Research in Progress (RIP)

SPR-5027: Evaluation of Recycled Concrete Pavement (RCP) for Base and Subbase Layers

Wed, 06 May 2026 15:26:33 GMT

This research will evaluate the feasibility, performance, and cost-effectiveness of incorporating recycled concrete pavement (RCP) into pavement base and subbase layers and subgrade replacement. The study will focus on mechanical, hydraulic, and durability characteristics of RCP gradations, fines control strategies, and field validation, aiming to provide practical implementation guidelines for the Indiana Department of Transportation (INDOT) pavement design framework. Further, the study will explore the viability of blending RCP with local fine-grained soils (such as American Association of State Highway and Transportation Officials (AASHTO) A-7-6 as a strategy to mitigate calcium leaching and reduce the risk of tufa formation, while maintain adequate drainage performance.

Seasonal Weight Restriction Decision Making Based on Understanding and Monitoring of Frost Susceptibility of Pavement Structures

Wed, 18 Feb 2026 11:28:12 GMT

This study aims to critically assess the variation of stiffness, temperature and moisture throughout the base and subbase structure to better determine the capacity of roads as the seasons transition from winter to spring. The objectives of this project are to critically assess the variation of temperature, moisture, stiffness and strength throughout the base and subbase structures during different driving seasons to better determine the capacity of roads from winter to spring to summer driving seasons. And propose an interpretation and analysis protocol of continuously collected data to create a decision-making process for the frozen road declaration, midseason thaw, ending the frozen road declaration, and imposing and ending spring weight restriction in the State of Wisconsin.

Pavement Design: Performance of Base versus Subbase

Tue, 27 Jun 2023 15:43:11 GMT

This work will consider material availability, load characteristics and quality indicators for performance of base and subbase materials. This project will provide guidance both to designers/practitioners to use key aggregate resources and to local agencies for evaluating locally available materials for designing cost-effective flexible and rigid pavements.The project will explore aggregate/pavement layer characteristics that should be evaluated, and determine when/how a thicker subbase and a thinner base is constructed.

Geotechnical Aspects of Pavements

Mon, 21 Nov 2022 16:26:25 GMT

This research will evaluate geotechnical aspects of pavements, including the design, construction, instrumentation, and performance of various base/subbase materials as part of the pavement structure.

Reclaimed Stabilized Base – Stabilizing Agent Selection & Design

Mon, 04 Nov 2019 09:50:14 GMT

Reclaimed stabilized base (RSB) is a common technique utilized to rehabilitate roadways (e.g. NCHRP 144 Report, 2009; NCHRP 421 report, 2011). RSB involves reclaiming the base material and adding a stabilizing agent (e.g. cement, lime, calcium chloride, emulsion, foamed asphalt) to increase the strength and durability of the subbase structure. In this project, the research team plans to investigate the suitability of the various stabilizing agents for common subbase materials encountered in Vermont roadways and develop a process for VTrans to determine the applicability of RSB for a project, and the appropriate types and percentages of stabilizing agents. The team plans to investigate the performance of the stabilized sub-base materials in winter conditions, including ice lens formation and stiffness as well as long-term (multiple-year equivalents) freeze-thaw implication for durability through accelerated cold room testing. The outcomes of this research will assist VTrans in the scoping phase of the projects to determine applicability of RSB, and in the design and construction phases with guidance on appropriate stabilizing agents, and installation parameters, respectively.

Soil-Recycled Aggregate-Geopolymer Road Base/Subbase Mixtures - Step Towards Sustainability

Fri, 23 Mar 2018 16:47:59 GMT

The proposed study focuses on the development and evaluation of sustainable Soil-Recycled Aggregate-Geopolymer (Soil-RAG-GP) mixtures for road base and subbase layers. In order to develop Soil-RAG-GP stabilized road base materials, various types of Class F fly ash, soil types, and activation agents (such as sodium hydroxide and sodium silicate) will be tested. The mechanical characteristics of the Soil-RAG-GP mixtures depend on various mix constituents, as well as the curing period and temperatures. Based on various combinations of variables, a statistical-based partial factorial experimental design will be developed to minimize mechanical testing. Unconfined Compressive strength, elastic and dynamic modulus, flexural, durability and shrinkage characteristics will be evaluated using standard test procedures. In addition to mechanical testing, oxide analyses and SEM micrographs will also be studied to understand the basic morphology and microstructure of Soil-RAG-GP to investigate the extent of Geopolymer reactions and strength gain mechanism with time. The mixes will be cured at various temperatures before testing. The strength and modulus tests results will be compiled, and preliminary statistical model will be developed to relate the strength with mix variables. The model will assist in sensitivity analysis of variables and determine the optimum/practical mix design parameters to be used in base/subbase layers. The developed “green” Geopolymer-based soil base/subbase materials will exhibit durability, high performance, and environment-friendly, and sustainability characteristics.

