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Pavement Engineering - Science topic

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Multi-lane roads are driven by various types of vehicles. Most cars move on the first lane. At the same time, in most countries, road pavement is designed the same for all lanes. The load of the first strip is taken as the design load. Our observations show that the real distribution of transport exceeds the norm. Therefore, the state of these bands is much worse than the others. Tell me how your countries take into account this distribution of vehicles on the lanes of multi-lane highways. Can pavements of multi-lane roads with lanes of different strengths be designed? Is there such an experience in your countries?
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As experience shows, cars move faster along the left lane (in right-hand traffic), naturally these are lighter cars, i.e. the alternative is simple - heavy but relatively slow, or fast but lighter. First you need to find out what type of load causes more wear on the road. I think that the road conditions in Russia and Belarus differ little. In Russia, partial repairs are carried out as the roads wear out, and I see that the left lanes are being repaired more often. In addition, changes from lane to lane should be taken into account. As a rule, these are made at a speed greater than the average and not only by passenger cars. In this case, the load is far from average and not only traffic lanes work, but also the boundaries between these.
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I want to model a moving concentrated force to simulate the moving wheel load on the pavement in a simplified way as shown in the attachment. So, is there any way to model the moving concentrated force in Abaqus (without modeling the wheel).
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Hello,
The moving concentrated forces of wheel load can be applied in ABAQUS using cyclic dynamic force. Find attached the paper on similar moving load analysis of a bridge beam subjected to moving wheel load for your reference..ok all the best..
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Dear reader
I hope this discussion finds you well in these difficult times
I am looking for some collaborators related to the mentioned field to work on some hot topics in the area of pavement materials.
If you are interest then please contact me on my email (aamardanish@gmail.com) or RG chat.
Regards
Aamar Danish
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yes what are the topics u will be discussing
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I want to use Box-Behnken design (BBd) For reducing my tests.(4PBT/SCB/ITS/ITSM)
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Greetings there,
To be laconic, I think if u can go through it, it might help.
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I am looking for asphalt binder database containing DRS data for frequency or Temperature sweep of Unaged/RTFOT/PAV samples.
It could be modified or neat asphalt.
Can someone assist me with it or give me a link to where I can download an open open-source database?
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Ikenna this is the link, in this site there is a lot of bibliography related to the topic, you must spend some time to find what you need
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I came upon a real planning case, where a small street with a max speed of 30 km/h requires a complete makeover. The existing cobble stones can either be replaced by new ones or by asphalt. Some aspects beside, like historic ambience, noise emissions, or rainwater infiltration, which alternative would have which global warming potential (GWP), roughly estimated?
In my search for an answer I first found the publication of Santero and Horvath (2009) regarding the "Global warming potential of pavements". Following its citations I came across several publications about asphalt, concrete, and their respective innovations, also regarding their GWP. I even came across a paper by Lo Presti and D'Angelo (2017) regarding their "Review and comparison of freely-available tools for pavement carbon footprinting in Europe". However, I did not find any comparison between asphalt and cobblestone. Probably because the latter does not play a major role for today's streets. Suggestions are welcome!
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Did you consider old cobblestone from another, previously demolished roads? For this kind of low-traffic volume and low speed roads around historical sections of the city we often use old (e.g. granite) elements. Personally I think that cobblestone pavements (old or new) are more enviromental friendly than asphalt pavements mainly because life cycle of this surface will exceed asphalt one. You can surely find granite pavements older than 100 years and they rarely need any extended rehabilitation treatment. Ofc I'm talking about low speed and low traffic volume roads. Cobblestone also helps to reduce car speed without any additional dedicated solutions.
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Attached, a question about pavement design by mechanical empirical approach that comparison between AASHTO 93 and KENPAVE.
AASHTO 93 design life : 20
KENPAVE design life : 9.8
Why does the huge difference occurs ?
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Agreed @Amjad Albayati
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Hi,
please help me with this question
I've been trying to model three-layer pavements (one rigid and one flexible) in Canada and I'm quite new to the design of pavements. My problem is the input. Do you have any suggestions as to where I can find the input data for pavements in Canada? I've been navigating the LTPP website, but it seems the data are not complete for the pavements. For instance, for one particular pavement, say SHRP_ID 0901, the input data are complete for all the layers but not for the Base Layer.
Thank you so much in advance!
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To model pavements with three layers (one rigid and one flexible) in Canada, it is necessary to collect this information from the design offices responsible for diagnosing and prospecting pavements affected by deterioration.
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What are the best plasticizers which can be used for the flexible pavements,available in the market?
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Actually, plasticizer in bitumen can also be used and its not just about concrete pavement.
i suggest you to read this article.
DOI: 10.3103/S1068364X15020076
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I compacted unbound aggregates at optimum moisture content and then let it dry in the oven for one day. The repeated load triaxial test was carried out on this sample in which I faced a weird behavior (please find the attached figures). The permanent deformation initially increases with a high rate and then its rate decrease slowly and finally it has a negative displacement (like expansion).
This behavior only happened in dried samples and the lower stress conditions (1.59 KN and 1.767 KN deviatoric stresses and 120 and 41.7 confining pressures). These samples have normal behavior, the permanent deformation keep increasing with load cycles, at higher loading environment.
I appreciate your time.
