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Publication Number: FHWA-HRT-05-053
Date: September 2005

Long-Term Plan for Concrete Pavement Research and Technology - The Concrete Pavement Road Map: Volume II, Tracks

Track 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)

TRACK 3 (ND) OVERVIEW

The research community has studied various NDT technologies for nearly 20 years. While this technology is beginning to impact pavement management equipment and some hand-held test equipment in construction technology, NDT technology has not been applied extensively to concrete paving. The advancing technology could benefit both the construction and inspection teams in several key ways. The equipment industry faces both a technical challenge and the challenge of investing in a methodology without being certain of a market. Establishing a working group that properly frames the issues, agrees on the technologies, and prioritizes the work efforts is critical for overcoming this investment challenge. Both industry and government will benefit from NDT by reducing reliance on slow and sometimes poorly managed small-sample testing programs. NDT technology also can be incorporated into an ICS that adjusts the paving process automatically while informing contractors and inspectors of changes and/or deficiencies in construction. Continuous and real-time sampling will be configured to detect changes to the approved mix design and the preprogrammed line and grade values. NDT technology also will allow industry and government to use the data collected for long-term pavement management and evaluation. In this regard, track 3 has significant links to track 10 (Concrete Pavement Performance).

The NDT/ICS methods developed in this track can measure the following properties that impact concrete pavement durability and performance:

Many problem statements in this track relate to track 1 (Performance-Based Concrete Pavement Mix Design System) and track 2 (Performance-Based Design Guide for New and Rehabilitated Concrete Pavements). Software standards will also ensure that the public can link to any software that the private sector produces.

Finally, human factors are critical for both researching and implementing this track. Pavement engineers, materials testers, and contractors need to understand NDT fundamentals to avoid the black box syndrome-that is, trying to get a technology to do something that they do not understand in principle. The following introductory material summarizes the goal and objectives for this track and the gaps and challenges for its research program. A phasing chart is included to show the approximate sequencing of the problem statements in the track. A table of estimated costs provides the projected cost range for each problem statement, depending on the research priorities and scope determined in implementation. The problem statements, grouped into subtracks, follow.

Track Goal

High-speed nondestructive QC can continuously monitor pavement properties during construction to provide rapid feedback. As a result, automatic adjustments can ensure a high-quality finished product that meets performance specifications.

Track Objectives
  1. Perform NDT QC tests and procedures that use continuous and real-time sampling to monitor performance-related concrete mix properties and reduce the number of human inspectors.
  2. Improve construction operations by providing continuous and rapid feedback to make changes automatically.
  3. Integrate data collection with materials management and pavement management systems (PMS) to solve future problems and evaluate performance.
Research Gaps
Research Challenges
Research Track 3 (ND) Phasing

The horizontal bar chart in figure 3 shows the approximate time phasing of the problem statements in this track grouped by subtrack across 10 years. The phasing information here is a summary of the approximate phasing included with the full written description of each problem statement in this track.

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Figure 3. Bar Chart. Track 3 (ND) subtrack and problem statement phasing chart.

Research Track 3 (ND) Estimated Costs

Table 12 shows the estimated costs for this research track.

Table 12. Research track 3 (ND) estimated costs.
Problem Statement Estimated Cost
Subtrack ND 1. Field Control
ND 1.0. Framework for Field Control (Subtrack ND 1) $350 k
ND 1.1. Field Quality Control/Quality Assurance Tests for Performance-Based Concrete Mix Design $2 M-$5 M
ND 1.2. Field Validation of Field Quality Control/Quality Assurance Tests $2 M-$5 M
ND 1.3. Revise Performance-Related Specifications (PRS) to Include Concrete Mix Properties $500 k-$1 M
Subtrack ND 2. Nondestructive Testing Methods
ND 2.0. Framework for Nondestructive Testing Methods (Subtrack ND 2) $600 k
ND 2.1. Concrete Temperature and Moisture Sensing $1 M-$2 M
ND 2.2. Concrete Pavement Thickness Sensing $500 k-$1 M
ND 2.3. Dowel/Tie Bar Alignment Sensing $1 M-$2 M
ND 2.4. Concrete Curing Effectiveness Sensing $500 k-$1 M
ND 2.5. Concrete Pavement Support Sensing $1 M-$2 M
ND 2.6. Workability Sensing $500 k-$1 M
ND 2.7. Sensing of Air Systems in Concrete Pavement $1 M-$2 M
ND 2.8. Concrete Mix Density and Volumetrics Sensing $1 M-$2 M
ND 2.9. Concrete Pavement Smoothness Sensing $1 M-$2 M
ND 2.10. Concrete Pavement Texture (Skid Resistance, Splash/Spray) Sensing $500 k-$1 M
ND 2.11. Tire-Pavement Noise Sensing $500 k-$1 M
ND 2.12. Integrated Intelligent Concrete Paving System $2 M-$5 M
Subtrack ND 3. Nondestructive Testing and Intelligent Control Systems Evaluation and Implementation
ND 3.0. Framework for Nondestructive Testing and Intelligent Control Systems Evaluation and Implementation (Subtrack ND 3) $150 k
ND 3.1. Workshops on Field Quality Control Testing of Concrete Pavement $1 M-$2 M
ND 3.2. Workshops on Nondestructive Testing and Evaluation of Concrete Pavement $1 M-$2 M
ND 3.3. Web-Based Training for Implementing Concrete Pavement Research Products $500 k-$1 M
ND 3.4. Unified Concrete Pavement Management System $1 M-$2 M
Track 3 (ND)
Total $19.6 M-$41.1 M
Track Organization: Subtracks and Problem Statements

Track 3 (ND) problem statements are grouped into three subtracks:

Each subtrack is introduced by a brief summary of the subtrack's focus and a table listing the titles, estimated costs, products, and benefits of each problem statement in the subtrack. The problem statements then follow.

SUBTRACK ND 1. FIELD CONTROL

This subtrack frames the actual field testing research, identifies key QC factors, and pools all the information into a PRS framework linking the information with track 1 (Performance-Based Concrete Pavement Mix Design System) and track 2 (Performance-Based Design Guide for New and Rehabilitated Concrete Pavements). Table 13 provides an overview of this subtrack.

