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Thesis for Highway/Materials Engineering

  • 1.  Thesis for Highway/Materials Engineering

    Posted 12-08-2020 10:59 AM
    Hi, I am looking for a topic in preparation to my thesis in Master of Science in Civil Engineering. I am interested on the subject of Highway or Materials Engineering. Mostly the concrete pavement (280mm thk) highway in my region is being constructed with an asphalt overlay (100mm thk). The lifespan of the asphalt overlay (mixed with some aggregates) is 5 years. Isn't it a bit expensive to remove it after 5 years and replace it with a new one? Not to mention the labor cost. Anyway, can you suggest or recommend something that I can place at the top of the asphalt overlay or add something like mixture with the asphalt to prolong the lifespan of the asphalt overlay? Any help will be much appreciated.

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    Arsadie Monte, R.Eng, M.ASCE
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  • 2.  RE: Thesis for Highway/Materials Engineering

    Posted 12-09-2020 09:14 AM
    To Start:
    1. asphalt thickness must be 2 &1/2 time the size of the coarse aggregate
    2. to much tack coat is just a bad and not enough
    3. a straight line gradation curve, on log chart, will give the good dense mix. make room for the ac + 3 to 5% air voids
    4. not using a meeting the desired density is the most common problem.
    5. rutting in the wheel lanes will tell you a number of things. a. low retained strength, b. to much as. c. low compaction. d.wrong ac for the temperature. and others
    6. on us military airport, round granite type coarse aggregate is used, many engineers say not to.
    7. check polarity of the ac and aggregated.
    8. if the coarse aggregates absorb moisture, not getting all the moisture out will cause stripping of the ac. Can tell by looking at the mix in the truck and seeing white rock
    9. The test for moisture, place a child tablet paper over the mix in the truck. If it drops down, it not dry, if it curls up, it's dry
    answer is. learn in th field and lab. much of this you will  not learn on college. unfortunately, the professors don't seem to want to get dirty anymore, just talk about it.

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    Robert Hinton, P.E- Life Member ASCE
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  • 3.  RE: Thesis for Highway/Materials Engineering

    Posted 12-09-2020 09:15 AM

    Many asphalt mixtures are available to extend service life. Given that subgrade is stabile, the primary reason for degradation is oxidation at the surface. One of the most practical and available admixture materials is scrim rubber from ground up automobile tires. 

    Ongoing maintenance for asphalt pavement addresses the surface decay and provides additional years of service. 


    Be sure to address wheel loading and look at the influence of heavy truck loads



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    Daniel Clark P.E., M.ASCE
    Retired
    Auburn CA
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  • 4.  RE: Thesis for Highway/Materials Engineering

    Posted 12-09-2020 11:14 AM
    Arsadie,

    A well designed asphalt overlay should provide 20+ years of service.
    I'm not sure about the rest of the U.S. but the Iowa Department of transportation utilizes an electronic reference library that can be accessed by anyone.
    https://iowadot.gov/erl/
    IM 510 details the steps for asphalt mix design using a gyratory compactor.

    Starting with the correct mix of aggregates and binder is the first step to a successful pavement.

    Rutting in your asphalt overlays can be caused by bad pavement design (poor gradation, wrong binder or both) or bad construction practice.(insufficient compaction)

    Another key element is correcting any deficiencies in the underlying pavement.
    You cannot correct failed areas by paving over them.
    Full depth patching with subgrade stabilization is money well spent.

    Add these items to Rober Hinton's check list and you should be on your way to a successful pavement rehabilitation.

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    DeWayne Heintz EI, A.M.ASCE
    Project Manager
    L.L. Pelling Company
    North Liberty IA
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  • 5.  RE: Thesis for Highway/Materials Engineering

    Posted 12-09-2020 11:13 AM
    Many techniques are used to extend road service life. You can chip seal the asphalt which is a process where a heavy coat of asphalt emulsion is placed and pea gravel is placed on the emulsion that creates a barrier prevented the oxidation of the top layer of asphalt. This chip seal will last several years up to 20 years. After the 20 years if the subgrade shows no signs to weakness the chip seal and top 1.5 to 2 inches is milled off and replaced with a new layer of asphalt.