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Cohesionless soils when sheared at low confining stress will dilate and generate negative pore pressures. The particles are interlocked but at some point of continued axial stain they must lift to ride across one another. The perfect example can be seen in the direct shear device with vertical axial stain measurements. Taught in basic soil mechanics. At high confining stress soil is contractive. Dense soil is dilative and loose soil is contractive and depsnds on confining stress.
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Hi,
I am currently studying Concrete Pavement. I will use a program called StreetPave. (A program prepared according to PCA 84). But I got stuck at a point about traffic data entry into the program. There are several examples made using the program, but the already existing Typical Traffic Spectrum data is used in the program. I have axle load class and frequency data for single, tandem, and tridem axles. So I need to define this data as Custom Traffic Spectrum as the program wants (Number of Axles / 1000 Heavy Trucks). I've been searching for a long time, but I haven't figured out how to get the data I need. Do you have any valuable ideas or suggestions?
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As I see it you have frequency data for each category. From the frequency for each vehicle category you can calculate the total number of single tandem or tridem axles and multiply that with the number for each axle load from the respective column in your attachment. And repeat that for every category.
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I ran MSCR on different samples with repetitions, I plotted the strain against the time. the graph seems not to move with conventional shapes. all samples display the same anomalies. I check the DSR settings and confirm its correct.
Does anyone know what I am missing?
Also, can you provide and excel example graph?
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can you send me the BS EN 16659:2015 standard , please Rufus Adjetey
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I am looking for documentation about the structural disorders in pavement after a long submersion due to flooding and the possible solutions for this issue.
Thansk in advance.
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Here are some impacts of long term flooding pertinent to structural distresses:
1. Reduction in structural strength
2. Increased deflections
3. Loss of sub-grade strength
4. Increase in roughness, rutting, and fatigue cracking
5. Potholes
6. Swelling
7. Joint deterioration
The underlying layers play a critical role. If fundamental drainage is an issue, then it would be convenient to either provide dense surface and drainage layers or a proper drainage system. Another solution could be the provision of gap-graded asphalt or porous asphalt / concrete in top surface course, followed by a concrete base course, and subsequent dense layers. Furthermore, utilize additive materials that reduce the pavement's susceptibility to moisture.
Attached are a few studies for your reference:
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I am trying to design a pavement using the MEPDG method in africa. since it can be calibrated anywhere how best can i go about the methodology without the AASHTOware software for a thesis?
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You can calculate the stresses and strains induced by your representative truck loads and at the different temperatures using any existing free software (Kenlayer, ELSYM 5, Bisar), then use the failure model (Fatigue, rutting) to calculate the damage using Excel or any other spreadsheet software. Of course, the MEPDG software uses models to find the temperature at different depths, etc. For your case just use uniform temperatures. The same applies to the water content of the subgrade soil and untreated base materials.
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There is a conjested and a solution would be to design a bypass route, How can i write a thesis about it? something that starts with analysis of and a procedure would be helpful.
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Keith Govo You may use this title for your thesis, "Feasibility of designing a bypass route by congestion assesment at [location]"
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I am looking for the best method to determine depth temperature of asphalt with the help of surface temperature of it.
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Quite a number, but as stated by Amara, look out for the AASHTO incorporated model.
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I mean the allowable tolerance compare to the Optimum Moisture Content in the lab compaction results
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Soil properties, gradation curve, compaction curve and soil type are all important factors in deciding! However, previous work done in this field suggest that plus-minus 2 of the OMC would be safe.
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I conducted CBR tests on unbounded aggregates. As you can see the CBR test results in the attachment, the curves concave up and there is a relatively enormous shift between two test results. Considering that two curves are parallel, it, somehow, can be concluded that two samples has comparable properties, but the presence of the shift make the interpretation of the results difficult.
Based on New Zealand and British standard these curves should not be corrected, however some references in the literature recommended correction of these type of curves (I attached the PDF file).
Question A- If I correct the curves (as explained in the PDF file) or shift the sample-2 the results for two replicated samples are comparable. Under this conditions, do I need to correct the CBR test results?
Question B- If I correct the curve and the resultant curve does not meet 2.5 mm penetration how can I interpret the CBR test results?
Question C- If I should not correct the curves what would be the CBR test results in my case?
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As per AASHTO T-193 if the curves start concave upwards they should be corrected by extending the linear portion of the curve until it intersects the x-axis (penetration) and use the intersection as the new origin of the axis.
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Besides providing load distribution in post-construction stage and working platform in construction stage, can we used a sub-base layer as a drainage layer to remove water from pavement?
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"Besides providing load distribution in post-construction stage and working platform in the construction stage, sub-base can also serve as a drainage layer to remove water coming from the pavement.
For thick layers of road pavement, it is likely that the water leakage from pavement is insignificant and therefore the sub-base layer mainly serves to support the traffic stresses. However, for thin pavement layers, water penetration is quite substantial and therefore sub-base may also act as a drainage layer to remove these water."
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I mean after doing the compaction practice in various water contents and determining the dry density corresponding to each water content, what would be the equation of the resultant compaction curve? Assuming that there should be only one optimum water content, I think the quadratic curve can be the best option to fit the bell shaped results. However, I could not find anything in the literature (the compaction curve is drawn without presenting the equation or a line simply connected data).
I was wondering if you could introduce me any reference about this matter.
It is a matter of great importance to me to determine the optimum moisture content consistently for all of my materials.