Table 13. Subtrack ND 1 overview.
Problem Statement Estimated Cost Products Benefits
ND 1.0. Framework for Field Control (Subtrack ND 1) $350 k A validated, sequenced, and detailed research framework for this subtrack. An effective, coordinated, and productive research program.
ND 1.1. Field Quality Control/Quality Assurance Tests for Performance-Based Concrete Mix Design $2 M-$5 M Testing techniques/devices for QC field testing of performance-based mix designs. Performance-based concrete mix properties for projects constructed using performance-based mix designs that owner-agencies can verify.
ND 1.2. Field Validation of Field Quality Control/Quality Assurance Tests $2 M-$5 M Best practice guides and recommendations for field QC tests. A guide for implementing and using field QC tests for performance-based mix designs that will be given to owner-agencies.
ND 1.3. Revise Performance-Related Specifications to Include Concrete Mix Properties $500 k-$1 M Recommended PRS for mix design properties. A guide for incorporating concrete mix design properties into PRS that will be given to owner-agencies.
Problem Statement ND 1.0. Framework for Field Control (Subtrack ND 1)
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems(ND)
Subtrack: ND 1. Field Control
Approximate Phasing: Years 1-3
Estimated Cost: $350 k
Subtrack ND 1 (Field Control) provides a set of research problem statements that will culminate in a significantly improved state of the art and practice. As the funding becomes available, an initial effort will be necessary to develop a framework for the research to be accomplished within this subtrack.
Tasks:
  1. Examine the problem statements in subtrack ND 1 (Field Control), modify as appropriate, and divide them into specific, manageable contracts.
  2. Arrange the contracts in a carefully sequenced plan that reflects a logical progress of research and available funding.
  3. Expand each of the broad research problem statements included in the subtrack into a detailed research plan with specific objectives, tasks, and funding recommendations.
  4. Review and provide direction for the various research contracts underway to ensure that they fulfill their objectives and allow future contracts to use their results. Guide the additional work required if a contract fails to achieve its objectives and additional work is necessary.
Benefits: An effective, coordinated, and productive research program.
Products: A validated, sequenced, and detailed research framework for this subtrack.
Implementation: This research will provide the organization and validation essential for the success of this subtrack. Implementation of this problem statement will set the stage for the rest of the problem statements in subtrack ND 1 (Field Control).
Problem Statement ND 1.1. Field Quality Control/Quality Assurance Tests for Performance-Based Concrete Mix Design
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 1. Field Control
Approximate Phasing: Years 3-10
Estimated Cost: $2 M-$5 M
As performance-based mix designs replace method-based and QC/quality assurance (QA)-based specifications, tests that properly measure mix properties in the field will be required. Examples of these properties for which practical field tests must be developed include heat signature, workability, watercement ratio, and air content (size and spacing). While heat signature data can be derived in the laboratory, there is a need to develop and implement a field-ready version of the adiabatic calorimeter. Workability affects concrete placeability, affecting both paver performance and finished pavement ride quality. Water-cement ratio, a key concrete mix property, is the primary factor affecting concrete strength and permeability, significantly influencing early-age performance and long-term durability. Unfortunately, the water-cement ratio specified for a job is rarely achieved when the concrete is placed, due to the water added to achieve workability and numerous other factors. Therefore, a quick, reliable test procedure that determines the water-cement ratio shortly before concrete placement as a QA check is needed. Air content (size and spacing of bubbles) also affects permeability and pavement performance (freeze-thaw performance), and should be measured after the concrete has been placed. The air void analyzer has provided reliable results and should be used as a routine QC tool for paving projects. QC devices for field testing performance-based mix design should be rugged, inexpensive, and capable of reproducing the data that current laboratory devices can provide.
Tasks:
  1. Identify performance-based concrete mix design properties.
  2. Determine suitable limits for performance-based mix design properties.
  3. Identify techniques/devices that can determine the desired mix design properties.
  4. Modify existing devices/techniques or develop new devices for measuring the mix design parameters accurately in the field, producing the same results as laboratory tests.
  5. Develop recommendations for deploying field tests on projects using performance-based mix designs.
Benefits: Performance-based concrete mix properties for projects constructed using performance-based mix designs that owner-agencies can verify.
Products: Testing techniques/devices for QC field testing of performance-based mix designs.
Implementation: This work will result in testing techniques/devices for field testing performancebased mix design properties.
Problem Statement ND 1.2. Field Validation of Field Quality Control/Quality Assurance Tests
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 1. Field Control
Approximate Phasing: Years 4-10
Estimated Cost: $2 M-$5 M
Before deploying QC tests in the field, extensive field validation testing will be required. Field validation should be completed under all conceivable conditions expected during future testing, including varying climatic conditions, material properties, pavement types, construction techniques, and mix designs. Best practices should be developed for each of the tests. The repeatability, reliability, and variability of the test results should be checked during the field validation process.
Tasks:
  1. Identify all tests required for field validation.
  2. Work with owner-agencies to identify test validation locations that represent different climatic conditions, materials, pavement types, construction procedures, and mix designs.
  3. Work with contractors and owner-agencies to perform validation testing at various field sites.
  4. Evaluate repeatability, reliability, and variability for each test.
  5. Recommend improvements to test equipment and procedures.
  6. Document the best practices for performing field validation tests.
Benefits: A guide for implementing and using field QC tests for performance-based mix designs that will be given to owner-agencies.
Products: Best practice guides and recommendations for field QC tests.
Implementation: This work will result in best practice guidelines and/or needed improvements to field QC tests.
Problem Statement ND 1.3. Revise Performance-Related Specifications to Include Concrete Mix Properties
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 1. Field Control
Approximate Phasing: Years 5-10
Estimated Cost: $500 k-$1 M
FHWA has had an ongoing research program studying PRS for rigid pavements to ensure the construction of high-performance concrete pavements. States are advancing through the continuum of methods specifications, from QC/QA specifications to PRS-based specifications. Because the relationship between concrete mix properties and pavement performance has become better understood, PRS-based specifications should include mix properties. Workability and air content/spacing are two basic mix properties known to affect pavement construction and performance; these should be included in PRSbased specifications. As with other PRS-based specifications, determining and setting limits on performance parameters is the first step in the development process. The next step will be to determine NDTs for the various concrete properties that can be used for QC/QA in the field.
Tasks:
  1. Identify the concrete properties shown to affect concrete pavement performance, including parameters indirectly affecting performance (i.e., properties that may affect constructability and thereby affect pavement performance).
  2. Determine limits for performance-based properties.
  3. Identify practical field tests for measuring mix properties.
  4. Develop recommendations concerning PRS for mix properties.
Benefits: A guide for incorporating concrete mix design properties into PRS that will be given to owner-agencies.
Products: Recommended PRS for mix design properties.
Implementation: This work will result in recommended PRS for concrete pavement mix properties.

