Effect of Lime on Ignition Furnace Calibration

2000 ◽  
Vol 1712 (1) ◽  
pp. 74-78 ◽  
Author(s):  
Brian D. Prowell ◽  
Jack Youtcheff
Keyword(s):  
Correction Factor ◽  
Hydrated Lime ◽  
Asphalt Binders ◽  
Department Of Transportation ◽  
Combustion Gases ◽  
Ignition Furnace ◽  
Additional Testing ◽  
High Concentrations ◽  
Virginia Department ◽  
Low Sulfur

This study investigated mix components, other than aggregate source, that were perceived to affect the ignition furnace mixture calibration. Four sets of experiments with one aggregate were designed and run to evaluate the effects of the amounts of lime, sulfur, calcium carboxylates, and fines. Five asphalt binders with different chemistries were evaluated. Two binders had high and low sulfur contents, respectively; two other binders contained relatively high concentrations of carboxylates. Various concentrations of hydrated lime (0 to 3 percent by weight) were added to mixtures and were found to have a significant effect on the ignition furnace correction factor for all five binders. The magnitude of the effect was large enough to cause the quality control tests to fail the tolerances established by the Virginia Department of Transportation. The lime appears to react with the sulfur dioxide (SO2) formed from the combustion of organic sulfur to generate calcium sulfate. The amount of sulfur present in the asphalt can significantly affect the ignition furnace correction factor. Initial thoughts that calcium carboxylates are reacting with carbon dioxide (CO2) to produce some form of calcium carbonate were not substantiated. The influence of carboxylic acid groups, however, does come into effect in the presence of lime. This suggests that lime reacts with the combustion gases to produce some form of carbonate. Basalt fines and portland cement did not have a significant effect on the ignition furnace correction factor. Additional testing should be conducted to assess the effects of fines representing other aggregates, particularly carbonates.

Bridge Substructure Repairs with Self-Consolidating Concrete and Galvanic Anodes

2018 ◽  
Vol 2672 (27) ◽  
pp. 56-64
Author(s):  
H. Celik Ozyildirim ◽  
Stephen R. Sharp
Keyword(s):  
Chloride Content ◽  
Visual Observation ◽  
Department Of Transportation ◽  
Corrosion Activity ◽  
Self Consolidating Concrete ◽  
Reinforced Concrete Bridge ◽  
Form Pressure ◽  
Virginia Department ◽  
Narrow Area ◽  
Chloride Contaminated

Historically, the Virginia Department of Transportation (VDOT) has repaired chloride-contaminated reinforced concrete bridge substructure elements that contain vertical and overhead sections with either shotcrete or a conventional A3 (3,000 psi) or A4 (4,000 psi) concrete. This study investigated using self-consolidating concrete (SCC), which has a high flow rate, bonds well, has low permeability, and provides smooth surfaces, as another option. The study also explored the use of galvanic anodes to control corrosion activity in SCC repairs. In VDOT’s Lynchburg and Staunton Districts, SCC repairs were made with and without the use of galvanic anodes. This provided a means for determining the benefit of using the anodes. The needed repair areas were determined by visual observation and sounding. After 7 years of service, SCC repair areas with and without anodes did not exhibit corrosion activity; small vertical cracks were evident in the SCC but did not affect performance. The anodes can provide protection to the steel immediately adjacent to the repair areas. However, unrepaired concrete areas away from the patched area with anodes now require additional repairs. SCC can be successfully placed; however, attention should be paid to form pressure and slump loss. Selection of repair areas should be based on corrosion-related measurements such as half-cell or chloride content, rather than sounding. Progression of corrosion demonstrates the necessity of removing all chloride-contaminated concrete not just adjacent to, but also away from the reinforcement, as anodes in the repair area will provide protection only in a narrow area around the patch.

Performance of Virginia’s Early Foamed Warm Mix Asphalt Mixtures

2018 ◽  
Vol 2672 (28) ◽  
pp. 178-189 ◽  
Author(s):  
Stacey D. Diefenderfer
Keyword(s):  
Dynamic Modulus ◽  
Permanent Deformation ◽  
Warm Mix Asphalt ◽  
Department Of Transportation ◽  
High Dynamic ◽  
Repeated Load ◽  
And Performance ◽  
Virginia Department ◽  
Performance Grading ◽  
Air Void