I attached my data and the quadratic curve passing through them. could you please let me know what is the optimum moisture content in these compaction data series and what is the compaction curve for them?
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I am looking for asphalt testing laboratory to conduct SuperPave test.
The test is on Binder alone.
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Try to contact The University of Nottingham. They have a specialised centre for Highways and pavement research, called Nottingham Transportation Engineering Centre, which provides such services.
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Geophone used in falling weight Deflectometer-to measure deflections.
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EGL Equipment Services Co, Ltd offers high-quality geophones for sale at competitive prices to clients from all over the globe.
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These are the questions I faced in my literature review I could not find an answer for them. Just for the record, I am going to do the CBR test on laboratory compacted base materials in the pavement.
1- In which moisture content and dry density this test is accomplished (generally for the scientific purpose). I mean, CBR can be employed directly after the compaction or after soaking in water for four days. Should the CBR test be done with various moisture content? Should it be done in 95% of MDD (as the compaction in field is usually 95% of compaction in the lab)?
2- What is the number of layers in the compaction process (if the vibratory hammer is used for the compaction)? 2 or 3 layers?
3- What would be the weight of surcharges if the pavement design includes an asphalt layer of 10 cm and a basecourse of 30 cm and the materials are to be used in the base layer?
4- While soaking aggregates in water, what should be the elevation of water above the sample?
Kind regards,
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You can refer to AASHTO T 193.
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Hello Everyone
Anyone who can share some points or any article about reliability of using CBR value for sub grade still in Flexible pavement design?
If using CBR is questionable then what are the reason behind it and is there any other alternative test or parameter which can be used in place of sub grade CBR value in flexible pavement design?
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Any pavement design method would have to consider 4 parameters:
1- traffic loads; 2- Environmental conditions ; 3- pavement materials' properties; and 4- Properties of the supporting subgrade.
Therefore, for the subgrade, early design method rely on the CBR test to get its bearing capacity. Then, AASHTO with its major experimental road test performed in the late 50s, switched from using CBR to resilient modulus for characterizing the subgrade. The resilient modulus is a weighted average based on the climatic conditions during the whole year. Therefore, for those who still use CBR as a Test and wanted to use the AASHTO statistical method needed a way to correlate between the two properties and many equations came out. With its recent mechanistic-empirical pavement design guide, AASHTO still uses the resilient modulus property, but use more complex equations that relate this property with moisture content and stress conditions.
In short, simple design method use simple easy to get properties, but people attack these methods because of their simplicity. More complex methods (such as the new AASHTO design guide) use sophisticated models in order to simulate the real conditions, but the average user finds himself/herself trying to input properties that are not easy to get and in most case use default values.
So now depending on which school you want to be, you can use simple design method or use more complex methods that are supposed to achieve more reliable designs. Of course, if you work in an engineering firm, the choice on which method to use comes from the client and not you.
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I want to analyse the airplane wheel load on a fiber reinforced concrete and find out its optimum depth and Allowed loading times
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Ansys, Abaqus and plaxis
This programs used to make finite element and used to know the stress and deflection on the pavement
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Based on the New Zealand standard the specimen height should be 125- 127 mm. My question is that what if the resultant height of the sample after the compaction was more than or less than this amount. I asked it because there is a height correction in Marshal compaction method of Asphalt materials. I thought there should be something for the compaction Unbound Materials.
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Vibration compaction tests include vibrating table test and vibrating hammer test.each method will give different results though dry unit weight and water contents are the same for a given granular soil.
However it has been suggested that impact factor be used and its result must be considered.
There is no index for correction for vibratory compaction.
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Temperature=70°C=160°F
Humidity=90%
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you can try to use MMA Colplastic material, this is thermosetting with 2 component product
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Topics included
pavement and subgrade improvement, finite element analysis of pavements, environment friendly additives in asphalt mixtures..
Thanks.
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The University of Nottingham. They have a specialised centre for Highways and pavement research. It is the UK's foremost university-based research organisation in highway engineering.
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IRC 115: “Guidelines for Structural Evaluation and Strengthening of Flexible Road Pavements Using Falling Weight Deflectometer (FWD) Technique” ,  is it possible to make model of temperature and seasonal correction for different part of india ?
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Yes it is possible not because of the physical properties but because every system can be configured and calibrated into doing what you want. Try and find the route. Good luck 
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pavement design
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There is a number of software for that. In addition to those already cited, there is also ELSYM5, it is old, but still very common.
If you like to generate nice graphics with color gradients have a look for "finite elements analysis" software, like Ansys (paid).
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I want to perform E* test , but I can get just 6in*6in sample ,NCHRP and ASTM require 4in*6in to perform this test,I know the geometrical parameter will affect the results but I want t o know how much will be the influence?
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The main reason for obtaining different material properties for different specimen size is the variation in the sate of stress and strain within the test specimen.
Theoretically, when you apply a uniaxial compression on cylindrical specimens, the material close to a free surface is not confined can deform laterally and there is a plastic deformation in this region. As the diameter decreases, the vertical normal stress through the diameter varies less, and it approaches the state of plane stress. As the specimen diameter increases, the material inside the specimen away from the free surface becomes laterally combined by the surrounding material, and it approaches the state of plane strain where it experiences elastic deformation. Therefore, the specimens with smaller diameter tend to be more ductile, while those with large diameters tend to be more brittle. This means that the larger diameter of your specimens might theoretically lead to higher values of the stiffness modulus and shorter fatigue life.
