Morse Brothers, Inc. Clackamas Concrete Cylinder Mold Investigation
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On May 5, 1986 Keith Johnson, Structural Materials Engineer, initiated an in house study of concrete cylinder molds. The purpose of this study was to prove if steel concrete cylinder molds produce higher compressive strengths than plastic concrete cylinder molds. Also, this study will determine the amount of strength difference, if any. This study was performed under the direction of Hal Baird, Assistant District Inspection Manager. All concrete was batched at the Morse Brothers Clackamas Pre-stress Plant.
Petrotac Bridge Deck Waterproofing Membrane on Five Mile Creek Bridge
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During the 1970’s, the Oregon State Highway Division was involved in a federally funded experimental program to evaluate various waterproofing membrane systems for bridge decks. Through this program, a list of approved products and/or systems was developed. Since the completion of that study, several of these products have been discontinued and replaced with new, redesigned products. While some of the original products are still available, it was felt the newer products, developed from current technology, should be evaluated, as these are purported to be more durable and often less expensive.
On October 17 and 18, 1985, one of these new bridge deck waterproofing systems, Bridge Deck Grade (BDG) Petrotac, was installed on the deck of Five Mile Creek Bridge. Manufactured by Phillips Fibers, Petrotac is an impermeable, non-woven fabric membrane used to protect a bridge's reinforcing steel from moisture and harmful chlorides. BDG Petrotac is manufactured in 36" wide strips, with a self-sealing edge to insure full closure when strips are overlapped.
A research program was implemented to inspect and evaluate this membrane over a period of two and a half years. This report documents the installation of the Petrotac system, and the results of the first evaluation.
Flyash in Continuous Reinforced PCC Pavement and Lean Concrete Base
Flyash is a byproduct of the coal combustion process in modern power stations. It is extracted from exhaust gases by electro-static precipitators, leaving relatively clean air to pass up the smoke stacks. In the presence of moisture, flyash combines with calcium hydroxide to produce a cementitious material which, when used as a replacement for a percentage of cement, is reported to enhance certain qualities of hardened concrete. Since flyash is actually a waste product, it costs considerably less than traditional materials for which it can be substituted.
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Nationwide, state highway departments are heeding a recent Federal Highway Administration directive to allow the use of flyash in Portland Cement Concrete (PCC) construction or risk the loss of federal funds. State agencies must remove any restrictions on using flyash modified PCC where technically appropriate, unless they can show why its use would be unsuitable.
Considering this, the Materials Section of the Oregon State Highway Division (OSHD) launched an experimental program in 1984 to evaluate the characteristics of flyash as an admixture in PCC, and develop recommendations for its suitability in Oregon construction. The program, documented in "Evaluation of Flyash as an Admixture in Portland Cement Concrete" (11, was based on tests conducted at the OSHD Engineering Laboratory and a review of available literature pertaining to flyash concrete. Properties studied included durability, strength, time of set, and alkali-aggregate reaction of concrete containing flyash. While results indicated flyash was suitable for use in PCC construction, the report concluded by recommending construction of test sections to evaluate the in-service performance of flyash in PCC pavements.
Experiences in Implementing the Corbett-Swarbrick Procedure for Separation in Four Generic Fractions
This paper presents an evaluation of the Corbett-Swarbrick procedure for separation of asphalt into four generic fractions. The Corbett-Swarbrick procedure, currently accepted as an ASTM standard (ASTM D4124-82) has been submitted for revision to the ASTM committee. The revised procedure involves considerable modifications to the existing standard.
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Oregon State University together with Oregon State Highway division have implemented both procedures (current RSTM standard and the revised procedure) and used them on a routine basis in an ongoing research program. The implementation of both procedures created a number of difficulties. Most of these difficulties were related to the interpretation of the standard and the lack of more complete information associated with the severa1 steps to follow when performing the entire test.
The purpose of the paper is to present the major difficulties encountered with the implementation of the test and present some recommendations for future revisions of the current standard. Several aspects of the test procedure are analyzed, such as: the method used for asphaltene prescription, filtration, solvent concentration and some
Problems related to the use of alumina and the chromatographic column.
