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Research Report Abstracts

Antistripping Additives Volume II

Effectiveness of Antistripping Additives Volume II

Volume I of the report summarizes the findings on the extent of stripping in 32 Oregon DOT projects and discusses the significant findings from a literature review.  Of the 32 projects, 10 had not used an asphalt or aggregate anti-stripping additive, 19 contained lime-treated aggregate, and 3 contained asphalt treated with an amine-type anti-stripping additive.  These projects range in age from 1-9 years.  The percent of aggregate coated with asphalt, which was used to determine if a project was stripping, was established from breaking and visually evaluating core samples taken from each project site.  Using the criteria that a coating less than 85% classified a project as stripping, the following results were obtained: 7 of the 10 projects without an additive, 5 of the 19 lime-treated aggregate projects, and 2 of the 3 amine-treated asphalt projects were identified as stripping.  The conclusion is that lime treatment of aggregate has proven effective in reducing the moisture susceptibility of an asphalt mixture.  In addition, a review of mix design test values for the index of retained strength (IRS) (AASHTO T-165) and resilient modulus (Mr) test indicates the IRS test does not reliably predict moisture susceptible mixtures.  The Mr test did provide a better indication of moisture susceptible mixtures.  This assessment is based on a limited amount of data and is not statistically based; therefore, the results may change with further information.  Volume II presents the complete literature review.


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Oregon Rockfall Hazard System

Report on the "Shakedown" Test of Oregon's Rockfall Hazard Rating System
Oregon Rockfall Hazard Rating System (RHRS) was field tested at over 50 locations statewide to determine where clarification and improvements to the system were needed.  Field use of the system demonstrated many areas where refinements were valuable.  These changes along with revised narratives explaining the various rating criteria have been incorporated into the new RHRS.
 
This opportunity confirmed the usefulness of the system as a prioritization tool.  Once completed through full scale implementation, the RHRS will allow States to systematically evaluate the rockfall hazards along their highways.  This will permit them to prudently direct project funding at their most potentially dangerous sites.


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Soffit Cathodic Protection Final Report

Demonstration Project Soffit Cathodic Protection System in a Coastal Environment
 
Part one of this demonstration project evaluated a contractor executed below deck cathodic protection system on two spans of a coastal structure.  It was found that the contractor, working with the guidance of a technical representative, very adequately completed the project.  The materials and methods were evaluated and the result was a good operating system.
 
Part two of the project evaluates the durability of the construction materials and operating parameters of the system.  The systems, operating in the constant voltage-current limited mode, continued to operate satisfactorily and the 100 millivolt depolarization criteria was satisfied.
 
during the course of the project the response of the Molybdenum trioxide permanent reference cells defraded until they were not suitable for any measurements.  System monitoring is now done with fresh copper-copper sulfate half-cells.  Plots of depolarization versus log (time) indicate an alternate procedure for determining depolarization may be possible.

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Asphalt Concrete

Thin Layer Asphalt Concrete Density Measurements Using Nuclear Gages

A Troxler 4640 thin layer nuclear gage was evaluated under field conditions to determine if it would provide improved accuracy of density measurements on asphalt overlays of 1-3/4 and 2 inches in thickness. Statistical analysis shows slightly improved accuracy resulting from the use of the Troxler 4640 gage compared to conventional gages.   Other apparent benefits of this gage (data storage capabilities and digital readout of actual densities) are not true advantages because they are now available in gages which operate like the conventional gage tested here.  One major disadvantage is that the gage lacks the versatility of conventional gages.  The Troxler 4640 or similar gages are not recommended for widespread use.
 
Further statistical analysis shows that density as measured in the laboratory, using cores is significantly higher than density measured by either of the two types of nuclear gages.  The difference can be removed by developing an adjustment factor from core densities on every project. The amount of this difference varies from project to project (varying form 1.7 to 3.2 pcf for the conventional gage in backscatter mode).
 
The three different operating modes of the conventional gage were also evaluated and compared.  As a result of this comparison, continued use of the backscatter mode with sand for seating is recommended
 


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Polymer Modified Asphalts

Results of the Questionnaire: "Use of Chip Seal Emulsions Containing Polymer Modified Asphalts"

A questionnaire was distributed to materials engineers in all 50 states and 3 FHWA Direct Federal Divisions.  The report summarizes the responses from 47 states and 2 Direct Federal Districts concerning their use of polymerized asphalt emulsions for chip seals.


