Research Report Abstracts
Hot Laid, Preformed, Patterned Striping Materials
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This construction report covers two experimental feature installations of a Permanent, Hot Laid, Preformed, Patterned, Striping Material. The permanent striping material used on these experimental feature projects is a 3M product called, "Stamark Pliant Polymer Marking Tape, series A 350". The preformed, patterned, marking tape consists of white or yellow films with glass beads incorporated to provide immediate and continuing retro-reflection. This helps improve marking visibility for drivers during night time and rainy driving conditions.
This study will evaluate the applications, reflectivity, durability and cost of the preformed striping material.
Evaluation of Performance and Cost-Effectiveness of Thin Pavement Surface Treatments Interim #2
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This is the second report to result from the subject study. It represents the first major effort to evaluate the available data on "thin pavement surface treatments" in Oregon and to define "cost effectiveness" for this purpose. The 87 projects studied here were constructed in 1984, 1985, and 1986. This report includes pavement condition data collected annually through 1989.
Three different "cost-effectiveness indices" are defined and used to compare similar types of treatments. The Longevity Cost Index (LCI) is based on the median service life, price, and traffic loading of each treatment type. After more of the treatments fail, this index is expected to be the most meaningful of the three. It is applied here in a preliminary effort to compare the cost-effectiveness of two types of chip seals. The two other indices, based on changes in pavement condition, are also explored for comparing the treatments.
As a supplemental effort, this report addresses the question, "Which treatment is the most appropriate in a given situation?". To accomplish this, an outline of selection criteria for various treatments is presented. This is based on experience in Oregon and the available literature.
Piezo-Electric Automatic Vehicle Classification System
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Oregon has 12 sites that are part of the SHRP LTPP program. Part of the data gathering on these sites involves vehicle weight and classification. This pilot project was to show SHRP how to specify, procure and install equipment that would provide the necessary data to characterize the sites for the LTPP program.
Castle Rock Consultants (CRC) were to provide specifications and technical aid on this project. After the project was completed CRC produced a paper for SHRP titled "Piezo-Electric Based Automatic Vehicle Classifier Pilot Project," December 1989. The purpose of this report is to complement the CRC report and discuss the project from Oregon's perspective.
This project, an installation in asphalt concrete, is the first of two pilot projects planned by Oregon. The second pilot project, in Portland Cement Concrete, will be installed in the spring of 1990.
In-Depth Study of Cold In-Place Recycled Pavement Performance
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Oregon has developed a mix design procedure for cold in-place recycled (CIR) asphalt concrete pavements. The procedure involves estimation of an initial emulsion content based on gradation of recycled asphalt pavement (RAP), asphalt content of RAP, and penetration and viscosity of recovered asphalt. When an estimated emulsion content is determined, Marshall-sized specimens are prepared for a range of emulsion contents with the range centered on the estimated emulsion content. Hveem and Marshall stability, resilient modulus, and index of retained modulus (IRM) tests are performed on the specimens and a design emulsion content is selected based upon these results. Because of variations in RAP properties, continual need for field adjustments, and the difficulty of interpreting mix property test results, only the estimation part of this procedure is currently implemented.
This paper describes the mix design procedure and presents lab results demonstrating the difficulty of choosing emulsion content based on Hveem and Marshall stability, resilient modulus and IRM. Data comparing design emulsion content with actual emulsion contents used in the field are presented. Selection of water content is discussed. Test results of mix properties monitored over time are presented, demonstrating the curing of the emulsion. Performance data for CIR pavements constructed from 1984 through 1988 are presented as well as initial results of an attempt to use lime during recycling to correct a stripped pavement.
Significant findings as a result of this study include the following:
- Field performance of CIR has been good, with a few exceptions. Proper project selection is extremely important.
- Estimation procedures for determining emulsion content serve as a good starting point for field operations. Continual monitoring and adjustment of emulsion content is required in the field.
- It is difficult to relate Hveem and Marshall stability, resilient modulus, fatigue and IRM laboratory testing to field construction conditions for CIR.Mix property test results indicate that the stiffness and fatigue properties of recycled mixtures increase over a period of years.
- Mix property test results indicate that the stiffness and fatigue properties of recycled mixtures increase over a period of years.
- Addition of 1% and 2% lime to RAP from badly stripped pavement produced better IRM results than the RAP without 1ime.
Evaluation of Asphalt Stripping Tests
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As part of the continuing effort to establish a standard for evaluating moisture susceptibility of asphalt concrete design mixes, this study evaluated and compared four tests methods by testing 15 diverse dense-graded mix designs during Oregon's 1988 construction season. The Index of Retained Strength (IRS), AASHTO T-165, and the Index of Retained Modulus of Resiliency (IRM Ř). OSHD TM-315, were the existing ODOT tests compared with the Root-Tunniclif, NCHRP 274, and the Modified Lottman, AASHTO T-283. None of the four tests predicted the same degree of asphalt stripping across the range of asphalt and aggregate tested.
