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    <title>Research in Progress (RIP)</title>
    <link>https://rip.trb.org/</link>
    <atom:link href="https://rip.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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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>
    <image>
      <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>Assessing Residual Strength of Post-Tensioned Elements with Corrosion-Induced Tendon Failure</title>
      <link>https://rip.trb.org/View/2652073</link>
      <description><![CDATA[The research team will assess the residual strength of post-tensioned (PT) bridge elements with corrosion-induced tendon failures to support the Texas Department of Transportation's (TxDOT) maintenance and evaluation efforts. The research team will develop recommendations for assessing structural capacity and identifying effective maintenance strategies. Experimental testing will be conducted in two phases to evaluate corrosion-induced bond degradation and tendon corrosion effects near the anchor points. These tests will evaluate bond degradation, stress redistribution, and failure mechanisms for strand configurations that are either centrally aligned or offset to one side of the tendon. The research team will also perform an analytical study using finite element modelling to simulate corrosion scenarios and validate structural performance. The research team will develop practical guidelines for Receiving Agency engineers, including assessment methodologies and maintenance recommendations.]]></description>
      <pubDate>Fri, 09 Jan 2026 16:32:17 GMT</pubDate>
      <guid>https://rip.trb.org/View/2652073</guid>
    </item>
    <item>
      <title>Trackless Tack Bond Strength Performance</title>
      <link>https://rip.trb.org/View/2417065</link>
      <description><![CDATA[In emulsion asphalt and non-tracking tack materials, bond strength significantly influences bituminous pavement performance. Kentucky Transportation Cabinet (KYTC) bituminous pavements show evidence of debonding. Debonding has also occurred on resurfacing projects. Non-tracking tack is a new material that is used as tack. Its adoption has raised several questions related to application rate, seasonal limitations, and equipment requirements. Leveraging previous work on the effect of bond strength on bituminous pavement performance, project activities will focus on implementing research, obtaining data on Kentucky pavements, and developing recommendations related to bond strength.]]></description>
      <pubDate>Mon, 12 Aug 2024 13:26:30 GMT</pubDate>
      <guid>https://rip.trb.org/View/2417065</guid>
    </item>
    <item>
      <title>Bond Performance Between Precast UHPC Substrates and Field Cast UHPC Connections</title>
      <link>https://rip.trb.org/View/2389412</link>
      <description><![CDATA[This research will investigate bond between hardened and freshly cast ultra high performance concrete (UHPC) and develop cohesion and friction coefficients which can be used with current AASHTO LRFD Bridge Design Specifications design capacity equations, unless the current equations prove to not fit well, in which case design capacity equations will be developed. Construction specifications will be written that Florida Department of Transportation (FDOT) can use to ensure durable joints can be achieved. Variables investigated will include UHPC mix design (both proprietary and non-proprietary), concrete strength and age (of both the precast and field-cast UHPC), surface treatment, and pre-wetting procedures. Surface treatment methods investigated will include multiple depths of form-liners, multiple grades of paste retarders, and combinations of both techniques. Surface treatment methods which result in exposed steel fibers will be investigated. Methods for preventing exposed steel fibers from corroding between pre-casting and field-casting will also be investigated.]]></description>
      <pubDate>Wed, 12 Jun 2024 07:23:16 GMT</pubDate>
      <guid>https://rip.trb.org/View/2389412</guid>
    </item>
    <item>
      <title>Bond Performance of Advanced Concrete Materials for Rapid Infrastructure Repair and Rehabilitation</title>
      <link>https://rip.trb.org/View/2291292</link>
      <description><![CDATA[Calcium sulfoaluminate (CSA) cements are a promising alternative hydraulic cements because of  high early strength and low shrinkage (rapid setting) or controlled expansion (shrinkage compensating). These properties make CSA cement attractive and effective for transportation infrastructure, including accelerated repair of pavement and/or mitigation of shrinkage cracking. Half of the bridges in the United States already have or will reach their anticipated design life in the next 10 years. Many of these bridges can have their service life safely extended  by targeted repair and rehabilitation using CSA cement. Using concrete mix designs developed at the University of Oklahoma (OU), the University of Arkansas, and Louisiana State University, the proposed research will evaluate the ability of CSA cement to bond to traditional concrete substrates and the durability of those bonds over time. The objectives of the proposed study are to (1) Evaluate the bond performance of CSA cement concrete for varying substrate conditions; (2) Evaluate the freeze-thaw durability of CSA cement concrete repairs; and (3) Develop and communicate recommendations for CSA cement concrete repairs.
