11 Sep 2025

Influence and Mechanisms of Mineral Chemistry and Sizing Effects on Cementitious and Pozzolanic Reactions

Abstract: This study investigated whether materials traditionally considered inert could become reactive with increased fineness. Researchers used multiple techniques to produce materials in a variety of fineness levels. The final products were then analyzed for pozzolanic reactivity in accordance with ASTM 1897 and for their influence on portland cement hydration in accordance with ASTM C1702. Results indicated that pozzolanic reactivity was not produced by successive grinding for either chemistry, at least within the limits of the techniques used. Both chemistries were shown to influence the rate of portland cement hydration when ground finer than cement. This phenomenon is known as the filler effect, and it became more significant with increased fineness.

10 Sep 2025

Geology, Geomorphology, and River Engineering in the Memphis-to-Rosedale Reach, Lower Mississippi River

Abstract: This study examines the geology and geomorphology of the Mississippi River between Memphis, Tennessee, and Rosedale, Mississippi, with a focus on the Tertiary (65 to 2 million years) surface and how the present-day river has impacted this surface. Previous mapping efforts involving the Tertiary surface by the US Army Corps of Engineers are reviewed. Relevant maps are included as plates herein to facilitate wider dissemination. Today’s channel has deepened through time due to river engineering, which includes oxbow cutoffs and hardening of river banks with revetment and training dikes to prevent uncontrolled bank caving and channel migration. The course of the river was fixed in place by 1962. The thalweg of the river intersects the Tertiary surface at Helena, Arkansas, at the Hardin oxbow cutoff, and near the vicinity of Memphis, Tennessee. At these three locations, the Tertiary surface occurs at shallow elevations and in close proximity to where Tertiary sediments outcrop. A deeply buried alluvial valley is present in the Tertiary surface. Erosion of Jackson Group sediments in this valley exposes the underlying Claiborne Group sediments. Jackson and Sunflower oxbow cutoffs occur in the deepest parts of the alluvial fill.

10 Sep 2025

Evaluation of the Plate Load Test for Design of Rigid Airfield Pavements Using Various Plate Sizes

Abstract: This report addresses the state of knowledge of the plate load test and modulus of subgrade reaction (k), industry’s desire to simplify the plate load test, and the effect of the k-value on rigid pavement design. The report traces back the theory behind the k-value over 150 years to evaluate the current state of knowledge. A total of 144 plate load tests were executed on three subgrade materials under varying base course thick-nesses. Plate load testing was designed to evaluate various plate sizes and testing standards (e.g., the military standard CRD-C 655-96 and the ASTM International [commonly called ASTM] standard ASTM D1196-21). By measuring plate load tests on varying base course thicknesses, field-measured effective k-curves were developed. Overall, results show that kASTM was higher than kCRD. Although a smaller plate setup produced similar results, additional variability was introduced when using smaller plates. The results of the field data imply that the current effective k-curves underestimate the global stiffness contribution provided by the base layer. Findings suggest the analytically generated effective k-curves validate the measured k-values in the field.

9 Sep 2025

Using Transfer Learning to Enhance Void Detection and Shear Wave Velocity Model Inversion from Near-Surface Seismic Shot Gathers

Abstract: A Convolutional Neural Network (CNN) has been designed to delineate the shear-wave velocity (Vs) models and detect subsurface void locations. Addressing the processing and interpretation challenges posed on real seismic data, our strategy emphasizes that leveraging the ground truth, which is the void location in this study, enables the CNN to catch the identical features in real waveforms. Initially, a synthetic dataset is employed, imparting foundational knowledge to the CNN regarding the Vs model and void locations. Drawing inspiration from transfer learning, this pre-trained CNN serves as an initial model and is refined using a real dataset focused on void locations. After refining, the CNN shows enhanced reliability to detect the void and extract the Vs model, as evidenced by the improved alignment between forward modeling and real waveforms. Our findings underscore how leveraging the ground truth can actualize the potential of CNN on velocity model extraction.

