Abstract:
The durability performance of asphalt concrete (AC) with various percentages of reclaimed asphalt material (RAM) has been a focal point of the asphalt industry, leading it to embrace the balanced mix design (BMD) concept. The goal of this research was to review and enhance WSDOT\'s AC materials selection, mix design, and standard specifications for optimized use of RAM, based on readily implementable technology, in collaboration with industry stakeholders for improved durability performance. The scope included a literature review, an assessment of RAM supply in the state, and a statewide comparison of low and high RAM pavement performance data to determine whether differences were observed;. The scope also included an evaluation of raw materials and field mixtures and an evaluation of laboratory mixed-laboratory compacted (LMLC), field mixed-laboratory compacted (FMLC), and field cored (FMFC) samples. The laboratory analysis included short-term and long-term aging of binders and mixtures with rheological and cracking tests performed on them. One recommendation of the study was to integrate volumetric parameters along with further performance testing in a BMD approach to increase effective binder content. Another was to implement all of the volumetric criteria in AASHTO M323 during mix design, test section and acceptance. Additional recommendations were to use ΔTc as an aging parameter in binder specifications; include RAM in all mix designs regardless of doses; maintain an IDT strength specification and transition to the CT-Index; add long-term aging for IDT/CT-Index test specimens in the future, maintaining the current Hamburg Wheel Track (HWT) rutting test and criteria; revise short- and long-term standard specification; and re-evaluate the performance of RAM pavements with time.

Authors:
Muench, T., Hand, A., Sebaaly, P., Hajj, E., Chhetri, K., Piratheepan, M., Elias, N., Howell, R., DeVol, J., Davis, S,

Keywords:
Asphalt concrete, performance, recycled asphalt materials, durability

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Abstract:
This report assesses various elements of the Washington State Department of Transportation (WSDOT) hot-mix quality assurance (QA) specification. Current WSDOT QA specifications contain measures of in-place density, asphalt content, and aggregate gradation for contractor pay and special provisions allow for additional pay factor items based on volumetric properties. Data from production paving projects suggests that use of the original pay items are adequate in determining the quality of hot-mix asphalt (as opposed to pay items based on volumetric mix properties). Additionally, the option of increasing the minimum compaction level (currently 91 percent of theoretical maximum density) is recommended to increase quality. In addition, a contractor quality control (QC) program is recommended for consideration by WSDOT.

Authors:
Willoughby,K. A., Mahoney,J. P.

Keywords:
specification, statistics, hot mix asphalt, HMA, asphalt concrete, pay factor, precision, Superpave, compaction, quality control, quality assurance

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Abstract:
This report clarifies the Washington State Department of Transportation (WSDOT) hotmix asphalt (HMA) statistical acceptance specification's statistical basis and how its key components influence overall specification performance and contractual pay.The WSDOT specification uses a variable sampling plan to measure in-place density, asphalt content, and aggregate gradation. Specification bands on these three quality characteristics are reasonable and consistent with typical material, sampling, testing, and construction variability. Pay is determined by calculating a percentage within limits (PWL), then applying a series of parabolic pay equations, depending on sample size.The methods used by WSDOT balance risk between the contractor and WSDOT well but result in two issues that differ from similar specifications: (1) expected pay for material produced at acceptable quality level (AQL) is greater than 1.0, and (2) WSDOT's AQL is 95 PWL but contractors seem to consistently produce material near 90 PWL The issues are not critical, and therefore, the specification should not be changed. However, if the third and final report in this series, which studies quality characteristics to be measured for Superpave design mixes, results in major recommended changes, then we recommend reviewing the AQL and pay factors to bring the specification into fine with actual practice.

Authors:
Muench,S. T., Mahoney,J. P.