The IRS test results showed the most stripping susceptible aggregates having a low test index when untreated, but when treated with lime or anti-strip additive there is a general improvement in the test indexes. The IRM Ř, tests results showed a greater inconsistency in the effectiveness of the lime-treated aggregate and anti-strip additive, but was the most severe test of the four evaluated. Neither the Root-Tunncliff nor Modified Lottrnan tests showed consistently higher stripping index for lime treated aggregate compared to anti-strip additive. Additionally, the Root-Tunncliff and Modified Lottman tests were the most difficult to perform and the least promising of the tests evaluated.
Based on the results of this study, the IRS Test Method continues to be considered a valid and useful stripping test. The IRM Ř, test appears to have the greatest potential for future improvement due to superior repeatability and apparent greater severity of the test.
As a result of the test findings, there still is a need for test equipment and procedure improvements to increase the accuracy and precision of the procedures and to improve the correlation between stripping tests.
Serb Guardrail In-Service Evaluation
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This report covers the installation of two Self-Restoring Barrier (SERB) guardrails on Interstate-5 south of Ashland Oregon. The SERB design was developed to reduce repair cost and increase safety when compared to conventional barriers. This is accomplished by a design that allows the rail to deflect up and back on impact. This allows the vehicle to be redirected smoothly and minimizes rail damage.
The installations were performed by contract and all work was inspected by ODOT personnel. The contractor did not have any major problems with the installation but found the SERB rail to be heavy and cumbersome to work with.
Ongoing evaluation will determine the cost-effectiveness and safety of the design. Part of the cost issue is concerned with the ease and cost of repair. As a preliminary evaluation, it appears that the internal splice design will make the rail difficult to repair. The manufacturer (SYRO Steel) recommends that future installations use a “lap-splice” design to improve the SERB'S repair-ability.
Improved Materials Systems in Marine Piling After Nine Years of Exposure in Yaquina Bay - Newport
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From 1979 to 1983 the Oregon State Highway Division participated with the FHWA in a demonstration project¹ to evaluate the feasibility of manufacturing pre-cast, pre-stressed marine piles from advanced structural materials. The materials that were evaluated include polymer concrete, polymer impregnated concrete, internally sealed concrete, and latex modified concrete. In addition to the pre-stressed piles, miniature, conventional concrete piles with epoxy coated rebar were evaluated. Included in the report are:
- A description of the laboratory work that preceded the preparation of the specifications
- A description of the manufacturing processes and problems for each system.
- A two year performance evaluation on each system.
After manufacture, the polymer concrete piles were structurally unsatisfactory since nearly 1/3 of the pre-stressing force was lost to elastic shortening, shrinkage and creep.
Geotextile Strips as a Reflective Crack Treatment for AC over AC
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This report covers an experimental feature where a geotextile fabric was used in an attempt to retard reflective cracking over severe thermal cracks. The application evaluated here is different from previous geotextile use in Oregon. It is the first time that narrow strips of fabric have been used instead of continuous full-width fabrics. The cracks were covered with 24-inch wide strips of non-woven geotextile fabric and then overlaid with 2-1/4 inches of dense graded polymer modified asphalt concrete.
One year after the overlay was constructed, many of the cracks have reflected through. There is no apparent difference in performance between the test section where geotextiles were placed and the control section where the cracks were left untreated.
Swalley Canal Ice Detection System
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This report evaluates the reliability of information provided by a “SCAN 16” surface condition analyzer. SCAN systems are designed to inform highway maintenance personnel when frost, ice, and snow are present on a roadway surface or bridge deck. The system evaluated here was installed on a bridge deck in a part of Oregon where frost, snow, and ice are frequently a hazard to traffic.
The evaluation of performance data suggests that the system cannot reliably report hazardous conditions on the deck. Local maintenance personnel, however, believe that they can make correct inferences from the system's output. Although it is not currently used to dispatch maintenance crews, a recent expansion of the system may change this. Sensors have been installed at a more remote location and now forecasting, as well as reporting of current conditions, is possible.
Procedures Manual for the Determination of International Roughness Index on HPMS Sites in Oregon - O
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The Oregon Department of Transportation (ODOT) is required to provide an annual measure of pavement condition based on International Roughness Index (IRI). The main coordination of this process with FHWA is done by the Highway Division's Planning Section. The data will be collected using a Mays Ride Meter (MRM). The Research Unit of the Materials and Research Section is responsible for calibration and operation of the MRM. The Data to be collected is on various highways across the State as directed by the Planning Section.
A Pavement Management Research Program for Oregon Highways - Final Report
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An extensive program was developed to measure pavement deflection skid resistance, and rideability throughout Oregon. The data from those "objective" measures were then evaluated for correlations with observed pavement distress and traffic factors.
It is concluded that "Dynaflect" deflections and other "objective" measures of pavement performance can best be used on the project level. The mechanized data gathering methods evaluated here have not proven valuable in network level pavement management.