However, the research has shown that values of the complex stiffness modulus from uniaxial compression test are mostly not influenced by the specimen size. You should also pay attention that different void distribution of gyratory compacted specimens depending on the specimen preparetoin (cored/uncored) could have a certain influence.
For more details please refer to the listed references. Please be fre to contact me for an further discussion.
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what is the difference between ASTM and AASHTO grooving tools in liquid limit determination?
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ASTM and AASHTO grooving tools make different groove shapes. A groove made with the ASTM tool has faces which form an angle of approximately 45°, while a groove made with the AASHTO tool form faces under the angle of 60°. The ASTM groove tool also shapes the top surface of the soil cake.
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Durability prediction and checks on designed Geotech facilities is a necessity to ensure their ability to withstand conditions within the limit states. Two procedures are before us. We need ideas to ensure a seamless operation 
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Dear Onyelowe;
1- This papar shows relationship between durability and unconfined compressive strength for fly ash.
DOI: 10.1061/(ASCE)0899-1561(2006)18:1(18)
2- In this paper, the resistance of loss in strength [durability] was determined as a ratio of the Unconfined Compressive Strength [UCS] after curing.
3- In the following paper, the results of conducted CBR tests are shown as durability Effect of stabilized soil.
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I am interested in knowing if it is possible to study the degradation of rutting and IRI on a flexible pavement. I already know the ones form World Bank to study the IRI but for a first approach and due to the lack of data I am looking for a simplified equation.
Many thanks
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You can find some simplified relations in the sources below. if you can be more precise, I would try to give you a more complete answer.
Al-Omari, B., Darter, M.I., 1994. Relationships between International Roughness Index and Present Serviceability Rating. Transportation Research Record, 1435, 130–136.
Carey Jr, W.N., Huckins, H.C., Leathers, R.C., 1962. Slope Variance as a Measure of Roughness and the Chloe Profilometer. Highway Research Board Special Report, 73, 126–137.
Sun, L., 2001. Developing Spectrum-Based Models for International Roughness Index and Present Serviceability Index. Journal of Transportation Engineering, 127 (6), 463–470.
Walker, R.S., Fernando, E., 2002. Evaluation of Ride Equation using Current Profiler Systems and New Sensor Technology. The University of Texas at Arlington.
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In the Field test ..what is the test procedure to find the modulus of subgrade reaction K value?
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Plate bearing test. Applying the concepts described in Yoder's textbook for pavement design. Good resource
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I have used KenPave and WESLEA to calculate displacement in different layers in a pavement. Both of these packages are built for pavement design only. I was wondering if there is another software package available for such a purpose. The basic purpose is to calculate the contribution of total displacement in each layer.
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You can use BISAR or Overstress to calculate pavement displacement.
ABBAS 
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Kindly, anyone know how to use ABAQUS for pavement engineering? I know that ABAQUS is used for Finite Element simulations of structural problems. So can we use it in pavement engineering ? And Is it possible to perform fatigue and rutting analysis of pavements on abaqus? For a partcular number of repetitions if possible ?? 
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You can simulate the pavement as a plate elements with the corresponding material properties. The supporting layer can be simulated as a semi finite layer with the corresponding material properties. The interface between the pavement and the underneath layer is simulated by a linkage elements in the horizontal and vertical elements with appropriate stiffnesses. 
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I am talking about the methodology of design like Road Note 31 is one method another might be Mc Leod Method, CBR method....
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Depending on the type of tests (fatigue, modulus) you carry out in your country the French method would be fine.
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The NCHRP rpt 513 says that the range of stress for unconfined test on asphalt concrete (both static and repeated load test) is 69 - 207 kPa and for confined test it is 483 - 933 kPa. The typical confinement range is 35 - 207 kPa.
What is the reason for stress range? (Whether the material will behave as linear viscoelastic?)
How to choose the a specific stress for loading?
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Dear Nithin..it depend into large extent on testing temperature due to the rheological properties of asphalt..anywhy..you can consider low limit of stress when testing on high temperature say over 40 degree Celsius otherwise when testing at low temperature you can pickup high stress level,,but you should remember that the testing loading cycles better to be more than 1000 repetitions to get good statistical relationship..regards   
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I have conducted FT-IR spectroscopy for my bitumen samples dissolved in CS2 5% by weight but I am getting negative value of absorbance for most of the samples. What is the reason behind this? Is there any way by which I can correct my data or will i have to conduct the test again?
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Dear Bhupendra,
There is a standard test protocol by BRRC for FTIR of asphalt binders. They have used Tetrachloroethylene solvent for the test.
The following link may help you.
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I have to  design a rigid pavement road and conduct geotechnical investigation along the road alignment. In this regard, I need to conduct a few California Bearing Ratio (CBR) tests along the road length. What is the requirement of CBR test frequency, namely, after how long distance, the test shall be repeated as per international standards such AASHTO or ASTM or so on?
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Dear Dr. Ullah:
I will scan some relevant pages for you and send them
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Any Methodology is appreciated.
I want to sample the water that enters the pavement based on the different mechanism.
I do not want to block the road, unless for putting the instrument of water sampling in place.
Heavy vehicles are using this road.
