Download or read book Installation of Warm Mix Asphalt Projects in Virginia written by Stacey D. Diefenderfer and published by . This book was released on 2007 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several processes have been developed to reduce the mixing and compaction temperatures of hot mix asphalt (HMA) without sacrificing the quality of the resulting pavement. The purpose of this study was to evaluate the installation of warm mix asphalt (WMA) to compile experiences and offer recommendations for future use. Three trial sections were installed using warm mix technologies between August and November of 2006. Two used the Sasobit technology, and the third employed the Evotherm technology. This report discusses the material makeup of these technologies and documents the production and placement of the three trial sections. The results of this study and further studies can serve as a basis for decision making by the Virginia Department of Transportation (VDOT) regarding the use of WMA technology. Trial sections were initiated through cooperative efforts by the Virginia Transportation Research Council; VDOT districts, residencies, and area headquarters; and participating contractors. Construction used typical mixture designs and practices so that performance under typical construction conditions could be evaluated. General experiences and processes used during construction were documented, and samples were taken for laboratory characterization. Density measurements and cores were taken at each site to determine the initial pavement properties. At the Evotherm installation, asphalt fume sampling was conducted by VDOT's Employee Safety & Health Division to evaluate differences in worker exposure between HMA and WMA pavement laydown operations. The study showed that WMA can be successfully placed using conventional HMA paving practices and procedures with only minor modifications to account for the reduction in temperature. The evaluated technologies affected mixture properties in slightly different ways such as changes in tensile strength ratios and variability in air voids. Additional monitoring of constructed sections was recommended to evaluate long-term performance. Inclusion of WMA technology as an option for paving operations provides potential benefits to VDOT and the contracting community. Theoretically, these technologies could extend the asphalt paving season into cooler weather, allowing for better optimization of paving resources. The technologies also allow the construction of asphalt pavements at lower temperatures, resulting in reduced cooling time before the pavement is opened to traffic. Lower production temperatures may also increase mixture durability by reducing production aging of the mix. Benefits to contractors may include the ability to increase hauling distances between the plant and project, reduced plant emissions resulting in improved air quality, and cost savings because of reduced energy costs. Because of the experimental nature of this study, no cost savings data are yet available to justify or refute the use of WMA technologies.

Download or read book Warm mix Asphalt Heating Up in Virginia written by Stacey D. Diefenderfer and published by . This book was released on 2011 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Performance of Virginia s Warm mix Asphalt Trial Sections written by Stacey D. Diefenderfer and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three trial sections using two warm-mix asphalt (WMA) technologies were constructed in various locations in Virginia in 2006, and experiences with these trial sections were used in the development of the Virginia Department of Transportation's special provision to allow the use of WMA. WMA for two of the sections was produced using Sasobit, an organic additive (developed by Sasol Wax), and WMA for the third section was produced using Evotherm ET (developed by MeadWestvaco Asphalt Innovations) as the modification method. The sections were evaluated over a 2-year period to assess the initial performance of the WMA and compare it with that of hot-mix asphalt (HMA) control sections constructed at the same time. Coring and visual inspections were performed during the initial construction and at intervals of 3 months, 6 months, 1 year, and 2 years. The cores were tested to determine air-void contents and permeability prior to undergoing extraction and recovery of the asphalt binder for performance grading. In addition, for the two Sasobit trial sites, historic data, core data, and ground-penetrating radar scans were collected and compared to provide documentation of the pavement structure for future analysis. Visual surveys indicated no significant distresses in either the WMA or HMA sections during the first 2 years in service. Evaluations of the core air-void contents indicated that generally the contents for the WMA and HMA were not significantly different in each trial. The air-void contents at different ages were significantly different in a few instances; however, no trends concerning air voids were observed. Permeability measurements did not indicate any trends concerning permeability over time. Performance grading of the recovered binder suggested that the WMA produced using Sasobit aged at a slightly reduced rate than the HMA, as indicated by decreased stiffening. No difference in performance grade was measured between the HMA and WMA produced using the Evotherm emulsion. Comparisons of historical data, core data, and ground-penetrating radar scans illustrated that each may indicate a slightly different pavement structure. From the results of this 2-year investigation, in general, WMA and HMA should be expected to perform equally. Any instances of improved performance of WMA (as compared to HMA) will depend on the WMA technology employed. Some WMA technologies may contribute to reduced in-service binder aging, depending on production temperatures and the nature of the technology. Further evaluation of WMA technologies developed since the inception of this work is recommended to determine their potential for leading to improved performance. During the period from February through October 2009, VDOT let maintenance contracts using HMA surface mixtures valued at approximately $101 million. If, conservatively, one-tenth of these mixtures were replaced with WMA produced using technologies having beneficial aging characteristics and the apparent trend of a 1-year reduction in the rate of aging continued, resulting in a 1-year deferment of repaving, VDOT could realize a one-time cost savings of approximately $1.15 million.

