Road Foundation Contamination and Drainage In-Service Evaluation and Best Practice Recommendations

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General Information
Solicitation Number: 1469
Status: Solicitation withdrawn
Date Posted: Mar 07, 2018
Last Updated: Apr 02, 2019
Solicitation Expires: Apr 01, 2019
Partners: FHWA
Lead Organization: Federal Highway Administration
Financial Summary
Commitment Start Year: 2019
Commitment End Year: 2022
100% SP&R Approval: Not Requested
Commitments Required: $1,200,000.00
Commitments Received: $700,000.00
Contact Information
Lead Study Contact(s): Michael Adams
mike.adams@dot.gov
Study Champion(s): Michael Adams
mike.adams@dot.gov
Phone: 202-493-3025
Organization Year Commitments Technical Contact Name Funding Contact Name Contact Number Email Address
Federal Highway Administration 2019 $700,000.00 Michael Adams Tom Yu 202-366-1198 tom.yu@dot.gov

Background

Background:

One of the largest transportation infrastructure asset is the foundation aggregate layers beneath roads; however, the foundation for roadways is often assumed to function as designed and constructed for the life of the pavement structure. Because the road foundation is hidden, it is often overlooked in forensic analyses, research, and most preservation programs. During the reconstruction of pavements, transportation agencies rarely investigate the loss of integrity and drainage in unbound aggregate layers due to contamination. Nationally, the issue of contaminated base courses has become even more relevant considering the age of the interstate, the increasing levels of traffic, road widening and other modifications, and pavement reconstruction; all of which can contribute to contamination and infiltration of fines.

Pavement design is based on distribution of traffic load through aggregate bases layers to the natural subgrade. Fundamentally, this concept is sound, provided the aggregate base layers retain their integrity and have adequate drainage throughout the design life of the pavement. However, with time, the initial conditions of the aggregate layers can change because of contaminative migration of fines, in combination of repeated application of heavy loads, leading to a reduction in stiffness, and drainage capabilities, leading to nonuniform foundation support conditions. Without knowing the current condition of the roadway foundation and understanding of the failure mechanism, pavement engineers can’t develop optimal design alternatives or readily implement solutions to prevent contamination.

Additionally, the research will investigate other options to maintain the strength and permeability of unbound support layers such as increasing the layer thickness to compensate for the estimated loss of properties and or including a separation layer such as a geotextile to prevent the contamination from occurring within the design life of the pavement. In the context of reworked aggregate base layers, the research should investigate procedures on how to best reuse partly contaminated road bases within the pavement profile perhaps by blending clean aggregate or chemical stabilizers to the mix, or adding a new base layer with geosynthetic for separation and/or reinforcement to supplement strength

Previous research has demonstrated the dramatic loss of strength, stiffness, and permeability of unbound roadway aggregate layers due to minimal, as little as 6%, subgrade contamination into unbound aggregates (Jorenby and Hicks 1986). With this understanding, combined with the fact that most graded aggregates specified by the States already contain a certain percentage of P200 fines, typically between 6 and 10 percent to ensure the appropriate stiffness, these dense-graded aggregate bases are already near their fine content that can provide sufficient drainage (Tutumluer, 2013). In other words, they typically drain provided additional fines are not added to the mix. The implication of this research conflicts with the current practice of building new roads with aggregate blends already at P200 near or above 10%.

The future of many major pavement reconstruction projects is leaning towards the reworking of existing road bases not full depth reclamation. This alternative, instead of complete aggregate base replacement, is less expensive considering the time requirements of reconstruction, logistics, and more feasible considering sources of quality road base is limited in some regions of the USA. Among various strategies proposed to alleviate this problem, the facilitation of drainage is perhaps the most important design detail for a long lasting durable pavement because the strength and stiffness of the base course is directly related to the moisture content of the base layers; lack of drainage can also contribute to spring-thaw weakening as well as saturation of joint areas, cracks, and other voids in the p

Objectives

The objectives of this research are to:

1) document the degree of contamination of unbound aggregate layers within different pavement structures across the USA, both new and rehabilitated.

2) determine and document the pavement foundation degradation process and the impact on pavement performance.

3) establish the means of quantifying the condition of the pavement foundation and the condition levels (desirable and minimum) needed to ensure good pavement performance system in terms of foundation support and facilitation of drainage. This will include evaluation of in-situ test methods and development of testing protocols to assess the condition of the pavement foundation as an alternative to laboratory sampling.

4) develop strategies to mitigate the effects of aggregate layer degradation and contamination as part of a life cycle analysis for both new and rehabilitated pavements. Specifically, how to design foundation to avoid degradation.

5) Develop best practice recommendations to prevent degradation, facilitate drainage, and how best to assess the condition of existing aggregate bases.

The primary products of this research include documentation of the pavement foundation degradation process, and development of protocols and methods to 1) sample, test, and quantify contamination/drainage in existing unbound layers; 2) assess condition of the existing pavement foundation; and 3) establish guidelines for design and rehabilitation of pavement foundation to ensure the integrity and longevity of the pavement foundation for both new and rehabilitated pavements. The results will lead to a better understanding and established criteria for the potential contamination of base layers based on subgrade conditions, aggregate gradations and other associated factors.

