Robert C. Deen

Road base construction utilizing coal waste materials

The paper describes the development and implementation of a no cement concrete mixture containing pulverized fuel ash (pva) and atmospheric fluidized bed combustion (afbc) byproducts as the cementitious components for combination with conventional limestone aggregates used as bulk filler. The paper presents a summary of laboratory evaluations and the application of those results to the design of a base for roadway construction. The paper also describes the construction, evaluation, and performance of a pilot application of this material used as a base for a thin bituminous pavement (a).

BREAKING AND SEATING OF RIGID PAVEMENTS

Breaking and seating have been used extensively in Kentucky to rehabilitate portland cement concrete pavements. Experience over 3 or 4 years with this type of design and construction is summarized and reported. Breaking to a range of nominal fragments is evaluated, and a report on the evaluation of two roller weights for seating is given. Also described is the use of dynamic deflections to gauge the effectiveness of the breaking and seating process and to measure the appropriateness of the asphaltic concrete overlay.

EVALUATION OF ASPHALTIC PAVEMENTS FOR OVERLAY DESIGN

To evaluate projects involving approximately 200-route-mile of interstate and primary pavements in Kentucky and Tennessee in relatively short time frames, it was decided to test, analyze, and design overlays using test equipment (road rater) and procedures developed by the University of Kentucky transportation research program. This paper presents the analysis methodology and the evaluation and overlay designs for selected projects, including the before and after analysis of milling on one project. The road rater applies a dynamic sinusoidal loading of known force and frequency. The velocity of the vibration waves are measured by sensors and integrated electronically to obtain surface deflections. An analysis of the shape and magnitude of the deflection bowl permits an assessment of whether the structure is performing as anticipated or whether some component is significantly weaker than designed. Analyses permit the determination of the behavioural or effective thickness of the asphaltic concrete layers and the in-place subgrade moduli. Strip charts of effective thickness and subgrade strength (or alternatively, overlay thicknesses) along the length of a project permit delineation of the project into relatively uniform segments. The arithmetic mean and standard error are determined for each segment to estimate design parameters. The required overlay thickness is the difference between the total thickness required for new construction to carry the anticipated traffic and the behavioural thickness of the existing pavement. For the covering abstract of the symposium see IRRD 286635. (Author/TRRL)

Modifications to chevron n-layer computer program

This report documents changes made to the chevron n-layer computer program to: 1) include superposition principles. 2) calculate strain energy density (or work) at specified locations within the pavement structure. 3) Analyze pavement response at specified radii from one circularly loaded area to permit comparison of analyses by the program as originally written with results incorporating superposition principles. 4) Evaluate pavement response to any combination of loads on circular areas defined by xy coordinates on the surface. Loads and contact pressures are permitted to be different from one loaded area to another, but must be constant for any one loaded area. 5) Simulate dynamic loads as the difference between the root mean squares of the maximum and minimum dynamic loads. This analysis is appropriate for constant vibratory testers such as road raters and dynaflects. Moduli of asphaltic concrete must be adjusted for frequency effects (a).

Reliability assessment of high risk steel bridges by nondestructive test methods

Fatigue-crack related failures of high-risk (fracture-critical) steel bridges may be prevented through application of nondestructive tests (NDT). Economical reliability assessment of those structures requires 1) application of a suitable NDT method, 2) testing of fatigue-susceptible members, and 3) periodic retests of those members to preclude problems with growing or previously undetected flaws. Six conventional NDT techniques were tested in the laboratory using butt-weld configured specimens having intentionally embedded cracks. Those NDT methods were 1) visual inspection, 2) magnetic-particle testing, 3) dye-penetrant testing, 4) fluorescent-enhanced surface testing, 5) eddy-current testing, and 6) ultrasonic testing. The other NDT methods provided better crack-detection capabilities than visual inspection. Visual inspections by different personnel produced low detection rates. Tests using the fluorescent magnetic-particle method missed several indications because of marginal test conditions. The other NDT methods detected all cracks. A stand-alone, microcomputer-based data acquisition and data processing system was designed and assembled to assist highway personnel in planning and prioritizing bridge inspections. The system has been tested and is capable of providing crack-initiation data useful for scheduling or prioritizing nondestructive inspections of bridges. Histogram stress data derived from the programs may be used with commercially available fracture-mechanics software to predict growth rates of fatigue cracks and critical crack sizes for failure. That information may be used to select the appropriate NDT method and periodic reinspection interval for fatigue-prone bridge details.

