Predictability of physical changes of clay-forming materials in Oklahoma

In cooperation with the Oklahoma Department of Highways and the Federal Highway Administration, Department of Transportation, a research project was undertaken on October 8, 1968 by the Oklahoma University Research Institute, Norman, Oklahoma to study the predictability of physical changes in clay forming materials. These materials include shale, claystones and their derivatives. The main objective of the study was to establish a systematic method of testing and criteria which will permit identification and classification of clay forming materials on the basis of the changes in their properties resulting from engineering processes associated with highway construction and utilization. The period of this study, initially approved, was three years. In March/April 1971, a request was made and approved to extend the period of study by six months. The final date of completion of this study is February 29, 1972. Reports were submitted quarterly indicating the progress of the work. Progress reports of more detailed nature were submitted annually during March/April of each year the study was in progress. In February, 1970, a special report was made on the "Disintegration of Shales Employing Ultrasonics". Much of the information contained herein has already been reported in the reports mentioned above.Final ReportN

Statistical quality control of Portland cement concrete pavements

The scope of this investigation was to study statistically the process of preparing concrete for Portland cement concrete pavements and to compare the data with the specifications in use. It encompassed the measurement of properties of the constituents of concrete, namely, coarse aggregate, fine aggregate, and cement; the determination of the properties of the finished concrete, namely slump, air content, compressive strength, and a mount of cement in the cured concrete; and the measurement of the thickness of the concrete pavement. This investigation was conducted in three phases. The first phase consisted of selecting three different concrete paving projects in Oklahoma which were subjected to a statistically based extensive sampling. The second phase included the laboratory or field testing of the samples collected for the determination of certain physical properties pertinent to concrete characterization. In the third phase, the data obtained from property determinations were statistically analyzed. Also, the mean values (average values) of the properties of concrete and its constituent materials were compared with the job specifications.N

Cyclic Testing of Aggregates for Pavement Design

Two most commonly encountered aggregates that are used as subbases/bases of roadways in Oklahoma were selected and tested under cyclic loading to evaluate their Resilient Modulus (RM). Following the repeated triaxial RM testing, the specimens were subjected to the triaxial compression tests from which the parameters of cohesion (C), and friction angle (Φ) were obtained. A good statistical correlation was established between RM and C and Φ. The repeated triaxial RM testing procedure serves as a “conditioning” prior to the static triaxial compression and it simulates the loads imposed by the moving vehicle. The effects of conditioning on C and Φ were investigated. The strength increase through conditioning was found to vary from 18 to 85 percent, depending confining pressure and aggregate type. Also, it was found that C increases and ø decreased because of conditioning

Strength characteristics of the stabilized boggy shale (79-09-2)

In cooperation with the Oklahoma Department of Transportation and the Federal Highway Administration, U.S. Department of Transportation, a research project entitled "Field Application of the Stabilization of Oklahoma Shales" (ODOT Study 79-09-2, ORA 158-867) was undertaken on June 1, 1979 by the University of Oklahoma. Initially, the Boggy shale in Atoka County was selected to be field stabilized. Later on, however, and because of seasonal limitations imposed on construction this site was abandoned for another site west of Enid. The laboratory work envisioned in Phase I had progressed to the point that it was considered prudent to continue and complete this effort. This Progress Report No. 1 presents the findings of this laboratory work. The stabilizing agents used were 12% portland cement, 5% hydrated lime, and 25% fly ash. The curing conditions were 28 days moist curing at 70 F and 100 F, and two compaction conditions were employed: no delay and 2 hours delay. The effectiveness of stabilization was evaluated in terms of the shear strength parameters of cohesion and internal angle of friction determined through triaxial compressive and direct shear strength tests as well as plasticity. Cement stabilization imparted maximum strength gain into shale with lime and fly ash giving lower but adequate strengths. Higher temperatures, namely 110 F, increased the effectiveness of stabilization but delayed compaction tended to slightly decrease it.Progress Report No. 1N

Determination of asphalt contents in bituminous pavements by neutron scattering

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Maintenance strategies for corroded structural steel