In-situ Mechanical Characterization for Compacted Aggregates

Sun, 21 May 2017 10:30:34 GMT

The evaluation of compacted unbound aggregate layers is perhaps the most common undertaking in transportation related projects. The assessment of compaction compliance in engineered fills, subgrades, subbases, and bases in roadways and railways is central to ensure the longevity of ground transportation infrastructure. As such, this study tackles one of the most common preventable causes of premature failure in pavement structures. The technical objective of this project is to conduct a review of theoretical methods for the determination of strength and stiffness. The scope of this project includes two specific tasks: to identify the barriers to the adoption of available in-situ test devices and to explore untapped theoretical advances that could be translated into new in-situ test devices. The research team will outline a pathway to automation for the highest ranked test method identified. By exploring the basic measurement requirements, the team will identify compatible electronics (sensors, controllers, data loggers, and communication systems), and create a blueprint for an automated prototype and prepare a proposal for its development. In the case of the most promising theories identified, the research team will formulate a needs assessment that outlines a series of steps needed for the translation from theory to application.

SPR-4116: Investigation of Design Alternative for the Subbase of Concrete Pavements

Thu, 19 Jan 2017 13:20:52 GMT

The study will develop recommendations for new subbase designs based on a comprehensive review of the literature, a survey of best practices across the US and abroad and an experimental program focused on unstabilized layers alone and in combination with geotextiles.

PPRC14 SPE 3.30: Standard Materials Library and Guidance

Wed, 04 Jan 2017 10:53:07 GMT

The objective of this project is to test and include additional regional materials in the California Department of Transportaiton (Caltrans) mechanistic-empirical (M-E) Standard Materials Library, including base, subbase and new recycled materials. Implement procedures to simplify the selection of material types for ME design by district designers, and develop guidance for asphalt mix designers to meet performance related mix design requirements. This study is a continuation of Task 2356. Specific objectives include: (1) laboratory testing; (2) field testing; (3) materials selection guidance; (4) performance based mix design guidance; and (5) project report.

Subbase Requirements for Utilizing Unsealed Joints in PCCP

Thu, 30 Jul 2015 01:01:12 GMT

The study will determine, through a literature search, the practices of other states utilizing unsealed joints, the economics of an Indiana Department of Transportation (INDOT) unsealed joint section, and the projected performance of an unsealed portland cement concrete pavement (PCCP) utilizing the mechanistic empirical pavement design guide (MEPDG), falling weight deflectometers (FWD) testing and International Roughness Index (IRI) testing. The unsealed PCP would then be compared to the sealed joints INDOT uses presently.

Improving the Foundation Layers for Concrete Pavements

Wed, 22 Jul 2015 01:02:50 GMT

Quality pavement foundation layers are essential to achieving excellent pavement performance. In recent years as truck traffic has greatly increased, the foundation layers have become even more critical to successful pavement performance. Unfortunately, there are still many pavement failures in the U.S. related to inadequate subbase, natural subgrade, and embankment (commonly referred to as foundation layers or roadbed). Factors that contribute to pavement foundation problems are believed to be poor construction practices, ineffective quality control/quality assurance (QC/QA) testing methods and sampling plans, material variability and unpredictable long-term material behavior, poor verification of material properties during construction, insufficient development of performance-related specifications, and low capital investment in the foundation layers. The objective of this research is to improve the construction methods, economic analysis and selection of materials, in-situ testing and evaluation, and development of performance-related specifications for the pavement foundation layers. The outcome of this study will be conclusive findings that make pavement foundations more durable, uniform, constructible, and economical. Although the focus of this research will be portland cement concrete (PCC) concrete pavement foundations, the results will likely have applicability to asphalt cement concrete (ACC) pavement foundations and, potentially, unpaved roads. All aspects of the foundation layers will be investigated including thickness, material properties, permeability, modulus/stiffness, strength, volumetric stability and durability.

