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    <title>Research in Progress (RIP)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Research in Progress (RIP)</title>
      <url>https://rip.trb.org/Images/PageHeader-wTitle-RIP.jpg</url>
      <link>https://rip.trb.org/</link>
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    <item>
      <title>Development of Multifunctional Cementitious Composites with Tailored Pore Structures for Intelligent Infrastructure Applications</title>
      <link>https://rip.trb.org/View/2696035</link>
      <description><![CDATA[In this study, porous cement-based electrolytes with three-dimensional interconnected microporous structures will be prepared using a controllable foaming strategy. The foaming process will be tailored to adjust pore size, connectivity, and overall porosity, enabling systematic investigation of how microstructural parameters influence ionic transport and overall functional performance. Multiple formulations, incorporating different foaming agents and mix proportions, will be developed to identify mixtures that maintain adequate mechanical integrity while providing enhanced ion mobility and stable electrochemical behavior.
The resulting cementitious electrolytes will be comprehensively characterized using electrochemical techniques, including cyclic voltammetry to assess charge–discharge behavior and electrochemical impedance spectroscopy to quantify ionic conductivity and interfacial resistance. These measures will be performed under varied curing conditions and testing environments to evaluate reproducibility and long-term stability. The data will correlate with microstructural observations (e.g., pore connectivity and distribution) and compressive strength results to establish quantitative relationships between pore architecture, mechanical performance, and electrochemical response. Through this approach, the project will define design guidelines for cement-based electrolytes that provide reliable functional properties suitable for integration into advanced, multifunctional civil infrastructure systems.
]]></description>
      <pubDate>Sat, 25 Apr 2026 12:31:31 GMT</pubDate>
      <guid>https://rip.trb.org/View/2696035</guid>
    </item>
    <item>
      <title>Ultrasonic Inspection of Reconditioned Railroad Bearing Components – Year 3</title>
      <link>https://rip.trb.org/View/2574196</link>
      <description><![CDATA[Freight rail bearings are often subjected to heavy loads such that the performance of each bearing plays a crucial role in the safe operation of the entire train. Even bearings that are properly maintained may still fail due to rolling contact fatigue (RCF) if local regions within the bearing race do not meet established effective case depth (ECD) standards. In addition, little is known about potential changes that may occur within the highest stress region after extensive service life. Ultrasonic grain scattering shows sensitivity to both microstructure and residual stresses such that nondestructive measurement methods based on diffuse ultrasonic backscatter have shown a high correlation with the overall status of the raceway. Results from the first year showed clear differences between new and reconditioned bearing cups in terms of their ultrasonic signatures. This work will be expanded to include spatial maps of raceways to identify locations that are outside the statistical bounds expected for a given part. Those locations will be identified and those parts will be tested in simulated service life testing at UTRGV for comparison with the predictions. ]]></description>
      <pubDate>Mon, 14 Jul 2025 19:01:11 GMT</pubDate>
      <guid>https://rip.trb.org/View/2574196</guid>
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    <item>
      <title>Microstructure Analysis with X-ray CT Scan Imaging to Develop Enhanced Full-Depth Reclamation (FDR) Mixes Through Optimized Mix Design Compaction Effort</title>
      <link>https://rip.trb.org/View/2480362</link>
      <description><![CDATA[The use of Full Depth Reclamation (FDR) and the development of novel binders have continued to grow over the last three decades in the US. The mix design is conducted through several steps including combining in-place materials, adding pre-mix water, applying and mixing binder, compacting, curing, and testing with or without conditioning. To “harmonize” testing conditions for different “stabilization” methods, agencies often utilize a generic “mix design” system, irrespective of the type of in-place materials and binders. This approach, while convenient, is not the most optimal, as it may not utilize the unique advantages of a specific binder and may also result in an inferior FDR base course. The single most important property that controls the strength of FDR mixes and their potential to deteriorate over time under traffic loading is the efficiency of compaction during the recycling process. Efficient compaction of FDR mixes can result in a favorable microstructure, which increases the density and strength, reduces the potential for moisture damage, and enhances its long-term durability. The microstructure of the compacted FDR is affected by the optimum binder content, which is mostly dictated by the compaction effort (number of gyrations with the Superpave Gyratory Compactor, SGC) that is utilized during mix design. Different research reports recommend different gyration numbers, and at the same time, tests indicate a significant difference in the strengths of samples compacted with different numbers of gyration. Some binders can significantly facilitate compaction at the expense of relatively more sensitivity to compaction effort. Therefore, a pertinent question is, what is the optimized compaction effort that could lead to the formation of the optimized microstructure of FDR mixes that are resistant to deterioration? The answer to this question will result in the development of new specifications to guide the mix designers to develop appropriate optimum binder content and the contractors to utilize appropriate compaction equipment and passes in the field. The research is proposed based on observations from the literature, inferences from the Cycle 1 SPTC study, and interviews with the FDR and cement industry.