SUBTRACK ND 2. NONDESTRUCTIVE TESTING METHODS

This subtrack addresses the specific research needed to develop the actual NDT elements of the new intelligent control system. Table 14 provides an overview of this subtrack.

Table 14. Subtrack ND 2 overview.
Problem Statement Estimated Cost Products Benefits
ND 2.0. Framework for Nondestructive Testing Methods (Subtrack ND 2) $600 k A validated, sequenced, and detailed research framework for this subtrack. An effective, coordinated, and productive research program.
ND 2.1. Concrete Temperature and Moisture Sensing $1 M-$2 M Devices for monitoring concrete temperature and moisture during construction. Quick determination and short notice adjustment of the optimal time for surface texturing, joint sawing/cutting, and opening to traffic, resulting in high-quality pavement that can be opened quickly to traffic.
ND 2.2. Concrete Pavement Thickness Sensing $500 k-$1 M Nondestructive techniques/devices for measuring pavement thickness during construction. Techniques/devices that provide continuous realtime pavement thickness measurements without removing cores from the slab, resulting in better QA for owner-agencies.
ND 2.3. Dowel/Tie Bar Alignment Sensing $1 M-$2 M Devices for detecting dowel and tie bar misalignment during construction. Paver adjustment and gross misalignment correction during construction, resulting from the detection of dowel and tie bar misalignment behind the paver; better joint and pavement performance.
ND 2.4. Concrete Curing Effectiveness Sensing $500 k-$1 M Devices for sensing concrete curing effectiveness during construction. Automatic adjustment to curing methods during and immediately after the paving operation, resulting from continuous monitoring of curing effectiveness after concrete placement; high-quality concrete pavement.
ND 2.5. Concrete Pavement Support Sensing $1 M-$2 M Devices for measuring pavement support during construction. Automatic adjustments to the mix design, slab thickness, and joint spacing during construction, resulting from continuous monitoring of pavement support in front of the paving operation; high-quality pavements constructed precisely forthe support over which they are placed.
ND 2.6. Workability Sensing $500 k-$1 M Equipment for continuously monitoring concrete workability during construction. Automatic adjustments to the concrete mix design and paver operating parameters during construction, resulting from continuous concrete workability monitoring during placement; durable, high-quality concrete pavement placed under optimal operating conditions for the mix.
ND 2.7. Sensing of Air Systems in Concrete Pavement $1 M-$2 M Nondestructive equipment for measuring air content/properties. Automatic adjustments to the concrete mix and paver operating parameters during construction, resulting from continuous air content monitoring (quantity and spacing) behind the paver; high-quality concrete pavement with the proper air content to meet the durability requirements for the climate in which it is constructed.
ND 2.8. Concrete Mix Density and Volumetrics Sensing $1 M-$2 M Nondestructive equipment for monitoring volumetric proportions of mix constituents. Continuous monitoring of the volumetric proportions of mix constituents to allow contractors and inspectors to ensure the proper mix proportions are being used; high-quality concrete pavement with the proper mix proportions.
ND 2.9. Concrete Pavement Smoothness Sensing $1 M-$2 M Wet smoothness-sensing equipment. Pavement smoothness monitored behind the paver, permitting surface deviations to be corrected while the concrete is still plastic and allowing the paver or batching operation to be adjusted to prevent further surface deviations; smoother as-constructed pavements that do not require additional measures (diamond grinding) to meet smoothness specifications.
ND 2.10. Concrete Pavement Texture (Skid Resistance, Splash/ Spray) Sensing $500 k-$1 M Equipment for predicting skid resistance and splash/spray potential. Continuously monitored surface texture, permitting real-time prediction of skid resistance and splash/spray potential; automatic adjustments to finishing and texturing processes to achieve the desired skid resistance and splash/spray characteristics, resulting in as-constructed pavements that meet surface texture requirements without the need for additional texturing measures.
ND 2.11. Tire-Pavement Noise Sensing $500 k-$1 M Equipment for predicting pavement noise characteristics during construction. Prediction of tire-pavement noise potential during construction, allowing surface textures to be corrected while the concrete is still plastic and automatic adjustments to the surface texturing process to meet the tire-pavement noise restrictions; as-constructed pavements that meet stringent tirepavement noise restrictions without the need for additional noise mitigation.
ND 2.12. Integrated Intelligent Concrete Paving System $2 M-$5 M An integrated intelligent paving system to predict future pavement performance. An integrated intelligent paving system that will predict future pavement performance during the construction process, allowing contractors and owner-agencies to adjust the paving process automatically to achieve the pavement performance requirements; high-quality concrete pavements that will achieve the intended 30-, 40-, or 50-year (or more) design life.
Problem Statement ND 2.0. Framework for Nondestructive Methods (Subtrack ND 2)
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 2. Nondestructive Methods
Approximate Phasing: Years 1-3
Estimated Cost: $600 k
Subtrack ND 2 (Nondestructive Methods) provides a set of research problem statements that will culminate in a significantly improved state of the art and practice. As funding becomes available, an initial effort will be necessary to develop a framework for the research to be accomplished within this subtrack.
Tasks:
  1. Examine the problem statements in subtrack ND 2 (Nondestructive Methods), modify as appropriate, and divide them into specific, manageable contracts.
  2. Arrange the contracts in a carefully sequenced plan that reflects a logical progress of research and available funding.
  3. Expand each of the broad research problem statements included in the subtrack into a detailed research plan with specific objectives, tasks, and funding recommendations.
  4. Review and provide direction for the various research contracts underway to ensure that they fulfill their objectives and allow future contracts to use their results. Guide the additional work required if a contract does not achieve its objectives and additional work is necessary.
Benefits: An effective, coordinated, and productive research program.
Products: A validated, sequenced, and detailed research framework for this subtrack.
Implementation: This research will provide the organization and validation essential for the success of this subtrack. Implementation of this problem statement will set the stage for the rest of the problem statements in subtrack ND 2 (Nondestructive Methods).
Problem Statement ND 2.1. Concrete Temperature and Moisture Sensing
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 2. Nondestructive Methods
Approximate Phasing: Years 2-6
Estimated Cost: $1 M-$2 M
NDT methods for temperature and moisture sensing are important QC checks for concrete placement and early-age monitoring. Temperature can significantly affect pavement performance, prompting many transportation departments to limit concrete temperature during placement. Additionally, moisture sensing not only is a surrogate for curing effectiveness, but also is a direct indication of the hydration process. New devices will allow inspectors to monitor the concrete temperature and moisture history to ensure that limits are not exceeded. Using maturity methods, concrete temperature and moisture can be related to concrete strength, allowing contractors to assess quickly the time before the pavement can be opened to traffic. However, more precise guidelines for the maturity measurement interval, accuracy, and monitoring locations are needed. In addition, guidelines for installing sensors should be developed, addressing concerns such as the effect of mounting sensors on steel dowels or reinforcement and the minimum cover required for proper temperature measurement. Predicting stiffness using the temperature and moisture history can benefit concrete pavement construction by permitting contractors to assess the proper timing for applying surface texture and cutting joints. All NDT devices used for these purposes should be economical and practical for field use.
Tasks:
  1. Identify NDT methods and devices for temperature and moisture sensing.
  2. Determine the reliability and variability of the test methods and devices under field conditions.
  3. Modify existing devices or develop practical new devices that accurately monitor temperature and moisture during pavement construction.
  4. Develop recommendations for deploying NDT techniques/devices for temperature and moisture monitoring.
Benefits: Quick determination and short notice adjustment of the optimal time for surface texturing, joint sawing/cutting, and opening to traffic, resulting in high-quality pavement that can be opened quickly to traffic.
Products: Devices for monitoring concrete temperature and moisture during construction.
Implementation: This work will result in reliable, practical, and economical techniques/devices for monitoring concrete temperature and moisture during pavement construction.
Problem Statement ND 2.2. Concrete Pavement Thickness Sensing
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 2. Nondestructive Methods
Approximate Phasing: Years 3-7
Estimated Cost: $500 k-$1 M
As-constructed pavement thickness must be assessed during construction to determine pay factors and to ensure that the owner-agency gets what it pays for. Current practice for verifying concrete pavement thickness is to remove cores from the pavement and measure their length with calipers. This is a timeconsuming and costly process. Several agencies are attempting to use nondestructive techniques, such as physical probes, impact-echo, and ground-penetrating radar equipment, to eliminate the need for core sampling. A systematic evaluation of these and other alternatives is needed to determine their accuracy and potential for use in concrete paving specifications. When using coring to sample thickness, a limited number of thickness measurements are feasible because the cost for each sample is high. The goal of new NDT is to increase the number of samples while decreasing the cost of testing and eliminating the core removal.
Tasks:
  1. Identify existing NDT techniques that determine pavement thickness.
  2. Determine the variability of existing methods and assess whether this variability is acceptable for QC testing.
  3. Modify existing nondestructive techniques or develop new techniques that measure slab thickness at intervals as short at 30.5 cm (1 ft) quickly, accurately, and cost effectively.
  4. Develop recommendations for deploying nondestructive thickness sensing devices.
Benefits: Techniques/devices that provide continuous real-time pavement thickness measurements without removing cores from the slab, resulting in better QA for owner-agencies.
Products: Nondestructive techniques/devices for measuring pavement thickness during construction.
Implementation: This work will result in nondestructive techniques/devices for measuring pavement thickness quickly at short intervals.
Problem Statement ND 2.3. Dowel/Tie Bar Alignment Sensing
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 2. Nondestructive Methods
Approximate Phasing: Years 4-8
Estimated Cost: $1 M-$2 M