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Chloride Sealant

Five Year Report Chloride Sealant on the Columbia River Bridge (Astoria) Contract No. C09738
In 1983 chloride analysis was performed on spans 41, 84, and 119 on the Astoria Bridge.  The need for sealing the concrete from future chloride intrusion was identified. Shortly thereafter, a contract was let to seal the bottom of the deck and the beams.  The sealing was completed by October 1984.  At the time the project was initiated, it was decided that a five year program to evaluate the effectiveness of the sealer should be undertaken.
 
A limited chloride analysis in 1986 indicated the overall rate of chloride intrusion had probably been reduced. Because of the relatively short time of exposure and the limited sampling, the results were not clear cut. The recommendation to do a 1988 sampling that paralleled the 1983 sampling was made.
 
The 1988 sampling was identical to the 1983 sampling with respect to the spans and areas of each span checked. The sampling procedures and Laboratory analysis were also in keeping with the 1983 methods. This was done to minimize variations in the data.


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Traffic Delineators

Experimental Use of Temporary Traffic Delineators
During construction, there is a safety need to provide highly visible channelizing delineation for temporary protection and direction of traffic. "Super Duck" Surface Mounted Delineator (SDR-328, Rounded) by Carsonite is marketed to meet that safety need.
 
The purpose of this study was to evaluate "Super Duck's" visibility and ability to remain in-place after vehicular impact thus not requiring any maintenance. This is the final report describing the performance of "Super Duck" which was installed on the Sutton Lake-Florence Project in January 1988.


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Pavement Deterioration Volume 1

Effect of Environmental Factors on Pavement Deterioration Volume I

A computerized model for the determination of pavement deterioration responsibilities due to load and non-load related factors were developed.  The model is based on a relationship of pavement performances, as predicted by pavement structure design equations and as measured in the field, and the quantification of level of routine maintenance.  Predicts pavement performance provides the basis to quantify total pavement deterioration due to load-related factors.  Field performance measurement and a quantification of level of routine maintenance are used to quantify total pavement deterioration due to both load and non-load related factors.  Proportionality assumptions are made to determine pavement deterioration responsibilities based on these quantities.  Finally, an introduction to the computer model is presented.


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Pavement Deterioration Volume 2

Effect of Environmental Factors on Pavement Deterioration Volume II

PBA (performance Based Approach) is a software package used to estimate the effect of environmental factors on pavement deterioration.  The software is based on the PBA as developed by Fwa and Sinha (1982).  This approach uses pavement performance as predicted by performance models and a relationship of pavement field performance to a quantification of level of routine maintenance, to evaluate pavement deterioration proportions of loan and non-load related factors.  The methodology of PBA is described in Volume I (Ordonez and Vinson, 1988); Volume II, the User’s Guide, introduces you to PBA, explains the use of the software, and includes examples which will help you to become familiar with the software.


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Hot Mix Pavement

Polymer Modified Asphalt in Hot Mix Pavement
This report presents a summary of a literature review to determine the most appropriate testing procedures for use with polymer modified asphalts.  In examining testing procedures, it was necessary to study the effects of polymer modifiers on both binder and mix properties.  The four additives most closely examined are styrene-butadiene (SB), styrene-butadiene-styrene (SBS), styrene-butadiene-rubber (SBR), and ethylene-vinyl-acetate (EVA).  It was found that standard binder and mixture testing procedures may be successfully used with polymer modified asphalts.  In addition, numerous other tests were investigated, the most promising of which are force ductility, toughness and tenacity, rubber industry tensile tests and dynamic shear analysis.  A testing program is proposed which will result in recommendations for a specification for polymer modified binders in hot mix.  A definite lack of study of long-term aging effects for polymer modified asphalt mixes was noted. Available information indicates a potential problem in this area and that additional research should be conducted.