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    Dustin Leduc A.M.ASCE
    Field Engineer
    Sambatek
    Shakopee MN
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  • 6.  RE: Thesis for Highway/Materials Engineering

    Posted 12-10-2020 10:41 AM
    Hello Arsadie,

    As with anything else, the problem has to be defined before it can be solved.  What is the mode of failure that has been observed?  Reflection cracking (cracks, joints in the underlying concrete "reflecting" to the surface), rutting, raveling (fretting), delamination/slippage?  It is difficult to suggest remedies without knowing the actual problem, because those that I listed have different causes.  Others have discussed problems at the surface of the asphalt layer-I'll go deeper into the pavement to what is the most likely culprit-the underlying concrete pavement.

    Typically, the biggest problem with asphalt overlays of concrete pavement is reflection cracking, and deterioration of those cracks under traffic.  These cracks are caused by movements in the concrete pavement resulting from poor load transfer at the joints and cracks.  The remedy for this depends a lot on project constraints-particularly surface drainage and the ability to deal with significant changes to the roadway profile.  For jointed-plain concrete, cracking and seating can stabilize the movement of the slabs and minimize cracking through the overlay.  Breaking and seating is a similar approach used for concrete pavements reinforced with deformed bars.  These techniques reduce the size of the slabs and firmly seat them onto the underlying subbase, thus reducing movement.  Another technique, rubblization, completely eliminates slab action by breaking or fracturing the concrete into small pieces in place.

    If there is evidence of pumping of fines from the subbase, subsurface drainage has to be improved to enable good long-term performance.

    When using any fractured slab technique, you should consider placing at least three lifts of HMA-a minimum of 15 cm total-more depending on the traffic loading/pavement structural design requirements for the project.  The reason for the number of lifts is to achieve the desired ride quality, since a fractured surface will not have a smooth profile.

    Another approach to consider is an open-graded asphalt crack relief layer placed directly on the concrete pavement.  These have been shown to be effective in significantly delaying reflection cracking, and in providing an outlet for moisture in the pavement.  The problem with this is that the resulting roadway profile will ultimately be raised by at least 20 cm, which might not be practical for situations other than rural highways.

    Last but not least, the asphalt mix design/materials criteria and construction practices must be appropriate for the conditions as others have noted in their comments.   Refer to Asphalt Institute MS-2 for mix design details whether using Superpave or Marshall mix design procedures.  Polymer (SBS) - modified asphalt binders are proven to improve resistance to rutting and cracking.  It's difficult to provide a specific recommendation for a binder grade/specification without knowing more details about the project, but the key features of the specification should be multiple stress, creep recovery (MSCR) requirements for compliance (Jnr) and recovery (%R), and the upper limit for DSR measured at 25°C after RTFO conditioning.

    I hope this is helpful.

    Gary L. Fitts, P.E.

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    Gary Fitts P.E., M.ASCE
    Manager, Market Development
    Garden Ridge TX
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  • 7.  RE: Thesis for Highway/Materials Engineering

    Posted 12-13-2020 10:00 AM
    Hi Mr. Hinton,

    Thank you for the very informative details regarding asphalt design. However, the asphalt design mix being used in the highway construction in my region is actually in conformance with the design specification given by the concerned government agency here in the Philippines. Our thesis is composed of two parts, first is the proposal, second is the final or defense. Now, I like to propose a topic that is something about extending the service life of an asphalt overlay. Introducing new asphalt design mix would be a great idea but it may require expertise or good actual experiences on highway construction that might be beyond my knowledge on the subject. I hope there is a way I can find this not difficult for me to formulate ideas for the first part of my thesis. But I will try then.