Keywords:
asphalt concrete, HMA, hot mix asphalt, pay factor, research, specification, statistical acceptance specification, statistics, Washington state

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Abstract:
Recently, WSDOT acquired a non-nuclear, non-destructive, density measuring device manufactured by TransTech called a Pavement Quality Indicator (PQI). TransTech's PQI measures pavement density indirectly by measuring its dielectric constant. A non-nuclear gauge is advantageousbecause it contains no radioactive source and is therefore not subject to radiological controls, and it can obtain readings in about 5 seconds versus I to 4 minutes with a nuclear gauge. Currently, TransTech is collecting data from different agencies to determine the PQI's suitability for measuring asphalt pavement density. This brief study presents density measurements from TransTech's PQI and compares them with nuclear density gauge and core density measurements from three WSDOT 1998 paving projects. This evaluation was a secondary study to WSDOT's 1998 study Asphalt Concrete Construction-Related Temperature Differentials in Washington State; therefore this study's experimental design was based entirely on the Temperature Differential study requirements, which resulted in non-random samples and multiple populations within the same sample groups. Despite these problems, results indicate that, when averaged, PQI readings compare favorably with both nuclear measurements and core measurements.

Authors:
Muench,S. T., Mahoney,J. P., Cawley,B.

Keywords:
asphalt concrete, density, pavement quality indicator, nuclear gauge, core densities, research

Abstract:
Recently, WSDOT acquired a non-nuclear, non-destructive, density measuring device manufactured by TransTech called a Pavement Quality Indicator (PQI). TransTech's PQI measures pavement density indirectly by measuring its dielectric constant. A non-nuclear gauge is advantageous because it contains no radioactive source and is therefore not subject to radiological controls, and it can obtain readings in about 5 seconds versus to 4 minutes with a nuclear gauge. Currently, TransTech is collecting data from different agencies to determine the suitability for measuring asphalt pavement density. This brief study presents density measurements from PQI and compares them with nuclear density gauge and core density measurements from three WSDOT 1998 paving projects. This evaluation was a secondary study to 1998 study Asphalt Concrete Temperature in Washington State; therefore this study's experimental design was based entirely on the Temperature study requirements, which resulted in non-random samples and multiple populations within the same sample groups. Despite these problems, results indicate that, when averaged, PQI readings compare favorably with both nuclear measurements and core measurements.

Authors:
Muench,S. T., Mahoney,J. P., Cawley,B.

Keywords:
agencies, asphalt, asphalt concrete, asphalt pavement, concrete, control, core densities, data, density, design, evaluation, experimental, group, indicator, ITS, nuclear gauge, pavement, pavement quality, pavement quality indicator, population, project, quality, Study, temperature, Washington, Washington state, WSDOT

Abstract:
The construction of the Washington State Department of Transportation's first hot in-place recycling project is documented. The project is located in the eastern portion of the state southwest of Yakima on SR-97. The two southbound lanes for approximately 5.5 miles were recycled using the Pyrotech brand of equipment.The report also includes a description of the hot in-place recycling process, equipment specifications, a discussion of the limitations and benefits of the process, and a survey of other state DOTs' experience with the process.

Authors:
Pierce,L. M.

Keywords:
asphalt concrete, recycling, in-place, construction

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Abstract:
The Washington State Department of Transportation (WSDOT) did a trial implementation of a quality assurance (QA) specification for asphalt concrete during the 1989 paving season. To assess the QA specification, data from both non-QA and QA projects built that year were compared. Based on these results, the QA projects were evaluated as having improved quality. Subsequently, the QA specification was fully implemented within WSDOT.

Authors:
Markey,S. J., Mahoney,J. P., Geitz,R. H.

Keywords:
quality assurance, statistics, asphalt concrete

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Abstract:
This report documents the construction of two experimental test sections of asphalt concrete pavement containing polymer and ground rubber additives. The two sections are located on I-5 south of Olympia, Washington and were constructed in the summer of 1992.The test sections were paved with an open-graded using PBA-6 and asphalt cement binders. PBA-6 is a performance based asphalt cement with a polymer additive. is a performance based asphalt cement but with ground tires as the additive. The is a for a new product developed by the U.S. Oil and Refining Company of Tacoma, Washington. The completed test sections are performing well, although the PBA-6GR section is flushing due to too high of an initial asphalt content. The sections will be monitored of 10 years to determine long-term performance.