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Rockfall Catch Fence Final Rep

Modified Rockfall Catch Fence Mayflower Creek - Detroit Dam
Many older rock cut slopes along the highways in Oregon are in need of repair.  The rock-fall f r o m these slopes can create a hazard to the traveling public.  Ditches are often inadequate to restrict rocks from rolling or bouncing onto the highway.  In some cases widening the ditch can solve the problem, but where the slopes are high this is not economically feasible.  In these areas the State has used chain-link fence draped over the slope and catch-fences at the bottom of high slopes.  Catch fences consist of an impact section and a screened section.  The impact section captures rocks rolling down the slope and channels them through the screened section into the ditch.  These types of slope protection can be used if the site is accessible and the slope uniform.


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Fabric Reinforcement

Experimental Use of Fabric Reinforcement in Flexible Pavement Overlay of Deteriorated Asphalt Pavement
Many Oregon highways are in need of an asphalt overlay treatment to correct deficiencies such as fatigue cracking, deformation and other distresses and provide an acceptable riding surface. These asphalt concrete overlays tend to experience reflective cracking.  It was proposed to use a full width geo-textile fabric to retard reflective cracking.
 
The purpose of this study was to evaluate the effectiveness of a Non-woven polypropylene fabric to retard or eliminate reflective cracking. The product chosen was Petromat Non-woven Fabric produced by Phillips Fibers Corporation. This is the final report describing the performance of the Petromat fabric membrane which was installed in July 1978.


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Cold In-Place Recycled Volume 3

Development of Improved Mix Design and Construction Procedures for Cold In-Place Recycled Pavement Volume 3
 
This is the third of a four-volume report prepared to document the results of the cold in-place recycling (CIR) effort in Oregon.  The overall objective of the project was to develop improved mix design and construction procedures for cold recycled pavements and to evaluate the effects of environmental factors and traffic loads on CIR mixtures.  Volume I of this report described the efforts to accomplish the first objective while Volume II contains supporting data for this research effort.
 
Volume III documents performance data over a two-year period (1986-1988) and includes recommendations for improved mix and pavement structure thickness design for cold recycled pavements.  Construction procedures and specifications for CIR as well as supporting data are contained in Volume IV.

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Cold In-Place Recycled Volume 4

Development of Improved Mix Design and construction Procedures for Cold In-Place Recycled Pavement Volume 4

This is the fourth of a four-volume report prepared to document the results of the cold in-place recycling (CIR) in Oregon.  The overall objective of the project was to develop improved mix design and construction procedures for cold recycled pavements.  Volume I of this report described the efforts to accomplish this objective while Volume II contains supporting data for this research effort.
 
Volume III documents performance data over a two-year period (1986-1988) and includes recommendations for improved mix and thickness design for cold recycled pavements.  Volume IV contains data to support the contents of Volume III as well as construction procedures and specifications for CIR.


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Tire Pressure on Asphalt

Procedures for Controlling the Effect of Increased Tire Pressure on Asphalt Concrete Pavement Damage
As the axle load increases, higher tire pressures become more popular for long-haul truck operators. In order to collect data on tire pressures and the types of tires in use, a survey was carried out at a weigh station located on Interstate 5 in Oregon during the summer of 1986. The data show that 87% of the tires surveyed were of radial construction. The average measured pressures (hot) of the radial and bias tires were 102 psi and 82 psi, respectively. 
 
This study investigates the influence of increased tire pressures on the fatigue and rutting performance (in terms of vertical compressive stress, tensile strain, and compressive strain) of asphalt-surfaced pavements, through use of elastic layer analysis (ELSYM5), for two typical state highways in Oregon. This theoretical analysis shows that the effect of increased tire pressure on vertical compressive stress is significant in the asphalt wearing layer. As tire pressure increases, the maximum tensile strain at the bottom of the asphalt layer increases.
 
Theoretical equivalency factors for the two asphalt pavements (SN = 3.0 and 3.4) were developed using ELSYM5 to take into account tire pressures (80, 100, 125, and 150 psi) and number of tires per axle (2, 4, and 8 tires). A single axle with an 18-kip load, dual tires, and a tire pressure of 80 psi was used as a standard axle load and tire pressure. The results indicate that a 25% increase in tire pressure could result in a 40 to 60% increase in the equivalency factor for a dual-tired single axle with an 18-kip load or a tandem axle with a 34-kip load. However, this theoretical analysis needs to be verified by field studies.
 
