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Abstracts III

Ice Detection System

Medford Viaduct Ice Detection System

The Medford Viaduct is a 3230 foot long structure which carries Interstate 5 across Bear Creek and several city streets.  Two ice related accidents which occurred on the structure in December of 1984 prompted concern about its safety during subfreezing weather conditions.  During the same time period, state maintenance personnel were finding success in using an ice detection system on the Fremont Bridge in Portland (Experimental Feature Final Report OR 80-01).  It was felt that a similar system could help to reduce the accident rate on the Medford Viaduct by giving maintenance personnel an early warning of potential icing conditions.  This would allow prompt application of sand and would signal the police to turn on ice warning signs.


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Effect of Moisture

Effect of Moisture on Asphalt Pavement Life

Considerable research has been carried out on the effect of water on asphalt mixtures, and test methods to investigate the effect of water have been developed.  However, most of this work has been related to stripping and the effect of additives, where external water enters or affects the pavement following construction.  There is little published research directly concerned with the problems of mixing moisture in hot mixed asphalt concrete and long-term durability related to mixing moisture.
 
This report presents the results of a study to investigate the effects of mixing moisture on mechanical properties of asphalt mixtures.  The potential benefits of lime and Pavebond Special were also investigated.  The repeated load diametral test device was used to measure the resilient modulus, fatigue, and permanent deformation characteristics of laboratory specimens prepared with and without moisture (0, 1, and 3%) and with and without lime (0, 1%) and Pavebond Special (0, 0.5%).  Mixtures were prepared which were representative of two projects for which considerable field data were available.  One project utilized marginal aggregate and the other good quality aggregate.  To evaluate the long-term durability of mixtures, they were tested before and after conditioning using the Lottman approach.
 
The test results showed that inferior performance occurred for mixtures with 3% moisture, but was most pronounced in mixtures with high void contents.  However, the mixtures with marginal aggregate showed improved performance at 1% moisture content, associated with their lower void contents, which may be due to absorbed moisture preventing asphalt absorption and the higher asphalt content of these mixtures.  The addition of lime resulted in distinct improvement of performance for moist samples from the project which had good quality aggregate, but high air void contents.  However, neither additive showed substantial benefit for moist mixtures from the project with marginal aggregate and low air void contents.


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Fly Ash as Admixture

Evaluation of Fly Ash as an Admixture in Portland Cement Concrete
The investigation of fly ash as an admixture in Portland cement concrete (PCC) was divided in to two phases.  Phase I consisted of an experimental program while phase II involved an evaluation of fly ash concrete based on research reported by other agencies.
 
Data obtained in the experimental program provide evidence that both Class F and Class C fly ash can be used to manufacture concrete of comparable strength as that produced from conventional materials.  In some cases fly ash concrete showed higher compressive strengths at both high and low cement factors depending on the fly ash source and its replacement ratio.  The variable properties and characteristics often associated with fly ash and fly ash sources on the compressive strength of concrete cylinders were verified.  Fly ash showed little effect on promoting expansion due to the alkali aggregate reaction, when used with a high alkali cement. The alkali content of fly ash may be more significant when used with a low alkali cement.
 
Research conducted by a wide variety of agencies lead to the conclusion that the addition of fly ash to PCC may cause a reduction in the water requirements o f the mix, increased workability, reduced heat of hydration, increased time of set, reduced permeability, and lower early strength. Although much is still unclear concerning the effect of fly ash on the air void system and freeze thaw durability of concrete, some research has indicated that fly ash may actually improve durability, depending on fly ash type and replacement ratio.
 
Recommendations have been developed in this report for specifications; mix designs procedures, and testing of fly ash.  Fly ash should conform to ASTM C618 except for the modifications as listed in this report.  It is recommended that fly ash not be allowed in bridge decks, PCI: pavements, or in pre-stressed concrete at this time. Further study should be undertaken to determine the feasibility of using fly ash in this manner.  Except for seals, fly ash for use in substructure work, walks, curbs, barriers , other non-critical structures, and cement treated base (CTB) should be considered as a substitute for Portland cement for a minimum of 1076 to a maximum of 20% by weight of Portland cement.
 


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Blowing Dust Final Report

An Experimental Blowing Dust Alarm System for Highways - Final Report
Blowing dust storms pose a visibility hazard to highway motorists. An experimental alarm which senses electrification of a metal antenna by blowing dust particles is described. The metal antenna can be an ordinary radio whip antenna or an insulated top strand of barbed-wire right of way fence to monitor a greater area. The sensor responded favorably under conditions of half mile visibility and 20 mph winds. Field tests were conducted by telemetry to an office microcomputer.
 