Authors:
Livingston,J., Anderson,K. W.

Keywords:
additive, asphalt, asphalt concrete, Asphalt Concrete pavement, Asphalt content, asphalt pavement, concrete, construction, counties, crumb-rubber, developed, experimental, line, open-graded, pavement, pavements, performance, performance based specifications, polymer, rubber, tire, tires, Washington

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Abstract:
The major objectives of this study were to examine: (1) the types of recycled materials that are appropriate and feasible as alternative paving materials such as glass and tires; and (2) the types of recycled materials, such as mixed-plastics and compost, that can be utilized in all types of transportation applications other than pavements. Seven key products are investigated: tires; glass; asphalt concrete fly ash; compost; mixed plastics; and sign stock. Performance and cost data for pavements is documented for both in-state and nationwide applications. The national experience \'with the use of waste glass as an additive to asphalt concrete and its use in unbound base material is so highlighted. Programs for experimental use of recycled material are outlined. Recommendations for staffing and program changes to deal with recycling are also discussed.

Authors:
Swearigen,D. L., Jackson,N. C.

Keywords:
additive, Alternative, applications, asphalt, asphalt concrete, base, base materials, concrete, construction, cost, data, experimental, fly ash, Glasphalt, highway, highway construction, ITS, materials, objectives, pavement, pavements, performance, program, recycled ACP, recycling, Rubber-asphalt, tire, tires, transportation

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Abstract:
This report describes the construction of an experimental section of asphalt concrete pavement overlay which contained the additive carbon black. A long term evaluation of the overlay seeks to determine if there is a significant difference in performance between it and an adjacent control section of pavement which contains no additive.Preliminary laboratory results indicate that the viscosity/temperature curve for the carbon black asphalt binder has been altered in a way that the temperature susceptibility of the pavement is decreased.

Authors:
Livingston,J.

Keywords:
additive, asphalt, asphalt concrete, Asphalt Concrete pavement, Carbon black, concrete, construction, control, evaluation, experimental, overlay, pavement, performance, susceptibility, temperature, terperature susceptibility

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Abstract:
Often upgrading an aged asphalt concrete pavement involves overlaying a cracked pavement with new asphalt concrete. However, usually the substrate cracks reflect through the new overlay under repeated service loading. Full depth cold-mix recycles asphalt is an alternative that eliminates the potential for reflective cracking. Generally, the performance of cold-mix recycled asphalt concrete pavements in the United States supports its use as base course in flexible pavements. The conditions of three Washington experimental 'cold-mix' pavements after about 6 years of service varied from fair to good, depending on the level of truck traffic. The wheel track rutting of those pavements was not significantly different from rutting that might be expected from conventional flexible pavements under the same conditions. Although the potential for fatigue cracking exists, as it does in conventional flexible pavements, full depth recycling of asphalt concrete eliminates the cause of reflective cracking.

Authors:
Babaei,K., Walter,J. P.

Keywords:
pavement, asphalt, cold-mix recycling, asphalt concrete, reflective cracking

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Abstract:
The two fabric reinforcement products, Petromat and Mirafi 140, placed between a 0.35 ft. overlay of asphalt concrete and an existing PCC pavement have successfully prevented the occurrence of transverse reflective cracking for the 11 year period since completion of the overlay.

Authors:
Allison,R. E.

Keywords:
asphalt, asphalt concrete, concrete, cracking, Fabric reinforcement, mirafi 140, overlay, pavement, PCC, petromat, reflective cracking, reinforcement

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External Links: http://wsdot.wa.gov/Research/Reports/100/175.1.htm

Abstract:
The use of BoniFibers fiber reinforced Asphalt Concrete Pavement (ACP) at three City of Tacoma intersections is reported. Product selection, fiber reinforced ACP mix design, old pavement removal, construction and evaluations are documented.BoniFibers fabric reinforced ACP appears to provide a durable roadway at intersections that have a high volume of turning and heavy traffic. Continued monitoring of the City of Tacoma fiber reinforced ACP is recommended until major deterioration occurs.