Scope of Work

Scope of Work:

Part I: In-Service Evaluation

• Coordinate with participating transportation agencies to identify opportunities for field sampling and forensic degradation evaluations. The work will include:

o Develop protocols for consistent aggregate sampling and testing procedures.

o Pavement section coring and aggregate sampling in both problematic and non- problematic sites to establish any correlations.

o Evaluation in-situ test methods for the assessment of pavement foundations. Laboratory analysis of the aggregate layers from pavements sections with both good and poor performance to correlate with the amount of degradation and contamination of base layers.

o Investigate the condition of the aggregate base layers during different types of pavement reconstruction projects, primarily those associated with base course failure, to collect site specific information, and document the condition of the base course, the level of contamination and permeability in the unbound aggregate layers. Conduct laboratory and field experiments to investigate the sensitivity of fines content in different pavement foundation systems.

o Assess drainage capabilities and details of the sites.

Part II: Development of Best Practice Recommendations for:

• Test procedures and protocols for the assessment of pavement foundations.

• Engineering control alternatives to prevent base contamination and to provide adequate drainage in new and existing pavements.

• Design guidelines using these testing protocols for evaluating the pavement foundation as a part of pavement rehabilitation necessary to determine the extent of foundation degradation (if any), and whether the foundation could be 1) left in place, 2) left in place with some mitigation treatments, or 3) replaced for more efficient longer lasting pavement systems.

Comments

The Technical Liaison for this project is Tom Yu from the FHWA Office of Asset Management, Pavements, and Construction (HIAP-20). Phone: 202-366-1198; Email: tom.yu@dot.gov

• The project duration is anticipated to be 5 years.

• Participating organizations will have representation on the technical working group to assist developing the SOW, project evaluation, and active participation in field site investigations as part of technology transfer.

• All States, MPOs, local agencies, private organizations, and businesses are welcome to participate.

• 100% SPR Funding has been requested

• Commitments to join the study can be either in the form of financial and/or in-kind contributions.

- Financial contributions for 2 years at $25,000/year funding level is requested to join the study.

- In-kind contribution involves assistance in identifying candidate field sites, assistance with traffic control activities, or the necessary support for evaluation and information collection.

Subjects: Maintenance Pavement Design, Management, and Performance Soils, Geology, and Foundations

No document attached.

Road Foundation Contamination and Drainage In-Service Evaluation and Best Practice Recommendations

General Information
Solicitation Number: 1469
Status: Solicitation withdrawn
Date Posted: Mar 07, 2018
Last Updated: Apr 02, 2019
Solicitation Expires: Apr 01, 2019
Partners: FHWA
Lead Organization: Federal Highway Administration
Financial Summary
Commitment Start Year: 2019
Commitment End Year: 2022
100% SP&R Approval: Not Requested
Commitments Required: $1,200,000.00
Commitments Received: $700,000.00
Contact Information
Lead Study Contact(s): Michael Adams
mike.adams@dot.gov
Commitments by Organizations
Agency Year Commitments Technical Contact Name Funding Contact Name Contact Number Email Address
Federal Highway Administration 2019 $700,000.00 Michael Adams Tom Yu 202-366-1198 tom.yu@dot.gov

Background

Background:

One of the largest transportation infrastructure asset is the foundation aggregate layers beneath roads; however, the foundation for roadways is often assumed to function as designed and constructed for the life of the pavement structure. Because the road foundation is hidden, it is often overlooked in forensic analyses, research, and most preservation programs. During the reconstruction of pavements, transportation agencies rarely investigate the loss of integrity and drainage in unbound aggregate layers due to contamination. Nationally, the issue of contaminated base courses has become even more relevant considering the age of the interstate, the increasing levels of traffic, road widening and other modifications, and pavement reconstruction; all of which can contribute to contamination and infiltration of fines.

Pavement design is based on distribution of traffic load through aggregate bases layers to the natural subgrade. Fundamentally, this concept is sound, provided the aggregate base layers retain their integrity and have adequate drainage throughout the design life of the pavement. However, with time, the initial conditions of the aggregate layers can change because of contaminative migration of fines, in combination of repeated application of heavy loads, leading to a reduction in stiffness, and drainage capabilities, leading to nonuniform foundation support conditions. Without knowing the current condition of the roadway foundation and understanding of the failure mechanism, pavement engineers can’t develop optimal design alternatives or readily implement solutions to prevent contamination.

