Analysis of Load-Induced Strains in a Hot Mix Asphalt Perpetual Pavement

This report presents the findings of a research study conducted to investigate the structural performance of a 275 mm hot mix asphalt perpetual pavement constructed as part of the WIM bypass lane at the Kenosha Safety & Weigh Station Facility. Two separate test sections were constructed using variable binder types and in-place air voids. Asphalt strain sensors were fabricated at Marquette University and installed during the construction of the HMA pavement. Sensors were positioned within the outer wheel path and located at the bottom of the 275 mm HMA pavement and at the interface between the lower layers at a depth of approximately 175mm from the surface. Strain sensors were oriented in both the transverse and longitudinal directions. A total of 16 strain sensors were installed during construction. Of these, only three survived to provide strain data under traffic loadings. Deflection data obtained from FWD testing was used as comparative measures to strain measurements obtained during testing and to estimate the combined dynamic HMA layer moduli at the time of testing and to develop monthly trends of dynamic HMA layer moduli as a function of the expected mean monthly mid-depth pavement temperature. A comparative analysis of measured strains to those predicted from FWD measurements provided generally good agreement. A mechanistic appraisal of the constructed test sections was completed using the outputs of the EVERSTRESS pavement analysis program. This analysis computed the expected monthly damage induced by the application of 521,000 monthly ESAL loadings. The results of the mechanistic appraisal indicate the expected service life to 50% bottom-up fatigue cracking is in excess of 90 years for sections with air voids of 4% within the lower layers. If the air void content increases to 5% - 6% in the lower layers, the expected fatigue life may be significantly reduced to between 13 – 32 years

Comprehensive Subgrade Deflection Acceptance Criteria - Pilot Implementation Report

This report has presents the findings of implementations of pilot specifications for subgrade acceptance based on measured deflections. The reconfigured rolling wheel deflectomter (RWD), portable truck-mounted deflection measurement systems, and dynamic cone penetrometer (DCP) were utilized on four subgrade construction projects during the 2001 construction season. Comparative nuclear density readings were obtained at selected locations within each project. Comparative soil stiffness gauge readings were also obtained on 2 of the pilot projects The research findings from this and previous study phases indicate that deflection test results may be appropriate for identifying areas of poor in-place stability within constructed subgrades. However, deflection testing alone may not provide all of the data necessary to properly differentiate acceptable and non-acceptable subgrade stabilities. It is important to note that deflection test results are related to the moisture-density conditions at the time of testing. Soils that show acceptable results (i.e., low deflections) may subsequently weaken due to changes in moisture content, freezing/thawing, etc. In instances where subgrade acceptance is well in advance of base course application, subgrade moisture changes may result in decreased soil support. For those conditions where soil compaction has been conducted at a moisture state near optimum, surface deflections should be correlated to the achieved level of compaction. The overall objectives of this research have been met, particularly in the development of useful correlations between subgrade deflections and in-place subgrade stability as measured by the California Bearing Ratio (CBR). Deflection data collected to date using instrumentation on the axles of loaded quad-axle trucks indicates this data source should be adequate for acceptance testing. It is recommended that implementations of deflection acceptance testing be conducted during the 2002 construction season on selected projects using a deflection threshold of 1.50 inches to identify areas which would not provide sufficient stability for subsequent construction operations. For use within Year 2002 implementations, this threshold value is recommended for use to identify potentially “failed” test locations. The project engineer should retain the right to require corrective actions to improve subgrade conditions based on the magnitude and extent of failed readings

Marquette Interchange Perpetual Pavement Instrumentation Project - Phase II

This report presents findings from the second phase of the Marquette Interchange instrumentation project and focuses on the maintenance of data recordation systems, development of computer programs to analyze data, and development of data packages for redistribution. The product of this research is a set of data which includes dynamic pavement response due to live traffic, vehicle information (weight, class, length, et cetera), and environmental data for the test site. The tasks within this project were not oriented for findings regarding pavement performance, but important and helpful conclusions can be drawn for similar future projects. The recordation systems have been maintained and recordation has been continuous. A handful of sensors did require attention and only a fraction of the critical strain sensors have ceased to function, making the project a success. The results of the computer programs written to analyze data show that reasonable accuracy has been achieved. Future work can help to generate more intricate programming making the processes more accurate

