APPENDIX A—BIBLIOGRAPHY

AASHTO AND ASTM STANDARDS

AASHTO T 99, Standard Method of Test for Moisture-Density Relations of Soils Using a 2.5-kg (5.5-lb) Rammer and a 305-mm (12-in.) Drop. These methods of test are intended for determining the relation between the moisture content and density of soils compacted in a mold of a given size with a 2.5-kg (5.5-lb) rammer dropped from a height of 305 mm (12 in.).

AASHTO T 110, Standard Method of Test for Moisture or Volatile Distillates in Hot-Mix Asphalt (HMA). This method is intended for the determination, by direct measurement, of moisture or volatile fractions of the bitumen in HMA.

AASHTO T 134, Standard Method of Test for Moisture-Density Relations of Soil-Cement Mixtures. These methods of test are intended for determining the relation between the moisture content and density of soil-cement mixtures when compacted before cement hydration as prescribed.

AASHTO T 217, Standard Method of Test for Determination of Moisture in Soils by Means of a Calcium Carbide Gas Pressure Moisture Tester. This method of test is intended to determine the moisture content of soils by means of a calcium carbide gas pressure moisture tester.

AASHTO T 255, Standard Method of Test for Total Evaporable Moisture Content of Aggregate by Drying. This test method covers the determination of the percentage of evaporable moisture in a sample of aggregate by drying both surface moisture and moisture in the pores of the aggregate.

AASHTO T 265, Standard Method of Test for Laboratory Determination of Moisture Content of Soils. This method covers the laboratory determination of the moisture content of soils.

AASHTO T 283, Standard Method of Test for Resistance of Compacted Hot-Mix Asphalt (HMA) to Moisture-Induced Damage. This method covers preparation of specimens and the measurement of the change of diametral tensile strength resulting from the effects of water saturation and accelerated water conditioning, with a freeze-thaw cycle, of compacted HMA. The results may be used to predict long-term stripping susceptibility of the HMA and evaluate liquid antistripping additives that are added to the asphalt binder or pulverulent solids, such as hydrated lime or portland cement, which are added to the mineral aggregate.

AASHTO T 310, Standard Specification for In-Place Density and Moisture Content of Soil and Soil-Aggregate by Nuclear Methods (Shallow Depth). This test method describes the procedure for determining the in-place density and moisture of soil and soil-aggregate by use of nuclear gauge. The density of the material may be determined by either direct transmission, backscatter, or backscatter/air-gap ratio method. The moisture of the material is determined only from measurements taken at the surface of the soil (i.e., backscatter).

AASHTO T 329, Standard Method of Test for Moisture Content of Hot-Mix Asphalt (HMA) by Oven Method. This method is intended for the determination of moisture content of HMA by drying in an oven.

AASHTO HDG-4, Highway Drainage Guidelines, 4th Edition. The Highway Drainage Guidelines provides a consolidated overview of highway hydraulic design and discusses possible hydrology problems in the following areas:

• Hydraulic Considerations in Highway Planning and Location.
• Hydrology.
• Erosion and Sediment Control in Highway Construction.
• Hydraulic Design of Highway Culverts.
• The Legal Aspects of Highway Drainage.
• Hydraulic Analysis and Design of Open Channels.

• Hydraulic Analysis for the Location and Design of Bridges.
• Hydraulic Aspects in Restoration and Upgrading of Highways.
• Storm Drain Systems.
• Evaluating Highway Effects on Surface Water Environments.
• Highways along Coastal Zones and Lakeshores.
• Stormwater Management.
• Training and Career Development of Hydraulics Engineers.
• Culvert Inspection, Material Selection, and Rehabilitation.
• Guidelines for Selecting and Utilizing Hydraulics Engineering Consultants.

ASTM D4867, Standard Test Method for Effect of Moisture on Asphalt Concrete Paving Mixtures. This test method can be used to test AC mixtures in conjunction with mixture design testing to determine the potential for moisture damage, to determine whether or not an antistripping additive is effective, and to determine what dosage of an additive is needed to maximize the effectiveness. This test method can also be used to test mixtures produced in plants to determine the effectiveness of additives under the conditions imposed in the field.

ASTM D7404, Standard Test Method for Determination of Emulsified Asphalt Residue by Moisture Analyzer. This test method covers a rapid and quantitative determination of the residue in emulsified asphalts using a moisture analyzer. It is applicable to all nonsolvent-containing emulsion types.

ASTM D7870, Standard Practice for Moisture Conditioning Compacted Asphalt Mixture Specimens by Using Hydrostatic Pore Pressure. This practice provides an accelerated conditioning method under cyclic loading. This system is capable of operating at higher-than-normal temperatures and creating pore pressure within a compacted asphalt mixture to achieve an acceleration of the effects that a mixture would experience over time from traffic at normal temperatures and conditions. The accelerated conditioning in this practice is intended to simulate the stresses induced in a wet pavement by a passing vehicle tire.

Table A-1. Agency and Industry Specifications, Plans, and Other Relevant Documents Specific to Pavement and Drainage

― N/A

CLIMATE IMPACTS

Drumm, E. C. and R. Meier. 2003. LTPP Data Analysis: Daily and Seasonal Variations in Insitu Material Properties. NCHRP Web Document 60. Transportation Research Board, Washington, DC.

http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_w60.pdf. As part of the Long-Term Pavement Performance (LTPP) Seasonal Monitoring Program (SMP), pavement sites across North America were instrumented to periodically measure the temperature and moisture conditions inside the pavement and some of the environmental factors that affect those conditions. Coupled with periodic falling weight deflectometer (FWD) tests to determine the stiffness of the pavement layers, this program has produced a data set that can be used to investigate daily and seasonal changes in pavement material properties and relate those changes to the changes in structural capacity that would necessitate load restrictions. This report presents the results of such an analysis of this data set.

Gaspard, K. Z. Zhang, G. Gautreau, M. Abufarsakh, and M. Martinez. 2019. Impact of inundation on Roadway Pavements: Case Study – LA 493. Report No. FHWA/LA.18/608. Louisiana Transportation Research Center. Baton Rouge, LA. This case study details the effects of inundation on LA 493 based on pavement assessments carried out both before and after inundation events. A rod- and-level survey at the roadway centerline showed elevation increases ranging from 2.44 to 44.5 mm after the first inundation event. IRI measurements were high and highly variable, and rutting measurements also showed high variability. FWD test results suggested that structural damage had occurred due to the inundation; increased deflections were translated into losses of equivalent thicknesses of asphalt pavement ranging from 0.2 to 2.61 inches. Finally, the amount of longitudinal cracking was much higher than expected for a pavement of this age and is ascribed to the inundation events.

CONSTRUCTION

Federal Highway Administration (FHWA). 2002. Construction of Pavement Subsurface Drainage Systems (Reference Manual). Federal Highway Administration, Washington, DC. http://isddc.dot.gov/OLPFiles/FHWA/013293.pdf. Reference manual for a workshop on the construction of pavement drainage systems for both rigid and flexible pavements. Includes examples of specifications used by several states. Covers permeable bases and longitudinal edge drain systems.