Authors:
Toney,C. A.

Keywords:
asphalt, asphalt concrete, Asphalt Concrete pavement, Bonifibers, concrete, construction, design, deterioration, evaluation, fiber Reinforced ACP, fiber reinforced pavement, monitoring, pavement, pavements, Polyester Fibers, Polymar Fibers, roadway, traffic, volume

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Abstract:
This is the final report of PlusRide being used as the wearing course on a bridge deck overlay.A Class D Asphalt Concrete pavement which is an open graded friction course was used on an adjacent bridge as a control for the PlusRide. The PlusRide claims were high friction resistance, reduced noise, increased fatigue properties and deicing characteristics. The PlusRide cost 50 percent more that the Class D and the friction resistance, noise levels and fatigue properties were the same for the PlusRide and Class D. The deicing characteristics could not be confirmed due to the absence of surface icing on highways in the Yakima area.

Authors:
Peters,A. J., Schultz,R. L.

Keywords:
asphalt, asphalt concrete, Asphalt Concrete pavement, asphalt pavement, bridge, bridge deck, bridge deck overlay, claims, Class D, concrete, control, cost, Deck, fatigue, friction, highway, Highways, noise, overlay, pavement, PlusRide, resistance

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Abstract:
This is the final report of an evaluation of an Asphalt-Rubber Binder Stress Absorbing Membrane Interlayer (SAMI) to control transverse, alligator and longitudinal cracking in the asphalt concrete overlay.A control section consisting of a tack coat of CSS-1 applied to the existing pavement was used to compare against the Asphalt-Rubber SAMI and a paving grade asphalt SAMI. Crack mapping for a period of 9 years disclosed the Asphalt-Rubber SAMI to perform slightly better that the paving grade asphalt and much better that the control.

Authors:
Peters,A. J., Schultz,R. L.

Keywords:
asphalt, asphalt concrete, asphalt overlays, Asphalt-Rubber, concrete, control, cracking, evaluation, membrane, overlay, pavement, SAMI, stresses

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Abstract:
This is the post construction and one year evaluation Report of being used as the wearing course on a bridge deck overlay under very high traffic volumes. A rubberized Class D Asphalt Concrete Pavement friction course was used on an adjacent bridge to compare against the PlusRide. The properties evaluated were friction resistance, noise, fatigue properties and deicing characteristics. The friction and noise properties are the same. The PlusRide has deeper ruts and large areas in the traveled lane have delaminated. The deicing characteristics have not been confirmed. The rubberized class ACP is performing better than the PlusRide.

Authors:
Peters,A. J., Schultz,R. L.

Keywords:
asphalt, asphalt concrete, Asphalt Concrete pavement, asphalt pavement, bridge, bridge deck, bridge deck overlay, bridges, Class D, concrete, construction, Deck, evaluation, fatigue, friction, friction course, noise, overlay, pavement, PlusRide, resistance, Rubberized, traffic, traffic volumes, volume

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Abstract:
The Washington State Department of Transportation (WSDOT) has completed construction of twenty-four hot-mix recycle projects as of January, 1985. At the begining of this study there were sixteen completed projects that were to be examined. Evaluation of the laboratory and pavement performance data shows that WSDOT\'s initial two projects, Renslow to Ryegrass (1977) and Yakima River to West Ellensburg Interchange (1978), are still performing very we1l. Although the other fourteed projects have been constructed only within the last two and a half years, the early data indicates equally promising results. Because of the impressive pavement performance exhibited by the recycled pavements, together with hot-mix recycle benefits such as conservation of natural resources, feasibility of construction, and its cost advantage over new ACP, hot-mix recycling has become an attractive addition to the WSDOT paving program.

Authors:
Peters,A. J., Gietz,R. H., Walter,J. P.