Additionally, the research will investigate other options to maintain the strength and permeability of unbound support layers such as increasing the layer thickness to compensate for the estimated loss of properties and or including a separation layer such as a geotextile to prevent the contamination from occurring within the design life of the pavement. In the context of reworked aggregate base layers, the research should investigate procedures on how to best reuse partly contaminated road bases within the pavement profile perhaps by blending clean aggregate or chemical stabilizers to the mix, or adding a new base layer with geosynthetic for separation and/or reinforcement to supplement strength

Previous research has demonstrated the dramatic loss of strength, stiffness, and permeability of unbound roadway aggregate layers due to minimal, as little as 6%, subgrade contamination into unbound aggregates (Jorenby and Hicks 1986). With this understanding, combined with the fact that most graded aggregates specified by the States already contain a certain percentage of P200 fines, typically between 6 and 10 percent to ensure the appropriate stiffness, these dense-graded aggregate bases are already near their fine content that can provide sufficient drainage (Tutumluer, 2013). In other words, they typically drain provided additional fines are not added to the mix. The implication of this research conflicts with the current practice of building new roads with aggregate blends already at P200 near or above 10%.

The future of many major pavement reconstruction projects is leaning towards the reworking of existing road bases not full depth reclamation. This alternative, instead of complete aggregate base replacement, is less expensive considering the time requirements of reconstruction, logistics, and more feasible considering sources of quality road base is limited in some regions of the USA. Among various strategies proposed to alleviate this problem, the facilitation of drainage is perhaps the most important design detail for a long lasting durable pavement because the strength and stiffness of the base course is directly related to the moisture content of the base layers; lack of drainage can also contribute to spring-thaw weakening as well as saturation of joint areas, cracks, and other voids in the p

Objectives

The objectives of this research are to:

1) document the degree of contamination of unbound aggregate layers within different pavement structures across the USA, both new and rehabilitated.

2) determine and document the pavement foundation degradation process and the impact on pavement performance.

3) establish the means of quantifying the condition of the pavement foundation and the condition levels (desirable and minimum) needed to ensure good pavement performance system in terms of foundation support and facilitation of drainage. This will include evaluation of in-situ test methods and development of testing protocols to assess the condition of the pavement foundation as an alternative to laboratory sampling.

4) develop strategies to mitigate the effects of aggregate layer degradation and contamination as part of a life cycle analysis for both new and rehabilitated pavements. Specifically, how to design foundation to avoid degradation.

5) Develop best practice recommendations to prevent degradation, facilitate drainage, and how best to assess the condition of existing aggregate bases.

The primary products of this research include documentation of the pavement foundation degradation process, and development of protocols and methods to 1) sample, test, and quantify contamination/drainage in existing unbound layers; 2) assess condition of the existing pavement foundation; and 3) establish guidelines for design and rehabilitation of pavement foundation to ensure the integrity and longevity of the pavement foundation for both new and rehabilitated pavements. The results will lead to a better understanding and established criteria for the potential contamination of base layers based on subgrade conditions, aggregate gradations and other associated factors.

Scope of Work

Scope of Work:

Part I: In-Service Evaluation

• Coordinate with participating transportation agencies to identify opportunities for field sampling and forensic degradation evaluations. The work will include:

o Develop protocols for consistent aggregate sampling and testing procedures.

o Pavement section coring and aggregate sampling in both problematic and non- problematic sites to establish any correlations.

o Evaluation in-situ test methods for the assessment of pavement foundations. Laboratory analysis of the aggregate layers from pavements sections with both good and poor performance to correlate with the amount of degradation and contamination of base layers.

o Investigate the condition of the aggregate base layers during different types of pavement reconstruction projects, primarily those associated with base course failure, to collect site specific information, and document the condition of the base course, the level of contamination and permeability in the unbound aggregate layers. Conduct laboratory and field experiments to investigate the sensitivity of fines content in different pavement foundation systems.

o Assess drainage capabilities and details of the sites.

Part II: Development of Best Practice Recommendations for:

• Test procedures and protocols for the assessment of pavement foundations.

• Engineering control alternatives to prevent base contamination and to provide adequate drainage in new and existing pavements.

• Design guidelines using these testing protocols for evaluating the pavement foundation as a part of pavement rehabilitation necessary to determine the extent of foundation degradation (if any), and whether the foundation could be 1) left in place, 2) left in place with some mitigation treatments, or 3) replaced for more efficient longer lasting pavement systems.

Comments

The Technical Liaison for this project is Tom Yu from the FHWA Office of Asset Management, Pavements, and Construction (HIAP-20). Phone: 202-366-1198; Email: tom.yu@dot.gov

• The project duration is anticipated to be 5 years.

• Participating organizations will have representation on the technical working group to assist developing the SOW, project evaluation, and active participation in field site investigations as part of technology transfer.

• All States, MPOs, local agencies, private organizations, and businesses are welcome to participate.

• 100% SPR Funding has been requested

• Commitments to join the study can be either in the form of financial and/or in-kind contributions.

- Financial contributions for 2 years at $25,000/year funding level is requested to join the study.

- In-kind contribution involves assistance in identifying candidate field sites, assistance with traffic control activities, or the necessary support for evaluation and information collection.

Subjects: Maintenance Pavement Design, Management, and Performance Soils, Geology, and Foundations

No document attached.

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