Development of Comprehensive Subgrade Deflection Acceptance Criteria - Phase 3 Report

This report has presented the findings of Phase III of research conducted to aid in the development of subgrade deflection acceptance criteria for WisDOT. The reconfigured rolling wheel deflectomter (RWD), portable truck-mounted deflection measurement systems, and automated dynamic cone penetrometer (DCP) were utilized on subgrade construction projects throughout the 2000 construction season. Laboratory analysis of soil properties, including Proctor, CBR and unconfined compression tests, were also conducted. The research findings have validated the concept of using deflection testing results to identify areas of poor in-place stability within constructed subgrades. It is recommended that pilot implementations of deflection acceptance testing be conducted in conjunction with subgrade penetration testing and moisture controls until more data has been collected, especially in moisture sensitive fine grained soil types. The use of deflection acceptance testing, in conjunction with in-situ penetration tests, should provide the data necessary to determine if the in-place support capacity for a given soil is sufficient to provide a stable construction platform for subsequent paving operations. However, it is important to note that both the RWD and DCP test results are related to the moisture-density conditions at the time of testing. Soils that show acceptable results (i.e., low deflections) may subsequently weaken due to changes in moisture content, freezing/thawing, etc. In instances where subgrade acceptance is well in advance of base course application, subgrade moisture changes may result in decreased soil support

Effects of Subsurface Drainage on Pavement Performance

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 Long-Term Pavement Performance (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

Investigation of Feasible Pavement Design Alternatives for WisDOT

The current pavement design and selection process of WisDOT for all new pavements or reconstructions of existing pavement structures provides for the design of one asphaltic concrete (AC) and one portland cement concrete (PCC) pavement alternative. Life-cycle costs analyses are then used to determine the preferred alternative for construction. Previous restrictions in the WisDOT pavement selection process have essentially excluded the construction of thick AC (AC thickness \u3e 150 mm) and thin PCC (PCC thickness \u3c 225 mm) pavements and thus the validity of current life-cycle cost inputs for these pavement types is under question. This report presents a performance analysis of existing thick AC and thin PCC pavements constructed in and around Wisconsin. The performance trends developed indicate current design assumptions utilized by WisDOT, related to the expected service life to first rehabilitation of AC and PCC pavements, may also be used for thick AC and thin PCC pavements

Portland Cement Concrete Pavement Over Rubblized PCC

This report has presented findings of research conducted to determine the viability of constructing Portland cement concrete pavements over rubblized PCC. Rubblization of aged PCC pavements is a common technique for in-place recycling of these pavements. For the vast majority of applications, the rubblized PCC layer is surfaced with hot mix asphalt (HMA). The use of Portland cement concrete as a surfacing material offers designers another option which may provide good performance and be cost-effective under certain conditions. The current concrete pavement design procedures utilized by WisDOT allow for the incorporation of a rubblized PCC base layer and an increase in the design value for the subgrade support k-value based on AASHTO guidelines. Over the practical range of rubblized concrete layer thicknesses investigated during this research, composite k-values were shown to increase by a factor of approximately 2 to 4 times, depending on the thickness of the rubblized layer and the quality of the natural subgrade support. This increase in composite k-value was shown to reduce the concrete layer thickness requirement between 0.25 to 1.45 inches, depending on subgrade quality and design ESAL loadings. The greatest reduction in required PCC thickness was seen for the combination of high subgrade support and low design ESAL loadings. As design ESAL levels increase, the allowable PCC thickness reduction decreases for all subgrade qualities. Based on the research results collected to date, there are no restrictions to the continued design and construction of Portland cement concrete pavements over rubblized PCC