Mohammad, L. H., and M. A. Elsiefi. 2014. “Optimization of Tack Coat for Hot-Mix Asphalt Placement.” Enhancing the Durability of Asphalt Pavements. Transportation Research Circular, Number E-C186. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/circulars/ec186.pdf. In the past several years, there have been a number of significant advances in asphalt materials and construction techniques for increasing the durability of pavements. This e-circular contains papers based on a Sunday workshop at the 92nd Annual Meeting of the TRB in Washington, DC, on enhancing the durability of asphalt pavements. The workshop focused on new design and construction approaches for extending pavement life while also improving their sustainability. The workshop also addressed the use of new materials, methods of mix analysis and cracking models, coupled with specific construction techniques that can significantly increase the life of the asphalt pavement. Furthermore, it covers actual application of these materials and approaches and some associated long-term benefits. The most significant outcome of this workshop was to show that these materials and approaches are readily available in the marketplace today and only require some relatively minor changes to specifications.

DRAINAGE SYSTEMS AND DESIGN

Ahmed, Z., T. D. White, and P. L. Bourdeau. 1993. Pavement Drainage and Pavement-Shoulder Joint Evaluation and Rehabilitation. Final Report, FHWA/IN/JHRP-93/2. Indiana Department of Transportation, Indianapolis, IN and Purdue University, West Lafayette, IN. http://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=2557&context=jtrp. The objectives of this research were to i) evaluate the performance of pavement subdrainage systems, ii) study the behavior of moisture conditions below pavements, and iii) provide recommendations for improved drainage criteria based on analysis of field data. Existing and retrofitted subdrainage collector systems were inspected through external visual inspection in combination with a probe for internal inspection. Distresses and deficiencies in construction observed were listed and compiled on video. A methodology for inspection is presented that can be used by highway agencies in monitoring the condition, need for maintenance, and performance of collector systems. Pavements with various types of subdrainage systems were

instrumented to monitor the effects of different parameters influencing flow. The instrumentation package included pressure transducers, moisture blocks, thermistor probe, rain gauge, tipping bucket flow meter, and a data recording and storage system. Laboratory investigations were conducted on subgrade and subbase samples collected from instrumented sites to assess their material and hydraulic properties. Parameters obtained by fitting Brooks & Corey’s model and Van Genuchten’s model to experimental data have shown good correlations with measured values. Data collected from instrumented sites show varying response rate and time of outflow with respect to precipitation for different types of pavements and collector systems. Statistical analysis has shown significant influence of base permeability in addition to pavement and drain types on pavement outflow. High correlations exist between precipitation and pore pressure underneath pavements. Data from instrumentation and laboratory tests will help in calibrating and validating an analytical seepage program developed separately as part of this research project.

Anderson, D. A., R. S Huebner, J. R. Reed, J. C. Warner, and J. J. Henry. 1998. Improved Surface Drainage of Pavements. NCHRP Web Document Number 16. Transportation Research Board, Washington, DC. http://www.nap.edu/openbook.php?record_id=6357. The purpose of this project was to identify techniques for improving the drainage of multi-lane highway pavements and to develop guidelines for implementing the most promising of these techniques. The drainage of highway pavement surfaces is important in the mitigation of splash and spray and hydroplaning. This study focused on improving surface drainage to reduce the tendency for hydroplaning. The main factor affecting the propensity for hydroplaning is the thickness of the water film on the pavement surface. Three general techniques were identified for reducing the water film thickness: controlling the pavement geometry, the use of textured surfaces to include porous asphalt surfaces and grooved surfaces, and the more effective use of drainage appurtenances. The prediction of the water film thickness is based on the use of the kinematic wave equation as a model to predict the depth of flow on pavement surfaces. Data supporting the model were obtained from the literature and from studies conducted to measure Manning’s n for a brushed concrete surface and for porous asphalt surfaces. Expressions for Manning’s n as a function of Reynold’s number were developed for portland cement concrete, concrete, AC, and porous asphalt surfaces. Full-scale skid testing was also conducted on grooved and brushed concrete surfaces and on porous asphalt surfaces; texture measurements were obtained for all of the tested surfaces (laboratory and field). The results have been integrated into an interactive computer program, PAVDRN. This interactive program allows the pavement design engineer to select values for the critical design parameters. The program then predicts the water film thickness along the line of maximum flow and determines the hydroplaning potential along the flow path. If the predicted hydroplaning speed is less than the design speed, the designer is prompted to choose from alternative designs that reduce the thickness of the water film.

Cedergren, H. R., K. H. O’Brien, and J. A. Arman. 1972. Guidelines for the Design of Subsurface Drainage Systems for Highway Structural Sections. Report No. FHWA-RD-72-30. Federal Highway Administration, Washington, DC. http://ntl.bts.gov/lib/27000/27000/27042/FHWA-RD-72-30.pdf. Design criteria and a design method for pavement subsurface drainage systems include inflow-outflow method of analysis, open-graded drainage layers, collector drains, pipe outlets and markers. Design examples are given for embankment sections, cut sections and superelevated curves. Emphasis is on draining water that infiltrates the pavement structure from the surface through cracks, construction joints, and through permeable surfaces, medians and shoulders. A final section of the report covers general guidance for the design, construction, and operation of subsurface drainage systems.

Ceylan, H., K. Gopalakrishnan, S. Kim, and R. F. Steffes. 2013. Evaluating Roadway Subsurface Drainage Practices. Iowa Department of Transportation, Ames, IA. http://www.iowadot.gov/research/reports/Year/2013/fullreports/TR-643%20Final.pdf. The bearing capacity and service life of a pavement is adversely affected by the presence of undrained water in the pavement layers. In cold climates like Iowa, this problem is further magnified by the risk of frost damage when water is present. Therefore, well-performing subsurface drainage systems form an important aspect of pavement design by the Iowa Department of Transportation (IDOT). Previous studies have reported that properly designed, constructed, and maintained pavements incorporation positive subsurface drainage features can greatly extend the life of a pavement. However, controversial findings are also reported in the

literature regarding the benefits of subsurface drainage. A focused project management strategy is essential for the successful completion of the project. The project Technical Advisory Committee (TAC), comprising city and county engineers along with IDOT representatives, will be formed in less than a month of the project starting date. Other project management activities including formulation of project scope, distribution of efforts, regular consultation with TAC, etc. will be carried out throughout the project duration.