Ultra High Strength Concrete Wearing Surface for Asphalt and Concrete Road as well as Bridge Deck

Fri, 22 Aug 2014 01:00:46 GMT

Pavements usually consist in base and sub-base layers which last 20-40 years or more, covered with a wearing coarse having a much shorter service life. The maintenance works for these surface layers induce high external costs. In order to solve the problem, intensive effort is devoted to introducing new generations of materials to enhance the performance of such surface layers. With regard to their amazing mechanical and durability performances, UHPC materials have changed to issues of great importance in this research area. Due to time, cost, and environmental considerations, developing new concrete materials for pavement applications to achieve the minimum possible thickness is of a great significance. But, besides the mentioned benefits of producing pavement materials of minimum possible thicknesses, these materials are prone to shrinkage and cracking. As solution for this problem, the idea of fiber-reinforced mortar for the wearing surface is proposed. Pavements manufactured from ultra-high performance concrete (UHPC) can provide significant durability improvement due to the high strength and extremely low permeability of the UHPC material. It is worth mentioning that to enhance both the mechanical and durability properties of these pavement materials, it is suggested to incorporate the steel and/or synthetic fibers in the mixtures as a technical and environment friendly solution. Besides it should be noted that the use of fibers can lead to a reduction in pavement depth, thus, reducing the overall costs, as well as speeding the on-site process and reducing trip hazards.

Use of Coal Fly Ash and Other Waste Products in Soil Stabilization and Road Construction - Including Non-Destructive Testing of Roadway - Columbia

Wed, 26 Jun 2013 01:00:18 GMT

Beneficial use of coal fly ash has an overall economic and environmental benefit. Fossil fuel power plans produce large quantity of coal fly ash each year. These fly ashes mostly disposed of in landfills and ponds. Nationwide, only approximately 40% of coal fly ashes are beneficially used. The use of fly ash in road subgrade applications can provide better properties and performance, and is superior to it being otherwise disposed and becoming a possible environmental liability. Meanwhile, the Missouri Department of Transportation (MoDOT) is also looking for non-destructive testing methods to evaluate the effectiveness of these materials in strengthening the road subgrade which can enhances inspection of other areas of roadwork. In the proposed research, we will firstly identify waste products, including coal fly ash and lime kiln dust, in soil stabilization to reduce the cost while enhancing road construction. Secondly, we will develop innovative non-destructive testing technologies to evaluate the physical and engineering properties of the stabilized subgrade, subbase and base materials and provide a guideline of use of fly ash and other waste products in Missouri.

Modeling Mechanistic Properties of Unbound Pavement Materials for New York State

Thu, 03 Jan 2013 15:47:30 GMT

This project will increase the applicability of the seasonal pavement materials models that were developed for the New York State Department of Transportation (NYSDOT) in an earlier research project entitled #C-01-54, Seasonal Variations of In Situ Materials Properties. The models from that project were designed to help NYSDOT implement the new mechanistic-empirical pavement design guide (MEPDG) while still being applicable with the existing NYSDOT Comprehensive Pavement Design Manual (CPDM). This project will expand on earlier research results, creating models of seasonal change in unbound (subbase and subgrade) layer moduli that are more broadly applicable across all of New York State. The original models covered about 60 percent of the geographic area of the state. The objective in this research is to increase the coverage of climatological and materials conditions, resulting in predictive models of pavement mechanistic properties, applicable to approximately 90 percent of the area of the state. The primary goal is to expand the inference space of the models of seasonal change in unbound (subbase and subgrade) layer moduli for use in mechanistic pavement design. Information gained from the initial study shall be used to focus the activities of this project.

Beneficial Use of Dredging Materials from Harbors and Channels

Thu, 03 Jan 2013 15:19:11 GMT

Dredging is necessary for maintaining marine freight transport. However, dredged material management options for commercial ports, particularly those involving confined disposal facilities or other long term or permanent placement, are diminishing. Many existing Great Lakes disposal facilities serving these ports are at or near capacity and high costs plus limited new site availability make prospects for new or expanded capacity increasingly unlikely. Beneficial use of dredged materials, alone or in mixtures, can have a major impact on the cost of dredging and on associated environmental benefits. Given the declining placement capacity, "disposal" of non-toxic dredged material into existing disposal facilities is no longer feasible as an ongoing management practice. Reuse or recycling of material suitable for beneficial use has emerged as the most practical approach to sustainable management. Using dredged materials instead of natural mined materials could contribute to environmental sustainability and energy independence. Beneficial reuse could include applications in construction of transportation facilities such as structural fills, backfills behind retaining walls, and pavement sub-base material. One factor favoring increased beneficial use is the improving physical quality of the material; however this message needs to be shared with potential users who historically have not utilized this material in the past. This project will bring dredged material property information and example beneficial use projects to a major partner in the overall freight coalition: the state departments of transportation.