9 Sep 2025

Damage Parameters and Crack Morphology in High Strength Concrete BBR9 Under Dynamic Uniaxial Compressive Loading: An Experimental Study

Abstract: There has been significant growth in the use of high-strength concrete in structures designed to withstand extreme events. Continuum damage mechanics has been utilized to develop constitutive models that can capture the damage evolution in concrete materials under such conditions. This study is aimed at investigating the damage initiation, progression, and morphology of HSC-Baseline Basic Research Mixture 9 when subjected to dynamic uniaxial compressive loading. A Kolsky compression bar system was implemented to introduce distinct damage states in the HSC-BBR9 specimens. The partially damaged specimens were tested to quantify their residual mechanical properties. Accordingly, stiffness-based and strength-based constitutive damage parameters were adopted to propose an indirect quantification of the damage state based on the deterioration of mechanical properties. The X-ray micro-computed tomography technique was utilized to extract measurements of 3D crack networks that provide a direct quantification of the damage state based on microstructural evidence. The results demonstrated the HSC-BBR9 material can maintain its residual mechanical properties into the post-peak regime. In the initial stages of damage, stiffness and strength deteriorate at a proportional rate; however, as damage accumulates, the rate of stiffness degradation increases. Correlations between constitutive damage parameters and 3D crack measurements were established.

3 Sep 2025

Optimal Transport-Based Full-Waveform Inversion for Shallow Seismic Data

Abstract: Full-waveform inversion is widely used to reconstruct subsurface properties at different geologic scales. For shallow land applications using surface waves, a lack of information on the source wavelet, dispersion, and presence of higher modes increases the nonlinearity of the inverse problem. The inversion can become more challenging with the presence of near-surface complexities associated with scattering, attenuation, and high-contrast variations in the elastic parameters. Compared with the least-squares formulation, GSOT provides a more convex misfit function and reduces dependence on the accuracy of the initial model. Although a few field-data applications have shown the potential and benefits of using GSOT-based FWI with body waves, there are limited real applications of the inversion with a GSOT misfit function for NS characterization. Despite considerable effort with blind benchmark tests in exploration seismology, typically synthetic FWI examples for NS applications are demonstrated through an “inverse crime” approach. Synthetic FWI examples performed compare the performance of LS- and GSOT-based FWI with more realistic scenarios. We demonstrate the GSOT misfit function improves the initial 1D velocity models and guides the updates toward the actual subsurface properties. This enables the recovery of higher-mode Rayleigh waves and reconstruction of the cavity with better precision.

3 Sep 2025

Three-Dimensional Simulation of Finite-Strain Debonding Using Immersed Meshes

Abstract: We propose a method for modeling interfacial damage and debonding under quasi-static loads using immersed meshes in 3D at finite strains. This is an extension of our previous work on an immersed variational multiscale discontinuous Galerkin method in 2D. The variational approach remains the same, but transitioning from 2D to 3D introduces significant complications in the computational geometry aspects. The immersed VMDG method is a stabilized interface formulation derived using variational multiscale ideas to apply discontinuous Galerkin treatment to the interface while employing a continuous Galerkin approximation elsewhere. Key benefits are the variationally derived stabilization terms that evolve during deformation and are free of user-defined parameters. Also, the transition from perfect bond to damage behavior at the interface is handled naturally by incorporating an interfacial gap variable governed by a yield criterion and a flow rule. To support 3D simulations, we introduce algorithms for integrating cut elements, forming interface segments, and computing the VMDG stabilization tensor. Cut-element integration is performed using voxel-based moment-fitting integration to avoid the robustness issues associated with using mesh Booleans and tetrahedral integration cells. Several numerical examples are presented to demonstrate the robustness, efficiency, and range of applicability of the method.