Christopher, B. R. 2000. Maintenance of Highway Edgedrains. NCHRP Synthesis 285. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_syn_285.pdf. This synthesis report will be of interest to pavement design, construction, maintenance, and materials engineers; geologists and hydrologists; highway contractors; and others interested in the maintenance of highway edge drains. It describes the current state-of-the-practice for the maintenance of highway edge drain systems (i.e., outlet, headwall, connection, longitudinal/mainline pipe) and procedures to reduce and facilitate the maintenance of edge drains. Information is provided on the maintenance of edge drains, its relation to pavement drainage and performance, and the importance and cost benefits of providing good drainage in highways. Information for the synthesis was collected by surveying US and Canadian transportation agencies and by conducting a literature search to document North American and European practices. This report of the TRB is an extension to the information provided by NCHRP Synthesis of Highway Practice No. 239, “Pavement Subsurface Drainage Systems” (1997). Design, material, and construction details and techniques, obtained from a survey of North American transportation agencies, are provided to demonstrate effective edge drain maintenance practices that promote highway drainage. Agency policies and procedures for edge drain maintenance are also provided. In addition, strategies to reduce edge drain maintenance costs and methods of increasing maintenance effectiveness are included.

Christopher, B. R. and V. C. McGuffey. 1997. Pavement Subsurface Drainage. NCHRP Synthesis 239. Transportation Research Board, Washington, DC. ftp://216.68.93.35/Applications/extranet.hsr.com/portfolio/Contech/CEResourceManual_CD1/Assets/PDF/NCHRP%20Synthesis%20239.pdf. This synthesis will be of interest to geologists; hydrologists; geotechnical, pavement, construction, and maintenance engineers; and researchers. State department of transportation (DOT) program managers and administrators will also find it of interest. The synthesis describes the current state-of-the-practice for the design, construction, and maintenance of pavement subsurface drainage systems. It provides information on the positive effects of good subsurface drainage and the negative effects of poor subsurface drainage on pavement surfaces. This report of the TRB presents data obtained from a review of the literature and a survey of the state DOTs. It is a supplemental update to NCHRP Synthesis of Highway Practice 96, “Pavement Subsurface Drainage Systems” (1982). The synthesis provides a supplement to design issues not found in Synthesis 96, but faced by current designers, e.g., type and quality of aggregate, compaction requirements for open-graded aggregates, asphalt and cement binders, and use of geosynthetics. In addition, it describes the effects of design, construction, and maintenance decisions on the performance of pavement subsurface drainage systems.

Federal Highway Administration (FHWA). 1994. Drainable Pavement Systems (Instructor’s Guide). Publication Number FHWA-SA-94-062. Federal Highway Administration, Washington, DC. http://www.fhwa.dot.gov/pavement/pub_details.cfm?id=146. A good compendium of FHWA’s drainage guidance of that period. A solid historical basis for FHWA’s drainage guidance. Some policy related issues covered. However, construction guidance provided here was updated in FHWA-IF-01-016. Much of the drainage guidance was retained in NHI Course 131026 published in 1999 along with more up to date information.

Grover, S., I. Madras, and A. Veeraragavan. 2010. “Quantification of Benefits of Improved Pavement Performance due to Good Drainage.” Journal of the Indian Roads Congress, Volume 71, Issue Number 1. Indian Roads Congress, New Delhi, India. http://irc.org.in/ENU/knowledge/archive/Technical%20Papers%20for%20Irc%20Journals/Quantification%20of%20Benefits%20of%20Improved%20Pavement%20Performance%20Due%20To%20Good%20Drainage.pdf. Subsurface drainage is a key element in the design of pavement systems. However, inadequate subsurface drainage continues to be identified as a major cause of pavement distress. The entrapment of water within the pavement leads to a ‘bathtub’ condition, resulting in premature failures and chronic pavement distresses. This leads to costly repairs or replacements to the pavements long before they reach their design life and increases life-cycle costs. The benefits of providing good drainage over the service life of a pavement are quantified. The pavement performance data collected from a national highway pavement section with good drainage and another section with poor drainage were used in this study. The performances in terms of deflection, roughness, cracking and raveling are predicted for do-nothing and after maintenance intervention. The benefits due to maintenance strategy are calculated by computing the vehicle operating costs and cost effectiveness for both the pavement sections. The benefits are compared for good drainage section and poor drainage section to bring out the advantage of providing good drainage. The effect of cost benefit analysis, vehicle damage factors and traffic growth rate is also analyzed for the maintenance treatment.

Hall, K. T. and C. E. Correa. 2003. Effects of Subsurface Drainage on Performance of Asphalt and Concrete Pavement. NCHRP Report 499. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_499.pdf. This report presents the findings of a research project to evaluate the effects of subsurface drainage features on the performance of pavements through a comprehensive analysis of data available through June 2001 from the LTPP experiments. The report will be of particular interest to engineers in the public and private sectors with responsibility for the design, construction, and rehabilitation of highway pavements.

Hall, K. T. and J. A. Crovetti. 2007. Effects of Subsurface Drainage on Pavement Performance: Analysis of the SPS-1 and SPS-2 Field Sections. NCHRP Report 583. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_583.pdf. This report evaluates the effects of subsurface drainage features on pavement performance through a program of inspection and testing of the subsurface drainage features present in the LTPP SPS-1 and SPS-2 field sections. The report will be of particular interest to engineers in the public and private sectors with responsibility for the design, construction, and rehabilitation of highway pavements.

Harrigan, E. T. 2002. Performance of Pavement Subsurface Drainage. NCHRP Research Results Digest 268. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rrd_268.pdf. This digest presents key findings of National Cooperative Highway Research Program (NCHRP) Project 1-34, “Performance of Subsurface Pavement Drainage.” It provides a useful summary of the effects of subsurface pavement drainage features on the performance of AC and portland cement concrete (PCC) pavements developed from an extensive body of field project data obtained through 1998. Further, it will serve as a good basis of reference for similar results now being obtained from Special Pavement Studies 1 and 2 in the LTPP program. Thus, the digest will be of particular interest to engineers in the public and private sectors with responsibility for the design, construction, and rehabilitation of AC and PCC pavements. The digest is organized in the following sections: Background; Controversy Over Subsurface Drainage; Key Questions Addressed; Data Collected in Project 1-34 and Data Obtained from Other Sources; Analyses Conducted; Effects of Subsurface Drainage on Flexible Pavements; Effects of Subsurface Drainage on Rigid Pavements; Findings for Retrofitted Edge drains; Cost Effectiveness Findings; Discussion of Findings; and Limitations of Findings. Two tables are included showing, respectively, a summary of AC pavement sections analyzed, and a summary of PCC pavement sections analyzed.

Johnson, F. L. and F.F.M. Change. 1984. Drainage of Highway Pavement. FHWA-TS-84-202. Federal Highway Administration, Washington, DC. https://www.fhwa.dot.gov/engineering/hydraulics/pubs/hec/hec12.pdf. This edition of Hydraulic Engineering Circular No. 12 incorporates new design charts and procedures developed from laboratory tests of interception capacities and efficiencies of highway pavement drainage inlets. A chart for the solution of the kinematic wave equation for overland flow and a new chart for the solution of Manning’s equation for triangular channels are provided. Charts and procedures for using the charts are provided for seven grate types, slotted drain inlets, curb-opening inlets, and combination inlets on grade and in sump locations. Charts, tables, and example problem solutions are included in the text where introduced and discussed. The text includes discussion of the effects of roadway geometry on pavement drainage; the philosophy of design frequency and design spread selection; storm runoff estimating methods; flow in gutters; pavement drainage inlets, factors affecting capacity and efficiency, and comparisons of interception capacity; median inlets; embankment inlets; and bridge deck inlets. Five appendixes are included with discussion of the development of rainfall intensity-duration-frequency curves and equations, mean velocity in a reach of triangular channel with unsteady flow, the development of gutter capacity curves for compound and parabolic roadway sections, and the development of design charts for grates of specific size and bar configuration. (FHWA).

