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    <title>Research in Progress (RIP)</title>
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    <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>
    </image>
    <item>
      <title>Development of a Job Mix Formula and QC/QA Framework for NCDOT Chip Seals</title>
      <link>https://rip.trb.org/View/2726547</link>
      <description><![CDATA[Chip seals are among the most efficient and cost-effective methods utilized by state highway agencies to preserve and rejuvenate existing pavements. Chip seal operations in North Carolina have been outsourced since their transfer from the North Carolina Department of Transportation's (NCDOT's) internal Road Oil program about 12 years ago. Some large contracting firms have developed the sufficient skills and experience needed to construct chip seals, but quality-related problems, such as raveling and too much fine material and moisture in the aggregate, have been found in some jobs. Quality control (QC) and quality assurance (QA) is an important step toward ensuring that pavements perform satisfactorily, and a job mix formula (JMF) designed specifically for chip seals is the first step toward well performing chip seals, which is currently lacking in the NCDOT chip seal specifications.

A series of chip seal research projects conducted at North Carolina State University (NCSU) can provide an excellent foundation for the development of a JMF for NCDOT chip seals. Findings from these projects cover a wide range of critical elements in developing a chip seal JMF, including the aggregate gradation and maximum fine content, emulsion performance graded specifications, performance test methods, and performance-based mix design method.

​The primary goal of the proposed research project is to develop a JMF for chip seals constructed in North Carolina. The scope of the proposed research includes double seals with granite and lightweight aggregates; however, the findings from the proposed research can be applied to single and triple seals as well. The research plan includes the characterization of different aggregate types with varied gradations, the characterization of emulsions using the test procedures currently used in the NCDOT specifications and procedures recommended by the NCHRP 09-50 project, the evaluation of aggregate-emulsion compatibility, chip  seal performance testing, refinement of NCSU's chip seal mix design method, and development of a chip seal JMF and QC/QA framework for the NCDOT using performance test data obtained from laboratory tests. The research products from the proposed project will result in improved control over chip seal design and construction compared to the current practice, enhanced chip seal performance, prolonged chip seal service life, decreased life cycle costs, improved NCDOT chip seal specifications, and potentially reduced carbon footprint.

]]></description>
      <pubDate>Thu, 09 Jul 2026 08:42:48 GMT</pubDate>
      <guid>https://rip.trb.org/View/2726547</guid>
    </item>
    <item>
      <title>Best Practice for Seal Coating &amp; Pavement Markings with Rumble/Mumble Strips</title>
      <link>https://rip.trb.org/View/2725884</link>
      <description><![CDATA[The research team will evaluate how chip seals influence rumble strip effectiveness. Complementary approaches will combine technical review, practitioner input, standardized testing, and in-service monitoring; and will provide both rigorous data and practical insights, ensuring that the resulting recommendations are scientifically grounded and applicable to Minnesota’s roadway network.]]></description>
      <pubDate>Wed, 08 Jul 2026 17:15:02 GMT</pubDate>
      <guid>https://rip.trb.org/View/2725884</guid>
    </item>
    <item>
      <title>A Photogrammetry-based Method to Determine Chip Seal Aggregate Embedment: A Feasibility Study
</title>
      <link>https://rip.trb.org/View/2627511</link>
      <description><![CDATA[Chip seals have been the most frequently used preventive maintenance treatment on flexible pavements in the United States and overseas. Chip seals enhance transportation safety through 1) sealing small cracks, 2) reducing further oxidation of the pavement, 3) improving surface texture and skid resistance, 4) preserving and extending pavement life, and 5) providing color contrast and noise differences. Despite the growing number of chip seal projects in the U.S., many chip seal surface distresses such as aggregate loss, bleeding, and skid resistance still need to be solved, which are strongly related to aggregate embedment depth. Proper chip seal aggregate embedment should be evaluated as a critical factor when considering the design and construction of a chip seal project. In addition, road users are rapidly becoming less tolerant of travel delays caused by road works, so the research will benefit road users substantially by reducing the time involved in measuring the texture of existing surfaces. However, currently there is no reliable method to measure chip seal aggregate embedment quickly and accurately in the field. The objective of this study is to develop a photogrammetry-based method to rapidly determine the embedment depth of a uniformly placed chip seal of known aggregate gradation, easy to use, reasonably accurate, and inexpensive. The study will start with laboratory explorations with a photogrammetry-based method to measure the emulsion/binder application rate, final cover aggregate rate, and aggregate embedment. The effect of design factors (i.e., binder type, application rate, aggregate size, shape, and gradation) will be assessed as well. 
]]></description>
      <pubDate>Thu, 20 Nov 2025 16:29:52 GMT</pubDate>
      <guid>https://rip.trb.org/View/2627511</guid>
    </item>
    <item>
      <title>Chip Seal for Uniform Usages</title>
      <link>https://rip.trb.org/View/2582918</link>
      <description><![CDATA[Chip seals are one of the most popular pavement preservation treatments for asphalt pavements due to their ability to seal the existing road surface from moisture damage and oxidation, improve skid resistance, seal minor cracks, and delay deterioration. They consist of a uniform spray application of an asphalt binder followed by a uniform application of aggregate coat cover which is then rolled with pneumatic tire rollers to achieve the desired embedment. This simple process can be conducted using local maintenance personnel with minimal equipment requirements, making it a cost-effective option.