Maintenance strategies for steel highway structures Is an old topic revisited by the Involved agencies due to recent changes and Increasing awareness in the condition of the environment and the regulations relating to it. Considerations for the acountablllty for the hazardous wastes created, become an Important element In the decision making process for the development of malntence strategies. The present Is a state-of-the-art report prepared for the Oklahoma Department of Transportation by the University of Oklahoma (Project 2112. ORA 158-266), and It was developed by assembling Information from numerous sources. After the first screening the Information was analyzed with the point of view of Including all significant knowledge. The report concentrates on painted structural steel, and exclude A588 weathering type steels, bridge decking and concrete reinforcement. The Information gathered was organized and evaluated on the basis of five subtopics which were considered the Influential elements involved In the development of current maintenance strategies. These elements constitute the topics of the first five chapters, namely: 1) Methods of removal of the old paint and rust; 2) Application and performance of coating systems; 3) Types of coating systems; 4) Cost considerations; and 5) Environmental regulations and Impact assessment Chapter 6 reports on the phone Interviews conducted with selected agencies In order to gather Information about any current performance evaluation of new methods and the general experience that these agencies have on the subject matter that has not found its way Into a publication.Feb-91N

Stabilization of Oklahoma shales field implementation phases

The improvement of U.S. 77 north of Ponca City, Oklahoma, into a four-lane divided highway involves the use of expansive clay as a subgrade material. To stabilize it, Portland cement, fly ash, lime and their conjunctive use were deemed necessary. Prior to field implementation, laboratory studies were conducted which showed that stabilization reduced the plasticity index substantially. The general amelioration of the shale subgrade is reflected in strength improvement after wet-dry cycles and the upgrading of the shear strength parameters of cohesion and angle of internal friction. The strength of short beams was correlated to unconfined compressive strength. The employment of the flexural and compressive moduli of elasticity is presented as an example of assessing pavement strength versus stresses induced by traffic. Data from X-ray diffractograms asvertain that the activity of the clay minerals in the raw shale is reduced as new crystals of hydrated and unhydrated calcium alumina and calcium silicates are formed. In addition, SEM observations depict these crystals and show that the void area is reduced thus rendering a more densified fabric.N

Cooling properties of asphalt surfaces (FHWA-OK-94-05) 2112

Cooling properties of hot mix asphalt (HMA) are important to transportation agencies and contractors in a surfacing or resurfacing operation. The cooling rate of an HMA overlay dictates how soon a roadway can be opened to traffic without having any potentially serious consequences on the pavement performance. The ease or difficulty of compacting HMA paving mixt?res by rolling is influenced by the viscosity-temperature characteristics of the asphalt cement and the temperature of the mix during compaction. Thus, knowing the cooling rate of HMA provides the contractor information such as the extent of time within which breakdown rolling must be completed to ensure quality of the pavement and also when a roadway can be opened to traffic following a surfacing/resurfacing job without any detrimental consequences. A telephone interview was conducted with selected DOTs. From the interviews, it became evident that although several DOTs do not specify a certain temperature range, they do suggest, based on their experiences, that it is preferable to open a roadway to traffic when the HMA temperature is below l40"F. This temperature is close to the 150"F reported in the Synthesis of Highway Practice by the National Cooperative Highway Research Program (NCHRP). HMA thickness and wind velocity have been rated by the DOTs as the most significant factors that influence the cooling rate of HMA. A finite difference computer code provided in the reference as well as a general purpose finite element program ABAQUS were used to compute the time needed by a HMA layer to cool to 150"'F. In this work, the time to cool to various given average mat temperatures was computed for various laydown (200-300ÁF) and base temperatures (50-120'F). Some field data was collected from a site on 1~35 near its intersection with State Highway 51. The field data compares favorably with that obtained from the numerical model predictions for similar conditions. Therefore, the results reported here can be used, with proper engineering judgement, to determine the time required to open the road to traffic.N

Assessment of resilient modulus testing methods and their application to design of pavements (FHWA-OK-91-08)

Resilient modulus (RM) is an important property of subgrade soils that accounts for repetitive loads due to vehicular traffic. Since AASHTO recommended its use in pavement design in 1986, various transportation agencies have devised procedures for testing and evaluation Of RM. A comprehensive literature search was conducted in this study with two objectives in mind: (i) to obtain information on current practices pertaining to RM testing of subgrade soils; and (ii) to compile information pertaining to the collective experience of various agencies in correlating RM with other engineering soil properties. Practices adopted by different transportation agencies in testing RM are not identical; some follow AASHTO guidelines, while others differ. The differences are centered around deviator stress, rate of loading, confining stress, moisture-density relationship, specimen preparation and stress sequence. The well known relationship between RM and CBR, proposed by AASHTO, does not correlate well for many soils. Efforts have been made by various researchers to correlate RM with other factors including clay, silt and organic carbon contents, plasticity index, liquid limit, group index, compressive strength, initial elastic modulus and confining pressure. Very limited efforts have been directed toward understanding the RM characteristics of bonded materials and aggregate bases.N