Morse Brothers, Inc. Concrete Cylinder Mold Investigation Phase Two Report
On June 13, 1986 OSHD and Morse Brothers, Inc. decided to engage in a joint effort to isolate the differences in compressive strength, which result when cylinders are cast in plastic molds and steel molds. The first experiment performed on June 24, 1986 proved false the theory, “The reduction in compressive strength is greatest in the most flexible molds.” This is the second of two scheduled experiments will show that the effect thermal conductivity has on compressive strength.
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Reliability of the Dimethyl Sulfoxide (DMSO) Accelerated Weathering Test to Predict Degradation of Aggregates
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The reliability of the Dimethyl Sulfoxide (DMSO) Accelerated Weathering Test to predict the degradation potential of untreated basaltic aggregates is evaluated. In the investigation two tasks were undertaken;
1) Correlation of the tests results to petro-graphic analysis, and
2) Establishment of acceptable weight loss limits after immersion of aggregates in DMSO.
From the study of eight rock quarries in Oregon, it was found that the DMSO Accelerated Weathering Test results correlate well to a Secondary Mineral Rating. The Secondary Mineral Rating is based upon petro-graphic analyses, which accounts for the content and distribution of deleterious minerals in a rock. The correlation equation which relates the DMSO weight losses to petro-graphic analysis neglected the results from two quarries containing the minerals analcime and calcite. The reaction of aggregates containing these two minerals occurs owing to the mechanisms by which DMSO is able to penetrate into membranes. In regard to the potential for the DMSO to react with minerals other swelling clays, it was suggested that a Clay Index test be conducted since this index was found to be insensitive to the presence of analcime and calcite. The validity of the DMSO test for an articular quarry can be established by comparing the weight loss and the Clay Index to the relationship given in the paper. If the result deviates substantially from the indicated relationship, a complete petro-graphic analysis may be required to determine the suitability of the aggregate. Data collected from this study indicate that an acceptable weight loss limit for untreated aggregate, utilizing the DMSO Accelerated Weathering Test procedure, should be in the range of 20 percent.
Evaluation of Asphalt Additives: Lava Butte to Fremont Highway Junction
This report covers four year's performance of ten test sections using dense-graded hot mix asphalt concrete with these additives: Plus Ride mix containing granulated tire rubber, Arm-R-Shield modified asphalt containing ground and dissolved tire rubber, Fiber Pave polypropylene fibers, Boni Fibers polyester fibers, Pave Bond anti-stripping asphalt additive, lime as an anti-stripping aggregate treatment, and CA (P) -1 asphalt containing an EVA polymer. The control section used conventional AC-20 asphalt.
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At the end of four years, none of the test sections performed better than the control. The only significant distresses were a slight loss of aggregate in the wheel tracks of the Plus Ride section and a comparatively large amount of wheel track and transverse cracking in the CA (P)-1 sections. None of this distress was severe enough to require repair.
The anti-stripping additives cannot be evaluated at this time, as no significant stripping has occurred on any section.
Distress measured on the roadway after four years was compared to the results of tests done on briquettes made out of mix sampled from behind the paver. The best correlations were: rutting vs. the 77˚ and 115˚ penetration, longitudinal wheel track cracking vs. the unconditioned diametral resilient modulus, transverse cracking vs. the 73˚ fatigue test results, and raveling and weathering vs. the index of retained strength and the freeze-thaw/unconditioned diametral resilient modulus ratio.
Modified Rockfall Catch Fence Mayflower Creek - Detroit Dam Interim Report
Many older rock cut slopes along the highways in Oregon are in need of repair. The rock-fall from 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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Morse Brothers, Inc. Concrete Cylinder Mold Investigation Phase One Report
On June 13, 1986 OSHD and Morse Brothers, Inc., decided to engage in a joint effort to iso1ate the differences in compressive strength which result when cylinders ore cast in plastic molds and steel molds. This the first of two scheduled experiments will show what effect mold flexibility has on compressive strength.