The New Mexico Department of Transportation (NMDOT) has not adopted a specific chip seal design procedure, and rather each district has independent methods to determine the material application rates, generally based on experience. The materials used vary throughout the state based on local availability. Recently, the use of reclaimed asphalt pavement (RAP) as chip seal aggregate has been adopted as an alternative to virgin aggregate due to the sustainability benefits associated with it.

OBJECTIVES: The objectives of this research are to:

Evaluate current NMDOT chip seal practices across the state of New Mexico, specifically materials and application rates. Assess the impact of these practices and/or factors on the performance based on the available pavement management system (PMS) database;
Develop a chip seal design procedure, addressing both local materials and geographic conditions across the state of New Mexico;
Develop statewide chip seal construction specifications;
Develop project selection criteria for NMDOT to obtain optimum performance and treatment life from chip seal applications, such as skid resistance and minimum chip loss.]]></description>
      <pubDate>Tue, 05 Aug 2025 12:00:31 GMT</pubDate>
      <guid>https://rip.trb.org/View/2582918</guid>
    </item>
    <item>
      <title>Field Performance Assessment of Chip Seals with Updated Chip Seal Specification and Fog Seal Treatment</title>
      <link>https://rip.trb.org/View/2558438</link>
      <description><![CDATA[The purpose of this study is to provide Virginia Department of Transportation (VDOT) with a data‐driven understanding of how recent specification updates and the addition of fog sealing influence the performance characteristics of pavement preservation treatments, particularly chip seals. Building on this, the study has two primary objectives: (1) to evaluate the efficacy and impact of the updated specification on the performance of modified single-layer chip seals; and (2) to assess the performance of chip seal applications incorporating fog sealing.  To achieve these objectives, the study will encompass field construction monitoring, laboratory characterization, and friction and texture measurements across various field sections.  All sections—built under both current and updated specifications, with and without fog seal—will be systematically monitored over the study period to capture performance trends over time and provide relative performance insights.]]></description>
      <pubDate>Tue, 27 May 2025 10:07:59 GMT</pubDate>
      <guid>https://rip.trb.org/View/2558438</guid>
    </item>
    <item>
      <title>Development of Novel and Affordable Chip Seals for Maintenance and Pavement Preservation using Sustainable Materials</title>
      <link>https://rip.trb.org/View/2480349</link>
      <description><![CDATA[Pavement infrastructure is vital for quality of life, the economy, and societal prosperity. With rising demands and limited resources, maintaining and preserving this infrastructure is increasingly crucial. Severe weather events heighten these needs. Chip seals, commonly used in Region 6 and nationwide, are essential for preserving pavements. They seal against water intrusion and improve safety by enhancing friction through better macro- and micro-texture. For effective chip sealing, high-quality cover aggregate and binder are essential. For projects involving High Friction Surface Courses, ODOT and other state DOTs in Region 6 currently use Bauxite as the cover aggregate. Although effective, use of this imported material increases cost and reduces affordability. Recent developments in pavement surfaces with high reflectivity, make engineered chip sealing a suitable tool for addressing the heat island effects, particularly in urban areas. 
To this end, the research team will develop an innovative chip sealing technology and test it in the field using local and sustainable materials. The team seeks to use Tar Creek mine chat from Oklahoma and silica sand from Texas as cover aggregates and a specialized asphalt binder with high reflectivity to develop this innovative and affordable chip sealing technology. This specialized binder is transparent in nature and can dissipate heat faster than conventional black asphalt binder. Moreover, chat materials are very hard and angular, making them (i.e., washed chat with desired gradation) a suitable cover aggregate. Similarly, silica sands, being mined in several quarries in Texas, possess cover aggregate qualities. In the proposed study, both of these cover aggregates will be used as a replacement of Bauxite. 