Many transportation agencies use dowel and tie bars to ensure adequate load transfer across joints in concrete pavements. If constructed properly, dowel bars should be exactly parallel to both the surface and centerline of the hardened slab. Unfortunately, this is not always the case, as misalignment can occur from either misplacement (incorrect initial positioning of the dowels), displacement (movement during the paving operation), or both. Tie bars should be centered over a longitudinal joint to secure adjacent slabs effectively. Misaligned dowel bars can cause joints to lock-up or even fault, and thus significantly affect pavement performance. There is no clear consensus among agencies on the level of practical limits on dowel placement tolerances. Normally, a maximum allowable alignment error of 0.64 cm (0.25 inch) per 45.7 cm (18 inches) length of dowel bar is specified, although the Georgia DOT specifies an allowable tolerance of 7.2 cm (3 inches) per 2.4 m (8 ft) both horizontally and vertically, and several other agencies specify an allowable tolerance of 2.5 cm (1 inch) per 1.2 m (4 ft) both horizontally and vertically. Unfortunately, these specifications are difficult to enforce because there is no efficient and reliable technique for determining in situ dowel misalignment. However, recent development of the MITSCAN-2 and MIT-SCAN-2F devices has provided an opportunity to obtain accurate dowel position information efficiently and cost effectively.

Research is needed that either modifies existing dowel bar alignment sensing equipment or develops new equipment for use during the paving process. Real-time measurements of dowel bar alignment immediately behind the paving operation will alert the contractor and inspectors to alignment problems, allowing for paver adjustments and possible corrections to misaligned dowel bars.