Keywords:
asphalt, asphalt concrete, benefit, benefits, construction, cost, data, evaluation, ITS, pavement, pavement performance, pavements, performance, program, project, recycling, rejuvenating agents, Study, transportation, Washington, Washington state, WSDOT

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Abstract:
The Washington State Department of Transportation (WSDOT) has completed construction of twenty-four hot-mix recycle projects as of January, 1985. At the begining of this study there were sixteen completed projects that were to be examined. Evaluation of the laboratory and pavement performance data shows that WSDOT's initial two projects, Renslow to Ryegrass (1977) and Yakima River to West Ellensburg Interchange (1978), are still performing very we1l. Although the other fourteed projects have been constructed only within the last two and a half years, the early data indicates equally promising results. Because of the impressive pavement performance exhibited by the recycled pavements, together with hot-mix recycle benefits such as conservation of natural resources, feasibility of construction, and its cost advantage over new ACP, hot-mix recycling has become an attractive addition to the WSDOT paving program.

Authors:
Peters,A. J., Gietz,R. H., Walter,J. P.

Keywords:
asphalt concrete, asphalt, recycling, rejuvenating agents

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Abstract:
The use of liquid anti-stripping additives (LAA) for reducing moisture damage in asphalt concrete pavements was evaluated using pavement cores from pairs of projects with-and-without LAA. Results were analyzed using the tensile strength ratio (TSR). In addition, a diazo-dye for determining the presence and concentration of LAA was attempted to access the value or the test as a field procedure. The chemical additive detection tests proved inclusive, but the TSR analysis gave a positive indication of the need for the use of LAA in the wetter environments of the state, For drier environments and for low traffic volumes, use of LAA may not be cost effective. The indirect tensile test was judged to be a potentially valuable tool for statewide use in the evaluation of stripping additive needs.

Authors:
Malsch,D. A.

Keywords:
additive, analysis, anti-stripping agents, asphalt, asphalt concrete, Asphalt Concrete pavement, bituminous concrete, Chemical, concrete, cost, cost effective, damage, detection, diazo-dye test, effectiveness, environment, evaluation, indirect tension test, moisture damage, pavement, pavement life, pavements, project, strength, stripping, tests, traffic, traffic volumes, volume

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Abstract:
This study was conducted to determine the wear characteristics of bridge decks overlayed with Class D (open-graded) asphalt concrete. A total of 74 bridges were inspected and rated during the period May to August, 1984.This study was conducted to determine the wear characteristics of bridge decks overlayed with Class (open-graded) asphalt concrete. A total of 74 bridges were inspected and rated during the period May to August, 1984. A rating system was developed to allow a numerical comparison between bridges, and also to establish levels of tolerable differences. Values for a variety of problem areas were assigned in ascending order according to severity. Refer to page 10 for deficiency rating values, To use the system the bridge deck is inspected and values assigned according to visual observations. For example, if a bridge deck had some raveling, severe rutting and a transverse crack at the expansion joint, a rating of 5 (some raveling) 6 (severe rutting) + 2 (traverse expansion joint crack) = 13 would be applied. To further clarify the rating system used on page 4 through under the column headed \"Class of Defects\", the following examples are used. 1. On page 4, Bridge No. E had a rating of The rating total would be = 10, which is in the column headed \"Rating\". 2. On page 5, Bridge No. W had a rating of B-4. The rating total would be B (expansion dam failure) + 4 (some rutting). Since there is no numerical value for B the total is 4, which is listed in the column headed \"Rating\". After comparing ratings of all 74 bridges, three of serviceability were established, Categories A, and C, which are discussed in detail in the memo of August 13, 1984, on page 2 Photo Examples Rating 0-Category A -Bridge No. 90/59E-N -page 35 Rating 2 -Category A -Bridge No. -pages 51-52 Rating 6 -Category -Bridge No. -page 13 Rating 10 -Category B Bridge No. E -page 15 Rating 21 -Category C -Bridge No. N -pages 46-47

Authors:
Gietz,R. H.