Conventional pavements absorb and retain heat, contributing to Urban Heat Islands (UHIs), particularly in urban environments where temperatures are significantly higher than in rural areas. Chip sealing with high reflectivity will not only enhance pavement life and functionality (i.e., adequate friction) but also reduce UHIs and help combat the effects of extreme weather. The specific objectives of this proposed project are: (1) develop chip sealing with Tar Creek mine chat and silica sand and the specialized asphalt binder and evaluate laboratory performance; (2) use the developed chip sealings in one of the maintenance projects and evaluate field performance; (3) investigate the economic and environmental impacts related to extreme heat on socio-demographic populations and develop correlations between pavement albedo, heat index, and network centrality measures.
The following tasks will be pursued in this study. Task 1: Collection of necessary materials; Task 2: Evaluation of binder properties; Task 3: Determination of cover aggregates properties; Task 4: Evaluation of compatibility between binder and aggregates; Task 5: Development of chip seal mixes; Task 6: Evaluation of laboratory performance; Task 7: Evaluation of field performance; Task 8: Assessment of socio-economic impact, and Task 9: Submission of quarterly progress reports and a final report.
]]></description>
      <pubDate>Wed, 01 Jan 2025 15:56:19 GMT</pubDate>
      <guid>https://rip.trb.org/View/2480349</guid>
    </item>
    <item>
      <title>A New Generation of Asphalt Emulsion: Advancing Sustainable Infrastructure Solutions</title>
      <link>https://rip.trb.org/View/2475702</link>
      <description><![CDATA[Hot applied asphalt cement, cutback asphalt, and emulsified asphalt have been used as tack coats and for chip seal applications. However, emulsified asphalt tack coats have been widely favored due to their additional benefits, such as reduced energy consumption and improved worker safety. The objective of this study is to conceive, test, and evaluate a new generation of emulsified asphalt using alternative materials to regular emulsified asphalts but with comparable performance. If successful, the proposed product may be used as an additional available emulsified asphalt in the market. State and federal agencies will be interested in the additional options provided by the proposed product and in order to minimize the impacts associated with road construction. Asphalt producers and suppliers will also be interested in adopting the new generation of emulsified asphalts to ensure that their products are tailored to the market needs in different parts of the country. 
The planned research activities include the following: Task (1) Conception and development of a new generation of emulsified asphalts (lead: UA); Task (2): Evaluation of the rheological and aging properties of the developed emulsified asphalts and comparing them to conventional emulsified asphalts (lead: LSU); Task 3: Assessing the mechanistic performance of the newly developed emulsified asphalts (lead: UA); Task 4: Analyzing the performance data, and cost effectiveness of emulsified asphalts (lead: LSU), and Task 5: Preparing final report (lead: LSU). The research team plans to explore various formulations for the emulsified asphalts. Once the most promising formulations are identified, the emulsions will be tested for paddle viscosity, sieve analysis, residue characteristics, particle size distribution using a laser diffraction analyzer, and storage stability. 
The availability of an innovative emulsified asphalt product, which incorporates recycled and degradable materials, has a strong value proposition for state highway agencies and contractors because it will allow them to reduce the impacts of road construction and will provide an additional option along with conventional emulsified asphalts. Based on the results of study, the research team will work with the intellectual property office at LSU to file a patent for the developed emulsified asphalts and pursue licensure opportunities. In addition, the multi-institutional research team will work with SPTC to organize a webinar to share the results of this study with the stakeholders on new advancements and findings.
]]></description>
      <pubDate>Mon, 16 Dec 2024 16:55:13 GMT</pubDate>
      <guid>https://rip.trb.org/View/2475702</guid>
    </item>
    <item>
      <title>Use of Recycled Materials in Pavement Preservation</title>
      <link>https://rip.trb.org/View/2414393</link>
      <description><![CDATA[Surface treatments such as chip seals and slurry surfacing systems are among the most popular preservation options available for flexible pavements. While the use of these treatments has been widely adopted by many state and local agencies, design and construction have typically been performed using virgin materials. To further enhance the benefits of pavement preservation, recycled materials may be incorporated into chip seal or slurry surfacing treatments (slurry seals and micro surfacing) to replace all or part of the virgin materials. Sources of recycled materials may include reclaimed asphalt pavement (RAP), recycled tire rubber (RTR), and recycled plastic. Some agencies have adopted this practice, most notably in the case of RAP, but the use of recycled materials is still limited due to a lack of information related to this topic. The objective of this study is to evaluate the potential use of recycled materials as substitutes for aggregate and/or as emulsified asphalt binder additives in terms of design implications, laboratory testing and relationship to field performance, and environmental and economic benefits.]]></description>