Laguros, J. G. and G. A. Miller. 1997. Stabilization of Existing Subgrades to Improve Constructability during Interstate Pavement Reconstruction. NCHRP Synthesis No. 247. Transportation Research Board, Washington, DC. This synthesis will be of interest to state DOTs’ construction, geotechnical, materials, and pavement system design engineers, engineering geologists, and research engineers, and others concerned with the constructability of new pavements over existing subgrades. The synthesis describes current practice for the stabilization of existing subgrades to improve constructability during interstate pavement reconstruction. It presents information regarding the methods available to evaluate and improve subgrade conditions for the purpose of meeting the constructability requirements of a reconstruction project. This report of the TRB presents data obtained from a review of the literature and a survey of the state DOTs. The synthesis reports on: subgrade evaluation methods including sampling, laboratory, and in situ test methods, as well as assessment of existing drainage systems; constructability factors such as existing and proposed pavement types, available equipment, and cost effectiveness of various subgrade stabilization techniques; methods of subgrade improvement including mechanical and chemical stabilization, use of recycled and waste materials, the use of geosynthetics in reinforcement and drainage applications; and construction methods with an emphasis on innovative approaches such as novel sequencing of construction traffic, use of lightweight equipment, and robotics. In addition, several case histories describing applicable pavement reconstruction projects are presented. Finally, suggestions to possibly improve the practice and the identification of research needs are also presented.

Mallela, J., G. Larson, T. Wyatt, J. Hall, and W. Barker. 2002. Drainage Requirements in Pavements (DRIP) User Guide. Federal Highway Administration, Washington, DC. User’s guide for DRIP 2.0 a Windows based microcomputer program for the subsurface drainage analysis of pavements. The guide also discusses the technical basis for the DRIP program. http://www.fhwa.dot.gov/pavement/pub_details.cfm?id=43.

National Cooperative Highway Research Program. 2004. Guide for Mechanistic-Empirical Design of New and Rehabilitated Pavement Structures, Appendix TT: Drainage Requirement in Pavements (DRIP) Microcomputer Program User’s Guide. Final Report. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/archive/mepdg/2appendices_tt.pdf. Moisture-related pavement distresses have long been recognized as a primary contributor to premature failures and accelerated pavement deterioration. The FHWA provides design guidance for drainage in its manual numbered FHWA-TS-80-224, “Highway Subdrainage Design.” Under a study known as Demonstration Project No. 87, or simply “Demo 87,” the FHWA Pavement Division developed a comprehensive effort to provide design guidance for handling water that infiltrated into the pavement structure from the surface. That study resulted in the production of the Participant Notebook for Demonstration Project No. 87. Engineers needed a concise and user-friendly microcomputer program that replicates the subsurface drainage design procedures in the Participant’s Workbook for Demonstration Project No. 87. Under a

contract from the FHWA (contract No. DTFH61-95-C-00008) the original version of the microcomputer program titled “Drainage Requirements in Pavements (DRIP) Version 1.0.” DRIP was finalized in 1997. In 1998, a new NHI course (Course No. 131026) titled “Pavement Subsurface Drainage Design” was developed to further improve the guidance on pavement subsurface drainage design, construction, and maintenance. DRIP Version 1.0 was integrated into this course to perform hydraulic design computations.

Oregon State University. 2006. Evaluation of Best Management Practices for Highway Runoff Control. NCHRP Report 565. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_565.pdf. This report presents guidance for the selection of best management practices (BMPs) for highway runoff control. These practices provide means of avoiding or mitigating the negative impacts of various pollutants that can be carried by rainfall into the groundwater and receiving waters. These pollutants include materials discharged by vehicles using the highway system, pesticides and fertilizers from adjacent landscapes, and particulates from breakdown of the pavements themselves. BMPs include the traditional treatments applied at or near the sources of the pollutants and a more distributed approach known as low-impact development. This report should be a valuable resource for all highway agencies that must evaluate and select the most effective and efficient means of managing pollution related to stormwater from highways.

Ridgeway, H. H. 1982. Pavement Subsurface Drainage Systems. NCHRP Synthesis of Highway Practice 96. Transportation Research Board, Washington, DC. This report reviews the basic principles and concepts of hydraulic flow that need to be considered in the design, construction, and maintenance of pavements. The need for drainage is noted and the sources and movement of water in the pavement are described. The analysis of basic information on highway geometrics, surface drainage systems, non-pavement subsurface drainage systems, climatology, and soil properties is discussed. The design of subsurface drainage (design criteria, removal of free water, filters), the rehabilitation of existing pavements (by longitudinal subdrains), and current installations (new pavements, edge drains) are also described.

Voller, V. 2003. Designing Pavement Drainage Systems: The MnDrain Software. Report No. MN/RC-2003-17. Minnesota Department of Transportation, St. Paul, MN. http://www.lrrb.org/media/reports/200317.pdf. This report outlines the development of a suite of computer codes embedded in a Microsoft Excel spreadsheet collectively referred to as MnDrain. These codes provide a user-friendly environment in which the consequences of an edge drain design decision can be investigated. Edge drains consist of pipes that run along the length of a road to remove moisture from the granular base of the road system. The pipes are placed in a high permeability gravel trench below the shoulder/road surface. The rate at which moisture is removed will depend on the geometry and materials used in the base and the soil type in the subgrade. A full copy of the MnDrain code, including all source programs and an online manual, can be downloaded on visiting http://www.ce.umn.edu/~voller/voller_research/task5/mndrainrequest.html. The main attributes of the MnDrain system are a relevant easy to use graphical interface, meaningful drainage design scenarios, flexible assignment of materials properties, an easy to maintain database for unsaturated properties, and a state-of-the-art saturated/unsaturated numerical solution engine. The code is freeware that can be readily reconfigured for alternative and novel applications. As it stands the MnDrain code is a solid initial framework from which further developments can be made. In this project the operation of MnDrain was purposely constrained to work with simple geometries (the scenarios) to establish a system that could be used by a field engineer with only a limited knowledge of soil physics and numerical modeling. Because MnDrain offers free access to all source codes, it can be reconfigured to deal with a large array of pavement drainage issues. To take advantage of this feature, further investigation is recommended.