Tasks:
  1. Identify existing nondestructive dowel and tie bar alignment sensing devices.
  2. Modify existing devices or develop new devices that permit testing during the paving operation.
  3. Evaluate the accuracy of the devices on actual pavement sections and make recommendations for deploying the devices for concrete paving construction projects.
Benefits: Paver adjustment and gross misalignment correction during construction, resulting from the detection of dowel and tie bar misalignment behind the paver; better joint and pavement performance.
Products: Devices for detecting dowel and tie bar misalignment during construction.
Implementation: This work will result in dowel and tie bar alignment sensing devices that can be used to assess dowel and tie bar alignment rapidly during construction.
Problem Statement ND 2.4. Concrete Curing Effectiveness Sensing
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 2. Nondestructive Methods
Approximate Phasing: Years 4-8
Estimated Cost: $500 k-$1 M
The effectiveness of curing methods used during concrete paving is an important factor that can affect pavement service life. Curing affects slab warping behavior, and rapid moisture loss at the surface also can weaken surface strength. While standard laboratory test methods for evaluating the effectiveness of curing compound exist, no test or device is widely used in the field. This research will identify an NDT that will allow for continuous monitoring of curing method effectiveness during and after concrete placement. Ideally, the test/device will be fully automated and will alert the inspector or contractor if additional curing measures are needed. The test/device could also be linked to automated curing equipment that would adjust curing depending on the amount of moisture loss detected in the slab. Such devices should be portable, economical, and unobtrusive and be capable of monitoring curing effectiveness at several locations along a day's worth of pavement placement.
Tasks:
  1. Identify existing moisture sensors or other devices that measure curing effectiveness.
  2. Modify existing devices or develop new devices to monitor curing effectiveness.
  3. Validate curing effectiveness detection devices on paving projects.
  4. Develop recommendations for deploying curing effectiveness detection devices.
Benefits: Automatic adjustment to curing methods during and immediately after the paving operation, resulting from continuous monitoring of curing effectiveness after concrete placement; high-quality concrete pavement.
Products: Devices for sensing concrete curing effectiveness during construction.
Implementation: This work will result in a device that senses curing effectiveness during and after concrete placement.
Problem Statement ND 2.5. Concrete Pavement Support Sensing
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 2. Nondestructive Methods
Approximate Phasing: Years 5-9
Estimated Cost: $1 M-$2 M
The support structure beneath PCC pavements significantly affects pavement design characteristics, such as thickness, joint spacing, and mix design. Unfortunately, when most pavements are designed, the variability of the supporting structure along the length of the pavement can be significant. Automated, nondestructive support-sensing devices would allow the support structure to be assessed continuously along the length of the pavement during the paving operation. Support-sensing devices could be fixed to the paving equipment to determine the stiffness of the support structure at the time of placement and as the paving operation progresses. Automated support-sensing devices could send support information to automated batching and paving equipment, causing the batching equipment to adjust the paving mix or the paver to adjust slab thickness or load transfer (joint spacing) automatically.
Tasks:
  1. Identify existing nondestructive support-sensing devices.
  2. Modify existing devices or develop new devices that continuously monitor pavement support layers.
  3. Integrate support-sensing devices into the paving operation to make adjustments automatically.
  4. Validate support-sensing equipment on actual paving projects.
  5. Develop recommendations for deploying support-sensing equipment on paving projects.
Benefits: Automatic adjustments to the mix design, slab thickness, and joint spacing during construction, resulting from continuous monitoring of pavement support in front of the paving operation; high-quality pavements constructed precisely for the support over which they are placed.
Products: Devices for measuring pavement support during construction.
Implementation: This work will result in automated support-sensing equipment that can measure pavement support continuously during construction.
Problem Statement ND 2.6. Workability Sensing
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 2. Nondestructive Methods
Approximate Phasing: Years 5-9
Estimated Cost: $500 k-$1 M
Fresh concrete workability can affect significantly the paving process and the quality of the finished product. Workability can dictate both the speed and efficiency (i.e., energy consumption) of the paving process as well as the finishability of the pavement, affecting both ride quality and surface texture. The process is commonly controlled in the field with routine sampling and testing of the concrete for strength, slump, and sometimes air content (or unit weight). While these measures provide critical feedback, they are not always timely or reliable. This research will investigate techniques that evaluate paving concrete properties-specifically rheological properties such as workability-more rapidly and continuously. With continuous workability monitoring, the batch plant could adjust mix proportions more quickly and reliably and the paving operator could adjust the paver operating parameters more quickly.
Tasks:
  1. Identify techniques/equipment for measuring concrete workability.
  2. Modify existing equipment or develop new equipment that continuously monitors mix workability.
  3. Validate workability sensing equipment on actual paving projects.
  4. Integrate workability sensing equipment with automated batching and paving equipment.
  5. Develop recommendations for deploying workability sensing equipment.
Benefits: Automatic adjustments to the concrete mix design and paver operating parameters during construction, resulting from continuous concrete workability monitoring during placement; durable, high-quality concrete pavement placed under optimal operating conditions for the mix.
Products: Equipment for continuously monitoring concrete workability during construction.
Implementation: This work will result in equipment for continuously sensing concrete workability that can be tied into automated batching and paving equipment.
Problem Statement ND 2.7. Sensing of Air Systems in Concrete Pavement
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 2. Nondestructive Methods
Approximate Phasing: Years 5-9
Estimated Cost: $1 M-$2 M

Placement activities, such as slipform paving, reduce the quantity of entrained air in concrete by as much as 2 percent. Air tests are not currently taken after slipform paving, but rather are taken from samples either at the plant or in front of the paving machine. However, this testing procedure systematically ignores the impact of the pavement placement operation on air content. Durability studies have revealed problems with freeze-thaw damage due to an inadequate quantity of entrained air. Studies also show that both the amount of entrained air and the spacing between the air bubbles is important. Air tests are not taken behind the paving machine primarily because these tests are destructive. The current testing standard, ASTM C 231, would require removing concrete from the finished slab.

This research will develop a test method or procedure to determine the air content (amount and spacing of bubbles) of plastic concrete after paving. Although the air void analyzer has been shown to indicate air content (amount and spacing of bubbles) accurately, it still usually requires that concrete be removed from the finished surface, and the testing apparatus is not necessarily suited for field applications. This research will identify appropriate technology to create accurate and durable test equipment that can determine air content properties quickly, permitting automatic adjustments to mix proportions.