AUTOMATED DATA ACQUISITION FOR LOW-VOLUME ROAD INVENTORY AND MANAGEMENT

Local governments need suitable inventories and condition surveys to accurately determine and rank their road funding needs. The data can be collected and processed by a central inventory management group. The inventory should include pavement characteristics, roadway geometrics, and roadside features. A concept is presented for a second-generation vehicle-mounted photologging system that can, in a single pass, photolog the roadway and automatically record measurements necessary to inventory and rate roadways. The major functions of a central inventory management group are also described. Second-generation photologging systems use either camera or video systems to record visual data. Particulars of those methods are presented and compared. Sensors for additional data measurement, including grade, superelevation, and road roughness, are described. Data recording methods are discussed with emphasis on data storage technological improvements. The function of the inventory management group is to obtain data and convert it to a usable form. This consists of five basic activities: operations management, data acquisition, data reduction, data interpretaion, and inventory preparation. Data reduction includes sorting and editing visual records (film or videotape) and digitizing analog recordings. Several methods for addressing those records and cross-correlating visual and sensor data are discussed. They range from manual sorting techniques to computerized, laser-disc data-processing systems. Data interpretation requires a review of acquired data in its formatted, addressable form. Analyses can include a combination of visual and sensor analyses for pavement condition and roadway geometrics. Other geometric-related analyses can be based almost entirely on visual recordings of roadside features. In some instances, such as unpaved roads, in which few accepted standards exist, new standards or criteria should be used. The road rating process and methods employed to rank pavement and traffic safety-related rehabilitations are discussed. The interaction between the central inventory management group and the low-volume road agency in preparing the final compiled inventory is also discussed.

Design and performance of highway shoulders

This report summarizes findings of a long term evaluation of the construction and performance of asphaltic concrete and portland cement concrete shoulders. Performance was used as the basis for the development of empirical criteria that permit the use of existing pavement thickness design procedures for the structural design of shoulders. Minimum thicknesses were determined on the basis of performance and review of literature (A).

Pavement designs based on work

Thickness design curves presented in the report provide a systematic methodology for the selection of equivalent pavement designs for a broad range of layered systems. This is a unified system since the failure criteria are founded on the same concept of work strain and work. The analyses of stress strain fields in the layered systems are based on elastic layered theory. This theory is represented by the Chevron N layered computer program. The report also summarizes the historical development and evolution of pavement design in Kentucky (A).

Implementation of a Pavement Management Program in Lexington-Fayette County, Kentucky

Le xington, in central Kentucky, is the second largest city in the state. Local government is by a mayor and council of elected representatives from twelve districts and three at-large representatives. The Department of Public Works headed by a Commissioner, who reports to the mayor and city-county council, administers the streets and roads system. The street and road network in Lexington consists of approximately 720 centerline miles. Approximately 100 miles are rural in nature and 620 miles are urban. Approximately 95 percent are bituminous surfaced roads; a majority of the remainder is constructed of portland cement concrete. Increasing costs for constructing and maintaining the street and road network was a stimulus to implement a systematic pavement and road surface management system. Available alternatives were reviewed, and it was decided to maximize in-house resources of the Lexington-Fayette Urban County Government. Meetings with public works officials were used to establish criteria for implementation of a management program: (a) program for visual condition survey of pavements, (b) procedure(s) to determine structural deficiencies for critical pavements identified in the visual condition survey, and (c) utilization of the above information to estimate rehabilitation strategies and their associated costs. The paper describes and documents three phases of implementation of a pavement and road surface management system. Phase I included development of a systemxad wide inventory of pavements and a pavement condition rating system for both flexible and rigid pavements. Phase II dealt with the modifications to a microcomputer program to process pavement condition ratings for ranking pavements on the basis of need and also to estimate pavement maintenance and rehabilitation costs. Phase III included administrative and training activities necessary for implementation of the pavement management program. Training generally addressed three areas: (1) collection of pavement condition and distress information, (2) operation of the microcomputer program for data processing and analyses, and (3) interpretation and utilization of results of the analyses, Finally, the paper describes current research and development relating to refinements and modifications for the Lexington situation.

Allocation of Resurfacing Monies to Highway Districts in Kentucky

Allocation of resurfacing and rehabilitation monies began in 1967 with the separate funding of a resurfacing program. Pavement projects for resurfacing and rehabilitation were selected more often than not on the basis of politics and arbitrary (i. e. , without the benefit of analysis of good inventory and condition data) judgments of decision makers. With the gradual introduction of more adequate roadway inventory and annual condition data, the formula for the allocation of funds has been gradually revised, updated, and improved so there is now a more logical and equitable distribution of funds. With the formation of a pavement management staff in 1981, the quality of inventory and pavement distress data was greatly improved. Creation of the staff also introduced an organizational means whereby pavement condition information could be routinely used as one of the inputs upon which to base decisions regarding allocation of funds to resurfacing and rehabilitation projects. The formula currently used to allocate funds is based upon the lane miles of highways in each district, the unit cost of asphaltic concrete in each of the districts, and the average pavement condition in each district. A modifying factor may be applied each year to assign greater weights to the conditions of the pavements in the various districts and to base allocations of funds more or less upon those conditions, depending upon objectives in any given year. The pavement management staff of the Transportation Cabinet visits the districts each year to share results of pavement condition evaluations, to discuss resurfacing needs in the district compared to other districts, to discuss various pavement management matters, to explain the allocation formula, and to indicate what monies may be provided for the next year. These reviews with district personnel have been effective in convincing them of the appropriateness of the formula and the fairness in the allocations. The intent is to bring about a more uniform condition of pavements throughout the Commonwealth of Kentucky as well as to improve the overall statewide condition of pavements. The allocation formula is seen as a means of distributing funds in such a way as to eventually meet these goals.