The objective of the proposed research is to investigate the effect of mix design compaction effort on the microstructure, density and strength, and thereby develop an optimized mix design procedure for mixes with different binders. The scope of work consists of preparing FDR specimens with different binders, using different compaction efforts, measuring their conventional laboratory properties, characterizing their microstructure using X-Ray CT scan, and correlating microstructure to the strength and stiffness of FDR mixes. Building on Cycle 1 findings, the matrix of materials will consist of one FDR blend of RAP and granular materials and two binders which are proven to be most promising in terms of strength and performance under accelerated loading and testing from Cycle 1, i.e., CSS1H emulsified asphalt, and high Yield emulsified asphalt. Three different laboratory levels of compaction will be used. The test results will include phase identification, density, porosity, damage evaluation from X-ray CT scan, as well as indirect tensile strength and stiffness with and without conditioning. The proposed research will be carried out in five tasks spread over a 12-month period. Task 1: Design FDR mixes using 50, 75, and 100 SGC gyrations per TxDOT specifications Tex-113-E and Tex-241. Task 2: Conduct Indirect Tensile Strength (per Tex-226-F), and stiffness (per AASHTO T307) tests on dry and moisture-conditioned specimens. Task 3: Carry out X-ray CT scan, conventional density test (Tex-113-E), and Indirect Tensile Strength (Tex-226-F) at different loading levels on samples compacted at optimum binder contents and different gyration levels. Task 4: Correlate microstructure and the extent of damage to strength and stiffness. Task 5: Prepare and submit the final report.
]]></description>
      <pubDate>Wed, 01 Jan 2025 17:15:15 GMT</pubDate>
      <guid>https://rip.trb.org/View/2480362</guid>
    </item>
    <item>
      <title>Development of Models for the Prediction of Shear Strength of Swelling Clays</title>
      <link>https://rip.trb.org/View/2137505</link>
      <description><![CDATA[Accurate prediction of the shear strength of swelling clays is critical for the design of roads, railway infrastructure, foundations, embankments, slopes, canals, erosion control, retaining walls, etc. The damage caused by swelling clays to the U.S. infrastructure is estimated to be of the order of about $13 billion per year (2009). Swelling clays are found in various parts of the United States and the world. Portions of North and South Dakota contain soils that have high swelling potential. Overestimation of strength parameters can lead to failures and underestimation can lead to significant increase in the cost of the project. Shear strength of soils with high swelling clay content can vary from high values when swelling is restrained to significant degradation in strength or even complete loss of strength due to swelling. The change in shear strength can also be seasonal. Fundamental strength parameters that define strength properties of soils are related to a variety of factors that include soil type, microstructural characteristics, fluid properties, mineralogy, saturation, etc. Reliable predictive tools that can accurately predict the shear strength of swelling clays are lacking. The project team's prior work on clays demonstrates the key role of molecular interactions on the evolution of microstructure and the macroscopic properties such as permeability, consolidation, and swelling pressure.]]></description>
      <pubDate>Tue, 14 Mar 2023 12:42:36 GMT</pubDate>
      <guid>https://rip.trb.org/View/2137505</guid>
    </item>
    <item>
      <title>Impacts of Magnesium Chloride Deicer on the Durability of Nanosilica-Modified HVFA Concrete</title>
      <link>https://rip.trb.org/View/1744725</link>
      <description><![CDATA[In the U.S., approximately 20 million tons of sodium chloride used for every typical winter season, along with unconventional deicers for snow and ice control present new challenges for the durability of concrete infrastructure, beyond freeze/thaw (F/T) damage. For instance, deicer magnesium chloride (MgCl2) is commonly used when pavement temperature drops below 15F, and our recent study [4] has revealed that this chemical can compromise the strength of ordinary Portland cement (OPC) concrete without any visible surface distress, thus evading the traditional inspection methods. In this context, there is an urgent need to identify concrete mixes that are more resistant to MgCl2 by design. High volume fly ash (HVFA) concrete can be cast with denser microstructure and reduced pore sizes, but its resistance to the impact of MgCl2 remains poorly known. Compared with OPC concrete, HVFA concrete (with or without modification by nanosilica) features different microstructure as well as different chemistry of hydrates, and thus may exhibit different behaviors when subjected to physical loading (e.g., F/T cycles) and chemical loading (e.g., MgCl2). The overarching goal of this project is to investigate the impacts of MgCl2 on the durability of HVFA concrete in cold climates and the role of nanosilica in the HVFA concrete, in terms of both engineering properties and fundamentals at the micron and nanometer scales. To achieve the goal, this study aims to:
(1) investigate the influences of concentrated and diluted MgCl2 solutions on the durability of HVFA concrete (with or without modification by nanosilica) under both constant ambient temperature and F/T cycling conditions,
(2) characterize physical and chemical deteriorations of the microstructures and different phases of HVFA concrete and elucidate the role of nanosilica on the improved resistance against MgCl2 attack.