Tasks:
  1. Identify existing equipment for classifying air content (quantity and bubble spacing) accurately.
  2. Modify existing equipment or develop new durable and economical automated equipment/sensors that can assess air content behind the paver quickly.
  3. Validate air sensing equipment on actual paving projects.
  4. Integrate automated air sensing equipment/sensors with batching and paving equipment.
  5. Develop recommendations for deploying air sensing equipment for paving operations.
Benefits: Automatic adjustments to the concrete mix and paver operating parameters during construction, resulting from continuous air content monitoring (quantity and spacing) behind the paver; high-quality concrete pavement with the proper air content to meet the durability requirements for the climate in which it is constructed.
Products: Nondestructive equipment for measuring air content/properties.
Implementation: This work will result in air sensing equipment that can quickly and accurately assess the air content and spacing behind the paver.
Problem Statement ND 2.8. Concrete Mix Density and Volumetrics Sensing
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 2. Nondestructive Methods
Approximate Phasing: Years 7-10
Estimated Cost: $1 M-$2 M
During typical paving operations, process controls measure such concrete properties as slump, air content, and strength. However, density is checked rarely, and volumetric proportions seldom are checked to determine whether the proper proportions are being batched. For this purpose, nondestructive equipment for sensing the density and volumetric proportions of the material onsite is needed. The equipment should determine both the density and the volumetric proportions of constituents quickly and continuously throughout the paving operation. Automated equipment could alert inspectors or the batch plant to adjust the mix.
Tasks:
  1. Develop sensing equipment that can determine the density of the mixture and volumetric proportions of concrete constituents quickly.
  2. Validate density and volumetric sensing equipment on an actual paving project.
  3. Develop recommendations for deploying automated sensing equipment.
Benefits: Continuous monitoring of the density and volumetric proportions of mix constituents to allow contractors and inspectors to ensure the proper mix proportions are being used; high-quality concrete pavement with the proper mix proportions.
Products: Nondestructive equipment for monitoring mixture density and volumetric proportions of mix constituents.
Implementation: This work will result in nondestructive density and mix volumetric sensing equipment.
Problem Statement ND 2.9. Concrete Pavement Smoothness Sensing
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 2. Nondestructive Methods
Approximate Phasing: Years 3-6
Estimated Cost: $1 M-$2 M

The California Profilograph is the equipment most commonly used to measure pavement smoothness, providing information to the contractor in as little as 4 to 6 hours after placing conventional concrete pavement. While this is the fastest available method for providing smoothness information, it is not fast enough to indicate bumps or dips to the paving crew during finishing operations. Wet smoothnessmeasuring devices that can be mounted to slipform machines or a trailing construction bridge are needed. These devices will provide direct feedback to the paving finishing crew and to automated paving equipment. The crew can then eliminate surface deviations while the concrete remains plastic, and the paving machine could adjust to correct smoothness irregularities caused by the paver. This method will provide a uniform surface and eliminate areas that must be ground after construction.

This research will develop a wet smoothness-measuring device that produces information translatable to the California Profile Index or IRI. Evaluating the accuracy of the smoothness-measuring device will be necessary to demonstrate its accuracy relative to the California Profilograph. In addition, a manual describing the testing equipment and indexing procedure should be developed to implement this equipment and procedure.