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This suggestion is untested for this type sampling for your purpose, but worked well for sampling water in irrigation study.  Plastic pipe with porous ceramic cups epoxied at one end, two hole stopper at other end with long and short tubes used in plastic pipe, short one for evacuating or pulling a suction and after water enters and accumulates, use pressure on the short tube to push water into long tube and out for collection.  In this type of installation, perhaps gravity could be used to deliver water if pipe installed from side of road with a grade for delivery.  I would try to use bentonite clay to seal up hole if necessary if it is not a tight fit (Note: Do not get bentonite on the ceramic cup (or anything else basically, wear gloves, eye and other protection) as it could seal ceramic cup and limit sampling.  Bentonite expands when moistened, and wont wash out of clothes and probably has some other hazards to review if using.). I dont know that this sampling approach would work, but relatively inexpensive to make and install, just use the same size soil corer and pipe, ceramic cup for a tight fit.  You may need to pull the vacuum on the pipe before the storm to ensure sample is taken.  If the sampler will not hold a vacuum, you may need to pull the vacuum after the storm or look into running such as a peristaltic vacuum pump to provide a continuous vacuum.  When removing sampler from road after done, use bentonite or other suitable fill, compacted in layers to refill hole. 
If you use the pipe installed on an gradient for delivery of water, even if the ceramic cup becomes cracked or smashed, the void may still be able to collect some water to provide a sample.  I would pick a place to sample along road where if the road surface is damaged for some reason, it is not going to create an accident or excessively damage the road. 
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I want to perform LAS test on asphalt binder with Rheotest DSR but, unfortunately, after defining job and method in software in CD OSC manner, the test does not start. Whether this device performs only stress constant tests or not? How I can solve this problem?
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Thank you all for your answers
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When performing HMA mix design by Marshall test according to the MS-2(7th), the mechanical hammer was selected, is it necessary to check the compaction number by the manual operation, and why to do it? Especially, is the same way for the 6-inch Marshall test?
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Dear all
Thank you very much to give me a hand, the AASHTO R68-15 section 3.2.2 and AI MS-2(7th) section7.2.4 both metioned the correlation procedure, it is really confused me. 
When performing automated operation, I agree with yours' opinion. it is due to many varaibles exists in the manual procedure.  
Thanks yours' help indeed
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Hello, 
I am planning to conduct conventional testing (dynamic modulus, flow number, four points bending beam, etc.) on asphalt materials (HMA, binder, unbound materials, and CBM). I wanted to know what would be the significant number of replicates that is significant to perform statistical analysis of the testing results. Standards mentioned that 3 replicates would be enough, but I believe that for statistical analysis, minimum of 6 replicates are required. I would appreciate if anyone can support my claim for the number of replicates required and provide me with references that help in that matter. 
Thanks.. 
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Dear Sadeq
for every laboratory testing, there is a degree of significance, as you are testing asphalt concrete specimens, 0.95 significance is sufficient for your purposes, the standard deviation of test results from the mean value should be within -+ 5%.
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My research is related to finite element modelling of reflective cracking in flexible pavements. I've been using ANSYS APDL 15.0. But the crack propagation part is difficult to be modelled. I dont find any inbuilt option for cracks.
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Hai,
      I am doing a project on crack growth simulation. May we could discuss about your project
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SAR backscattering coefficients
asphalt roughness
roads quality evaluation
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1. Is there relationship between asphalt roughness and SAR backscattering coefficients?
A. Obviously. But results will be severely biased by car traffic, off-road infrastructure (road signs, poles, ads), trees (remember all RS radars are backscattering radars), buildings, hills and mountains, etc.
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Looking for good paper(s) that deals with estimation of the curve number of pervious asphalt from the hydrological point of view
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Unfortunately, I don't have the pdf file. You can try to request the full text through the link provided above.
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I am undertaking experimental study on modifying asphalt binder using different percentages of different materials to enhance asphalt resistance to cracking and deformation and was wondering if there is a way to optimize this whole process to find the best percent that would provide the best properties. Keeping in mind that, for the most part, cracking and deformation are inversely related.
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The attached file implemented the stat-of-the-art optimization algorithms in excel and you can use it.
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The equations for analysis stress and strain of flexible pavements as mentioned in "pavement analysis and design" for (Y.Huang) have E term for modulus of elasticity but as known that there are more than one type of elastic modulus of HMA such as static,dynamic,resilience so which one is used in these equations? and how I can measure it ? 
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For granular layers, the elastic modulus based on the recoverable strain under repeated loads is used. This is the resilient modulus Mr. for granular materials, this modulus is determined by the repeated load triaxial test. For asphalt mixtures, indirect tensile tests can be used. It is worth noting however, that most advanced pavement analysis tools rely on the dynamic modulus. The dynamic modulus test provides a better characterization of HMA than the resilient modulus test because it provides full characterization of the mix over temperature and loading frequencies
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good day, please does anyone have an idea on calculations involved in flexible pavment design, and it will be helpful if I can also get articles.
thank you
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If you are following AASHTO there is an equation 
which described in a graph
this site is summarizing this method
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Please consider a specimen that is compacted in Optimum Moisture Content (OMC). I want to increase the moisture in this specimen so that the moisture distribute throughout of the specimen uniformly. For example, imagine that the OMC is equal to 10% and I want to increase the amount of moisture in this specimen after compaction to 15%
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Ebrahim,
Here is the procedure of increasing water content after compaction:
-Find an appropriate mold (maybe plastic pipe for cylinder or wood made for cubic)
-Start with an initial water content which matches with saturation ratio and  dry density target .