2 Sep 2025

Morphology Control in Waterborne Polyurethane Dispersion Nanocomposites Through Tailored Structure, Formulation, and Processing

Abstract: Waterborne polyurethane dispersions (PUDs) have garnered increasing interest in recent years due to the growing demand for environmentally friendly materials. The unique phase-separated morphologies exhibited in PUD films and coatings provide opportunities for directing the distribution of functional additives and controlling properties. Although there has been extensive research on polyurethanes for several decades, the mechanisms underlying the PUD morphology formation are poorly understood. The morphologies are driven by interactions between hard segments (HS), and the process is further complicated by the presence of colloidal particles and the intricate interaction between the urethane/urea linkages and water. In this work, structure−property-processing relationships between HS content and structure, relative humidity, particle size, and the resulting dry film morphology of PUDs were determined in two diisocyanate systems: hexamethylene diisocyanate (HDI), a symmetric, flexible diisocyanate; and isophorone diisocyanate (IPDI), an asymmetric, sterically hindered cyclic diisocyanate. HDI-based films exhibited semicrystalline morphologies with HS superstructures that are sensitive to relative humidity. IPDI-based films displayed spherical coalescence-suppressed morphologies influenced by particle size and zeta potential. PUD compositions and processing conditions were controlled to produce nanocomposite films with an enhanced dispersion of nanoadditives.

29 Aug 2025

Nanofiber Fabrication by Electrospinning Technology: Optimization, Characterization, and Application

Abstract: This project explores electrospinning (ES) as one of the most successful technologies to produce nanofiber materials. Electrospun nanofibers are used in various military technologies, including advanced filtration systems, impact-resistant protective gear, thermal insulation, radar absorption for camouflage and stealth, antimicrobial wound dressings, drug-delivery patches, rapid healing, efficient solar cells, and self-cleaning materials for regeneration. Researchers at the US Army Engineer Research and Development Center (ERDC) investigated electrospinning effects on morphology, crystallinity and distribution of metal oxides for photocatalytic activities, and magnetic and mechanical properties in reinforcing composites. This study includes the following fabricated electrospun mats: -iron and titanium oxide (Fe3O4 and TiO2) with polyvinyl alcohol (PVA) -graphene, graphene oxide, and reduced graphene oxide with polyvinylidene fluoride (PVDF) -graphene-polyacrylonitrile (PAN) -metal-organic frameworks (MOF), graphene-MXene with PAN The research presented herein includes electrospinning theory, process, and parameters; sol–gel technology in solution preparation; and electrospinning sample characterization to guide readers in the fabrication of electrospun fibers with targeted characteristics. Future studies explore electrospun MOFs and MXene, a class of two-dimensional inorganic compounds with transition metal carbides, nitrides, or carbonitrides composites. These studies are invaluable for advancing military programs and enhancing warfighter support and civil works.

12 Aug 2025

Carbon Nanotube-Based Segregated Thermoplastic Nanocomposites Structured via Electromagnetic Melt Processing

Abstract: The EM-processed TPNCs prepared with EM-susceptible carbon nanotubes exhibited a significant enhancement in transport and mechanical properties, outperforming conventionally processed TPNCs. Thus, EM-processed TPNCs demonstrated an ultralow electrical percolation threshold and a remarkable increase in volume electrical conductivity of 8 orders of magnitude at only 1.0 wt % CNT loading. This highlights the superior network formation, level of segregation, and structuring enabled by EM processing. Differential scanning calorimetry and X-ray diffraction revealed EM-processed TPNCs exhibited higher crystallinity and a predominantly α crystal phase compared to hot-pressed TPNCs. Microstructural inspection by electron microscopy disclosed EM processing led to segregated but interconnected multiscale networks of a thin and well-defined CNT interphase that encompassed from the nanoscale of CNTs to the macroscopic scale of TPNCs. The EM-processed TPNCs developed a statistically higher stiffness and in certain cases, even better strength than hot-pressed TPNCs. However, EM-processed TPNCs displayed significantly lower ductility, owing to their higher crystallinity, more brittle crystal α phase, and potential formation of microvoids in the bulk of the TPNCs inherent to the unoptimized EM processing. This work provides an understanding of an alternative and unconventional processing method capable of achieving higher structuring in nanocomposites with advanced multifunctional properties.