These objectives will be achieved by experimental evaluation of CSA cement concrete mix designs developed at OU and SPTC partner institutions through six specific tasks. Task 1 will involve identifying CSA cement concrete mix designs for use in further testing. Task 2 will examine the bond of the CSA cement concrete repair materials to conventional concrete substrates with different surface preparations, using direct pull-off testing. In Task 3 freeze-thaw resistance of the repair interface will be evaluated using rapid freeze-thaw cycles. Repair interfaces for both newly cast specimens and concrete from in-service bridges will be tested for freeze-thaw resistance. In Task 4 bond and freeze-thaw results will be compared to the results for other advanced concrete materials. Task 5 will involve the construction of a large-scale repair demonstration for DOT officials that will then be used for long-term performance evaluation. Task 6 will include the development of educational materials including a prerecorded training module, live workshop, and demonstration for high school outreach events.
]]></description>
      <pubDate>Thu, 16 Nov 2023 16:48:00 GMT</pubDate>
      <guid>https://rip.trb.org/View/2291292</guid>
    </item>
    <item>
      <title>Characterization of the Long-term Behavior of Textured Epoxy Coated Rebars in Bridge Decks</title>
      <link>https://rip.trb.org/View/2229006</link>
      <description><![CDATA[Steel reinforcing bars are placed in concrete to strengthen bridges. Placing a textured epoxy coating (TEC) on rebars not only prevents corrosive materials from damaging them, but also improves the composite behavior between steel and concrete. The aim of this project is to evaluate the bond between steel, coating and concrete in textured epoxy-coated rebars and verify that the corrosion protection is equal to coated rebars without texture. The objectives of this research are as follows: (1) verify the consistency in the roughness and bond strength of the new generation of TEC bars, (2) study the impact of TEC bars on controlling crack growth under thermal cycles and high-cycle fatigue loads (service-level live loads) and how it compares to epoxy-coated bars, (3) explore the effect of TEC bars in mitigating the progression of cracks in bridge decks subjected to realistic surface wet conditions, (4) determine the factors impacting the rebar development length and ultimate strength of bridge decks reinforced with TEC bars, (5) establish the corrosion resisting ability of TEC bars subjected to an environment that represents a concrete bridge deck in Illinois. If testing is successful, the use of textured epoxy-coated rebars will lead to longer-lasting bridge decks.]]></description>
      <pubDate>Mon, 14 Aug 2023 11:32:05 GMT</pubDate>
      <guid>https://rip.trb.org/View/2229006</guid>
    </item>
    <item>
      <title>Bond Behavior of Nano-Enhanced Polymer Concrete for Bridge Deck Overlays</title>
      <link>https://rip.trb.org/View/2221099</link>
      <description><![CDATA[Polymer concrete overlays are light weight, wear resistant, skid resistant and waterproofing characteristics make them an intelligent and durable decision for new construction, maintenance, rehabilitation and preservation of bridges. A polymer concrete overlay also minimizes traffic disruption. It’s generally applied at a total thickness of only one-half to three-quarter inch. Their rapid cure (open to traffic within 3 hours) characteristic is highly suitable for accelerated bridge construction applications. In some cases, workers can place the overlay at night then open it to traffic the next day. Moreover, these overlays are corrosion resistant, providing a barrier between the dissimilar materials to minimize galvanic corrosion, saving the expense of applying additional corrosion-resistant primers to the steel reinforcement; have very good cracking resistance and have superior durability [1]. When bridge deck overlays are considered, a strong bond to the existing concrete surface and/or reinforcement is required. The properties discussed above make polymer-based materials a favorable material for bridge deck overlays [2] but improving the bond strength of polymer concrete is heavily unexplored and can bring significant benefit in accelerated bridge construction. Polymer-based overlays show no delamination with the substrate concrete beams after 2 million cycles of fatigue loading [3]. It is important for the bonded joint to be able to sustain all expected in-service loads and environmental conditions, which can vary considerably.]]></description>
      <pubDate>Sun, 30 Jul 2023 21:06:39 GMT</pubDate>
      <guid>https://rip.trb.org/View/2221099</guid>