      <pubDate>Fri, 09 Aug 2024 16:41:25 GMT</pubDate>
      <guid>https://rip.trb.org/View/2414393</guid>
    </item>
    <item>
      <title>Materials-Based Methods to Improve Rumble Strip Durability</title>
      <link>https://rip.trb.org/View/2414317</link>
      <description><![CDATA[The use of centerline rumble strips (CLRS) has been shown to reduce severe head-on crashes on two lane roads by up to 64%. The Federal Highway Administration (FHWA) has included rumble strips in their new “Proven Safety Countermeasures” initiative, which may result in more widespread use of rumble strips. Through the lens of pavement performance, installing CLRS in asphalt pavements may accelerate deterioration of the pavement at the longitudinal construction joint. Recent research has measured this effect and suggested chip sealing new rumble strips as a preventive measure; however, chip sealing following installation may not be practical or desirable for many reasons. Other materials that have a demonstrable impact on centerline joint durability, without sacrificing the functionality of the rumble strip, have been described, namely Void Reducing Asphalt Membrane (VRAM) and Rapid Penetrating Emulsion (RPE). This project will evaluate the efficacy of these material methods for improving CLRS durability while maintaining safety through the use of full-scale field projects.]]></description>
      <pubDate>Fri, 09 Aug 2024 11:45:36 GMT</pubDate>
      <guid>https://rip.trb.org/View/2414317</guid>
    </item>
    <item>
      <title>Long-Term Field Performance Evaluation of Chip-Seals</title>
      <link>https://rip.trb.org/View/2377926</link>
      <description><![CDATA[This project aims to determine the effect of chip seal treatment timing on asphalt pavement aging while determining the optimal time for treatment application based on laboratory test results and field performance data.]]></description>
      <pubDate>Tue, 07 May 2024 16:00:26 GMT</pubDate>
      <guid>https://rip.trb.org/View/2377926</guid>
    </item>
    <item>
      <title>Guidelines for the Selection of Performance-Related Tests for the Acceptance of Preservation Treatments</title>
      <link>https://rip.trb.org/View/2361977</link>
      <description><![CDATA[Pavement preservation provides a means for maintaining and improving the functional condition and safety of an existing highway system. Although pavement preservation is not expected to substantially increase structural capacity, it generally leads to improved pavement performance and longer service life. Although a great deal of information on the design, materials, and construction practices of several preservation treatments is available, there is no nationally accepted guidance on the performance-related tests required for their acceptance. There is a need to develop guidelines for the selection of performance-related tests for the acceptance of preservation treatments, particularly chip seals and microsurfacing, to help highway agencies with the acceptance of these treatments and achieving the most benefit from their application.
OBJECTIVE:  The objective of this research is to develop guidelines for the selection of performance-related tests for the acceptance of preservation treatments. The research shall focus on chip seals and microsurfacing. For the purpose of this research, acceptance tests include those required for design, production, and placement of the treatment.  
]]></description>
      <pubDate>Mon, 01 Apr 2024 15:55:15 GMT</pubDate>
      <guid>https://rip.trb.org/View/2361977</guid>
    </item>
    <item>
      <title>Benefit/Cost of Applying a Higher Asphalt Film Thickness (AFT) vs. Doing a Chip Seal at 1 Year</title>
      <link>https://rip.trb.org/View/2290368</link>
      <description><![CDATA[In Minnesota, reducing the influence of oxidation is a continuous challenge. Researchers will compare the effectiveness of two different methods: applying a surface treatment (typically a fog or chip seal) and increasing the asphalt film thickness during original construction.]]></description>
      <pubDate>Tue, 14 Nov 2023 16:48:55 GMT</pubDate>
      <guid>https://rip.trb.org/View/2290368</guid>
    </item>
    <item>
      <title>Development of a Field Test to Determine Chip Seal Aggregate Embedment</title>
      <link>https://rip.trb.org/View/1957114</link>
      <description><![CDATA[Chip seal aggregate embedment has a significant influence on chip seal performance. Too little embedment can cause raveling and too much embedment can lead to bleeding. In both situations, safety and performance are compromised. Proper aggregate embedment shall be evaluated as a critical factor when considering a chip seal treatment's design, construction, and performance.