- Compact your sample till calculated height (still you are not on your targeted water content)
- Calculate target water content on the wet side of optimum density and matches with saturation ratio-dry density and pour half of it on the top. let it be isolated for 1-3 days depending on your soil type. ours was cohesive clay and we kept it for 2.5 days.
- Reverse the sample and pour other half of water on the bottom. Keep it isolated for the same time.
- Now your sample is almost homogeneous in water content percentages. 
-Run a water content test from top, bottom and middle of every sample after you ran your test as a report.
* you may see some error according to change in height, expansion, non homogeneous distribution and ...  You have to verify them with measuring height after reaching water content as well as water content tests.
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I am mainly looking for the reaction that may affect the mechanical performance of the soil.
Thanks
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Dear Mr. Sangsefidi:
your question is too general in its essence and tries to be all embracing. Climate, parent material etc. have such a strong impact as the hydraulic regime and the geomorphology. You ask about opinions on chemical reactions and refer to physical processes leading to mechanical performance.
What is it all about? Be more focused, please.
Harald G. Dill
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I know that cations play an important role in Diffuse Double Layer thickness. Furthermore, I know that the concentration of anion increases as the distance from aggregate increases.
So, what is the difference between monovalent and divalent anions in the diffuse double layer?
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Dear Ebrahim:
Look at the formula for the thickness of the diffuse electric double layer in the Gouy-Chapman theory. The charge of the ion is in the denominator . Therefore the thickness of the diffusion layer decreases with increasing ionic charge.
Regards.
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I mean what is the consequence of changing the amount of these ions (for any reason) in the soil (increase or decrease).
In addition, I am eager to know that in what form these ions appear in the soil.
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Fe+3 should increase the soil strength as it acts as a binding material.  Fe+2 is soluble, so it will actually have the opposite effect on soil strength.
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Hi, I want to run Multiple stress and creep recovery (MSCR) test on pen 40/50 bitumen. This test is generally conducted at the high temperature of the Superpave performance grading or PG (i.e., max pavement temperature). I do not have pen 40/50 bitumen with us so that we could do the PG. Can anyone please tell what would be the equivalent PG of the pen 40/50 binder?
More details on bitumen:
Penetration 45-49
Softening point 51-53 C
Thanks
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You can't really determine the equivalent without testing. The range of rheological properties for a given Pen grade is much wider than PG. Based on my limited experience with Pen 40/50, its HTPG could be 70 or perhaps 76. To run your MSCR you may try 64 or 70 as your base temperature. But, if you want to go to the trouble of doing the MSCR, why don't you just determine the HTPG as well. You have to do RTFO aging and make DSR samples, you might as well make a few extra samples and run the HT PG on both age and unaged as well. You need to do that and find the S grade and then see if it satisfies H or not. Read the following short article: 
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After doing preliminary research scan (lots and lots of semi-relevant research), I am still looking for research on motorway conditions where pavement quality generally good, and the variation in roughness (IRI), regulation, micro- and macrotexture are fairly small. Is there still a detectable effect on safety outcomes? If so, for which crash types? Seminal and leading research leads will be appreciated. 
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You might find help, at least on the methodology, in this study of accidents on all types of roadways (not just highways), their geometry and detailed surface conditions (ch 9, enclosed).
If you want more details, you have to look at the final table in the detailed paper, enclosed also. The last variables in the list (Groups 13 and 14) are all surface quality variables. But the source of the data, the French technical road services, forced us to hide the detailed results for eight variables (A...H) in that section. They were afraid of lawsuits, as were occurring in Germany at the time, based on the idea that better surfaces increase speed and perhaps accident risk or severity.
Hoping this helps. Marc Gaudry
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Hello Everyone
I'm trying to model the mechanical behavior of asphalt concrete...and i need a some sobroutine to do this. Someone knows if I can do this or if i can download a Subroutine to do it?
If anybody knows some tutorial for UMAT i´ll be very grateful
Thanks 
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Hello
I Do not finished....I'm Sorry. I´ll Try to do another hing in my research. I´ll try to model whit DEM. Thanks for your answer. 
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I know there is some test to assess asphalt aging in the pavement service life.
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Dear Ravi,
Thank you for your response.
I totally agree with you, but I am seeking for a method to accelerate the aggregate deterioration due to the presence of water. In the other word, I want to simulate the effect of water on aggregate during pavement life.
for example, the effect wetting and drying, freezing and thawing and etc. 
Thank you.
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For example, AASHTO recommended six aggregate gradation range (A to F).
How can a designer select a special range for a road base or subbase materials?
How have these special ranges been determined? Is it possible to not to consider these aggregate gradation ranges?
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Dear Ebrahim,
Like Harith said,
I think it depends on your design loads, base on that, you can calculate and choose which materials and gradation that fulfill your needs. For example, according to AASHTO, soil classified as A-1-b, A-2-5, A-3, A-2-6 with CBR test result from 20-50 described in "Good criteria" for base and subbase, but even so, sometimes that is not what we need, maybe our pavement design needs already fulfilled by the use of soil in the medium criteria, because materials selection also related to our cost, so we have to choose wisely.
So it depends on your design calculation, with that needs, which materials acceptable to support it, what gradation and etc.
Hope that could help...
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I'm looking for a valid and accurate relationship 
but i don't know witch relationship is better.
power models or regression?