Keywords:
asphalt, asphalt concrete, bridge, bridge deck, bridge deck overlay, bridge decks, bridges, Class D, concrete, Deck, overlay, overlays

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Abstract:
This report summarizes the placement and performance of sulfur extended asphalt (SEA) paving mixtures at a highway test site (SR 270) near Pullman, Washington. The report includes a summary of the mixture and structure designs and construction details. This is followed by a discussion of the data collection and analysis accomplished over a three year evaluation period (1979 - 1982). A major experimental feature of the study was the use of 0/100 (conventional asphalt concrete), 30/70 and 40/60 SEA binder ratios (sulfur/asphalt ratios are expressed as weight percents) in the experimental paving mixtures.

Authors:
Mahoney,J. P.

Keywords:
analysis, asphalt, asphalt concrete, asphalt pavement, concrete, construction, data, data collection, data collection and analysis, design, evaluation, experimental, extended asphalt, highway, mixture, pavement, pavement performance, performance, Study, sulfur, Washington, weight

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Abstract:
This report summarizes the placement of sulfur extended asphalt (SEA) paving mixtures at two test sites near Pullman, Washington. One site was on an existing state highway and the other made use of the Washington State University Test Track. The report includes the preliminary mix designs, pavement thickness determination, construction details and initial performance data for the test pavements. A major experimental feature of the study was the use of 0/100 (conventional asphalt concrete), 30/70 and 40/60 SEA binder ratios in the experimental paving mixtures.

Authors:
Mahoney,J. P., Christensen,D. R., Terrel,R.

Keywords:
asphalt, asphalt concrete, asphalt pavement, concrete, construction, data, design, evaluation, experimental, extended asphalt, highway, mixture, pavement, pavement evaluation, pavement performance, pavements, performance, Study, sulfur, test track, Washington, Washington state

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Abstract:
Two forms of pavement distress were noted on recent asphalt concrete overlay projects. A general loss of wearing surface under traffic action, termed surface ravelling, was observed on three projects starting the first season after construction.Two forms of pavement distress were noted on recent asphalt concrete overlay projects. A general loss of wearing surface under traffic action, termed surface ravelling, was observed on three projects starting the first season after construction. A concentrated, local loss of surface material in narrow longitudinal strips, designated as strip ravel ing, was observed on four projects approximately the second season after completion. Construction record reviews and field testing and sampling of these projects along with four undistressed projects were made to define the construction methods and equipment used and to obtain samples from areas of good and bad pavement condition. These samples were tested to determine the strength of the compacted mix, and of the aggregate and asphalt constituents. Common factors from the projects showing surface ravelling were a thin lift pavement overlay placed late in the paving season with a tendency toward less than optimum asphalt content. The resulting pavement had high air void content and was readily abraded by traffic during ensuing severe winter weather. Recurrence of this type of problem can best be prevented by increased emphasis on proper compaction and mix design. Remedial work on the present projects should be directed toward a seal coat application. Strip ravelled projects were found to have similar pavement properties in ravel and non-ravel led sections and general to be within desirable limits. Lower strength in resilient modulus tests and physically observed asphalt stripping in the ravelled sections indicate a localized failure of the asphalt aggregate bond. The failure occurrence in narrow longitudinal strips indicates a cause associated with paving operations--possibly differential compaction or hydrocarbon contamination. Preventive measures should ensure uniform compaction and more thorough checking of stripping tendencies. Corrective measures will require continued patching and possibly removal and replacement of affected pavement.

Authors:
Gietz,R. H.