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Improving Materials and Methods for Installing Inductive Loop Detectors
This report is the final report of this research project. It describes a compiling of materials utilized by various agencies for use in formation of inductive loop detectors. It further lists methods by which different agencies install materials in order to obtain a resilient detection system. Tested were loop sealants, loop wire, preformed loops and loop saw-slot cleanout methods. Included is a "Results of Survey" chart depicting materials and methods used by eight states.
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It was found that though many different materials and methods are used to form inductive detector loops, there exist some major problems. These are, most commonly, loop sealant failure (loss of adhesion) and poor installation technique (inadequately cleaned saw-slots).
Evaluation of Bond-Controlled, Epoxy-Coated Prestressing Strand on Hubbard Creek Bridge
Oregon's many coastal bridges are subject to a severely corrosive environment, being exposed to frequent rain and fog and a nearly constant misting of salt spray. Heavy rains flush ocean salts off the sides and decks of bridges, but leave the undersides covered with salty ocean spray. Because of this spray, coastal bridges are more subject to corrosive attack on the underside than from chlorides applied to the deck. A significant number of coastal bridges are succumbing to the effects of this harsh environment and will be in need of replacement over the next several years.
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Pre-stressed concrete bridges will most likely be chosen to replace these deteriorating structures. Corrosive agents can attack the steel reinforcement contained in pre-stressed concrete structures, causing tensile stresses which fracture the concrete. Coating the reinforcing steel with epoxy encases and protects the steel from these corrosive agents.
While epoxy coated reinforcing steel has been used successfully to combat corrosion for several years, epoxy coating for pre-stressing strand is a relatively new development. A NCHRP study "Corrosion Protection of Pre-stressing Systems in Concrete Bridges" (Project 4-15, FY '82) is currently underway to test the mechanical behavior and corrosion resistance of epoxy coated 7-wire strand used in pre-tensioning applications. However, an evaluation of actual girders in service in t he appropriate environment, as opposed to laboratory tests and simulations, was considered
Evaluation of Asphalt Properties and Their Relationship to Pavement Performance - Interim Report
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This interim report presents the findings of the literature review and information regarding selection, implementation, and development of a chemical composition procedure for asphalt cements.
The chemical composition analysis selected was the Corbett-Swarbrick method, standardized as ASTM D4124. This procedure will be used in a comprehensive study for which eight highway projects throughout Oregon State were selected. This report outlines the program study which involves the study of highway performance, laboratory aging procedures, and methods of asphalt extraction from cores.
During implementation of the Corbett-Swarbrick method, a number of refinements were made to improve its efficiency. These are presented in a comprehensive user’s manual as an appendix of this report.
Field Verification of Asphalt Aging in Hot Mix Plants
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As a measure of the aging of asphalt concrete mixes in the mixing and placement process, a formula was developed to determine the percentage of expected change in asphalt viscosity at the time of paving (Lund and Wilson, 1 9 8 4 ). A value of 30 or higher was used in 1983-84 for acceptance on paving projects At the conclusion c)f the 1981-83 study, a follow-up survey was made of all projects. Two major areas of interest were covered in the follow-up questionnaire: 1) the characteristics of the asphalt mix and pavement at the time of placement, and 2) the characteristics of the pavement at the time of receiving the questionnaire (March, 1984).
The responses to the questionnaire, even though they are subjective, appear to identify and confirm relationships between the "C" value and asphalt mix problems. The strongest correlation appears to be more with problems at the time of construction than with long term pavement performance problems. Using statistical tests, the significant problems that were identified during construction were tenderness, shoving and rutting, segregation and mix being too cold. The long term significant problems developing after construction were stripping and cracking.
When the individual characteristics were evaluated, the great majority had the significance level peak at the less 40 “C” value. That is, a greater percentage of the samples that were below 40 had some problems in the field.
In early 1985, the Oregon Highway Department raised the minimum acceptable “C” value to 40. Mix with a value less than 40 is to be removed, or at the discretion of the
Engineer, it may be left in place and a reduction in a Composite Pay Factor calculated (OSHD Spec. 403.39).