Download or read book Asphalt Paving Technology 2011 written by Eugene L. Skok and published by DEStech Publications, Inc. This book was released on 2011-06-28 with total page 801 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Recommendations for Compaction Temperatures in the Field to Acheive Denisty and Limit As built Permeability of HMA in Wisconsin written by and published by . This book was released on 2009 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Pavement Engineering written by Rajib B. Mallick and published by CRC Press. This book was released on 2022-12-30 with total page 819 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pavement Engineering: Principles and Practice examines a wide range of topics in asphalt and concrete pavements from soil preparation and structural design to life cycle costing and economic analysis. This updated Fourth Edition covers all concepts and practices of pavement engineering in terms of materials, design, and construction methods for both flexible and rigid pavements and includes the latest developments in recycling, sustainable pavement materials, and resilient infrastructure. New and updated topics include material characterization concepts and tests, pavement management concepts, probabilistic examples of life cycle cost analysis, end-of-life considerations, waste plastic in asphalt, pervious concrete, pavement monitoring instrumentation and data acquisition, and more. The latest updated references, state of the art reviews, and online resources have also been included.

Download or read book The Next Step Toward End result Specifications for Hot mix Asphalt Materials and Construction written by Charles S. Hughes and published by . This book was released on 2007 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 2000, the Virginia Department of Transportation's (VDOT) Chief Engineer asked the Virginia Transportation Research Council to develop a vision of how and when VDOT would have a working end-result specification for hot-mix asphalt. The response to that question was that it would take several years and many steps to achieve. This report discusses the next step in that ongoing effort, which includes the development and simulated application of two statistical quality assurance (SQA) special provisions, one for asphalt concrete material and the other for asphalt concrete pavement. The criteria for these prototype SQA provisions included the application of standard national terminology and approach, a firm basis in existing VDOT specifications, and quality characteristics that represent the best practical performance measures. This report describes the outcome of a "shadow" application of the proposed SQA specifications to a subset of Virginia's annual maintenance-resurfacing projects. Although the involved production and placement activities were not subject to the requirements of the SQA specifications, the sampling and testing were designed to represent what would have been required had the special provisions been in effect. The study further determined the likely acceptance outcome for each shadow project and explored future modifications to specification limits and pay adjustment criteria. The most desirable benefit from effective end-result specifications stems from the ability to rededicate available inspection to those key production and placement processes (e.g., joint tacking and surface preparation) that cannot be measured upon delivery to the owner/agency. A less desirable, but more tangible, financial benefit results when these specifications permit a reduction in the overall inspection force. One conservative estimate suggests that VDOT could save more than $2 million per year in inspector salaries through an end-result specification for acceptance of hot-mix asphalt pavements

Download or read book Hot mix Asphalt Placement written by David W. Mokarem and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Superpave Mix Design written by Asphalt Institute and published by . This book was released on 2001-01-01 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Field Trials of Asphalt Rubber Hot Mix in Virginia written by G. W. Maupin and published by . This book was released on 1995 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: Four test sections using asphalt rubber hot mix were placed in Virginia during the period of 1990 through 1993. The purpose of these installations was to familiarize both contractors and Virginia Department of Transportation (VDOT) personnel with the construction process and compare the performance of different types of mixes containing ground tire rubber. The MacDonald and Rouse processes, both wet processes, were used successfully. Densegraded surface mixes, a gap-graded surface mix, and a base mix were manufactured. A stress absorbing membrane interlayer was also used on one project in an attempt to deter or eliminate a variety of types of cracking. The asphalt rubber mixes have performed as well as the conventional mixes over the short term. More evaluation time is needed to determine if the long-term performance of the asphalt rubber mixes is superior to that of the conventional mixes. The cost of the asphalt rubber mixes was 64 to 102 percent more than that of the conventional mixes; however, this cost would probably decrease if substantial quantities were placed. VDOT has the necessary experience to contract placement of asphalt rubber mixes if the suspended ISTEA mandate is effected.

