Fly Ash Stabilized Bases in Kentucky

With the escalating costs of materials and construction for highways and streets, many agencies charged with the responsibility of designing and constructing highways are utilizing byproduct stabilized (pozzolanic) materials. Low-strength (pozzolanic) materials have been used fairly extensively in some areas of the United States as well as abroad. In general, pozzolanic materials have been used to stabilize an aggregate base or subbase by addition of fly ash and a source of lime to develop a cementitious reaction. Additionally, portland cement or cement kiln dust have been used to stabilize aggregate subbase and (or) base materials. Until recently, the use of stabilized materials in highway and street construction in Kentucky was not often economically competitive with abundant supplies of high-quality aggregates. However, as costs of production and processing aggregate materials have increased, so has the feasibility of stabilized bases, and particularly pozzolanic base materials. Mixtures that have been considered recently and evaluated to some degree include the following: Lime kiln dust, fly ash, and dense-graded aggregate; Byproduct lime and dense-graded aggregate; Lime kiln dust, fly ash, dense-graded aggregate, and sand; Lime kiln dust, fly ash, and limestone mine screenings (waste material from limestone quarrying operations); and Scrubber sludge, quicklime, and dense-graded aggregate or pond ash. Pozzolanic base or subbase materials have been utilized on an experimental basis for a number of Lexington, Kentucky, street projects. Two projects for the Kentucky Transportation Cabinet also are being evaluated. Thus, performance experience currently is limited, but at the same time evolutionary

Demonstration Project No. 59: The Use of Fly Ash in Highway Construction, Fayette County, Kentucky

This report summarizes preliminary site investigations, design criteria and procedures, construction criteria and procedures, and results of initial and final evaluations of an experimental road base utilizing lime kiln dust, fly ash and aggregate. Observed performance has been satisfactory. Compressive strength evaluations indicate exceptional early strength and continued strength gain of the pozzolanic base. Back calculation of specific elastic layer moduli indicate that the moduli of the pozzolanic base material is most likely within a range of 500,000 to 1,000,000 psi. Based upon observations to date, treated bases enhance overall pavement performance and their use should be continued. It is quite probable that pavement life may be extended at reduced costs

Road Rater and Benkelman Beam Pavement Deflections

The Benkelman beam has been one of the most commonly used methods of measuring surface deflections of a highway pavement. A Benkelman beam is based on a simple lever-arm principle and uses dial guages to measure surface deflection under an applied load. In 1971, the Commonwealth of Kentucky purchased a Road Rater for use by the Department of Transportation, Division of Research. The Road Rater applies a sinusoidal force to the pavement at a fixed frequency; surface wave velocities are measured and electronically integrated to obtain surface deflections, Since 1971, work has progressed toward the development of a pavement evaluation methodology using Road Rater deflections. Analyses presented in this report will illustrate some relationships between the Benkelman beam and Road Rater deflections. Theoretical and field measured deflections are considered

Manual on Bridge/Culvert Maintenance

The basic objective of this course is to provide background (introductory) technical information that will aid the manager of bridge/culvert installations. In most instances, information presented may not be sufficiently complete for the student to perform the required work. However, the intent is more to familiarize than to instruct In many instances, professional engineering and experienced labor are necessary to ensure successful completion of tasks. Once the local official responsible for bridges and culverts has completed this workshop, he should have a basic understanding of the most common bridges/culverts encountered in counties and municipalities, the major components of common bridge/culvert types and their functions, common bridge/culvert materials, material deterioration in bridge/culvert service, various bridge/culvert maintenance requirements, specific bridge/culvert rehabilitation techniques, and decision-making procedures for bridge/culvert managemen

Unstable Subgrade, I 65, Hardin County (I 65 - 5 (17) 92; FSP 047-0065-091-0396)

During construction of the southbound lanes of I 65, Stations 120+00 to 218+00, in Hardin County, Kentucky, near Elizabethtown, large deformations were observed when dense-graded aggregate (DGA) base courses were loaded with construction traffic. Rutting and cracking of the DGA also was noticeable. A study was performed to determine the causes of the unstable subgrade and base, recommend remedial actions, and evaluate the effectiveness of the remedial measures. The stability, or bearing capacity, of the unstable pavement was determined for different construction stages and combinations of pavement layer thicknesses using a relatively new stability model HOPK-I. The stability of the pavement during early construction stages also was analyzed using Vesic’s bearing capacity equations; results were compared to those obtained from the ROPK-I stability model. Initially, a geotextile fabric had been placed on the clay subgrade in an attempt to stabilize the subgrade. Remedial action consisted of mixing the top 6 to 9 inches of DGA with 7 to 10 percent of portland cement. A 3-inch layer of DGA was placed between the cement-DGA mixture and asphaltic concrete to minimize reflective cracking. Remedial actions were analyzed using the HOPK-1 model and evaluated using the Road Rater. Based on stability analyses, the failure of the granular base was a result of a bearing capacity failure in the clay subgrade; the original design vas inadequate. Stability analyses and Road Rater results showed that the remedial action vastly improved the structural behavior of the pavement. Results indicate that the HOPK-I model may be a good analysis tool. The study also emphasizes the need to determine and analyze the constructability of pavement designs

Crushed Rock Bases

Prepared in cooperation with the US Department of Transportation, Federal Highway Administration. Gradations containing high, medium, and low percentages of fines were evaluated by laboratory tests and by behavioral responses in situ. Significant differences in strength parameters were not found. Differences in densities were not significant

Water Under Pavements

This report summarizes the construction and performance of a Cedergren-type underdrain system. Other installations of edge drains are reported for record. Outflows have been sufficient to cause minor erosion of fill slopes. Road Rater tests disclosed no weaknesses. Remaining life was estimated

Overlay Recommendations for I 64: Rowan, Carter, and Boyd Counties

A method was developed in 1978 for designing asphaltic concrete overlays for flexible pavements. This procedure utilizes Kentucky\u27s theoretical flexible pavement design curves, estimates of pavement fatigue from traffic data, estimates of subgrade strengths, and estimates of the structural capacity of the existing pavement. Overlay designs were recommended for the asphaltic concrete pavement sections of I 64 in Rowan, Carter, and Boyd Counties. Road Rater deflection data were used to estimate the subgrade strength and the effective worth of the pavement structures. Pavement rutting and roughness were also considered in determining the final overlay thicknesses

Breaking and Seating of Rigid Pavements

Breaking and seating has been utilized extensively in Kentucky to rehabilitate portland cement concrete pavements. Experience over three or four years with this type of design and construction are summarized and reported. Breaking to a range of nominal fragments is evaluated. Evaluation of two roller weights for seating is reported. The use of dynamic deflections to evaluate the effectiveness of the breaking and seating process and to measure the appropriateness of the asphaltic concrete overlay

Evaluation of a Full-Depth Asphaltic Concrete Pavement

This study was initiated to verify a newly-developed set of design curves for full-depth asphaltic concrete pavements. Quality control during construction was checked using nuclear density testers, Benkelman beams, and a Road Rater. During the course of this study, an analysis system (predicated upon the elastic theory model) was developed to interpret the dynamic deflections as measured by the Road Rater. The thickness design curves were verified by elastic theory and deflection testing within the accuracy of construction variations. Measured rut depths were analyzed in terms of potential rut depth resulting from consolidation under traffic due to lack of obtaining 100-percent of Marshall density during compaction. Traffic was monitored using automatic traffic counters, manual classification/volume counts, and weigh-in-motion scales installed in the pavement