In order to evaluate current asphalt concrete specifications and mix design criteria, aggregate from four different sources were tested. Two of the aggregates were treated with 1% lime slurry prior to testing. Six different aggregate gradations, including Fuller maximum density gradation, were tested. In addition to the routine asphalt concrete mix tests, a simple creep test was run for 3 hours at 40°C with a compression stress of 0.1 MPa.  In general, the creep stiffness decreased proportionally to the percentage of fines passing the #200 size sieve. The effect of the percentage of aggregates passing 1/4-in. or #10 sieve sizes on the creep stiffness is not clear. The results show that treating the aggregates with 1% lime slurry improves the resistance to deformation of the asphalt concrete mixes.
 


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Nuclear Asphalt Content Gauges

Precision and Accuracy of Nuclear Asphalt Content Gauges to Determining Asphalt Content in Asphaltic Concrete Pavement
Use of nuclear asphalt content gauges for determining asphalt content of asphaltic concrete pavement are gaining acceptance as an alternative method to the vacuum extraction process.
 
The reasons nuclear asphalt content gauges are considered promising are as follows:

  1. Recent technological advances in nuclear asphalt content gauges improved their precision and accuracy.
  2. Relative safety of their use compared to the use of potentially hazardous solvents is advantageous.
  3. A potential for lower overall test costs exist.
  4. Ability to obtain more timely test results.
 
This study incorporated a multi-task work plan which included:

  1. A literature review.
  2. A survey of use by western states.
  3. An in-house two phase testing program.
    1. Field bituminous mixture evaluation.
    2. Laboratory fabricated samples evaluation.
 


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Pavement Performance Part 1

Evaluation of Asphalt Properties and Their Relationship to Pavement Performance Part 1
This report is Part 1 of the final report for the research project titled Evaluation of Asphalt Properties and Their Relationship to Pavement Performance."  The overall objective of the research was to implement an analytical chemical procedure that could be used to characterize asphalt pavement materials. Results from the chemical analysis were subsequently used for the evaluation of pavement performance. 
 
The chemical test procedure used corresponded to that developed by Corbett and Swarbrick. Fractional compositions were statistically related to a number of physical tests and asphalt temperature susceptibility indices.
 
This report also presents an evaluation of four different asphalt extraction/recovery procedures and an evaluation of a pressure oxygen bomb device used for asphalt laboratory aging.
 
The significant findings were:

  • Fractional compositional analysis of asphalt showed that recovered asphalt is different than laboratory aged asphalt.
  • Some physical properties of asphalt showed a good correlation to asphalt composition in the higher testing temperature range. At lower temperatures, however, relationships were more scattered.
  • Different temperature susceptibility parameters have different relationships with chemical fractional composition.
  • Different extraction/recovery procedures yielded different chemical fractional composition for the same asphalt.
  • Pavement performance statistically relates to groups of asphalt properties.
 
Part 2 of this final report presents a microcomputer inventory for routine asphalt data.


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Pavement Performance Part 2

Evaluation of Asphalt Properties and Their Relationship to Pavement Performance Part 2

This report is Part 2 of the final report for the research project titled, "Evaluation of Asphalt Properties and Their Relationship to Pavement Performance."  Part 1 of the final report presented the results and an evaluation of a laboratory test program.
 
The Oregon State Dept. of Transportation, Highway Division, Materials Section, currently maintains its asphalt sample data manually. A computer database program has been developed and documented to maintain this data efficiently on a microcomputer.  This report describes the database management program, applications, operation procedures, examples of data summaries, statistics , and program documentation.  In its current form, the program may be used for simple storage, sorting, and retrieval of data.
It has been developed in a modular fashion to enable future development if desired. 
 
The asphalt laboratory test data files are managed using commercial computer software.
The software is dBASE III PLUS published by the Ashton Tate Corp. This software was selected based on efficiency of database collection, management, and user friendliness.  In this program the entered data is scored in a database file. The user can change, find, rearrange, analyze, relate, and print any data stored in the database.
 
This report presents data evaluation examples. The first example considers lay-down temperatures, and from an examination of the database, concludes that the current Oregon
State Highway Division practice of using a temperature of 280°F (138ºC) is sound practice.  The second example attempted to establish a relationship between penetration ratio (PR) and penetration index ( P I ) , with a view towards recommending use of a required temperature susceptibility in asphalt specifications. No relationship was determined and therefore no ensuing recommendation was made.


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