Preliminary Engineering, Monitoring of Construction, and Initial Performance Evaluation: Use of Ponded Fly Ash in Highway Road Base

This report summarizes findings of laboratory and field trial evaluations of ponded fly ash used as a component In a stabilized aggregate base course. Ponded fly ash is the fine portion of pond ash which is a by-product of a coal burning process and Is disposed by sluicing to a disposal pond. Three stabilized aggregate base mixtures containing various proportions of dense graded aggregate, ponded fly ash, and hydrated lime were evaluated In the laboratory relative to maximum dry density, optimum moisture content, and unconfined compressive strength. The mixture that was selected for field trial evaluation had the highest unconfined compressive strength and consisted of 85% dense graded aggregate, 11% ponded fly ash, and 5% hydrated lime. A 750-foot section of a 22-fool wide roadway was constructed in May 1988. Approximately 80 tons of ponded fly ash were utilized in constructing the experimental base. Prior to construction, in-place California Bearing Ratio tests, moisture content determinations and Road Rater deflection tests were performed on the prepared subgrade. The stabilized aggregate base was placed in one 8-inch lift During construction, relative compaction and moisture content of the base material were monitored by nuclear devices. Post construction evaluations included Road Rater deflections tests and coring to obtain samples for laboratory evaluation. To dale, the section containing the stabilized aggregate base Is performing very well in comparison to the conventionally paved section

Experimental Road Base Construction Utilizing Atmospheric Fluidized Bed Combustion Residue

This report summarizes findings of laboratory and field trial evaluations of two experimental test sections constructed adjacent to one another. One experimental section contained a mixture of pulverized fuel ash, residue from an atmospheric fluidized bed combustion process, and limestone aggregate. The second section contained a similar mixture but included a small amount of Type Ill cement. Both experimental sections were constructed to a total nominal thickness of nine inches. The typical design section included six inches of the experimental mixtures, used as base materials, beneath three inches asphaltic concrete. A previous report documented construction of the test sections and preliminary performance evaluations or the experimental base mixtures (UKTRP 87·15). Analyses of additional periodic deflection testing are detailed within this report. The experimental sections were monitored over a three year period. It was concluded, based upon performance observations and evaluation activities, that both experimental mixtures are suitable for use as a road base material. Both test sections performed well with no cracking, rutting or unexpected deterioration observed. Results of the deflection testing activities indicated that the pavement structure containing cement had somewhat higher stiffness values and generally maintained those values over time

Performance Evaluations of Crushed Sandstone Aggregates in Bituminous Bases

The principal objective of the research effort was to develop historical performance data for bituminous sandstone pavements and bituminous limestone pavements relative to visual distress, pavement rutting characteristics, and structural condition using deflection measurements. Data relative to Road Rater deflections, pavement rutting, condition ratings based on subjective visual surveys and objective data such as skid resistance and rideability, were collected and analyzed during the course of the study and reported herein for the routes investigated. It was concluded, based upon information gained during the evaluation period and presented in this report, that pavements constructed with bituminous sandstone bases do not develop excessive rut depths, are more resistant to shoving and pushing, but appear to exhibit cracking at an earlier age than pavements constructed with bituminous limestone bases. The use of bituminous sandstone mixtures addresses problems such as haul costs, rutting, skid resistance, etc. Field engineers indicated that although bituminous sandstone surface mixtures have a slight tendency to ravel, they are very resistant to rutting and applications of bituminous sandstone base and surface mixtures have been very successful in their estimation

Construction of Highway Base and Subbase Layers Containing Residue from an Atmospheric Fluidized Bed Combustion Process