MATERIALS

Azari, H. 2010. Precision Estimates of AASHTO T283: Resistance of Compacted Hot-Mix Asphalt (HMA) to Moisture-Induced Damage. NCHRP Web Document 166. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_w166.pdf. This work presents an interlaboratory study (ILS) resulting in a precision and bias statement for AASHTO T283, “Resistance of Compacted HMA to Moisture-Induced Damage.” To gain insight into the variability of the T283 test results, a micro-scale finite element analysis using X-ray images of the test specimens was conducted. The ILS included preparing and testing six replicate specimens according to AASHTO T283 using two different aggregate sources and two compaction methods. The two aggregate sources were selected based on their moisture susceptibility. A sandstone aggregate representing moisture susceptible and a limestone aggregate representing moisture resistance were selected for the study. Marshall and Superpave gyratory compactors were selected as means of compaction to create test specimens with different structures. The statistical analysis of the ILS results indicated that the average tensile strength ratios (TSR) of the Marshall and gyratory specimens and that of limestone and sandstone mixtures were significantly different. Despite the difference in the average TSR values, the variability of TSR of Marshall and gyratory compacted specimens of limestone and sandstone mixtures were not significantly different. In this respect, the TSR statistics of the four specimen types (two mixture types and two compaction methods) were combined to prepare the precision estimates for AASHTO T283. The simulation of moisture infiltration in the X-ray images of gyratory and compacted specimens indicated that moisture penetrates to the center of Marshall specimens much faster than to the center of gyratory specimens. The reason for this was found to be the difference in size and distribution of outside and inside pore spaces in gyratory and Marshall specimens. Additionally, the conditioning procedure, as described in the current T-283 standard was found to not represent the actual moisture infiltration time frame that produced damage in the field. This could explain the often-encountered discrepancy between laboratory and field moisture performance.

Bonaquist, R. 2014. “Impact of Mix Design on Asphalt Pavement Durability.” Enhancing the Durability of Asphalt Pavements. Transportation Research Circular, Number E-C186. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/circulars/ec186.pdf. In the past several years, there have been a number of significant advances in asphalt materials and construction techniques for increasing the durability of pavements. This e-circular contains papers based on a Sunday workshop at the 92nd Annual Meeting of the TRB in Washington, DC, on enhancing the durability of asphalt pavements. The workshop focused on new design and construction approaches for extending pavement life while also improving their sustainability. The workshop also addressed the use of new materials, methods of mix analysis and cracking models, coupled with specific construction techniques that can significantly increase the life of the asphalt pavement. Furthermore, it covers actual application of these materials and approaches and some associated long-term benefits. The most significant outcome of this workshop was to show that these materials and approaches are readily available in the marketplace today and only require some relatively minor changes to specifications.

Christopher, B. R., C. Schwartz, and R. Boudreau. 2006. Geotechnical Aspects of Pavements. Report No. NHI-05-037. National Highway Institute, Federal Highway Administration, Washington, DC. http://www.fhwa.dot.gov/engineering/geotech/pubs/05037/. This is the Reference Manual and Participants Workbook for the FHWA NHI’s Course No. 132040 - Geotechnical Aspects of Pavements. The manual covers the latest methods and procedures to address the geotechnical issues in pavement design, construction and performance for new construction, reconstruction, and rehabilitation projects. The manual includes details on geotechnical exploration and characterization of in-place and constructed subgrades as well as unbound base/subbase materials. The influence and sensitivity of geotechnical inputs are reviewed with respect to the requirements in past and current AASHTO design guidelines and the mechanistic-empirical design approach developed under NCHRP 1-37A, including the three levels of design input quality. Design details for drainage features and base/subbase material requirements are covered along with the evaluation and selection of appropriate remediation measures for unsuitable

subgrades. Geotechnical aspects in relation to construction, construction specifications, monitoring, and performance measurements are discussed.

Choi, Y. 2007. Case Study and Test Method Review on Moisture Damage. Publication No. AP-T76-07. ARRB Group Limited, Vermont South, Victoria, Australia. https://www.onlinepublications.austroads.com.au/items/AP-T76-07. This report presents an extensive literature review on case studies of moisture damage in pavements and moisture sensitivity testing methods available worldwide. It includes summaries of interviews with Australian practitioners. Case studies generally agree on the importance of prevention of moisture ingress and the necessity of a suitable moisture sensitivity test during the mix design stage. The AASHTO T283 test method (also known as modified Lottman) and variations on it are the most widely used methods at present.

Epps-Martin, A., E. Arambula, F. Yin, L. G. Cucalon, A. Chowdhury, R. Lytton. J. Epps, C. Estakhri, and E. S. Park. 2013. Evaluation of the Moisture Susceptibility of WMA Technologies. NCHRP Report 763. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_763.pdf. Recently, interest in warm-mix asphalt (WMA) has dramatically increased. WMA is now seen as an alternative to HMA offering the potential to lower energy demand during production and construction, reduce emissions at the plant and the paver, and increase allowable haul distances. However, there are still questions about the long-term performance and durability of WMA pavements. One key issue is the moisture susceptibility of WMA pavements. Concerns about WMA moisture susceptibility include the possibility that aggregates will be inadequately dried at lower production temperatures and the fact that several WMA technologies introduce additional moisture in the production process. The moisture susceptibility of HMA is evaluated by a variety of standard laboratory tests. The results of these tests on WMA indicate that WMA may be more susceptible to moisture damage than HMA. However, more limited data suggest that the resistance of WMA to moisture damage improves with time and may ultimately be equivalent to that of HMA. In some situations, anti-strip agents are added to WMA to address the issue of moisture susceptibility. However, as is the case with HMA, anti-strip agents may not always be compatible or work effectively with WMA. The objectives of this research are to (1) assess whether WMA technologies adversely affect the moisture susceptibility of flexible pavements and (2) develop guidelines for identifying and limiting moisture susceptibility in WMA pavements.

Lu, Q. and J. T. Harvey. 2005. Investigation of Conditions for Moisture Damage in Asphalt Concrete and Appropriate Laboratory Test Methods. Report No. UCPRC-RR-2005-15. California Department of Transportation, Sacramento, CA. http://www.ucprc.ucdavis.edu/PDF/UCPRC-RR-2005-15.pdf. Statistical analysis in California revealed that air void content, pavement structure, cumulative rainfall, mix type (DGAC vs RAC-G), use of anti-strip additive (lime or liquid), and pavement age significantly affect the extent of moisture damage in pavements. High air void contents not only allow more moisture to enter mixes, but also significantly reduce the fatigue resistance of mixes in wet conditions. Less-than-optimum binder contents also reduce the moisture resistance of asphalt mixes under repeated loading. The effectiveness of the Hamburg Wheel Tracking Device (HWTD) test to determine moisture sensitivity of asphalt mixes was evaluated and it was found that the test can correctly identify the effect of anti-strip additives. A fatigue-based test procedure for evaluating moisture sensitivity was explored in this study. A test procedure was developed for comparative evaluation of different mixes. The long-term effectiveness of both hydrated lime and liquid anti-strip agents was evaluated by both the TSR test and the fatigue beam test. Results showed that both types of treatment are effective in preventing moisture damage for up to one year’s continuous moisture conditioning in the laboratory. A database with all field and laboratory results has been prepared for the California DOT (Caltrans).