The engineering properties of HVFA concrete will be characterized through weight change, compressive and split tensile strengths, water sorptivity and surface resistivity tests. Afterwards, the physical and chemical deteriorations of the microstructures and different phases as well as the beneficial role of nanosilica for the durability will be examined and analyzed through microhardness test, SEM/EDX, XRD, DSC/TGA, EMPA/WDS, and 29Si/27Al MAS-NMR.]]></description>
      <pubDate>Mon, 12 Oct 2020 11:02:09 GMT</pubDate>
      <guid>https://rip.trb.org/View/1744725</guid>
    </item>
    <item>
      <title>Coarse Aggregate Deterioration in Granular Surfaces and Shoulders TR-769</title>
      <link>https://rip.trb.org/View/1578591</link>
      <description><![CDATA[The objective of the proposed research is to characterize the microstructural changes in coarse aggregate (CA) as it is exposed to weathering in granular surfaces and shoulders on Iowa roads. The research team will assess this though both petrophysical testing and petrographic inspection to identify the chemical (e.g., dissolution of primary minerals, precipitation of secondary minerals) and physical weathering processes (e.g., abrasion and freeze-thaw cycles) responsible for CA deterioration. The team will assess how current Iowa DOT grading for concrete stone CA (e.g., Iowa Pore Index test) predicts performance of CA used in granular surfaces and shoulders. The ultimate outcome of the proposed research will be a set of guidelines to better predict the performance of CA used in granular surfaces and shoulders. This project will continue collaborative research between geologists and engineers at Iowa State University, the Iowa Department of Transportation, and Iowa county governments towards developing a better understanding of CA quality.]]></description>
      <pubDate>Mon, 14 Jan 2019 11:07:50 GMT</pubDate>
      <guid>https://rip.trb.org/View/1578591</guid>
    </item>
    <item>
      <title>Improved Performance of Concrete in Rigid Pavements and Other Transportation Structures Through Modeling of Cement Hydration
</title>
      <link>https://rip.trb.org/View/1369873</link>
      <description><![CDATA[The purpose of this interagency research project with the National Institute of Standards and Technology (NIST) is to work cooperatively with the Federal Highway Administration (FHWA) on cement hydration kinetics modeling research. The focus will be on clearly defining the causes of the onset and end of the induction period of alite, which controls set, strength, and subsequent microstructural development. The researchers will simulate the presence of mineral and chemical admixtures by introducing aluminate and sulfate ions and organic retarders at ratios known to perturb normal hydration. The researchers will also use new experimental methods capable of measuring chemical and microstructural changes on the nanometer to micron scale during hydration; the goal is to use this insight to improve the ability of NIST’s HydratiCA model to predict hydration kinetics and microstructure in the presence of supplementary cementing materials (SCMs), such as fly ash, slag and metakaolin, as well as in organic admixtures. This detailed understanding will also lead to the improvement of the boundary nucleation and growth (BNG) model to permit prediction of hydration kinetics and setting behavior, using a software tool that is powerful but simple enough to be used in the field.
]]></description>
      <pubDate>Mon, 21 Sep 2015 15:59:50 GMT</pubDate>
      <guid>https://rip.trb.org/View/1369873</guid>
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