This report summarizes findings of laboratory and construction evaluations of using residue from an atmospheric fluidized bed combustion (AFBC) process as a component in an experimental road base and subbase application. The base mixture contains pulverized fuel ash, AFBC residue, and limestone aggregates used as bulk filler. The subbase mixture contains AFBC residue and pond ash (ponded fly ash and bottom ash). Mixtures containing various proportions of each component were evaluated in the laboratory relative to maximum dry density, optimum moisture content, and compressive strength development. Two 750-foot test sections of a 22-foot wide roadway, containing the experimental mixtures, were constructed in May and June 1988. Prior to construction, in-place California Bearing Ratio tests, moisture content determinations and Road Rater deflection tests were performed on the prepared subgrade. During construction of the experimental base and subbase layers, relative compaction and moisture contents of the materials were monitored by nuclear devices. Specimens were compacted for subsequent evaluations. Initial post-construction evaluations included compressive strength development, elastic modulus, Road Rater deflection analyses, and monitoring expansion of the experimental mixtures both in the field and in the laboratory

Performance Evaluations of Crushed Sandstone Aggregates in Bituminous Bases (Data Appendix to Report KTC-90-26)

The principal objective of the research effort was to develop historical performance data for bituminous sandstone pavements and bituminous limestone pavements relative to visual distress, pavement rutting characteristics, and structural condition using deflection measurements. Data relative to Road Rater deflections, pavement rutting, condition ratings based on subjective visual surveys and objective data such as skid resistance and rideability, were collected and analyzed during the course of the study and reported herein for the routes investigated. It was concluded, based upon information gained during the evaluation period and presented in this report, that pavements constructed with bituminous sandstone bases do not develop excessive rut depths, are more resistant to shoving and pushing, but appear to exhibit cracking at an earlier age than pavements constructed with bituminous limestone bases. The use of bituminous sandstone mixtures addresses problems such as haul costs, rutting, skid resistance, etc. Field engineers indicated that although bituminous sandstone surface mixtures have a slight tendency to ravel, they are very resistant to rutting and applications of bituminous sandstone base and surface mixtures have been very successful in their estimation

Performance of Experimental Highway Base and Subbase Layers Containing Coal-Fired Power Plant By-Product Materials: KY Route 3074, Bleich Road

Three 750-foot test sections of a 22-foot wide roadway were constructed on newly constructed subgrade in May and June, 1988. The three experimental sections contained experimental base and subbase layers comprised of mixtures utilizing by-product materials from a coal-fired power plant One test section included a base layer containing residue from an atmospheric fluidized bed combustion (AFBC) process, size No. 57 aggregate, and Class F fly ash. The second test section included a base layer constructed ponded fly ash, hydrated lime, and dense-graded aggregate. The third test section included a subbase layer constructed of pond ash stabilized with AFBC residue. A control section was included in the study for comparison purposes. Previous reports have documented preliminary engineering, construction details, and initial performance evaluations of the three experimental sections constructed on State Route 3074 in McCracken County, Kentucky. This report summarizes performance information derived from the field trials. Performance measurements included distress surveys, Road Rater deflections, pavement rutting measurements, and field cores of the experimental base and subbase layers were obtained for laboratory evaluations. The two test sections containing residue from the AFBC process were regarded as failures due to the excessive expansion of the materials, although efforts were made to eliminate, or minimize, the inherent expansive properties of the residue by prehydrating the AFBC residue prior to its use in the mixtures. The two layers were eventually removed and replaced with conventional materials. The remaining experimental section has given good performance and service. No significant distresses have been noted. Rutting measurements indicated less rutting occurring in the ponded fly ash-hydrated lime-dense grade aggregate section than in the control section. Analyses of deflection data indicate superior structural characteristics compared to the control section. Unconfined compression tests indicate excellent strengths of the experimental mixture. The accomplishment of this application confirms that waste fly ash may be used successfully in stabilized road base construction