Lu, Q. J. T. Harvey, and C. L. Monismith. 2007. Investigation of Conditions for Moisture Damage in Asphalt Concrete and Appropriate Laboratory Test Methods. Summary Report No. UCPRC-RR2005-01. California Department of Transportation, Sacramento, CA. http://www.ucprc.ucdavis.edu/PDF/UCPRC-SR-2005-01.pdf. Moisture damage in asphalt pavements is a complex phenomenon affected by a variety of factors, and has not been fully understood, with major knowledge gaps in three areas: major factors contributing to moisture damage in the field, appropriate laboratory test procedures, and the effectiveness of treatments. Both field and laboratory investigations were performed in this

study to provide additional information in these three areas. Statewide condition survey and field sampling were conducted to identify factors contributing to moisture damage, other than aggregate source. Statistical analysis revealed that air void content, pavement structure, cumulative rainfall, mix type (DGAC versus RAC-G), use of anti-strip additive (lime or liquid), and pavement age significantly affect the extent of moisture damage. Laboratory experiments revealed that high air void contents not only allow more moisture to enter mixes, but also significantly reduce the fatigue resistance of mixes in wet conditions. Less-than-optimum binder contents also reduce the moisture resistance of asphalt mixes under repeated loading. The effectiveness of the HWTD test to determine moisture sensitivity of asphalt mixes was evaluated by testing both laboratory-fabricated specimens and field cores. It was found that the test can correctly identify the effect of anti-strip additives; its results generally correlate with field performance except that the test may sometimes fail mixes that perform well in the field and, in a very few cases, provide false positive results. A fatigue-based test procedure for evaluating moisture sensitivity was explored in this study based on AASHTO T 321. A test procedure was developed for comparative evaluation of different mixes. Application of the test procedure for use in pavement analysis/design is suggested for expensive projects. The long-term effectiveness of both hydrated lime and liquid anti-strip agents was evaluated by both the TSR test and the fatigue beam test. Results showed that both types of treatment are effective in preventing moisture damage for up to one year’s continuous moisture conditioning. A database with all field and laboratory results has been prepared for Caltrans.

Santucci, L. 2010. Minimizing Moisture Damage in Asphalt Pavements. Pavement Technology Update. Volume 2, Issue Number 2. University of California, Berkeley, CA. http://www.techtransfer.berkeley.edu/pavetech/prc_update_vol2_no2.pdf. This article explains how moisture damage in asphalt pavements is caused by adhesive failure between the asphalt film and aggregate or cohesive failure within the asphalt binder itself. The author writes that construction practices that trap moisture in pavement layers, such as a high air void content mix placed between low air void content lifts or placing a chip seal over a moisture sensitive pavement, can create moisture damage. He suggests the use of liquid anti-strip additives or lime to minimize moisture damage. Good compaction procedures to reduce the air void content of dense-graded asphalt pavements have been shown to improve moisture resistance.

Solaimanian, M., R. F. Bonaquist, and V. Tandon. 2007. Improved Conditioning and Testing Procedures for HMA Moisture Susceptibility. NCHRP Report 589. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_589.pdf. This report presents the findings of a research project to investigate whether combining the environmental conditioning system with the simple performance test would provide a superior procedure for determining the moisture susceptibility of HMA. The report will be of particular interest to materials engineers in SHAs, as well as to materials suppliers and paving contractor personnel who are responsible for the design and evaluation of HMA.

Stuart, K. D. 1990. Moisture Damage in Asphalt Mixtures – A State-of-the-Art Report. Report No. FHWA –RD-90-019. Federal Highway Administration, McLean, VA. http://isddc.dot.gov/OLPFiles/FHWA/013679.pdf. This state-of-the-art report is on the moisture susceptibility of asphalt mixtures used in highway pavements. It addresses the known causes of moisture damage, methods for controlling damage such as antistripping additives, and moisture damage tests. Several current research studies are a1 so given in the report. Moisture damage in asphalt mixtures is a complex mechanism which is not well understood and has many interacting factors. This report is mainly concerned with dense-graded hot asphalt mixtures as most of the 1iterature discusses these types of mixtures. Some information on chip seals and emu1sion mixtures is a1so included. One of the intents of this report is to indicate where data is lacking so that research can be performed in these areas. State-of-the-art reports often give the impression that more is known than is really known. More knowledge is needed in all areas dealing with moisture damage in asphalt pavements. How to develop moisture damage tests so that they relate to pavement performance needs to be addressed.

Tunnicliff, D. G. and R. E. Root. 1995. Use of Antistripping Additives in Asphaltic Concrete Mixtures: Field Evaluation. NCHRP Report 373. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_syn_373.pdf. The long-term general objective of this research is to provide information on the selection and use of antistripping additives which are materials used to improve the asphalt-aggregate adhesion in AC. A laboratory study has been completed, and the

immediate specific objectives of the current research are, by means of a field study, to (1) measure the long-term effectiveness of antistripping additives in preventing moisture damage, and (2) determine the ability of laboratory tests to measure antistripping additive performance. Full-scale test projects, each including a control section with no additive and a test section containing an antistripping additive, have been built in eight states, and extensive laboratory testing of the materials and mixtures from these projects has been completed. The field evaluation phase of the research includes testing of cores and condition surveys. Agreement between cores and condition surveys is very good. After 6 to 8 years, the performance of eight of the nine additives was satisfactory. The exception was an additive that did not perform as well as the control section. The original laboratory tests correctly predicted pavement performance found by the field evaluation on six of the eight projects. On one project an additive section performed worse than expected. On another project the experimental sections were never wet. Altogether, the expected performance was found on 16 of the 19 experimental sections. The conclusion is that the original laboratory test is suitable for use in moisture damage testing and additive evaluation.

Transportation Research Board. 2003. Moisture Sensitivity of Asphalt Pavements, A National Seminar. TRB Committee on Bituminous-Aggregate Combinations to Meet Surface Requirements. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/conf/reports/moisture_seminar.pdf. Moisture damage in asphalt pavements is a national concern. Correctly identifying the problem and isolating the contributing factors—materials and construction—are equally challenging. The goals of this national seminar are twofold: technology transfer on the topic from leading experts and the start of a road map to solve this problem. The topics addressed include the following:

• Identification of the problem—distinguishing between materials-induced and construction-related factors.
• Fundamental concepts—binder and aggregate considerations and failure mechanisms.
• Test methods—laboratory and field.
• Remediation—additives and construction practices.
• Field performance and case studies.
• Specifications—shortcomings and need for improvements.
• Environmental and health issues.

The papers included in this volume document the work accomplished during the national seminar held in La Jolla, California, on February 4–6, 2003. The objectives of the papers, and the breakout sessions that followed, were to identify best practices, gaps in knowledge, and research needs. More than 100 people participated in the national seminar, and this document contains the proceedings of the meeting. In addition to the papers, summaries of the questions raised and answers given are included.