Comprehensive Subgrade Deflection Acceptance Criteria - Executive Summary

This executive summary presents a summary of the findings of all study phases conducted to develop recommendations for the development of specifications for subgrade acceptance based on measured deflections. The rolling wheel deflectomter (RWD), portable truck-mounted deflection measurement systems, and dynamic cone penetrometer (DCP) were utilized on numerous subgrade construction projects between the 1998 and 2001 construction seasons. Comparative nuclear density and soil stiffness gauge readings were also obtained at selected locations on many of the included construction projects. The research findings indicate that deflection test results may be appropriate for identifying areas of poor in-place stability within constructed subgrades. However, deflection testing alone may not provide all of the data necessary to properly differentiate acceptable and non-acceptable subgrade stabilities. It is important to note that deflection test results are related to the moisturedensity conditions at the time of testing. Soils that show acceptable results (i.e., low deflections) may subsequently weaken due to changes in moisture content, freezing/thawing, etc. In instances where subgrade acceptance is well in advance of base course application, subgrade moisture changes may result in decreased soil support. For those conditions where soil compaction has been conducted at a moisture state near optimum, surface deflections should be correlated to the achieved level of compaction. Based on the deflection data gathered during this research study from test areas which were considered as passing based on visual observations, a deflection acceptance threshold of 1.50 inches was selected as reasonable to limit associated acceptance errors. For use within project implementations, this threshold value was recommended for use to identify potentially “failed” test locations. It was recommended that the project engineer retain the right to require corrective actions to improve subgrade conditions based on the magnitude and extent of failed readings

Cost Effective Concrete Pavement Cross Sections - Interim Report

The present pavement selection policy of the Wisconsin Department of Transportation (WisDOT) limits the design alternatives for Portland Cement Concrete (PCC) pavements and inhibits the designer\u27s ability to select cross-sections deviating from uniform slab thicknesses with doweled transverse joints. Currently, uniform slab thicknesses and conventional joint load transfer devices are incorporated into the design based on the heavy truck traffic in the outer lane. While this strategy provides for adequate pavement structure in this truck lane to limit faulting and slab cracking to tolerable levels, there is a potential for over-design in other traffic lanes which receive significantly lower Equivalent Single Axle Load (ESAL) applications over the service life of the pavement. Analysis of PCC pavement design alternatives, including variable slab thickness within and/or across traffic lanes, variable load transfer designs, and alternative base layer drainage desi gns, were completed. Based on the results of these analyses, four alternative dowel patterns were developed to reduce the number of dowel bars installed across transverse pavement joints. These patterns were developed to be consistent with dowel bar installation equipment currently used within the State of Wisconsin while still providing necessary load transfer mechanisms in the wheel path areas of both travel lanes. In additional to dowel placement alternates, test sections were constructed using alternative dowel materials, including fiber reinforced polymer (FRP) composite dowels, solid stainless steel dowels, and hollow core - mortar filled stainless steel dowels. This report presents details relating to the design, construction, and first year performance of concrete pavement test sections constructed in the State of Wisconsin along STH 29 in Clark and Marathon Counties. These test sections were constructed during the Summer of 1997 to validate the constructability and cost-effectiveness of alternative concrete pavement designs incorporating variable dowel strategies and slab thicknesses

Cost Effective Concrete Pavement Cross Sections - Final Report

This report presents the findings of a study of alternate pavement designs targeted at reducing the initial construction costs of concrete pavements without compromising pavement performance. Test sections were constructed with alternate dowel materials, reduced dowel placements, variable thickness concrete slabs and alternate surface and subsurface drainage details. Performance data was collected out to 5 and 7 years after construction. The study results indicate that FRP composite dowels may not be a practical alternative to conventional epoxy coated steel dowels due to their reduced rigidity, which results in lower deflection load transfer capacities at transverse joints. Ride quality measures also indicate higher IRI values on sections constructed with FRP composite dowels. Study results for sections constructed with reduced placements of solid stainless steel dowels also indicate reduced load transfer capacity and increased IRI values as compared to similarly designed sections incorporating epoxy coated dowels. Reduced doweling in the driving lane wheel paths also is shown to be detrimental to performance for most constructed test sections. The performance of sections with reduced doweling in the passing lane wheel paths indicates that this alternate may be justifiable to maintain performance trends similar to those exhibited by the driving lane with standard dowel placements. Performance data from sections constructed with variable slab geometry and drainage designs indicate that one-way surface and base drainage designs are performing as well or better than standard crowned pavements with two-way base drainage. The drainage capacity of the base layer, constructed with open graded number 1 stone, appears sufficient to handle all infiltrated water