In-Place Recycling and Reclamation of Asphaltic Concrete Pavements in Kentucky

Full-depth reclamation has been defined by the Asphalt Recycling and Reclaiming Association as a “rehabilitation technique in which the full thickness of the asphalt pavement and a predetermined portion of the underlying material (base, subbase, and/or subgrade) is uniformly pulverized, blended and compacted to provide an upgraded, homogeneous material resulting in a stabilized base course.” The Kentucky Transportation Cabinet has utilized the full-depth reclamation (FDR) process as a method to address asphalt pavements exhibiting widespread base failures. The FDR process transforms the existing hot mix asphalt (HMA) pavement and underlying granular materials into a stabilized base layer. The stabilized layer is then overlaid with a new HMA surface layer. However, the process of when and how to use the FDR process has not been well defined in Kentucky. The Cabinet commonly uses its Special Note for Cement Stabilized Roadbed as guidance for a stabilized subgrade and is dependent upon the road contractor for a suitable mixture design. The research reported herein presents suggested guidelines to the Kentucky Transportation Cabinet for the design and construction for FDR pavements. Special Notes for Full-Depth Reclamation of Hot Mix Asphalt pavements using cement and asphalt emulsions as stabilizers are presented for consideration. This report, along with the Special Notes, includes a process to identify potential projects for the FDR process, criteria for selecting the stabilizer best suited to the conditions, the optimum thickness of material to be recycled, and the amount of stabilizer to be added

Space Weather Effects on Mid-Latitude HF Propagation Paths: Observations and a Data-Driven D-Region Model

A two-pronged study is under way to improve understanding of the D region response to space weather and its effects on HF propagation. One part, the HF Investigation of D region Ionospheric Variation Experiment (HIDIVE), is designed to obtain simultaneous, quantitative propagation and absorption data from an HF signal monitoring network along with solar X-ray flux from the NOAA GOES satellites. Observations have been made continuously since late December 2002 and include the severe disturbances of October–November 2003. GOES satellite X-ray observations and geophysical indices are assimilated into the Data-Driven D Region (DDDR) electron density model developed as the second part of this project. ACE satellite proton observations, the HIDIVE HF observations, and possibly other real-time space weather data will be assimilated into DDDR in the future. Together with the Ionospheric Forecast Model developed by the Space Environment Corporation, DDDR will provide improved specification of HF propagation and absorption characteristics when supplemented by near-real-time propagation observations from HIDIVE

Construction and Performance of Highway Soil Subgrades Modified with Atmospheric Fluidized Bed Combustion Residue and Multicone Kiln Dust

In an effort to increase the utilization of by-product materials in highway construction projects, the Kentucky Transportation Cabinet authorized the experimental use of reside from an atmospheric fluidized bed combustion (AFBC) process and multicone kiln dust (MKD), a by-product resulting from the production of lime, as subgrade soil modifiers. This report presents information relative to preconstruction and post-construction laboratory evaluations, construction procedures, construction monitoring activities, and performance evaluations of a highway subgrade solid modified using AFBC spent lime, MKD, Type IP cement, and hydrated lime. An untreated section served as a control section for the project located on Kentucky Route 11 in Lee and Wolfe Counties. The laboratory testing program consisted of determining select engineering properties of the solid in a natural state and in a state altered by the chemical admixtures. Index tests were performed, moisture density relationships were determined, and bearing ratio and swell tests were performed. Based on the laboratory unconfined compression tests and bearing capacity tests, the two waste by-products significantly improved the shear strength and bearing strength of the subgrade soil. Field monitoring activities were comprised of both construction monitoring and post-construction monitoring. Construction procedures were essentially the same for all admixture types and no significant problems were encountered. Satisfactory moisture and density were achieved. Construction activities were documented through moisture content and density compliance tests. In-place bearing capacity tests and Road Rater deflection tests were performed on the untreated subgrade and again after modification. The analyses indicated significant improvement in subgrade strength after admixture modification. Post-construction monitoring included determining in-site bearing capacities, assessing moisture conditions and determining soil classifications of the treated and untreated subgrade layers. Road Rater deflection tests were conducted to assess the structural condition of the pavement structure. Results of the field monitoring program confirmed that each chemically modified subgrade continued to exhibit greater strengths than the untreated subgrade section. However, because of non-uniform mixing, the soil-AFBC subgrade sections exhibited severe differential swelling shortly after construction. The bituminous pavement required milling the eliminate humps on the pavement surface. The pavement was overlaid and apparently the subgrade swelling has ceased. However, due to the expansive nature of the AFBC spent lime, future use as a soil modifier could not be recommended. Results of field monitoring activities indicated that MKD was a suitable solid modifier and future use was recommended