs experiencing military traffic. The LWD is portable, simple to use, and more suitable than the FWD for LVRs when high rut depths are permitted. LWD data trended similarly to FWD data and therefore can be recommended as an alternate to the FWD in assessing the structural condition of LVRs for contingency planning.

27 Jan 2026

Procedure for Determining the Thermal Properties of Asphalt Binder

Purpose: This technical note documents a testing procedure developed and used by the US Army Engineer Research and Development Center (ERDC) to measure the thermal properties of asphalt binder. While these properties can be measured using specialized precision equipment that is unavailable in most asphalt testing laboratories, no standardized test methods exist to determine the thermal properties of asphalt binder. The test method described herein employs user-friendly equipment to measure the thermal properties of interest. The repeatability of the test procedure was evaluated on samples of asphalt binder blended with varying amounts of graphite and was found to be acceptable.

27 Jan 2026

Evaluation of European Rapid-Setting Concrete Products for Airfield Repairs

Abstract: The USAF is assessing European cementitious repair products to certify them for spall and crater repairs on airfield pavements. As part of this ef-fort, the USAF asked the US Army Engineer Research and Development Center (ERDC) to evaluate and test three European-manufactured rapid-setting materials at the Silver Flag Exercise Site, Ramstein Air Base, Germany. ERDC evaluated and tested two cementitious products manufactured by Concretum, a company in Switzerland (country code CH), and one product, AC Concrete Rapid Set, from CTS Cement Manufacturing Corporation. The product was provided by Korodur International, a German (country code DE) distributor. Rapid pavement repair activities are critical to economically and efficiently sustaining airfield operations with existing pavement infrastructure. Repairing spalls and craters in Portland cement concrete airfield pavements will help lower repair costs from aircraft impact damage and prolong the service life of the pavement, ultimately saving money over its lifespan. Numerous partial-depth spall and full-scale crater repairs were constructed along existing inner and outer slab joints and backfilled with rapid-setting cementitious repair products following manufacturer mixing requirements.

22 Jan 2026

Carbon Partitioning Effects on Martensitic Phase Transformation of Type 301 Steel Under Various Thermal Processing Conditions

Abstract: Simultaneous improvement of strength and ductility in steels has been a daunting challenge for materials scientists, as these properties are by nature mutually exclusive. One design approach that has the merit to use traditional steel processing technologies is the thermo-mechanical stabilization of the austenitic phase. Owing to its highly symmetric FCC crystal structure, if austenite can be maintained during processing, and then further preserved under mechanical deformation, the final microstructure can solve the Pareto design problem where the high strength does not compromise the ability of the material to resist strain localization/incompatibility. The thermomechanical stability of austenite is achieved through compositional modification of the phase, thereby making the control of the elemental partitioning mechanism between existing phases during manufacturing as the main design metric. In this work, we have developed a phase field framework to model the partitioning mechanism of one of the cheapest austenite stabilizers, carbon, in a 301 stainless steel grade. The model uses a coupled framework between thermomechanical and latent heat effects to capture carbon partitioning during martensite nucleation, propagation, and growth kinetics as well as austenite stability and distribution during and after various heat treatment routines. Various microstructures were simulated for the quench state only as well as quench-and-temper heat treatment routines. The resulting microstructure and carbon distribution shed light on various evolutionary effects such as carbon segregation, grain boundary effects, stable martensite morphology, austenite distribution, and phase fraction. In particular, the model was able to reproduce the evolution of carbon-depleted martensite zones and carbon-enriched austenite regions as well as carbon distribution similar to experimental observation at austenite–martensite interfaces.

22 Jan 2026

Exopolysaccharides from Rhizobium Tropici Modified the Surface Characteristics of a Mississippi River Levee Soil Clay and its Bulk Soil Properties

Abstract: Global climate change has led to the increased frequency of extreme flooding events and heightened the vulnerability of river levees to flood related damage. One promising approach to enhancing the sustainability of levee stabilization is the use of eco-friendly, biologically produced soil additives as alternatives to conventional materials for erosion control. This study investigates the effects of exopolysaccharides (EPS) produced by Rhizobium tropici on the physical and engineering properties of clayey soil from a Mississippi River levee. Specifically, the study examines how EPS affects particle size, surface charge, surface area, and key bulk soil properties, including Atterberg limits, compaction behavior, and hydraulic conductivity. Soil samples were collected from a levee embankment located in south of Vidalia LA, an area historically prone to slough slides due to highly plastic nature of its floodplain clay soils. X-ray Power Diffraction was used to characterize the mineralogy of soil clay, EPS and EPS-clay composites. Particle size distribution and Zeta potentials measurements were performed on EPS and EPS-amended clays. Engineering test included Atterberg limit determinations (liquid and plastic limits) and standard compaction tests. The addition of EPS significantly increased the aggregate particle sizes of the levee clay through formation of EPS-clay composites. A strong correlation was observed between mean particle sizes and zeta potential in the composites. EPS also increased the liquid limit and plasticity of the soil while significantly reducing its hydraulic conductivity. Overall, EPS-amended soil demonstrated improved resistance to seepage and erosion, indicating that EPS has the potential to enhance levee soil stability and contribute to more sustainable flood control infrastructure.

14 Jan 2026

Field Demonstration of Magnesium Phosphate Concrete Pavement Repairs for Resilience to Heat and Petroleum, Oils, and Lubricants Exposure

Magnesium phosphate concrete (MPC) represents a possible alternative to portland cement concrete (PCC) that may be more resilient to unique types of distress created by aircraft operated by the United States Armed Forces. Aircraft such as the V-22 Osprey expose airfield pavement to petroleum, oils, and lubricants (POL) as well as surface temperatures up to 400°F. These conditions cause damage to the surface of concrete pavements, resulting in the exposure of aggregates, erosion of the surface, and the creation of foreign object debris. The US Army Engineer Research and Development Center (ERDC) has developed a nonproprietary MPC mixture, which in this study was refined and used to implement full and partial-depth repairs of a V-22 parking apron experiencing heat and POL damage at Cannon Air Force Base.