    </item>
    <item>
      <title>Assessment and Enhancement of Concrete Interface Bond</title>
      <link>https://rip.trb.org/View/2096593</link>
      <description><![CDATA[Concrete-to-concrete interfaces are a common occurrence in infrastructure construction.  The bond of the freshly placed concrete to the new concrete is dependent on a number of factors.  It is possible to increase the bondability of the old concrete and the new concrete through various method.  It is also possible to quantitatively assess the bond, and thus specifying bond thresholds in construction documents is possible.  This research will investigate methods of bond assessment and enhancement.]]></description>
      <pubDate>Fri, 13 Jan 2023 14:49:31 GMT</pubDate>
      <guid>https://rip.trb.org/View/2096593</guid>
    </item>
    <item>
      <title>Bond Performance of Post-tensioning Tendons with Corrosion Inhibitor</title>
      <link>https://rip.trb.org/View/1982731</link>
      <description><![CDATA[The objective of this research is to determine whether injection of a corrosion inhibiting liquid into grouted internal post-tensioned tendons has a detrimental effect on bond performance and flexural capacity of girders. To achieve this objective, laboratory-scale tests will be conducted on post-tensioned concrete girders, both with and without an injected corrosion inhibitor, and over a range of tendons sizes, tendon profiles, grout types, and duct types at critical sections.]]></description>
      <pubDate>Thu, 16 Jun 2022 08:45:15 GMT</pubDate>
      <guid>https://rip.trb.org/View/1982731</guid>
    </item>
    <item>
      <title>Exploring Fiber-Reinforced Polymer Concrete for Accelerated Bridge Construction Applications</title>
      <link>https://rip.trb.org/View/1838517</link>
      <description><![CDATA[The use of precast concrete superstructure elements can expedite project delivery, improve work-zone safety, and reduce overall project cost. To accelerate construction, the precast elements must be connected quickly on-site, ideally using as little additional material as possible. While the excellent tension and bond strengths of ultra-high performance concrete (UHPC) make it ideal for this purpose, the time at which UHPC achieves its design strength is directly proportional to the rate of hydration of the cementitious binder. While UHPC may provide the best solution in many instances, alternative joint materials that utilize polymer binders, instead of cementitious ones, may be more suitable if rapid strength gain is needed. This project explores a potential alternative closure joint material, fiber-reinforced polymer concrete (FRPC), which displays levels of the two critical characteristics (bond and tension strength) that are comparable to, or potentially better than, those of UHPC. FRPC has the advantage of requiring shorter closure windows (approximately 4 hours versus 72 hours of UHPC) due to the very rapid strength gain of the polymer, which could be ideal for overnight construction or rehabilitation projects, and provides an additional option to the engineer and contractor when choosing a closure joint material for a given circumstance.]]></description>
      <pubDate>Tue, 09 Mar 2021 11:32:06 GMT</pubDate>
      <guid>https://rip.trb.org/View/1838517</guid>
    </item>
    <item>
      <title>Test Methods and Bond Performance Characterization of Shotcrete-Concrete Interface</title>
      <link>https://rip.trb.org/View/1744729</link>
      <description><![CDATA[Shotcrete has become attractive for fascia and retaining walls in many states. Shotcrete is particularly well adapted to vertical and overhead work where conventional formworks and repairs are difficult to make, costly, and often short-lived. However, this practice could also possibly reduce the life expectancy of structures if the interface bond properties between shotcrete and concrete are not well developed when the substrate concrete surface is lack of cleanliness and soundness; multi-layered shotcreting makes it difficult to achieve effective integrity without proper preparation. In addition, long-term freeze-thaw weathering in northern states also degrades the bond strength of interface and results in debonding from the existing concrete structures and corrosion of rebars. Thus, properly placing of shotcrete and its bond properties to underneath concrete substrates are of paramount importance to service performance and durability in shotcrete application. In this proposed project, both bond strength and fracture-based concepts combined with finite element modeling, damage mechanics and computational peridynamics are used to develop effective