Laboratory Study of Test Methods for Polymer Modified Asphalt in Hot Mix Pavements
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Increasing use of asphalt binders modified with elasto-meric or plastic modifiers makes the specification of binders a difficult task. Ideally, a generic specification would allow various suppliers and additives to compete based on expected performance differences in the hot mix pavements resulting from the use of these binders. This paper describes research whose objectives were to investigate unique characteristics of polymer modified hot mix and to determine if there are binder tests and properties which could be used to predict mix performance whether the binders used are conventional or modified. Two mix designs incorporating three conventional asphalts and six different modified asphalts were tested during two phases of testing. The objective was to determine what binder tests had promising correlations with important mix properties. Fraass Point and PVN showed the most promise for controlling temperature susceptibility of the hot mix at low temperatures. Penetration at 25ºC and force ductility areas, particularly "peak area," showed the most promise for predicting strength properties of mixes. The best prediction of fatigue life and permanent deformation as measured by diametral testing resulted from a combination of penetration at 25ºC and force ductility area values as independent variables in multiple regression analysis.
Evaluation of Shale Embankment Construction Criteria
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A 1.5 mile section of the Coos Bay-Roseburg Highway in Oregon was reconstructed in 1983. The project was located in an area where degradable fine-grained siltstone and sandstone would be encountered in the through cuts. After the construction of the adjacent Slater-Mystic Creek section in 1974, it was recognized that significant settlement and stability problems were developing as a result of the use of these degradable rocks in the construction of embankments. The Oregon Department of Transportation (ODOT) completed a demonstration study described herein to evaluate the use of these materials for embankments and riprap revetment at nine structures.
The study concluded that use of visual classification, aided by slake durability testing, was reliable in the selection of rock-like materials for use in slope revetments. Where rock was determined to be nondurable, it was physically broken down and placed and compacted as soil. The performance of the embankments in the five years following construction has been very good and no appreciable settlement is evident. The rock placed as revetment has performed as anticipated, with about 25 percent of the material degrading. This is attributable to limitations in sorting the durable and nondurable material during excavation. As a result of this demonstration study, ODOT has implemented a practical and effective embankment specification for selection and treatment of degradable rock materials in highway construction.
Resilient Modulus and Fatigue
Repeatability of Testing Procedures for Resilient Modulus and Fatigue
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Extensive use of diametral resilient modulus and fatigue testing is made by the Oregon State Highway Division to evaluate asphaltic concrete materials. Test results on similar materials (e.g., adjacent field cores), however, often indicate a poor level of repeatability.
In this study, laboratory fabricated briquettes were tested to evaluate the repeatability of the diametral modulus test at two laboratories - Oregon State Highway Division (OSHD) and Oregon State University (OSU) - and the repeatability of the fatigue test at a single laboratory (OSU). Modulus tests at the OSHD laboratory were conducted at one temperature and three strain levels while modulus tests at the OSU laboratory were conducted at two temperatures and the same three strain levels. Fatigue testing at the OSU laboratory was conducted at two temperatures and at one initial strain level.
As a result of the test program involved in this study, the significant findings include:
- Modulus tests are highly repeatable within each laboratory.
- Modulus tests under similar test conditions could not be satisfactorily reproduced (at the 5% significance level) between laboratories.
- Depending on test conditions, fatigue tests had a very low to high level of repeatability.
Concrete Barrier Marker Study
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Concrete barrier markers provide permanent or temporary night-time delineation along concrete barriers. The Oregon State Highway Division (OSHD) has qualified two basic types of barrier markers, a prismatic lens type and a retro reflective tape type. Both types meet the minimum requirements of OSHD’s roadside delineation specifications, however, several field personnel have commented on the apparent superiority of prismatic over tape reflectors.
The objective of this study is to compare the different types of barrier markers for reflectivity and durability through laboratory testing.
Verglimit at Hole-in-the-Wall Slide Section
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The issue of icy roads and bridges is a problem that the highway department and motorists must deal with each winter. Many measures are implemented to reduce the risk to drivers, but these corrective actions normally occur only after ice has already formed on highways and bridge decks. A Verglimit overlay may be a solution to this problem.
Verglimit is the brand name for an anti-icing, multi-component defroster that can be added to an asphalt concrete wearing surface during construction. It is composed mainly of encapsulated calcium chloride crystals, which are released and activated in small quantities by traffic induced abrasion. Verglimit is produced in Germany and has been used primarily in Europe. In view of favorable reports from Europe and New York State, it was decided to evaluate Verglimit in Oregon.
Use of Fabrics for Reflective Crack Control in Asphalt Concrete Overlays Over PCC Jointed Pavements
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This report summarizes the installation and performance of three geo-textile fabrics used to retard reflective cracking in an asphalt overlay test project. The project consisted of fifteen test sections, including twelve fabric sections; two control sections, and a non-fabric test section. Test sections included fabrics placed mid-level and full depth. In addition, half of the test sections included bond breakers while the other half were without bond breakers.
Fabrics placed at mid-level with and without bond breakers were effective at retarding reflective cracks. Fabric placed at full depth with bond breakers performed best. Fabric placed at full depth without bond breakers did not provide any more protection than control sections. Results from this study may not apply to AC Overlays on AC Cracked Pavements.
Effectiveness of Antistripping Additives Volume I
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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 susceptinility 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 (Mŗ) test indicates the IRS test does not reliably predict moisture susceptible mixtures. The Mŗ 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.