For more information
Call 1-800-351-0222

ASPHALT IN ROAD CONSTRUCTION.
  Term Paper ID:19382 		Get This Paper Free! or
Essay Subject:
Design considerations, durability, cost desirability over concrete,... More...
6 Pages / 1350 Words
7 sources, 17 Citations, MLA Format
$24.00

More Papers on This Topic


Paper Abstract:
Design considerations, durability, cost desirability over concrete,

Paper Introduction:
Introduction The most important use of asphalt today is in road construction (Zakar 148). When it has been properly mixed with the correct aggregate material it becomes highly suitable for all kinds of pavement applications. It is also widely used to prepare the base of roads. Asphalt road construction is multi-layered in form. The subgrade layer is itself covered by a base cover upon which is laid a final coating. Early classical base courses consisted of a handmade, packed layer which was then graveled. Later this technique of construction was replaced, on a global basis, by a flexible asphalt layer in which asphalt gravel or sand asphalt had been mixed (Ibid. 149). Asphalt as a road construction and/or road repair solution

Text of the Paper:
The entire text of the paper is shown below. However, the text is somewhat scrambled. We want to give you as much information as we possibly can about our papers and essays, but we cannot give them away for free. In the text below you will find that while disordered, many of the phrases are essentially intact. From this text you will be able to get a solid sense of the writing style, the concepts addressed, and the sources used in the research paper.