The Virginia Department of Transportation began allowing the use of warm mix asphalt (WMA) in 2008. Although several WMA technologies were investigated prior to implementation, foamed WMA was not. This study evaluated the properties and performance of foamed WMA placed during the initial implementation of the technology to determine whether the technology had performed as expected. Six mixtures produced using plant foaming technologies and placed between 2008 and 2010 were identified and subjected to field coring and laboratory testing. Coring was performed in 2014, resulting in pavement ages from 4 to 6 years. Three comparable hot mix asphalt (HMA) mixtures were cored at 5 years for comparison. Cores were evaluated for air-void contents and permeability and were subjected to dynamic modulus, repeated load permanent deformation, and overlay testing. In addition, binder was extracted and recovered for performance grading. Similar properties were found for the WMA and HMA mixtures. One WMA mixture had high dynamic modulus and binder stiffness, but overlay testing did not indicate any tendency for premature cracking. All binders had aged between two and three performance grades above that specified at construction. WMA binders and one HMA binder aged two grades higher, and the remaining two HMA binders aged three grades higher, indicating a likely influence on aging of the reduced temperatures at which the early foamed mixtures were typically produced. Overall results indicated that foamed WMA and HMA mixtures should be expected to perform similarly.

Natural Bridge, Virginia: Complementary Geotechnical Investigation and Analysis Methods for Mobility Planning

2020 ◽  
Vol 26 (2) ◽  
pp. 141-148
Author(s):  
Brian S. Bruckno ◽  
Chester F. Watts ◽  
George Stephenson ◽  
Christopher Mau
Keyword(s):  
Cultural Resources ◽  
Department Of Transportation ◽  
Geotechnical Investigation ◽  
Non Invasive ◽  
Transportation Corridor ◽  
Historic Landmark ◽  
Potential Risks ◽  
Potential Damage ◽  
Virginia Department ◽  
Privately Owned

ABSTRACT Natural Bridge, in Rockbridge County, Virginia, is a geological arch carrying U.S. Route 11 over Cedar Creek. The area has significant historical and cultural importance; it is listed on the National Register of Historic Places and is a Virginia Historic Landmark. Until 2015, the arch and area below were privately owned and operated, with only the pavement structure of U.S. Route 11 held by the Virginia Department of Transportation. Since then, the arch and area below have been leased to the Virginia Department of Conservation and Recreation, potentially transferring liability to the Commonwealth. As part of the Commonwealth's due diligence and to help ensure that the arch is preserved for future generations, the Department of Transportation, in partnership with Radford University, completed a comprehensive, non-invasive geological and geotechnical investigation in 2017 and 2018. A complementary variety of geophysical, laser, optical, seismic, and traditional geological methods of study were used to allow for integrated data analysis. The investigation revealed potential risks to the integrity of the arch, which may eventually reduce its suitability for use as a transportation corridor. The investigation methodology allowed planning for protection of the environment, cultural resources, and local economies while avoiding any potential damage to the arch. As of the date of this article, plans are under way to relocate U.S. Route 11 onto an alternate alignment entirely, thereby helping to preserve this valuable cultural, historical, and geological asset.

Measuring Smoothness of Virginia’s Asphalt Overlays

2000 ◽  
Vol 1712 (1) ◽  
pp. 86-92
Author(s):  
Kevin K. McGhee
Keyword(s):  
South Dakota ◽  
Asphalt Pavement ◽  
Critical Assessment ◽  
Department Of Transportation ◽  
International Roughness Index ◽  
Roughness Index ◽  
Virginia Department ◽  
Asphalt Overlays ◽  
Special Provision

In the summer of 1996 the Virginia Department of Transportation (VDOT) initiated the pilot of a new special provision regarding the smoothness of asphalt pavement surfaces. This special provision is based on the international roughness index (IRI) and is administered with a laser-equipped South Dakota–style inertial road profiler. A critical assessment of the nontraditional equipment and methods used to administer the special provision is provided. Issues addressed in the critique include provision exemptions, the ability to identify and contend with construction variability, and peculiarities of the equipment that affect the ability of VDOT to administer a modern acceptance provision.