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Dear Hossein,
The report that Tatjana sent is good. But, please note the comments made by Luis and Sinnappoo. The correlations will be very much dependent on the level of maintenance and rehabilitations. For example the IRI in the wheelpath picks up mainly the distresses such as corrugation, depression (short lengths), bumps and sags, potholes. But, not the low and moderate ravelling, bleeding, carackings (unless they are severe enough to contribute to roughness), etc, So, the correlations as commented by others can best be used as a rough estimate. Because, they depend on the class of the road, level of maintenance, environment, etc. that could be very different from a country to anither. Therefore, You can't use the ones from the Washington DC area to your locality of Zanjan.
Regards,
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TxDOT use DS and CS as pavement indicators 
in other side i find the article that developed pavement prediction(based on PCI) model based on TxDOT model. but the model in not sensitive to climate and traffic condition 
i have to obtain this model for all traffic an climate conditions.
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Dear Hossein Mohammadi,
I suggest a paper link which is useful for your research work.
See Paper No. 590 “Pavement Deterioration Modeling for Low Volume Roads” by
Vandana Tare, H.S. Goliya, Atul Bhatore and Kundan Meshram, Journal Of The
Indian Roads Congress Volume 73-4, pp. 67.
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I am intending to work on a simulation software in pavement engineering. I am interested to simulate asphalt behavior using the simulation software. Which behavior of asphalt should I start with? For Example, crack propagation simulation, microstructural simulation (I saw a paper). Can you also suggest a suitable software. Regards,
Imtiaz Ahmed
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Many studies suggested that Discrete Element Method (DEM) via PFC2D and PFC3D software (Itasca) could be used to to simulate deformation and fracture in different materials, even in asphalt mixes. The discrete element algorithm models a continuum as a system of distinct, interacting, and general-shaped particles subjected to laws of motion and deformation, which are bonded together. When the maximum stress in a contact bond is reached, the bond is broken and a separation of these particles (cracks) can be observed. 
PFC software is a little tricky and not that user friendly, especially if you are going to use your own model to simulate asphalt mixes responses.
Good luck.
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Dear researchers,
I am a young researcher in pavement engineering, I work on the HDM-4 (highway development and Management 4).
In this context, I try to contact specialists, researchers, etc ..., who work with this incredible tool, and to exchange with them and discuss their experience in the field of maintenance roads.
Abdelilah Bannour
Cadi Ayyad University, Marrakech, Morocco. {email removed by admin}
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Please find attached a good article regarding your question above. hope it will help.
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 An issue that has come up recently in our technical meetings is the use of FWD measurements as a tool for controlling the structural capacity of the pavements in our Design-Build projects. Since a few years ago we have started with this kind of contracts for both new and rehabilitations (bearing capacity improvement) projects in which we only set functional requirements (rut formation, cracking, IRI) during the guarantee period and no specific structural requirement is set on the . The guarantee period in our current Design-Build contracts are 10 years due to socioeconomic aspects.
 
The 10-year guarantee period is not very favorable for us from the technical point of view as there is a risk that we get pavement structures that are not very robust and require relatively high maintenance costs after the guarantee period is over. Therefore, we are looking for developing a method in which we can indirectly set structural requirements for the design through use of FWD data for our road network. Currently, we conduct FWD measurements shortly after opening of the road to traffic, but this is only done for the sake of documentation and no requirement is applied using the FWD measurements for the approval of the product.
1. I am wondering if similar kind of contracts are used elsewhere? If yes, do you apply any structural requirements to approve the final product in such contracts?
2. Is FWD used for such purpose?
3. Any suggestion on how we can develop a suitable method through use of FWD data for setting structural requirements in Design-Build Projects?
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Dear Farhad Salour ,
SRRY For getting U delay Bcoz  "  Act of God in My Place ''
Follow  IRC - Indian Road Congress Standard If Suitable Further Details also I will Enclose , Now Here you asked the Details below,   
IRC:115-2014
GUIDELINES FOR STRUCTURAL EVALUATION AND STRENGTHENING OF FLEXIBLE ROAD PAVEMENTS USING FALLING WEIGHT DEFLECTOMETER (FWD) TECHNIQUE
Contents - 4 - Page - 4 to
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Please kindly help me regarding this issue, especially for flexible pavement. If it is possible, help me also with the references.
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Surface deflection, as like as stress/strain, is a pavement response which may be considered to be dependent upon various internal and external factors. Internal factors, i.e. material specifications and characteristics, are those which are usually selected to produce different types of asphalt mixture, and base/subbase courses; while the external factors, e.g. loading frequency, aging condition, temperature, etc., are related to different traffic and/or environmental conditions to which the pavement may be exposed.
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The distance between aggregate particles decreases due to the compaction effect and eliminate the air voids. Specimens of known design information (Gradation , Asphalt Content and Air Voids) will be sliced - Cut sections - then scanned and by using the nearest neighbor distance method such as Delaunay Triangulation (where we can incorporate computer programs as AL Illustrator For triangulation and distances calculation) to study the change in the inter-particle distances and area distribution .
So my question is on the scanning process and type if any one have a clear idea about the most effective way to determine the inter-particle distances ?