In 1985 “C” values were again analyzed to see if any changes had occurred since the 1981-1983 study. Forty-nine projects constructed or under construction from August 1983 to July 1985 were reviewed, from which 193 individual "C" values were obtained. Comparing the results with the 1981-83 data, indicated that individual variables such as burner fuel type, dust collection system, and plant type no longer are associated with changes in “C” values. Instead, the entire operation (adjustment) of the asphalt plant is the major Influence on the “C” value. Due to plant adjustments, several contractors, having poor results in the past, have been able to raise their average “C” value.
Eugene Sand & Gravel
Eugene Sand & Gravel High-Strength Concrete Report Study
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This research study was undertaken in response to the production of substandard high-strength concrete by the Eugene Sand and Gravel Company on three separate highway construction contracts (five separate bridge structures). The routine testing of concrete cylinders collected for acceptance testing indicated that the concrete did not meet the minimum strength requirements specified for the contracts. Table 1 summarizes the test results which document the substandard concrete strengths.
In reviewing the test results with the concrete supplier, the validity of the results were challenged because plastic cylinder molds were used on some of the projects instead of the steel cylinder molds customarily used by Eugene Sand and Gravel (ESCG), Questions were also raised about the method of transport of concrete cylinders to the Oregon State Highway Division (OSHD) Materials Laboratory.
This research study was undertaken to determine the effect of different test variables such as mold type, method of transport, method of sealing, and type of test equipment of tested concrete cylinder strength.
Effect of Moisture and Aging on Asphalt Pavement Life Part 1
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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 effective 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.
Effect of Moisture and Aging on Asphalt Pavement Life Part 2
This report presents the results of a study to evaluate the effect of oxidative aging on asphalt mixtures. The results of tests on field core samples from 8 projects representing different regions in Oregon were compared with those from laboratory mixture samples for selected projects subjected to accelerated aging tests. The study also involved laboratory tests on asphalt used in those projects selected for the laboratory aging process for mixtures.
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The procedure selected for aging laboratory mixtures involved using a Pressure Oxygen Bomb (POB), a sealed container in which mixture and/or asphalt samples were subjected to pure oxygen at 100 psi pressure at 140ºF (60ºC), for periods of up to five days. The asphalt samples were ages on a Fraass plaque to achieve minimum disturbance of the sample, and the degree aging assed by change in the Fraass breaking temperature.
The results of this study showed that the POB was an effective means of producing measurable changes in both mixtures and asphalt samples. However, the mixture properties were substantially different to those measured for the field core samples, while the asphalt properties were similar. The study also indicated that aging rate is a function of the air voids in the mixture, and the amount of asphalt and its properties. The study therefore confirms the well established principle that low air voids and thick asphalt films are required to produce durable asphalt mixtures.
Siskiyou Summit Negative Grade Arrester Bed for Runaway Trucks
Long downgrades often cause trucks to lose their brakes and go out of control, creating a hazardous stretch of roadway with an abnormally high accident rate. In an attempt to prevent these accidents, three principle methods are currently employed: signs to alert drivers of long descents, brake test areas at the beginning of descents, and escape ramps.
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Most escape ramps are designed to use gravity as the primary deceleration mechanism. These ramps provide an exit from the roadway to an adjacent hillside, ascending at grades of up to 40%. Loose gravel is often used on these ramps which, while aiding in the deceleration, is primarily provided to prevent the trucks from rolling back down the ramp. Unfortunately, ascending ramps are not possible in all locations where they are needed. This report presents the results from a special type of escape ramp, a ramp that is located on a descending grade.
Ice Detection Systems
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In the fall of 1980, an experimental ice detection system was installed on the Fremont Bridge in Portland, Oregon. This bridge, which carries 1-405 over the Willamette River, has a history of icing problems when the deck is wet and the temperature hovers near freezing. The upper deck of the main span is especially vulnerable because of its height and thin deck section. The ice detection system allows bridge surface conditions and temperatures to be monitored constantly from a remote location, and assists maintenance workers in their response to the deicing needs of the bridge.
The experimental feature of this project was to evaluate, under actual field conditions, the mechanical and electrical reliability of an ice detection system and the validity of its output in Oregon.