test methods to characterize bond properties, obtain bond strength and fracture energy properties, evaluate long-term performance in cold regions, and predict damage accumulation and life of the interface between shotcrete overlay and concrete substrate in shotcrete application. Laboratory test methods and specimens will be first developed for static bond strength and fracture energy tests, and they will be subsequently used evaluate long-term interface performance and decay under accelerated freeze-thaw action. The results of this study will provide general guidelines for bond performance evaluations of overlays to substrate in shotcrete application, qualifications of existing and new shotcrete structures, and eventually for standardization of test procedures.]]></description>
      <pubDate>Mon, 12 Oct 2020 10:23:23 GMT</pubDate>
      <guid>https://rip.trb.org/View/1744729</guid>
    </item>
    <item>
      <title>Fatigue Life Analysis of Reinforced Concrete Beams Strengthened with Composites</title>
      <link>https://rip.trb.org/View/1742607</link>
      <description><![CDATA[Extending the service life of existing structures through their rehabilitation and strengthening rather than demolishing to build a new construction is not only a sustainable choice but also cost effective. For key transportation structures, repairing or strengthening rather than substituting a bridge element may benefit the economy of an entire community. Fiber-reinforced composites have been proven to be an effective solution to increase or restore the capacity of reinforced concrete (RC) members. The most common type of composite is fiber-reinforced polymer (FRP) composites that are comprised of continuous fibers embedded in an organic matrix such as epoxy. Although the FRP technology has been abundantly studied, certain drawbacks, such as the low glass transition temperature and the difficulty of applying the composite on wet surfaces, raise some questions on the use of FRPs. A new type of composite, often called fiber-reinforced cementitious matrix (FRCM) composite, that employs inorganic matrices appears to be a viable alternative to FRP in some key applications. However, as the bond mechanisms of FRCMs are somehow different from those of FRP, there is an urgent need of understanding the fatigue behavior of FRCM-strengthened RC beams and increase the knowledge on the fatigue response of FRP-strengthened RC beams. The proposed research aims at providing design recommendations on the use of FRCM composites for structures subjected to fatigue loading and providing practitioners and department of transportation (DOT) personnel with guidelines on the fatigue limits of RC structures strengthened with FRP and FRCM composites. An experimental campaign at the material and structural levels will be used to build a fatigue model of the bond behavior that could be implemented in numerical simulations to study the key parameters of the fatigue response of strengthened beams and therefore allow to determine the conditions under which FRCM rather than FRP could be a more suitable solution.]]></description>
      <pubDate>Fri, 02 Oct 2020 10:41:04 GMT</pubDate>
      <guid>https://rip.trb.org/View/1742607</guid>
    </item>
    <item>
      <title>Rapid Repair and Retrofit of Timber Piles Using UHPC
</title>
      <link>https://rip.trb.org/View/1688732</link>
      <description><![CDATA[This project proposes the use of ultra high performance concrete (UHPC) as repair and retrofit material for timber piles, however, many research questions should be answered such as the bond strength between timber and UHPC, the surface preparation for timber piles to enhance the bond strength with UHPC, the effect of UHPC thickness of repair/retrofit. These questions, among others, will be answered under this project. The objectives of this research project are: (1) Studying the bond strength between timber and UHPC as repair/retrofit material; (2) Defining the best surface preparation for timber piles in order to enhance the bond strength; (3) Studying the load-carrying mechanism of timber piles repaired or retrofitted using UHPC; (4) Conducting small scale testing to study the bond strength and load-carrying mechanism between timber and UHPC; (5) Conducting large scale component testing of timber piles repaired/retrofitted using UHPC under realistic axial and lateral loading schemes; (6)   Studying repair methods for in-service weathered piles; and (7) Developing detailed finite element models for both small scale material testing and large scale component testing for better understanding of the local and global behavior of timber piles repaired/retrofitted using UHPC.