West, R., J. R. Willis, and M. Marasteanu. 2013. Improved Mix Design, Evaluation, and Materials Management Practices for Hot-Mix Asphalt with High Reclaimed Asphalt Pavement Content. NCHRP Report 752. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_752.pdf. The objectives of this project were to (1) develop a mix design and evaluation procedure that provides satisfactory long-term performance for asphalt mixtures containing high reclaimed asphalt pavement (RAP) contents—in the range of 25 to 50 percent or greater—and (2) propose changes to existing AASHTO standards to adapt them to the design of high RAP content mixtures. The project team conducted a comprehensive laboratory experiment to answer basic questions about preparing and characterizing RAP materials for mix designs. A series of mix designs was then prepared with materials from four different parts of the United States with different RAP contents and different virgin binders. Those mix designs were evaluated against standard Superpave criteria and a set of performance-related tests to further assess the mix designs for their susceptibility to common forms of distress, particularly fatigue cracking, low-temperature cracking, and moisture damage. A concurrent effort developed a set of best practices for RAP management in field production and construction from information obtained through a literature review, surveys of current practices in the industry, discussions with numerous contractor quality control (QC) personnel, and analysis of contractor stockpile QC data from across the United States The research found that only minor, though important, revisions to the current AASHTO standards for asphalt mix design, AASHTO R 35 (Superpave

Volumetric Design for Hot-Mix Asphalt) and M 323 (Superpave Volumetric Mix Design), were needed to adapt them for the successful design of high RAP content asphalt mixtures. As expected, high RAP contents substantially increased the dynamic modulus of the asphalt mixtures as well as their rutting resistance as measured by the confined flow number test. TSRs of high RAP content mixtures as measured by AASHTO T 283 were comparable to those of control mixtures without RAP, indicating similar moisture damage susceptibilities. As might be expected, compared to control mixtures without RAP, the high RAP content mixtures generally had lower fracture energies at test temperatures used to evaluate susceptibility to fatigue and low-temperature cracking. This finding suggests that careful attention should be given to the selection of the performance grade of the virgin binder used in high RAP content mixtures to minimize any long-term risk of cracking distress.

White, T. D., J. E. Haddock, and E. Rismantojo. 2006. Aggregate Tests for Hot-Mix Asphalt Mixtures Used in Pavements. NCHRP Report 557 Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_557.pdf. This report presents recommendations for performance-based procedures to test aggregates for use in pavements utilizing HMA mixtures and provides guidance on using these procedures for evaluating and selecting aggregates for use in specific mixture applications. This information will guide materials engineers in selecting the aggregates that should contribute to well-performing pavements; this information can also be used in conjunction with performance-related specifications. The content of this report will be of immediate interest to materials engineers, researchers, and others concerned with the construction and performance of HMA pavements.

Zapata, C. E. 2010. A National Database of Subgrade Soil-Water Characteristic Curves and Selected Soil Properties for Use with the MEPDG. NCHRP Web Document 153. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_w153.pdf. This final report describes the approach followed to create the national database of unbound material properties required as input in the AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG). This database contains measured index soil properties as well as Soil‐Water Characteristic Curve (SWCC) parameters, for use at the three optional hierarchical levels of the analysis implemented in the MEPDG. This database is based and has been developed on soil properties directly measured in the field for agricultural and geotechnical (pavement) engineering purposes to depths up to 100 in. (8 – 9 ft). The database comprises 31,100 soil units distributed in more than 9,800 soil profiles covering the continental USA, Hawaii and Alaska, and Puerto Rico. Data from the US Department of Agriculture’s Natural Resources Conservation Service was downloaded and summarized in both tabular and spatial files. The tabulated data was organized by soil profiles, each of them comprising one or more soil units. The spatial data allowed for the creation of 814 maps within the United State and Puerto Rico. Finally, a user interface was created in Excel© to allow searching for specific locations within a State, by using the maps created in the project.

PAVEMENT DESIGN

Chatti, K., N. Buch, S. W. Haider, A. S. Pulipaka, R. W. Lyles, D. Gilliland, and P. Desaraju. 2005. LTPP Data Analysis: Influence of Design and Construction Features on the Response and Performance of New Flexible and Rigid Pavements. NCHRP Web Document 74. Transportation Research Board, Washington, DC. http://www.trb.org/Publications/Blurbs/155980.aspx. This report documents and presents the results of a study on the relative influence of design and construction features on the response and performance of new flexible and rigid pavements, included in SPS-1 and SPS-2 experiments. The SPS-1 experiment is designed to investigate the effects of HMA layer thickness, base type, base thickness, and drainage on flexible pavement performance, while the SPS-2 experiment is aimed at studying the effect of PCC slab thickness, base type, PCC flexural strength, drainage, and lane width on rigid pavement performance. The effects of environmental factors, in absence of heavy traffic, were also studied based on data from the SPS-8 experiment. Various statistical methods were employed for analyses of the LTPP NIMS data (Release 17 of DataPave) for the experiments. In summary, base type seems to be the most critical design factor in achieving various levels of pavement performance for both flexible and rigid pavements, especially when provided with in pavement drainage. The other design factors are also important, though not at the same level as base type. Subgrade soil type and climate also have considerable effects on the influence of the design factors. Although most of the findings from this

study support the existing understanding of pavement performance, the methodology in this study provides a systematic outline of the interactions between design and site factors as well as new insights on various design options.

Hall, K. and J. Crovetti. 2022. Subsurface Drainage Practices in Pavement Design, Construction, and Maintenance. NCHRP Synthesis 579. The National Academies Press. Washington, DC. This synthesis documents the state-of-the-practice of DOTs with respect to the design, construction, and maintenance of subsurface pavement drainage systems. It is based on information collected through a literature review and a survey of agency practices. It also includes four case examples. The use of subsurface drainage varies based on many factors, including pavement type, location, and other site-specific conditions. Most agencies use standardized drainage design details and material gradations. Permeable aggregate bases are the most common, followed by asphalt-treated permeable layers and cement-treated permeable layers. A range of measures are used to ensure proper construction, maintenance, and performance of drainage systems. Two issues were identified as unresolved: whether subsurface drainage extends pavement life or improves performance and whether maintaining longitudinal edge drains leads to better pavement performance compared to pavements with longitudinal edge drains that are not well maintained.

Heitzman, M., K. Maser, N. H. Tran, R. Brown, H. Bell, S. Holland, H. Ceylan, K. Belli, and D. Hiltunen. 2013. Nondestructive Testing to Identify Delaminations between HMA Layers. Report No. SHRP 2 Report S2-R06D-RW-1, -2, -3, and -4. Transportation Research Board, Washington, DC. http://www.trb.org/Main/Blurbs/167281.aspx. Asphalt pavements with delamination problems experience considerable early damage because delaminations provide paths for moisture damage and the development of damage such as stripping, slippage cracks, and pavement deformation. Early detection of the existence, extent, and depth of delaminations in asphalt pavements is key for determining the appropriate rehabilitation strategy and thus extending the life of the given pavement. This report presents the findings of the first two phases of Strategic Highway Research Program 2 Renewal Project R06D, Nondestructive Testing to Identify Delaminations Between HMA Layers. The main objective of the project was to develop nondestructive testing (NDT) techniques capable of detecting and quantifying delaminations in HMA pavements. The NDT techniques should be applicable to construction, project design, and network-level assessments. During Phase 1 of the project, the research team evaluated NDT methods that could potentially detect the most typical delaminations in asphalt pavements. Both laboratory and field testing were conducted during this task. Based on the findings from this testing, the manufacturers of two promising technologies conducted further development of their products to meet the goals of this project in Phase 2. The two technologies advanced in this research were ground-penetrating radar (GPR) and impact echo/spectral analysis of surface waves (IE/SASW). Additionally, the project developed guidelines and piloted both NDT technologies in collaboration with highway agencies. Once completed, the results from this additional scope of work will be published as an addendum to this report.