Initial Approach to Performance (Balanced) Mix Design: The Virginia Experience

2019 ◽  
Vol 2673 (2) ◽  
pp. 335-345 ◽  
Author(s):  
Stacey D. Diefenderfer ◽  
Benjamin F. Bowers
Keyword(s):  
Performance Testing ◽  
Performance Criteria ◽  
Mix Design ◽  
Department Of Transportation ◽  
Innovative Methods ◽  
Asphalt Mix ◽  
Performance Additives ◽  
Virginia Department ◽  
Selection Of

Performance mix design (PMD) of asphalt mixtures, often referred to as balanced mix design, is a design methodology that incorporates performance testing into the mix design process. The Virginia Department of Transportation (DOT), like many owner agencies, is interested in ways to specify asphalt mix designs better in an effort to make its roadway network more sustainable, longer lasting, and more economical. By adding performance criteria through a PMD framework, that goal can be achieved. Further, a PMD framework should allow for the development of new, innovative methods to increase pavement recyclability, new performance additives, and other means to enhance pavement performance. This paper provides details and documentation of the approach being taken by the Virginia DOT in their efforts to develop a PMD specification. Aspects of development presented include PMD method options, selection of performance tests, and determination of acceptance criteria. A discussion about validating specifications with in-service performance data and addressing quality control and quality assurance is also provided. Although additional work is needed for full development and implementation, the methodology being applied has been found to provide useful outcomes for the Virginia DOT even in the initial stages of development.

Effect of Speed, Flow, and Geometric Characteristics on Crash Frequency for Two-Lane Highways

2000 ◽  
Vol 1717 (1) ◽  
pp. 76-83 ◽  
Author(s):  
Nicholas J. Garber ◽  
Angela A. Ehrhart
Keyword(s):  
Department Of Transportation ◽  
Deterministic Models ◽  
Crash Frequency ◽  
Crash Rates ◽  
The Past ◽  
Speed Flow ◽  
Lane Width ◽  
The Mean ◽  
Virginia Department ◽  
Made In

Although during the past several years significant progress has been made in improving safety on U.S. highways, the frequency and severity of crashes continue to be of concern. A better understanding of the factors associated with crashes will facilitate the identification of suitable countermeasures that could further reduce the occurrence of crashes. Results are presented from a study that determines how the characteristics of speed, flow, and geometry affect the crash rates for two-lane highways. Deterministic models that relate the crash rate with the mean speed, standard deviation of speed, flow per lane, lane width, and shoulder width are presented. The multivariate ratio of polynomials method was used to develop the models. Research was limited to two-lane roadways in Virginia with speed limits of 89 km/h (55 mph). The data were obtained from speed-monitoring stations established by the Virginia Department of Transportation and from police accident reports from January 1993 to September 1995.

Effect of Hydrated Lime on Long-Term Oxidative Aging Characteristics of Asphalt

2002 ◽  
Vol 1810 (1) ◽  
pp. 17-24 ◽  
Author(s):  
Shin-Che Huang ◽  
J. Claine Petersen ◽  
Raymond Robertson ◽  
Jan F. Branthaver
Keyword(s):  
Phase Angle ◽  
Fatigue Cracking ◽  
Hydrated Lime ◽  
Age Hardening ◽  
Asphalt Binders ◽  
Asphalt Pavements ◽  
Initial Stiffness ◽  
Oxidative Aging ◽  
Useful Lifetime

An experiment involving neat asphalts AAD-1, ABD, and their mixtures with two different grades of hydrated lime was conducted to investigate the effect of lime on the long-term aging characteristics of asphalt binders. Rheological properties of unaged and aged asphalt-lime mixtures were measured with a dynamic shear rheometer at 25°C (77°F) and 60°C (140°F). The addition of hydrated lime to one asphalt (AAD-1) effectively reduced oxidative age hardening. In addition, the phase angle reached the same value as aging time reached after approximately 800 h at 60°C in the pressure-aging vessel for AAD-1 and its mixtures with lime. After 800 h of aging, the phase angle was greater for the limetreated asphalt than for the untreated asphalt, and it continued to decrease at a slower rate. This result indicates that the addition of lime to this asphalt increases the initial stiffness of the binder, but, more importantly, it preserves elasticity during long-term oxidative aging. Thus, for this asphalt, at a level of oxidation typical of pavements, limetreated and untreated asphalts arrived at the same viscosity with time, but the lime-treated asphalt had better viscous flow properties than the untreated asphalt. It could then be predicted that the aged, lime-treated asphalt would be more resistant to fatigue cracking. The other asphalt tested (ABD) did not exhibit substantial effects of lime on the rate of oxidative age hardening. This highly compatible, low-asphaltene asphalt is not typical of most paving asphalts. Because hydrated lime has been shown to reduce oxidative age hardening both in the laboratory and during the first few years in the pavement, adding hydrated lime should extend the useful lifetime of most asphalt pavements.

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