The effect of ambient light on asphalt is less well known. The durability of an asphalt road is measured in terms of thefollowing four characteristics (Barth 591): 1) Elimination of rutting 2) Prevention of shoving due to turns made at high speeds 3) Skid resistance 4) Ability to reflect light at night Agents key in influencing the aging characteristics of asphalt are: 1) Loss of oils 2) Oxidation 3) Ambient light Since today's asphalt is a byproduct of the oil refining process, itinherently contains various oils and emollients. Asphalt: Science and Technology. New York: Chemical Publishing Company, Inc.,1971.----------------------- 1 Although asphalt may lack the very long term durability of concrete,it is much easier to use and requires less in the way of equipment forapplication to the road surface. Asphalt. Washington D.C.:Transportation Research Board -- National Research Council, 1986.Zakar, Pal. Aggregate material usually consists of crushed stone,gravel, slag, and sand (Ibid.). Later this technique of construction was replaced, on aglobal basis, by a flexible asphalt layer in which asphalt gravel or sandasphalt had been mixed (Ibid. With reflection cracking, there occurs a replication ofcracks and joints which are in the underlying layers of the pavement andthe foundation materials. With the state-of-the-art available today, ten to twelve years ofmaintenance-free life can be expected from a typical asphalt-rubber basedseal. The following willserve to put these issues into perspective.Design Considerations Asphalt products are used to produce low cost, "flexible" pavementsfor primarily highway and airport applications. When it has been properly mixed with the correct aggregatematerial it becomes highly suitable for all kinds of pavement applications. Thus the asphaltserves only as a cementing agent which is used to bind the aggregate intothe position necessary to transmit the applied wheel loads to theunderlying layers of the road structure where these loads can be dissipatedinto the road bed. Works CitedBarth, Edwin J. Highly flexible applications utilize more asphalt and are used in thoseinstances where there are high wheel loads and high traffic volumes (Ibid.178). Clearly, the life expectancy of an asphalt surface can besignificantly extended by timely applications of standard chip seals and/orresealing the surface with an asphalt-rubber mixture (Schnormeir 66).Cost Asphalt paving represents a lower cost alternative to other methods,most notably concrete. These are routinely lostby volatility and /or by absorption by porous aggregates. Additionally, it is much easier to repair--especially if small sections of the roadway are involved. Assignment to one ofthese sub-units usually depends on whether solid or liquid asphalt materialis utilized in the construction process. Asphalt surface treatments and overlays have been widely used tomaintain and rehabilitate city streets, highways, and airport pavements.Historically, the use of conventional surfacings of four (4) inches or lessin thickness has resulted in "reflection cracking" which is a relativelynew phenomenon. This "flexible pavement" classification may be further divided intohighly flexible and marginally flexible sub-units. Low or marginally flexiblepavements are made with emulsion products and are widely used. Changingthe wavelength of light applied to the road surface does alter themagnitude of the influence. Asa rule of thumb, an increase in road strength value is directlyproportional to the increase in thickness of the pavement. In 1971, three miles ofconventionally sealed asphalt roads could be placed for every mile ofasphalt rubber-based material. Rigid pavements are used when the application requires a highbeam strength (Larson 177). Early classical base courses consisted of a handmade, packed layer whichwas then graveled. Asphalt Pavement Construction: New Materials andTechniques. Since 1971, the costs of asphalt rubber-based paving systems haveincreased by approximately two percent annually. In mostapplications, the addition of typically 1.5 percent to 5 percent of arubber material (often latex based) has proven to be most effective.Durability The individual problems arising in road construction will not bedealt with at this time. (ed.). In contrast, the normal life expectancy now available from aconventional chip seal is only six to eight years including somemaintenance. Recent advances in asphalt paving technology have significantlyimproved the lifetime of asphalt road systems. In those applications where high bearing strengthis not required, asphalt represents a very viable alternative to othermethods. New York: Gorgon andBreach Science Publishers, 1968.Keyser, Joseph Kode and Ruth, Byron E. Asphalt pavements represent a combination of mineral, aggregate andasphaltic material which is constructed in various types and thicknesses.Wheel loading, for which a pavement structure is designed, governs therelative thickness of the pavement and the type of construction method tobe used. "Analysis of Asphalt Concrete TestRoad Sections in the Province of Quebec, Canada," TransportationResearch Record #968. The latter are termed "rigid" pavementstructures. Portland Cement and Asphalt Concretes. Lightdoes exert a catalytic influence (Ibid. When properly combined with thecorrect aggregate and binder materials it becomes very suitable for avariety of road surfacing uses. 6 8). 149). New York:McGraw-Hill Book Company, 1963.Peterson, J. Although there is little value added to the roadin terms of load support, this type of road will furnish an all-weathersurface and protect the underlying surfaces from damage by traffic and theforces of nature. Therefore, by doubling the life and reducing the maintenance, asphaltrubber-based system costs will equal conventional chip costs over a 12-yearperiod (Ibid.).Conclusion Use of asphalt in road construction represents a relatively low costalternative to the use of concrete. One study conducted in 1968 (Keyser and Ruth 54)verified that greater age-hardening will take place when in-service asphaltpavements have air voids in excess of four (4) percent. By 1986, only two miles of conventionalchip seals could be placed for every mile of asphalt rubber-based material(Ibid.). Light and air have access to the variouslayers of the road construction--especially in the case of open gradedpavements (Ibid. It is also widely used to prepare the base of roads. Oxidation reactionsoccur at velocities which are proportional to the concentration of oxygenat the surface of the road (Barth 6 3). Clearly,the economic result of meeting the wide range of technical roadrequirements will depend on the right selection of the constituentmaterials as well as the budgetary restraints of the project. "Chemical Composition of Asphalt As Related toAsphalt Durability: State of the Art," Transportation Research Record#999. Washington, D.C.: Transportation Research Board--NationalResearch Council, 1984.Scherocman, J.A. 6 6) on asphalt roads. Once this new surfacing has become fractured,further deterioration of the pavement occurs resulting in a reduction ofthe effectiveness and strength of the road structure thus requiringadditional maintenance (Scherocman 3). Regardless of the thickness or type of asphalt pavement, the loadapplied to the road surface is transmitted through the aggregate materialwhich has been mechanically combined with the asphalt. Asphalt road construction is multi-layered in form. Thin asphalt pavements provide an economical wearing layer forlightly travelled roads. This fluctuation hascaused asphalt rubber-based system costs to change as well. Preparation and design of an asphalt road surfacewill inevitably require compromise, as do most design processes. The term "flexible" isused to distinguish this type of pavement structure from those madeutilizing portland cement. This additional maintenance can becostly, especially over time. The subgradelayer is itself covered by a base cover upon which is laid a final coating. Asphalt as a road construction and/or road repair solution offersdesign, cost and durability advantages over concrete. Claine. Fundamentalto the process is, of course, choosing the most suitable asphalt/ingredientmix for the construction of a satisfactory as well as durable roadstructure (Zakar). To counter the negative influences of reflection cracking, asphaltmixes have been modified through the addition of rubber additives. "Asphalt Analysis, Sulfur Mixes, and Seal Coats," Transportation Research Record #1 96. With currentmaterial specification and construction practices, age and hardeningeffects due to these phenomena have been significantly reduced over thatwhich was experienced twenty years ago (Peterson 13). Heavy-duty asphalt pavements (Martin and Wallace 1) are usually threeinches or more in thickness and offer much in the way of value added to thestrength and load bearing support value of the overall road structure. Philadelphia, Pennsylvania: American Society for Testingand Materials, 198 .Schnormeir, Russell H. Introduction The most important use of asphalt today is in road construction(Zakar 148). The cost of conventionalchip seal coating based systems has increased by three percent annually.The cost of the primary ingredient other than the aggregate has alsofluctuated during the measurement period (1971-1986). In lowflexibility applications, the aggregate material and the asphalt productare separately applied to the roadbed and there mixed to form the pavement. With routinepreventative measures--which are themselves inherently low cost, theaverage lifetime of the road surface can be significantly extendedespecially if rubber-based materials are used. Oxidation of asphalt is an irreversible effect. The presence of air voids in the mixture has also been a variable indetermining the speed with which these asphalt mixtures age and begin tolose their effectiveness. Washington D.C.: Transportation Research Board--National Research Council 1968.Larson, Thomas D. The ability of thin asphalt pavements to carry lighttraffic wheel loads is considered good.

If this paper is not what you are looking for, you can search again:

Search for:

or

We can write a Custom Essay just for you.


Browse Essays by Subject