National Cooperative Highway Research Program (NCHRP). 2004. Guide for Mechanistic-Empirical Design of New and Rehabilitated Pavement Structures. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/archive/mepdg/home.htm. The overall objective of this Design Guide is to provide the highway community with a state-of-the-practice tool for the design of new and rehabilitated pavement structures, based on mechanistic-empirical (M-E) principles. This objective was accomplished through developing the following: the Design Guide itself, which is based on comprehensive pavement design procedures that use existing M-E technologies; and user-oriented computation software and documentation based on the Design Guide procedure. This Guide provides a uniform and comprehensive set of procedures for the design of new and rehabilitated flexible and rigid pavements. It employs common design parameters for traffic, subgrade, environment, and reliability for all pavement types. Recommendations are provided for the structure (layer materials and thickness) of new and rehabilitated pavements, including procedures to select pavement layer thickness, rehabilitation treatments, subsurface drainage, foundation improvement strategies, and other design features. The procedures can be used to develop alternate designs using a variety of materials and construction procedures. The Guide is presented in four parts. Part 1 provides an introduction. Part 2 includes definitions and procedures on how to obtain the necessary inputs for the design of new or reconstruction projects, as well as for rehabilitation projects. Part 3 includes detailed background material to assist the

user in understanding the concepts used in the development of the Guide and in the proper application of the design procedures. All aspects of pavement design including subsurface drainage design, shoulder design, as well as the design of new, reconstruction, and rehabilitation flexible and rigid pavement projects are discussed in Part 3. Part 4 discusses how the M-E process can be applied in designing pavements subjected to low traffic volumes. The appendices to the Guide contain detailed information related to a number of additional design considerations.

Underwood, B. S. 2014. “Use of Models to Enhance the Durability of Asphalt Pavements.” Enhancing the Durability of Asphalt Pavements. Transportation Research Circular, Number EC186. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/circulars/ec186.pdf. In the past several years, there have been a number of significant advances in asphalt materials and construction techniques for increasing the durability of pavements. This e-circular contains papers based on a Sunday workshop at the 92nd Annual Meeting of the TRB in Washington, DC, on enhancing the durability of asphalt pavements. The workshop focused on new design and construction approaches for extending pavement life while also improving their sustainability. The workshop also addressed the use of new materials, methods of mix analysis and cracking models, coupled with specific construction techniques that can significantly increase the life of the asphalt pavement. Furthermore, it covers actual application of these materials and approaches and some associated long-term benefits. The most significant outcome of this workshop was to show that these materials and approaches are readily available in the marketplace today and only require some relatively minor changes to specifications.

Zapata, C. E. and W. N. Houston. 2008. Calibration and Validation of the Enhanced Integrated Climatic Model for Pavement Design. NCHRP Report 602. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_602.pdf. This report summarizes the results of research to evaluate, calibrate, and validate the Enhanced Integrated Climatic Model (EICM) incorporated in the original Version 0.7 (July 2004 release) of the MEPDG software with measured materials data from the LTPP SMP pavement sections. The report further describes subsequent changes made to the EICM to improve its prediction of moisture equilibrium for granular bases. The report will be of particular interest to pavement design engineers in SHAs and industry.

PRESERVATION AND REHABILITATION

Decker, D. 2014. Best Practices for Crack Treatments for Asphalt Pavements. NCHRP Report 784. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_784.pdf. Crack sealing and crack filling are widely used treatments for maintenance of asphalt pavements. However, successful crack sealing and crack filling applications continue to be viewed as an art. When not properly applied, these pavement preservation treatments can result in early failures and costly corrective maintenance for highway agencies. Although much research has been performed in the United States and abroad on the materials, techniques, and designs for crack sealing and crack filling, variability in the current state-of-the-practice regarding construction techniques and the resulting effectiveness of crack sealing and crack filling have not been investigated. The objective of NCHRP Project 20-07/Task 339 was to identify current best practices for crack sealing and crack filling of asphalt pavements. The research included a critical review of the worldwide literature on crack sealing and filling, with emphasis on identifying current best practices. A survey of state, local, and provincial highway agencies was then conducted to fill gaps in the results of the literature review. This report fully documents the research and includes chapters on the current states of the art and practice that support the chapter discussing the selected best practices.

Johnson, D. R. and R. Freeman. 2002. Rehabilitation Techniques for Stripped Asphalt Pavements. Report No. FHWA/MT-002-003/8123. Montana Department of Transportation, Helena, MT. http://www.mdt.mt.gov/other/research/external/docs/research_proj/remediation_methods.pdf. Asphalt stripping is a fairly common form of distress for pavements in Montana, particularly for pavements that were surfaced with an open-graded friction course. Currently, the technique for rehabilitating these pavements involves the costly removal of most or all of the stripped material, prior to the placement of an overlay. The goal of this research was to determine whether the stropped material can remain in-place,

serving as a structural layer within the rehabilitated pavement. This study has involved the construction office test sites, which were incorporated into larger overlay projects. At each of these sites, stripped material was removed from a control section and stripped material was left in-place for a test section, prior to the placement of the overlay. Leaving stripped AC surface material in-place during rehabilitation, to be overlayed with new AC, did not tend to make the rehabilitated pavement more susceptible to either stripping damage or load-induced damage. Life-cycle cost analyses should consider rate of stripping deterioration (in/year) to new AC to be the same, whether or not stripped material is removed prior to placing an overlay. Overlay thickness and mix design methods for resisting stripping are the important factors for extending the life of a rehabilitated stripped asphalt pavement.

Transportation Research Board. 2001. Rehabilitation Strategies for Highway Pavements. NCHRP Web Document 35. Transportation Research Board, Washington, DC. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_w35-a.pdf. This project was conducted to develop a process for selection of appropriate rehabilitation strategies for the ranges of pavement types and conditions found in the United States. A review of the pavement rehabilitation practices of State DOTs, and the literature available on pavement evaluation, rehabilitation techniques, and selection of rehabilitation strategies, was conducted for this project. The rehabilitation strategy selection procedures used by the various state DOT agencies differ in their details, but typically consist of: (1) data collection, (2) pavement evaluation, (3) selection of rehabilitation techniques, (4) formation of rehabilitation strategies, (5) life-cycle cost analysis, and (6) selection of one pavement rehabilitation strategy from among the alternatives considered. This report provides a step-by-step process and guidelines for each of these activities.