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    Arsadie Monte R.Eng, M.ASCE
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  • 8.  RE: Thesis for Highway/Materials Engineering

    Posted 12-13-2020 10:00 AM
    Hi Mr. Clark,

    Thank you for introducing to me about the scrim rubber. That is very interesting. I only wish that admixture materials had no extensive studies being published (by book or on the internet) neither been introduced to the market industry nationwide or worldwide so that I can propose it as a topic for my thesis. Our theses advisers suggest to choose a topic that has not been yet studied and developed locally or internationally so that such topic can be approved by the thesis evaluators =) By the way, there is an ongoing maintenance for the asphalt pavement, only their asphalt overlay is designed up to 5 years of service in my region. I am not so sure about the rest of the Philippines if it has the same service life.

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    Arsadie Monte R.Eng, M.ASCE
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  • 9.  RE: Thesis for Highway/Materials Engineering

    Posted 12-13-2020 10:01 AM
    Hi Mr. Heintz,

    Thank you for the useful information. The design mix of asphalt being used in the highway construction in my region is actually in conformance with the design specification given by the concerned government agency here in the Philippines. I am not so sure either if the rest of the Phils have the same lifespan of asphalt overlay which is 5 years of service. Anyway, I am hoping to propose a topic about extending the service life of the said subject that had not been published (by book or on the internet) neither been introduced to the market industry nationwide or worldwide. If possible, a topic that does not requires expertise or good actual experiences in the field of highway construction would be of good choice at this time =)

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    Arsadie Monte R.Eng, M.ASCE
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  • 10.  RE: Thesis for Highway/Materials Engineering

    Posted 12-13-2020 10:01 AM
    Hi Mr. Leduc,

    Thank you so much for suggesting me about this chip seal process. I think this one is effective and very interesting. Is this technique already being used in your country nationwide or an extensive study about this chip seal process had been published (by book or on the internet)? If not then I can propose it as a topic for my thesis. I hope to get more information about this technique.

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    Arsadie Monte R.Eng, M.ASCE
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  • 11.  RE: Thesis for Highway/Materials Engineering

    Posted 12-13-2020 09:56 AM
    Hi Mr. Fitts,

    Thank you for a very helpful information about asphalt overlay on a concrete pavement. The common problems that have been seen are rutting and raveling. There could be some cracks in the underlying concrete pavement. The design mix of this asphalt overlay is in conformance with the design specification given by the concerned government agency here in the Philippines. Its service life is up to 5 years and it is being applied in my region, but I could be wrong as I am not so sure about the rest of the Phils, maybe they have more longer service life of this asphalt overlay. But let me give you some information about how they construct the highway/roadway in my area. It goes like this, a subgrade preparation is being placed first with a depth of not exceeding 200mm in loose measurement, second would be the aggregate subbase course with 150mm of compacted depth, third would be the aggregate base course with the same depth of the preceding layer, fourth would be the portland cement concrete pavement having a thickness of 280mm. Then there goes the overlying asphalt with a thickness of 100mm. Also, a prime coat and tackcoat are included in these processes. Anyway, our thesis is composed of two parts, first is the proposal (introduction and background of the study, review of related literature and studies, methodology of the study), second part is the final or defense (presentation, analysis, and interpretation of data, summary of findings, conclusions, and recommendations). Our theses advisers are suggesting to choose a topic that had not been published (by book or on the internet) neither being introduced to the market industry nationwide or worldwide so that our topic can be approved by the theses evaluators. I want to propose a topic about extending the service life of an asphalt overlay on the concrete pavement. I am hoping something like you know it does not require that much of a good actual experiences or expertise in the field of highway construction. My knowledge on the subject is very limited. To be honest, formulating ideas to make a whole thesis is really hard for me, especially when English is not your primary language. Lol

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    Arsadie Monte R.Eng, M.ASCE
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