Keywords:
aggregate, asphalt, asphalt concrete, asphalt pavement, compaction, concrete, condition, construction, construction methods, contamination, design, Distress, investigaton, overlay, pavement, resilient modulus, sampling, season, strength, tests, traffic, winter

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Abstract:
This report presents some data obtained from testing twenty-two different types of overlays on three concentric tracks at the G.A. Riedesel Pavement Testing Facility at Washington State University. Six different passenger winter tires were tested, including unstudded, a garnet dust snow retread, and four different types of studs. The data represents a testing period from November 20, 1972 to February 20, 1973 and a total 300,000 revolutions, that is 900,000 wheel applications on the inside track and 300,000 wheel applications on the outside track.The results reveal that the different polymer, concretes show the least wear, and that rubber additives improved the performance of some of the asphalt concrete overlays. The type #2 stud continually showed less wear than the other types of studs. Comparisons with the previous ring reveals that the present ring overlays showed less wear, and that stud protrusions are much less. A comparison and discussion of the results from both rings a t this wheel application range is presented. The results from the present data are also discussed. The results are tentative and may change as the present test continues.

Authors:
Krukar,M., Cook,J. C.

Keywords:
applications, asphalt, asphalt concrete, concrete, concrete overlays, data, effects, facilities, Interim, overlay, overlays, pavement, Pavement overlays, performance, Phase II, polymer, rubber, snow, Studded, studded tire, studs, tire, tires, Washington, Washington state, winter

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Abstract:
Four different types of pavement marking materials were tested in Ring #6; three brands of striping paints and one thermoplastic stripping tape. These striping materials were applied on two sections, the ploymer ranked on the basis of appearance, wear, and whiteness.The thermoplastic striping material consistently outperformed the three paints. The materials wore more rapidly on the polymer cement concrete that on the asphalt concrete and the ranking order for the paints was different for the two sections. The Type #3 stud seemed to have worn the paints more rapidly than either #4, #2, GST, US and UST studs and tires in that order respectively. The superiority of the ethermoplastic striping tape was due to its thickness and its construction. Last year Kennametal, Inc. sent the Transportation Systems Section four different types of traffic paint and a thermoplastic striping tape. Time did not permit the testing of these materials in Ring #5, so these materials were tested in Ring # 6.

Authors:
Krukar,M.

Keywords:
asphalt, asphalt concrete, concrete, construction, effects, ITS, materials, pavement, Phase II, polymer, striping, striping paints, stripping, Studded, studded tire, studded tires, studs, System, systems, tire, tires, traffic, transportation

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Abstract:
Three different kinds of base material of varying base thicknesses were tested at the Washington State University Test Track on Ring #3 during the fall of 1967 and the spring of 1968. Twelve 18-foot test sections consisting of 4.5, 7.0, 9.5 and 12 inches of untreated crushed rock surfacing top course base; 3.0, 5.0, and 7.0 and 9.0 inches of emulsion treated crushed surfacing top course base; and 0.0, 2.0, 3.5 and 5.0 inches of special non-fractured screened aggregate asphalt treated base, covered by a uniform 3.0-inch thick Class "B" asphalt concrete wearing course were tested during this period. This pavement structure was built on a clay-silt subgrade soil.Instrumentation consisted of moisture tensiometers, strain gages, pressure cells, LVDT gages and thermocouples for measuring moisture, strain, stress, dynamic deflections and temperatures. Benkleman beam readings were taken.The testing period revealed that the fall failure modes were different from the spring failures. The fall failure patter started from transverse cracks in the thin sections which developed into alligator cracking patterns. These cracks appeared after a period of cold weather and heavy rains followed by a warming period. It seems that thermal and mechanical loads were responsible for the fall failures on the thin sections. The spring failures were very rapid and sudden and were due to environmental factors which led to saturated subgrade, thus resulting in poor bearing capacity. Punching shear was the failure mode. The thickest sections survived without cracks but developed severe rutting. Examination revealed that these ruts extended into the subgrade and that fatigue cracking was developing on the bottom of the bases.Comparison of the results with those obtained from Ring# 2, which was similar in base materials and thickness, show that they were similar in many respects. This indicates that the test track is capable of replicating results and is a reliable research instrument.Equivalencies were developed for the different materials. On this basis the special aggregate asphalt treated base was superior to the emulsion treated and untreated crushed rock bases in that order. These results were comparable to those obtained from test Ring #2.Maximum values for static and dynamic deflections, strains and stresses for different times and temperatures were developed. The lateral position of the dual tires with respect to the gage severely affected the strain, stresses and deflection values. Temperature also caused variations in the measurements. Spring instrument readings for static and dynamic deflections, strain and stress show increased values by as much as 2 to 4 times of those obtained in the fall. Spring subgrade conditions probably are responsible for these differences.Ring #3 series operational time was twice that of Ring #2 and sustained four times the wheel load applications. Construction and testing environmental conditions were superior to those for Ring #2 and hence contributed to the longer test period. This points out that environmental factors are very important in pavement life.