Dust related radio noise which blanks out broadcast reception is attributed to electrification of metallic objects and subsequent corona or spark discharge.
 
An experimental acoustic sensor for blowing sand is also described, along with comment on application of an ionization chamber to detect motionless dust.


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Asphalt Aging in Hot Mix Plants

Evaluation of Asphalt Aging in Hot Mix Plants

Asphalt concrete pavement tenderness, due to inadequate aging or unexpected soft consistency of the asphalt, has caused problems such as rutting, surface flushing, stripping, ravel1ing and segregation in Oregon highways over the past ten years.  In order to identify the causes of the pavement tenderness, data was gathered from various construction projects throughout the state.  As a measure of the aging in the mixing and placement process the following formula was developed to determine the percentage change in asphalt viscosity at the time of paving:
 


C= R - A
x 100%
B - A
  Where, A = absolute viscosity of the original asphalt, B = absolute viscosity of the rolling thin film oven residue (RFTC) of the original asphalt, and R = absolute viscosity of the asphalt recovered from the mixture. Based on field observations of paving projects, no paving problems (tenderness) were experienced when "C" values were above 50 percent, some problems were experienced when "C" values were from 30 to 50 percent, and pavement problems were always experienced when "C" values were less than 30 percent. A value o f 30 or higher was then used for acceptance on paving projects (OSHD Specification 403.39).
 
A number of variables were documented in the field to identify the cause of the indicated pavement tenderness. These included, testing delay, contractor operation, asphalt plant type, dust collection system, grade and supplier of asphalt cement, burner fuel type, asphalt concrete mix class, and limited mix temperature data.  Special emphasis was placed on the collection and evaluation of data on burner fuel contamination of asphalt. These variables were correlated against "C" values of 111 asphalt samples from 29 paving projects.
 
Results from the study indicated that the selection of burner fuel type is critical in producing a satisfactory mix. Some lower grade fuels (reclaimed oils), due to poor combustion, caused contamination of the mix by softening the asphalt. Low temperature in the mixing or aggregate drying process, especially in drum mixer plant burners, is detrimental to the mix. This will produce poor combustion of burner fuel and less aging. The overall operation and construction of asphalt plants, burner fuel type, mixing temperature and the use of bag house dust collectors, has a significant influence on the tenderness of the produced mix.


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Diamond Barricades

Evaluation of Diamond Barricades in Construction Zones
Experimental diamond barricades, developed by the Federal Highway Administration, were deployed and evaluated on two construction projects in Oregon.  The diamond barricades, types II and III were fabricated by the state sign shop and were installed in place of standard striped barricades at typical work zone lane closures, one on an interstate freeway, the other on an urban arterial highway.  Observations and measurements of traffic flow characteristics were made in an effort to compare the two barricade designs and to identify any potential deficiencies in the diamond barricades.
 
Data obtained from vehicle speed and lane change measurements did not conclusively prove either barricade type to be superior to the other. As a traffic control device, both panel designs were equally effective.  Traffic conflict and erratic maneuver rates, on the other hand, were significantly lower for the diamond barricades at the urban site.
 
No particular problems were found in the barricade fabrication process. If the barricades were to be made a standard, production costs would not increase over the current cost of producing striped barricades, except for costs associated with larger panel sizes. In the field, the diamond barricades were found to be more visible than the striped barricades, due to an increased panel width (8" t o 129, as well as the tendency of the diamond pattern to stand out from the background better than the striped pattern. The overall performance of the diamond panel in these tests indicates that it is an acceptable alternative to the striped panel design f o r use on barricade rails.


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Clackamas River Bridge

Polymer Concrete Overlay of Clackamas River Bridge
During the week of August 15, 1983, a thin methyl methacrylate polymer concrete overlay was placed on a portion of the Clackamas River Bridge on Highway 99E in Oregon City.  The purpose of this overlay was to determine the skid number of an FHWA formulated polymer concrete and to observe its wearing characteristics.  The polymer concrete overlay was applied to a portion of the two northbound lanes during a two day period by 16 state bridge maintenance workers.
 
The polymer materials for this project were purchased from Dural International, Inc. of New York after they were determined to be the low bidder.  The specifications for the polymer materials were taken from the FHWA report entitled "Polymer Concrete Patching" report number FHWA-IP-82-10.  These formulations were developed by Brookhaven National Laboratory for FHWA and had been successfully used for patching Portland cement concrete.  After the contract to furnish the polymer materials was awarded, Dural began purchasing the various ingredients for the powder component.  All items were readily available except for the designated initiator, BFF-50.  Permission was granted for another benzoyl peroxide initiator, BCP-35 to be substituted at 42% higher concentration.  The exact formulations for the polymer materials are shown in Table 1.  The aggregate used in making the polymer concrete was acquired from Lone Star Industries, a local producer. 