Download or read book Use of Manufactured Waste Shingles in a Hot mix Asphalt Field Project written by G. W. Maupin and published by . This book was released on 2008 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Virginia Department of Transportation (VDOT) is faced with trying to maintain its roads with materials whose cost is increasing at an alarming rate. The significant cost increase for asphalt concrete, which is used to pave a majority of Virginia's roads, is primarily linked to the cost increase for the petroleum products from which asphalt binder is produced. In the 1990s, VDOT developed a special provision to allow contractors, upon request, to use waste shingles in asphalt concrete. These shingles contain approximately 20 percent asphalt, which replaces part of the expensive virgin binder in the mix. In 2006, a contractor requested that the manufactured waste shingles be allowed on an overlay paving project in southeast Virginia. The 4.1-mile two-lane section was paved using a surface mix containing 5 percent shingle waste and a surface mix containing 10 percent recycled asphalt pavement for comparison. Density tests were performed on the pavement, and various laboratory tests such as permeability, fatigue, tensile strength ratio, rut, and binder recoveries were performed on samples of mix collected during the construction of the section. Both the field and laboratory test results indicate that the behavior and performance of the two mixes should be similar. The study recommends that VDOT's Materials Division prepare a permanent special provision to allow the manufactured waste to be used in asphalt. Because of the success of using manufactured waste, tear-off shingle waste resulting from replacing home shingles should also be investigated. Although manufactured waste shingles are available only in the northeastern part of North Carolina, several Virginia counties near the North Carolina border may be able to realize a cost reduction if shingles are used in the future. There is potential for approximately 50,000 tons of hot-mix plant mix containing waste shingles to be supplied to VDOT's Hampton Roads District per year. It was estimated that as much as $2.69 could be saved for every ton of asphalt that uses the waste shingles.

Download or read book Constructing Smooth Hot Mix Asphalt HMA Pavements written by Mary Stroup-Gardiner and published by ASTM International. This book was released on 2003 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: This publication contains papers presented at a December 2001 symposium, focusing on hot mix asphalt (HMA) smoothness measurements, specifications, and equipment. Five papers provide insight into the development and implementation of roughness specifications for pavements, and two papers offer natio

Download or read book A Cost comparison Methodology for Selecting Appropriate Hot mix Asphalt Materials written by Kevin K. McGhee and published by . This book was released on 2007 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Virginia Department of Transportation's (VDOT) Road and Bridge Specifications lists 9 dense-graded hot-mix asphalt (HMA) surface mixes (three aggregate gradations x three binder types) that could be used on Virginia's highways. VDOT's Special Provision for Stone Matrix Asphalt (SMA) provides 4 additional surface mix options (two gradations x two binder types), for a total of 13 mixes. Although the specifications offer recommendations regarding the types of facilities to program for each mix type, local conditions and experiences heavily influence the predominantly selected mix. Over the past 4 years or so, district pavement managers have routinely used only about 4 dense-graded mixes and 3 of the SMA surface mixes. As material prices continue to climb without budgets doing the same, local circumstances are more often going to contribute to the selection of the less expensive mixes, especially as long as these managers lack a defensible rationale for specifying a more expensive option. This study offers an economic analysis procedure to help field (i.e., district) pavement engineers select the most cost-effective mix for a given application. The procedure is based on the expected performance of each mix. The performance predictions were developed using the 2006 "windshield" condition rating for Virginia's interstate and state primary roads, which reflects the performance for at least 6 years of Virginia's contemporary dense-graded HMA mixes and for up to 11 years of SMA surface mixes. Through examples using typical project families, the study demonstrated that premium prices for SMA can generally be justified by better performance. In one illustration using actual condition and awarded price data, a life cycle cost analysis revealed that the use of SMA in lieu of dense-graded mixtures on interstates might save VDOT in excess of $7,500 per lane-mile in net present value costs. Extrapolated to the entire Virginia interstate system, the net present value costs associated with an SMA-only resurfacing program would be approximately $25 million less than the next best hot-mix alternative. A final step in this illustration suggests that VDOT can afford (within the FY 2008 spending plan) to pursue an interstate resurfacing program that makes extensive (if not exclusive) use of SMA.

Download or read book A Manual for Design of Hot Mix Asphalt with Commentary written by and published by Transportation Research Board. This book was released on 2011 with total page 285 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laboratory Evaluation of a Warm Asphalt Technology for Use in Virginia written by Stacey D. Diefenderfer and published by . This book was released on 2008 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rising energy costs and increased environmental awareness have brought attention to the potential benefits of warm asphalt in the United States. Warm-mix asphalt (WMA) is produced by incorporating additives into asphalt mixtures to allow production and placement of the mix when heated to temperatures well below the 300°F+ temperatures of conventional hot-mix asphalt (HMA). Potential benefits such as reduced plant emissions, workability at lower temperatures, extension of the paving season into colder weather, and reduced energy consumption at the plant may be realized with different applications. Trial installations of WMA, including two sections using the Sasobit WMA additive, have been investigated in Virginia. This study presents the results of laboratory testing to evaluate the performance of the mixtures used in the two Sasobit trial sections. The evaluation included comparisons of compactibility, volumetric properties, moisture susceptibility, rutting resistance, and fatigue performance between the HMA and WMA mixtures used in each section. Mixtures produced in the laboratory under conditions of varying temperatures and aging periods were tested, and the effects of temperature and aging were evaluated. The long-term performance of the two test sections was also modeled using the Mechanistic-Empirical Pavement Design Guide.Few differences were found between the HMA and WMA mixtures evaluated. The performance of WMA and HMA was similar when evaluated for moisture susceptibility, rutting potential, and fatigue resistance. The MEPDG-predicted distresses supported these conclusions; the predicted long-term performance of WMA and HMA was comparable. From these results, the recommendation was made that the Virginia Department of Transportation develop a special provision for the use of WMA. Despite its benefits, direct cost savings from the use of WMA are unlikely to be seen by VDOT. Currently, one concern with the use of WMA is the initial cost, which varies depending on the technology used. The use of WMA technology requires either additives, a recurrent cost, or asphalt plant modifications, requiring capital investment. Over the long term, the use of WMA could save VDOT considerable dollars if the reduced aging of the mix translates into longer life; however, this has yet to be proven as WMA has not been employed for a sufficient time period to allow an evaluation of this benefit.