Authors:
Krukar,M.

Keywords:
aggregate, Alligator Cracking, applications, asphalt, asphalt concrete, base, base materials, bearing capacity, Benkleman beam, concrete, condition, construction, cracking, dual tires, environmental, experimental, fatigue, fatigue cracking, loads, materials, pavement, pavement life, pressure, pressure cell, rain, research, research at the WSU, strains, stresses, subgrade, temperature, test track, tire, tires, volume, Volume No.4, Washington, Washington state, wheel load

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Abstract:
Three different kinds of base material of varying base thicknesses were tested at the Washington State University Test Track on Ring #3 during the fall of 1967 and the spring of 1968. Twelve 18-foot test sections consisting of 4.5, 7.0, 9.5 and 12 inches of untreated crushed rock surfacing top course base; 3.0, 5.0, and 7.0 and 9.0 inches of emulsion treated crushed surfacing top course base; and 0.0, 2.0, 3.5 and 5.0 inches of special non-fractured screened aggregate asphalt treated base, covered by a uniform 3.0-inch thick Class "B" asphalt concrete wearing course were tested during this period. This pavement structure was built on a clay-silt subgrade soil.Instrumentation consisted of moisture tensiometers, strain gages, pressure cells, LVDT gages and thermocouples for measuring moisture, strain, stress, dynamic deflections and temperatures. Benkleman beam readings were taken.The testing period revealed that the fall failure modes were different from the spring failures. The fall failure patter started from transverse cracks in the thin sections which developed into alligator cracking patterns. These cracks appeared after a period of cold weather and heavy rains followed by a warming period. It seems that thermal and mechanical loads were responsible for the fall failures on the thin sections. The spring failures were very rapid and sudden and were due to environmental factors which led to saturated subgrade, thus resulting in poor bearing capacity. Punching shear was the failure mode. The thickest sections survived without cracks but developed severe rutting. Examination revealed that these ruts extended into the subgrade and that fatigue cracking was developing on the bottom of the bases.Comparison of the results with those obtained from Ring# 2, which was similar in base materials and thickness, show that they were similar in many respects. This indicates that the test track is capable of replicating results and is a reliable research instrument.Equivalencies were developed for the different materials. On this basis the special aggregate asphalt treated base was superior to the emulsion treated and untreated crushed rock bases in that order. These results were comparable to those obtained from test Ring #2.Maximum values for static and dynamic deflections, strains and stresses for different times and temperatures were developed. The lateral position of the dual tires with respect to the gage severely affected the strain, stresses and deflection values. Temperature also caused variations in the measurements. Spring instrument readings for static and dynamic deflections, strain and stress show increased values by as much as 2 to 4 times of those obtained in the fall. Spring subgrade conditions probably are responsible for these differences.Ring #3 series operational time was twice that of Ring #2 and sustained four times the wheel load applications. Construction and testing environmental conditions were superior to those for Ring #2 and hence contributed to the longer test period. This points out that environmental factors are very important in pavement life.

Authors:
Krukar,M., Cook,J. C.

Keywords:
aggregate, Alligator Cracking, applications, asphalt, asphalt concrete, base, base materials, bearing capacity, Benkleman beam, concrete, condition, construction, cracking, dual tires, environmental, equivalencies, experimental, fatigue, fatigue cracking, loads, materials, pavement, pavement life, pressure, pressure cell, rain, research, research at the WSU, soil, strains, stresses, subgrade, temperature, test track, tire, tires, volume, Washington, Washington state, wheel load

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