]]></description>
      <pubDate>Mon, 24 Feb 2020 19:38:11 GMT</pubDate>
      <guid>https://rip.trb.org/View/1688732</guid>
    </item>
    <item>
      <title>The Effects of Surface Condition and Long-Term Environmental Exposure on the Bond Between Carbon Fiber-Reinforced Polymers and Steel</title>
      <link>https://rip.trb.org/View/1675693</link>
      <description><![CDATA[Bridge engineers in Virginia are increasingly looking for innovative, yet cost-effective
ways of repairing and maintaining the existing bridge inventory with sufficient capacity
to carry legal loads. One option for deteriorated steel members is to use carbon fiber-
reinforced polymers (CFRP). This research project will investigate whether the use of
CFRP retrofits is feasible and cost effective based on several parameters, including the
degree of base metal degradation and environmental exposure (e.g. moisture,
chlorides). The environmental variables will be examined in both an accelerated
laboratory test and in-situ field exposure to determine the accuracy of current
accelerated testing. There will also be an economic analysis comparing this
strengthening approach to other methods. The research will serve as a body of
knowledge to help guide bridge engineers on when and where the use of CFRP retrofits is suitable for the strengthening steel bridges.]]></description>
      <pubDate>Fri, 27 Dec 2019 12:30:48 GMT</pubDate>
      <guid>https://rip.trb.org/View/1675693</guid>
    </item>
    <item>
      <title>Research for AASHTO Standing Committee on Highways. Update of the 2012 AASHTO Guide Specification for Design of Bonded FRP Systems for Repair and Strengthening of Concrete Bridge Elements</title>
      <link>https://rip.trb.org/View/1650153</link>
      <description><![CDATA[Bonded Fiber-Reinforced Polymer (FRP) systems have proven to be an economical means for the repair and strengthening of concrete bridge elements in many projects. The first edition of the AASHTO Guide Specifications for Design of Bonded FRP Systems for Repair and Strengthening of Concrete Bridge Elements, published in 2012, provides design tools for bridge elements subjected to flexure, shear and torsion, and combined axial force and flexure. However, many projects have been constructed and changes in the state of practice have occurred since the publication of these guide specifications. Also, during this period, substantial research on the different aspects of bonded FRP system applications has been performed. In addition, the current guide specifications are limited in scope (e.g., do not explicitly cover flanged sections, prestressed concrete elements, and FRP anchoring design). Because of these changes and limitations, there was a need for updating the guide specifications to recognize these issues and provide updated information and guidance on all aspects bonded FRP systems for repair and strengthening, including topics such as FRP near surface mounted applications, anchorage detailing, material specifications, and test requirements. The updated guide specifications will help highway agencies address relevant issues and improve the use of FRP systems for repair and strengthening applications.

The objective of this research was to update the 2012 AASHTO Guide Specifications for Design of Bonded FRP Systems for Repair and Strengthening of Concrete Bridge Elements.]]></description>
      <pubDate>Mon, 09 Sep 2019 19:04:20 GMT</pubDate>
      <guid>https://rip.trb.org/View/1650153</guid>
    </item>
    <item>
      <title>Engineered Geopolymer Composites (EGC) for Sustainable Transportation Infrastructure</title>
      <link>https://rip.trb.org/View/1642178</link>
      <description><![CDATA[The objective of this study is to develop novel Engineered Geopolymer Composites (EGCs) implementing locally available ingredients to produce a new generation of materials that are practical, cost-effective, and eco-friendly for repair and new construction of transportation infrastructure in the South-Central region. In order to achieve this objective, EGC mixtures will be designed with different types and proportions of locally available precursor materials (mainly locally available fly ash and metakaolin). EGCs fresh and hardened properties will be evaluated to identify key parameters ensuring EGC strain hardening response as well as optimum design of the composition balancing fresh and hardened properties. Furthermore, bonding properties of EGC with regular concrete will be assessed. Finally, a cost analysis for EGC implementation will be performed by comparing the cost of EGC materials to current materials utilized in the field.]]></description>
      <pubDate>Fri, 02 Aug 2019 06:30:37 GMT</pubDate>
      <guid>https://rip.trb.org/View/1642178</guid>
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