Download or read book Laboratory Tests for Hot mix Asphalt Characterization in Virginia written by and published by . This book was released on 2005 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project reviewed existing laboratory methods for accurately describing the constitutive behavior of the mixes used in the Commonwealth of Virginia. Indirect tensile (IDT) strength, resilient modulus, static creep in the IDT and uniaxial modes, flexural beam fatigue, and dynamic modulus tests were conducted on two typical mixes used in Virginia: SM-9.5A (surface mix) and BM-25.0 (base mix). The tests conducted produced a wealth of data on typical values for the properties of the two mixes studied over a wide range of temperatures and loading frequencies. The results suggest that the IDT strength test is an effective test to characterize the tensile strength of hot-mix asphalt (HMA), especially for thermal cracking evaluation. The resilient modulus test and the static creep test in the IDT setup are practical and simple to perform, but the analysis of the measurements is complicated, and the variability of the results is high. The compressive uniaxial dynamic modulus and the uniaxial static creep tests were found to be simple to conduct and to analyze because of the homogeneous state of stress in the specimen during testing. The flexural fatigue test was time consuming, but the test produces valuable information about the fatigue properties of hot-mix asphalt. The investigation also found good correlations among the IDT strength, resilient modulus, and dynamic modulus results. A variety of tests is recommended for characterizing the mechanistic-empirical pavement analysis and design. These tests would provide the properties needed to characterize the asphalt layers for the pavement analysis and design. The recommended tests are as follows: IDT strength for characterizing HMA susceptibility to thermal cracking, dynamic modulus for characterization of the constitutive behavior of the HMA, uniaxial creep for characterizing permanent deformation characteristics, and flexural fatigue tests to characterize fatigue properties. Materials characterization testing can be a valuable tool in pavement design. The use of mechanistic-empirical modeling can be used to predict the performance of a pavement. With this type of testing and modeling, the materials used in pavements will be of better quality and more resistant to environmental and structural deterioration. A more durable pavement will aid in reducing the frequency and costs associated with maintenance.

Download or read book A Functionally Optimized Hot mix Asphalt Wearing Course written by Kevin K. McGhee and published by . This book was released on 2009 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this report was to highlight the preliminary findings of the design, production, placement, and early life performance of a new generation open-graded surface course (also referred to as porous friction course [PFC]) for use in Virginia. The primary objective of the larger research project is the design of a functionally optimized hot-mix asphalt wearing course. This report documents important aspects of the mix design and construction and the initial functional quality of the new surface. General observations associated with the trial section and normal production and placement activities are accompanied by a summary of the quality characteristics of the material. Special emphasis is placed on the very early life functional characteristics of the new wearing course. Among these key characteristics are ride quality, skid resistance, and tire-pavement noise. Observations made during trial production and placement led to "lighter" recommended application rates and reduced temperatures. Preliminary functional tests indicated that the PFC is exhibiting exceptional early-age skid resistance, incentive-quality smoothness, and low tire-pavement noise. On the basis of initial cost and early-life functional performance, the PFC is cost-competitive with traditional mixes placed at traditional application rates (when those mixes are used for functional rather than structural improvement). The report includes (as an appendix) a revised special provision for PFC that incorporates the recommendations pertaining to mix production and placement. It encourages Virginia Department of Transportation pavement engineers to consider a PFC when lower noise, exceptional skid resistance, and good ride quality are desired and additional structure is not necessary. However, it also cautions against widespread application of the technology until at least a final report on performance can be issued. The projected completion date for this report is winter 2010. In the absence of long-term performance data, the costs and benefits assessment is focused on initial costs and initial performance criteria. As a wearing course only, the PFC is $0.28 per square yard cheaper than a comparable dense-graded mix ($5.08 versus $5.36) if both mixes are placed at the normally recommended application rates. The PFC further offers the quantified benefits of much greater skid resistance and noticeably lower noise production. The additional advantages of reduced splash and spray are acknowledged but not quantified.