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Membrane Protection Yaquina Bay

Membrane Protection for Steel Stringer Tops - Yaquina Bay Bridge
Direct coastal exposure imposes serious problems to structural and reinforcing steel in bridges. Corrosion causes expansion of the steel resulting- -in a variety of problems including spalling of reinforced concrete. This problem can become especially severe under the deck where salt-laden moisture condenses and is not washed away by the rain.
 
The Yaquina Bay Bridge in Newport, Oregon suffered from severe corrosion problems making it necessary to replace the deck and sidewalk sections throughout the three steel arch spans. With the new deck in place, the tops of the steel deck stringers are inaccessible for sandblasting and painting and are thus subject to corrosion. The purpose of this experimental features study was to determine the effectiveness and suitability of the Chevron Industrial Membrane (CIM) for providing permanent corrosion protection on the tops of steel deck stringers and other similar members in conjunction with the deck replacement project on this structure.


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Fuels and Asphalts

Characterization of Fuels and Asphalts
This report describes a study of thirteen samples of fuel oil, original asphalt, and recovered asphalt received in 1983 May.  Some additional work on a set of three samples received in 1982 October was also done.


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Stripping in Flex Pavement Phase 1

Identification & Quantification of the Extent of Asphalt Stripping in Flexible Pavement Phase 1 
 This report is the first phase of a study in Oregon to evaluate the effect of material sources, void content and additive type on the retained strength (AASHTO T-165) or retained modulus (NCHRP 196). A total of 20 projects were evaluated.  The results clearly indicate that material and additive type affect asphalt-aggregate interaction.


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Marine Piling Final Report

Use of Improved Structural Materials Systems in Marine Piling
This report contains the results of a study to evaluate the feasibility of manufacturing pre-cast, pre-stressed marine piles from polymer concrete, polymer impregnated concrete, internally sealed concrete and latex modified concrete.  Included in there port are
 

  1. a description of the laboratory work that preceded the preparation of the specifications
  2. a description of the manufacturing process and problems with each system
  3. the initial results of the short term performance of the various structural concretes.
 
Only the polymer concrete piles were rated unsatisfactory after the first two years.


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Polymer Concrete Overlay Field Trials

Type A Polymer Concrete Overlay Field Trials
On July 31 and August 1, 1982, the Oregon State Highway Division successfully placed a methyl methacrylate polymer concrete overlay on a portion of one span of a major interchange ramp in Portland, Oregon.  Two proprietary polymer concretes were used in this experimental overlay project.  They were Crylcon, formulated by DuPont, and Fabucrete, produced by Dural International.  The main objectives of the project were
 

  1. to evaluate the mixing and placement characteristics of the methyl methacrylate polymer concretes as overlay materials,
  2. to examine the durability, skid resistance, impermeability and crack susceptibility of the materials in bridge deck construction and
  3. to evaluate the preparation of the deck surface using an airless shotblast machine.
 


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Concrete Box Culverts

Precast Reinforced Concrete Box Culverts 
In 1977 an extensive storm drainage system was constructed along Interstate Highway 5 in northeast Salem, Oregon.  Included in this project was the installation of approximately 2,400 ft of twin box culvert.  Because several portions of this box culvert were placed under existing roadways which could either not be closed to traffic or only partially closed for short durations, three different methods of culvert placement were used.  For the 2,000 feet of culvert which did not affect traffic, the standard poured-in-place method was used.  For the segments of culvert where the poured-in-place method would have resulted in undesirable traffic interruptions, two additional methods, open trench and jacking, both using pre-cast reinforced concrete boxes, were specified.  Because these two methods of placing pre-cast box culverts were relatively new, these portions of the project were classified as experimental features and evaluations and reporting were scheduled.  This is the final report on the experimental aspects of the study.
 
The importance of the Market Street Interchange on Interstate Highway 5, where the culvert passes beneath the southbound on-off ramps, made it desirable to maintain unimpeded traffic during construction.  Pre-cast box sections were jacked under the ramps allowing an almost uninterrupted flow of traffic.  Where the culvert crosses Market Street, a main arterial, traffic volumes dictated that only one half the roadway could be closed at a time and safety considerations dictated that construction occur only during daylight hours.  Pre-cast box sections were placed in an open trench under one half of the roadway while traffic was maintained on the other half.  Complete installation required only two days, one day for each half of the roadway.