Tasks:
  1. Identify wet smoothness-measuring devices.
  2. Adapt the smoothness-measuring devices to slipform paving operations.
  3. Develop a system that combines the new smoothness measurements with software that automatically calculates the simulated California Profile Index and IRI.
  4. Validate the wet smoothness measurements on an actual paving project.
  5. Develop recommendations for deploying the smoothness-sensing equipment during the paving operation.
Benefits: Pavement smoothness monitored behind the paver, permitting surface deviations to be corrected while the concrete is still plastic and allowing the paver or batching operation to be adjusted to prevent further surface deviations; smoother as-constructed pavements that do not require additional measures (diamond grinding) to meet smoothness specifications.
Products: Wet smoothness-sensing equipment.
Implementation: This work will result in wet smoothness-sensing equipment that can be adapted to slipform paving operations.
Problem Statement ND 2.10. Concrete Pavement Texture (Skid Resistance, Splash/Spray) Sensing
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 2. Nondestructive Methods
Approximate Phasing: Years 5-10
Estimated Cost: $500 k-$1 M
The primary purpose of pavement surface texture is to improve friction (skid resistance). However, reducing splash and spray also must be considered, as these can affect driver visibility. Predicting both skid resistance and splash/spray potential during pavement construction can ensure that an adequate and safe surface texture is applied. Because skid resistance and splash/spray potential are difficult to measure or quantify on fresh concrete surfaces, surface texture (type and depth), skid resistance, and splash/spray potential may need to be correlated. Measuring surface texture properties during construction will allow the contractor to adjust the paving equipment to improve surface texture and possibly correct still-plastic in place concrete. Surface texture sensing equipment could be mounted on the paving train immediately behind the finishing and texturing processes to determine texture properties in real time. The sensing equipment would provide instant results for a large enough section of pavement to indicate the whole surface adequately.
Tasks:
  1. Identify surface texture measurement equipment/techniques that can be used on fresh (plastic) concrete to determine skid resistance and splash/spray potential.
  2. Identify correlations between surface texture measurements, skid resistance, and splash/spray potential.
  3. Modify existing equipment or develop new sensing equipment that measures surface texture properties on fresh concrete.
  4. Develop necessary correlations between surface texture properties, skid resistance, and splash/spray potential.
  5. Validate surface texture measurement equipment on actual paving projects.
  6. Develop recommendations for deploying surface texture sensing equipment.
Benefits: Continuously monitored surface texture, permitting real-time prediction of skid resistance and splash/spray potential; automatic adjustments to finishing and texturing processes to achieve the desired skid resistance and splash/spray characteristics, resulting in as-constructed pavements that meet surface texture requirements without the need for additional texturing measures.
Products: Equipment for predicting skid resistance and splash/spray potential.
Implementation: This work will result in equipment that can predict the skid resistance and splash/spray potential of fresh concrete pavement.
Problem Statement ND 2.11. Tire-Pavement Noise Sensing
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 2. Nondestructive Methods
Approximate Phasing: Years 8-10
Estimated Cost: $500 k-$1 M
Tire-pavement noise is very important to consider in concrete pavement construction, and many States have implemented noise-level restrictions on new pavement construction. Tire-pavement noise can increase the cost of a paving project significantly if noise mitigation measures are required. Therefore, determining potential tire-pavement noise during construction is important if measures are to be taken to reduce noise levels. Research to develop techniques and equipment for measuring pavement noise potential during construction is needed. Sensing equipment mounted to the paving train immediately behind the finishing and texturing operations could sense and predict noise potential in real time. This information would allow the contractor to adjust the paving equipment to reduce noise potential and perhaps correct in place concrete that is still plastic. Noise-sensing equipment will provide instant results for a large enough section of pavement to indicate the noise potential for whole surface adequately.
Tasks:
  1. Identify surface texture measurement techniques/equipment that can predict tire-pavement noise.
  2. Modify existing equipment or develop new techniques/equipment that predict tire-pavement noise from surface texture measurements on fresh concrete.
  3. Develop necessary correlations between surface texture measurement and pavement noise.
  4. Validate noise-sensing equipment on actual paving projects.
  5. Develop recommendations for deploying noise-sensing equipment.
Benefits: Prediction of tire-pavement noise potential during construction, allowing surface textures to be corrected while the concrete is still plastic and automatic adjustments to the surface texturing process to meet the tire-pavement noise restrictions; as-constructed pavements that meet stringent tire-pavement noise restrictions without the need for additional noise mitigation.
Products: Equipment for predicting pavement noise characteristics during construction.
Implementation: This work will result in noise-sensing equipment that can be used for new PCC pavement construction.
Problem Statement ND 2.12. Integrated Intelligent Concrete Paving System
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 2. Nondestructive Methods
Approximate Phasing: Years 7-10
Estimated Cost: $2 M-$5 M
Pavement performance often can be linked to construction practices or problems encountered during construction. For this reason, an integrated intelligent paving system that predicts future pavement performance behind the paving operation in real time is needed. The intelligent paving system will predict concrete pavement performance using various sensors and equipment on and around the paving operations. The intelligent paving system minimally would incorporate monitoring of the following: concrete and ambient temperatures, workability, air properties, mix constituent proportions, strength, slab thickness, dowel bar alignment, curing effectiveness, pavement support, smoothness, texture (skid resistance and splash/spray potential), and noise potential. The intelligent paving system could allow contractors and inspectors to make adjustments automatically to improve future pavement performance and increase pay factors or performance-based incentives.
Tasks:
  1. Identify models that have been shown to predict concrete pavement performance based on construction variables.
  2. Identify sensing equipment that could be incorporated into the intelligent paving system.
  3. Integrate sensors/equipment and models into the intelligent paving system.
  4. Validate the intelligent paving system on actual paving projects.
  5. Develop recommendations for deploying the intelligent paving system.
Benefits: An integrated intelligent paving system that will predict future pavement performance during the construction process, allowing contractors and owneragencies to adjust the paving process automatically to achieve the pavement performance requirements; high-quality concrete pavements that will achieve the intended 30-, 40-, or 50-year (or more) design life.
Products: An integrated intelligent paving system to predict future pavement performance.
Implementation: This work will result in an intelligent paving system that can predict future pavement performance during construction.

SUBTRACK ND 3. NONDESTRUCTIVE TESTING AND INTELLIGENT CONTROL SYSTEM EVALUATION AND IMPLEMENTATION

This subtrack addresses the field evaluation and implementation elements of the track. Table 15 provides an overview of this subtrack.