Research is needed to develop a field test method(s) to measure chip seal aggregate embedment rapidly and accurately.

The objective of this research is to identify, adapt, or develop a rapid field test method(s) to determine the percentage embedment depth of a uniformly placed chip seal of known aggregate gradation.

The term “rapid” for this project refers to a test method(s) that can be used as part of the quality control (QC) process, and can provide its results after the initial chip seal sweeping, allowing for real-time adjustments during the construction process.




]]></description>
      <pubDate>Tue, 24 May 2022 10:25:21 GMT</pubDate>
      <guid>https://rip.trb.org/View/1957114</guid>
    </item>
    <item>
      <title>Effectiveness of Epoxy Chip Seals for SD Bridge Decks</title>
      <link>https://rip.trb.org/View/1844017</link>
      <description><![CDATA[Since the early 1990’s, the South Dakota Department of Transportation (SDDOT) has been using epoxy chip seals on bridge decks to reduce the water and chloride infiltration that leads to rapid deck deterioration. To check the effectiveness of the epoxy chip seals, SDDOT conducted tests on core samples from two bridge decks, a bridge deck with an epoxy chip sealing overlay and a deck without an overlay. It was found that the core samples with the overlay had more chloride contamination than those without the overlay. This obviously casts doubt on effectiveness of the current epoxy chip seals in preventing water or chloride infiltration. Research on the effectiveness and performance of different types of epoxy chip seals for bridge decks is required to reduce maintenance costs, and improve structure life. The objectives of this research are to: (1) Determine the effectiveness of various deck sealers for chloride infiltration available on the market today and (2) Determine if single or double coats of epoxy deck sealers are more effective at reducing chloride infiltration. ]]></description>
      <pubDate>Mon, 29 Mar 2021 14:40:49 GMT</pubDate>
      <guid>https://rip.trb.org/View/1844017</guid>
    </item>
    <item>
      <title>Effectiveness of Concrete Bridge Deck Sealants</title>
      <link>https://rip.trb.org/View/1691457</link>
      <description><![CDATA[The South Dakota Department of Transportation (SDDOT) questions if the use of the polymer chip seals is efficient and cost-effective in preventing water and chloride infiltration on bridge decks. Polymer chip seals are commonly used to seal the decks, resulting in improved friction (skid resistance). Since the early 1990s, SDDOT has used polymer chip seals on decks to reduce water permeability and chloride penetrability. This prevents deterioration due to corrosion of the steel reinforcement from chloride ingress in the decks. The seals' failure on the deck causes rapid degradation that significantly increases maintenance costs to prolong service life of the decks. To determine the effectiveness of deck sealants and their performance on bridge decks in South Dakota, immediate and rigorous laboratory and field testing-based research considering different types of deck sealants must be done. This work will not only help validate the claim for efficiency and cost-effectiveness of the sealants for South Dakota bridge decks, but also provide technical recommendations regarding their practical use.]]></description>
      <pubDate>Fri, 06 Mar 2020 17:19:02 GMT</pubDate>
      <guid>https://rip.trb.org/View/1691457</guid>
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