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Epoxy Coated Reinforcing Steel

Evaluation of Epoxy Coated Reinforcing Steel in Oregon Bridges
Since the early 1960's when the use of deicing salts became prevalent, premature deterioration of bridge decks has been a major drain on highway maintenance budgets. Much of the deterioration has been in the form of concrete spalling due to the corrosion of reinforcing steel.  Because the corroding steel expands, stresses are created which exceed the tensile strength of the concrete causing delamination and eventually spalling; galvanic corrosion of the reinforcing steel is accelerated by the presence of chloride in the concrete deck.
 
One of the methods available for combating this problem is epoxy coating the reinforcing steel.  By insulating the reinforcing steel from the galvanic circuit, the epoxy coating prevents corrosion.
 
In October 1975, under the National Experimental and Evaluation Program (NEEP) of the Federal Highway Administration, the Oregon Department of Transportation began this investigation. The purpose of the study was to determine the effectiveness of epoxy coated reinforcing steel in preventing bridge deck deterioration.  Two bridges were selected; the Yachats River Bridge on the Oregon Coast Highway (US 101) in Lincoln
County and the Shelton Ditch Bridge on 13th Street S.E., in Salem, Oregon.


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Marine Piling

Use of Improved Structural Materials Systems in Marine Piling
This report contains the results of a study to evaluate the feasibility of manufacturing pre-cast, pre-stressed marine piles from polymer concrete, polymer impregnated concrete, internally sealed concrete and latex modified concrete.  Included in there port are
 
1) a description of the laboratory work that preceded the preparation of the specifications
2) a description of the manufacturing process and problems with each system
3) the initial results of the short term performance of the various structural concretes.


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Rubber-Asphalt Chip Seals

Evaluation of Rubber-Asphalt Chip Seals in Oregon

The Oregon State Highway Division, in cooperation with the Federal Highway Administration, participated in a demonstration project on the evaluation of rubber-asphalt chip seals. The trial projects were placed in Maintenance District 11, in the vicinity of Klamath Falls.  The object of project was to give this type seal coat a working test. The process has been used for several years in Arizona. Sahuaro Petroleum of Phoenix, Arizona has been the major concern behind the process.
 
Two small sections of rubber-asphalt chip seal were placed in the Klamath Falls area in July of 1974. The performance obtained from these trial sections was very good. When FHWA provided the opportunity for Oregon to participate in the demonstration project program to provide a more extensive test of the process, District 11 requested that the work be done in that district.
 


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Properties on Asphalt Life

Impact of Variation in Material Properties on Asphalt Pavement Life

The effect of variations in asphalt concrete mix properties on pavement performance life is a crucial factor in highway pavement construction.  In this study, data on samples prepared from field mix designs and using materials from North Oakland-Sutherlin, Castle Rock-Cedar Creek and Warren-Scappoose projects were analyzed by using the Statistical Interactive Programming System (SIPS) of Oregon State University.  Regression analysis techniques were used to develop predictive models of pavement performance life based on each of the mix characteristics.  The asphalt concrete mixture properties that were evaluated in this study were percent air void, asphalt content, gradation and aggregate type used.  The percent air void for mix density is found to be the most dominant factor and most highly significant in controlling both fatigue cracking and rutting failure.  The mixtures compacted to low void content showed remarkably long fatigue lives and high resistance to deformation.  The highest performance life was obtained when the asphalt content and the amount of fines were at an optimum level, respectively.  Deviation from optimum content in either of these properties causes a reduction in pavement life.  The optimum asphalt content also appeared to be a function of aggregate type used.  Thus, the degree of influence of air voids and asphalt content on mix behavior is reflected by the type of aggregate.  Pay adjustment factors were developed based upon fatigue performance life compared to proposed standard pavement life.  Summary tables of pay adjustment factors are included in the chapter on recommendations.


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Rapid Test Methods

Rapid Test Methods for the Evaluation of Concrete Properties

The objective of the project was to place a CERL/Kelly-Vail testing unit and a microwave oven in the field to perform tests of plastic concrete on construction projects.
 
The CERL/K-V tests were to determine water and cement content of the concrete and were evaluated as a method of predicting 28-day concrete strength.
 
Although the water and cement contents can be determined with a reasonable degree of accuracy, there are too many variables involved in the field to accurately predict strength.
 
The microwave oven used in the defrost mode is a fast and accurate method to determine water content with a minimum of equipment and operator training.


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