Table 15. Subtrack ND 3 overview.
Problem Statement Estimated Cost Products Benefits
ND 3.0. Framework for Nondestructive Testing and Intelligent Control Systems Evaluation and Implementation (Subtrack ND 3) $150 k A validated, sequenced, and detailed research framework for this subtrack. An effective, coordinated, and productive research program.
ND 3.1. Workshops on Field Quality Control Testing of Concrete Pavement $1 M-$2 M Workshops that provide QC field testing. Technology transfer on QC field testing for performance-based mix designs through workshops that are a minor investment for owner-agencies.
ND 3.2. Workshops on Nondestructive Testing and Evaluation of Concrete Pavements $1 M-$2 M Workshops on NDT equipment and evaluation. Technology transfer for NDT equipment and evaluation through workshops that are a minor investment for owneragencies.
ND 3.3. Web-Based Training for Implementing Concrete Pavement Research Products $500 k-$1 M Web-based training modules and a continuously maintained Web site for new NDT and ICS products and technologies. Technology transfer for implementable NDT and ICS products that is accessible to anyone with an Internet-ready computer.
ND 3.4. Unified Concrete Pavement Management System $1 M-$2 M A concrete PMS that includes records for construction, materials, performance, and maintenance. A unified management system for concrete pavements that significantly improves design and construction operations, with a direct link between these factors and the observed inservice performance and maintenance requirements.
Problem Statement ND 3.0. Framework for Nondestructive Testing and Intelligent Control System Evaluation and Implementation (Subtrack ND 3)
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 3. Nondestructive Testing and Intelligent Control System Evaluation and Implementation
Approximate Phasing: Years 1-3
Estimated Cost: $150 k
ND 3 (Nondestructive Testing and Intelligent Control System Evaluation and Implementation) provides a set of research problem statements that will culminate in a significantly improved state of the art and practice. As funding becomes available, an initial effort will be necessary to develop a framework for the research to be accomplished within this subtrack.
Tasks:
  1. Examine the problem statements in subtrack ND 3 (Nondestructive Testing and Intelligent Control System Evaluation and Implementation), modify as appropriate, and divide them into specific, manageable contracts.
  2. Arrange the contracts in a carefully sequenced plan that reflects a logical progress of research and available funding.
  3. Expand each of the broad research problem statements included in the subtrack into a detailed research plan with specific objectives, tasks, and funding recommendations.
  4. Review and provide direction for the various research contracts underway to ensure that they fulfill their objectives and allow future contracts to use their results. Guide the additional work required if a contract does not achieve its objectives and additional work is necessary.
Benefits: An effective, coordinated, and productive research program.
Products: A validated, sequenced, and detailed research framework for this subtrack.
Implementation: This research will provide the organization and validation essential for the success of this subtrack. Implementation of this problem statement will set the stage for the rest of the problem statements in subtrack ND 3 (Nondestructive Testing and Intelligent Control System Evaluation and Implementation).
Problem Statement ND 3.1. Workshops on Field Quality Control Testing of Concrete Pavement
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 3. Nondestructive Testing and Intelligent Control System Evaluation and Implementation
Approximate Phasing: Years 4-10
Estimated Cost: $1 M-$2 M
Before implementing performance-based specifications, owner-agencies must recognize which tests can monitor performance-related properties during concrete pavement construction. While new tests and equipment are constantly being developed, transportation agencies are often slow to adopt new techniques due to unfamiliarity with new technologies and a lack of research resources. Workshops provide an environment ideal for familiarizing and training agencies in new tests and equipment. These workshops will give an overall view of QC testing in the field, with an emphasis on monitoring performance-based properties, and introduce new tests and equipment for QC field testing.
Tasks:
  1. Compile information on QC field tests and equipment, particularly for monitoring performance-based properties.
  2. Develop workshops and present material on QC field testing.
Benefits: Technology transfer on QC field testing for performance-based mix designs through workshops that are a minor investment for owner-agencies.
Products: Workshops that provide QC field testing of concrete pavement.
Implementation: This project will result in numerous workshops on QC field testing at various venues throughout the United States.
Problem Statement ND 3.2. Workshops on Nondestructive Testing and Evaluation of Concrete Pavements
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 3. Nondestructive Testing and Intelligent Control System Evaluation and Implementation
Approximate Phasing: Years 2-10
Estimated Cost: $1 M-$2 M
While new NDTs and equipment constantly are being developed, transportation agencies often are slow to adopt new techniques due to unfamiliarity with these new technologies and a lack of research resources. Workshops provide an ideal environment for familiarizing and training agencies in new NDTs and equipment, as well as evaluation procedures for using these tests. Workshops will be developed to provide technology transfer of concrete pavement NDT techniques.
Tasks:
  1. Compile information on NDTs and equipment for PCC pavement construction.
  2. Develop workshops to introduce NDT equipment and evaluation procedures to contractors and owner-agencies.
Benefits: Technology transfer for NDT equipment and evaluation through workshops that are a minor investment for owner-agencies.
Products: Workshops on NDT equipment and evaluation.
Implementation: This project will result in numerous workshops on NDT equipment and evaluation procedures at various venues throughout the United States.
Problem Statement ND 3.3. Web-Based Training for Implementing Concrete Pavement Research Products
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 3. Nondestructive Testing and Intelligent Control System Evaluation and Implementation
Approximate Phasing: Years 3-10
Estimated Cost: $500 k-$1 M
While many new products and technologies are developed and ready for implementation every year, transportation agencies are often slow to adopt new products and technologies due to unfamiliarity with these new technologies and a lack of research resources. Workshops offer contractors and owner-agencies the opportunity to learn about new products and technologies, but often agencies cannot afford to send employees to workshops or may be restricted from traveling to a workshop outside the home State. Fortunately, with Web-based training, contractors, designers, and owner-agencies can explore new products and technologies from any computer with Internet access. On-demand Web-based training can use features such as video streaming to visually demonstrate new products and technologies.
Tasks:
  1. Compile information on NDT and ICS products and technologies ready for implementation, including thorough descriptions, photos, and video.
  2. Develop Web-based training modules for each new product or technology.
  3. Create a Web site for accessing the training modules and maintain the Web site with updates or refinements for new and existing products.
Benefits: Technology transfer for implementable NDT and ICS products that is accessible to anyone with an Internet-ready computer.
Products: Web-based training modules and a continuously maintained Web site for new NDT and ICS products and technologies.
Implementation: This research will result in Web-based training modules for new NDT and ICS products and technologies related to concrete pavements.
Problem Statement ND 3.4. Unified Concrete Pavement Management System
Track: 3. High-Speed Nondestructive Testing and Intelligent Construction Systems (ND)
Subtrack: ND 3. Nondestructive Testing and Intelligent Control System Evaluation and Implementation
Approximate Phasing: Years 3-10
Estimated Cost: $1 M-$2 M
For concrete pavements, independent management systems currently exist for materials, construction, performance, and maintenance. This research will combine these management systems into a unified system, producing a database capable of linking the materials and construction used on a specific pavement segment to the segment's observed performance. This will allow for more informed decisions to be made in selecting optimum design and construction features.
Tasks:
  1. Structure a unified concrete PMS that considers user needs.
  2. Identify the databases for concrete pavements currently in use and the potential links between these databases.
  3. Develop a prototype system and populate it with a limited set of data. Evaluate this system and update it as necessary.
  4. Develop and deploy the final unified concrete PMS.
Benefits: A unified management system for concrete pavements that significantly improves design and construction operations, with a direct link between these factors and the observed inservice performance and maintenance requirements.
Products: A concrete PMS that includes records for construction, materials, performance, and maintenance.
Implementation: This project will result in a unified PMS that can be used to improve concrete pavement design and construction practices.

 


The Federal Highway Administration (FHWA) is a part of the U.S. Department of Transportation and is headquartered in Washington, D.C., with field offices across the United States. is a major agency of the U.S. Department of Transportation (DOT).
The Federal Highway Administration (FHWA) is a part of the U.S. Department of Transportation and is headquartered in Washington, D.C., with field offices across the United States. is a major agency of the U.S. Department of Transportation (DOT). Provide leadership and technology for the delivery of long life pavements that meet our customers needs and are safe, cost effective, and can be effectively maintained. Federal Highway Administration's (FHWA) R&T Web site portal, which provides access to or information about the Agency’s R&T program, projects, partnerships, publications, and results.
FHWA
United States Department of Transportation - Federal Highway Administration