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I think you can define another term namely "inter-particle areas" instead of "inter-particle distances". In other words, if you can use the image processing method on your photos, you may calculate the net area surrounded by the particles. The mentioned area, which is an indication of air void content, decreases as the compaction effort increases for constant mix characteristics. Finally, if you can correlate the air void content as well as the compaction degree, both of which may be determined by the direct measurements, to the newly defined "inter-particle areas", it is possible to develop predictive models. It must be noted that the method of compaction may have a significant effect on the distribution of air voids within the specimen depth/height. So, you have to calculate the average of "inter-particle areas" determined for different slices.
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I am working on pavement performance so need to determined PSI.
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I support the good answer stated by dear Rawand. To complete the mentioned explanation, it may be noted that the primary factor which is used in the existing literature to determine the PSI may be considered to be longitudinal roughness. Thus, some researchers have not used the other factors, e.g. cracking, patching, etc., in their correlations. Therefore, PSI may be determined solely by the use of pavement roughness, especially for the rural pavements, with a high degree of accuracy.
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I recently came across a case of a lightly trafficked pavement in which a particular type of clear binder is mixed with naturally colored aggregate. The surface is suffering from premature top-down cracking. My preliminary work on the binder used indicates that the binder could be the source of the problem. I wonder if any of you folks have worked with such type of binders. Clear binders are generally synthetic binders that contain no asphaltene molecules. They are used to allow coloring of pavement surfaces for safety and aesthetic reasons. These binders offer the possibility of making asphalt mixtures of any color by varying the color of the aggregate or by adding pigments.
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Professor Cong: I totally agree with your comment about the lack of  ductility of these types of binders.  That was actually confirmed through laboratory testing.  Aging does not seem to be a problem though according to the RTFO aging protocol. I could not find sound literature about such types of binders to compare my data with.
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I conducted a temperature sweep from 25-80 ºC and I got the following graph for different asphalt specimens. The phase angle data are noisy in the initial temperature range (lower temp. range) for the PAV aged binder  (purple colored phase angle curve) and other  binders . Can Anybody explain me the reason for this noisy data? the data were collected at a rate of 1data/2 seconds. This was a stress controlled test at 10 Pa and the 25 mm plate geometries were used in DSR.
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The Purple sample was a PAV aged VG 20 grade binder without any modification. 
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Pavement Engineering, asphalt binder materials, road construction technique  What factors influence to failure of chip seal (surface dressing) in tropical climate?
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Assuming you are asking what issues are unique to hot weather seals...... most sealing binders, in order to be able to wet the stone at normal temperatures, have low softening points – at least compared to asphalt binders. If not sealed during the hottest weather, the bitumen can then go soft when very hot. This is a high risk during the first summer when the volatiles escape – but soften the bitumen beforehand. My message is: do not seal in hot weather environments except during the hottest weather, and never seal in the coolest weather when cutter is required to wet the stone.  Also pick the most high-temperature resistant bitumen you can without adversely impacting your ability to wet the stone during construction.  I have numerous papers on sealing airport pavements which all address this issues.
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pavement material
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You can benefit from the Texas Transportation Institute report FHWA/TX-09/0-5627-1. A good reference.  Check pages 75-77 in particular which talk about the British Pendulum testing. You might be able to download it from the following link:
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I need to know the maximum compressive strength achieved so far with porous concrete. Any article for references?
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Dear scholar, Thank you so much to initiate this discussion. This is an interesting discussion to follow. Thank you Mr Kundan Meshram for your information as well.
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Looking for recent research/literature on improving the engineering characteristics of soils containing high amount of gypsum to be used in the granular layers of a pavement structure.
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Dear Khalid
I am interested in asphalt stabilization of gypseous soil and had published many papers on the subject, kindly inform me if this is matching your problem so I will send you my work.
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Concrete pavement - terminal system - restraint movement - anchor lug
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Hi Soheil, Designing rigid pavements includes two main aspects, flexural fatigue of the concrete rigid layer (called base in Australia f'c=32 MPa for highways or the top pavement layer in Iran) and vertical erosion of subbase/subgrade under concrete joints. Kenslabs and other pavement software programs can design the pavement part based on the miner's low over the pavement design life. I don't see any reason for using anchor lug in the ordinary rigid pavements that relates to enhancement of the pavement fatigue. Anchor lug treatments are generally applied in continuous reinforced concrete CRCP, especially at the approach for bridges to restrict the pavements movements in both directions. they make pavement like a T shape slab. typically three to five beams of reinforced concrete with the dimension of widthxdepth 50x100mm are enough. they should be placed at  5 meter distances before the bridge under the pavement.  design the the top CRCP with Kenslabs and keeping the resulted thickness add the supporting concrete beams in the bottom. connect anchor lug to the pavement with Q10 or Q12 mm reinforcement.
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Hi, I am trying to determine the time needed for asphalt pavements to cure (after final compaction) before opening the road to traffic. Does anyone have any relevant papers that I can use? Thank you in advance.
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The word "curing" appears more appropriate for cold asphalt mixtures (CAM) whereas for hot-mix asphalt (HMA) "cooling" and, afterwards, "aging" is what you should focus on.
Assuming you are dealing with HMA all you need (almost) can be found the excellent textbook: Roberts, F. L., Kandhal, P. S., Brown, E. R., Lee, D. Y., & Kennedy, T. W. (1996). Hot mix asphalt materials, mixture design and construction. (there is also an updated edition).
Normally you can open to traffic when the pavement is "cool" enough, so that the "consistency" of the bitumen allows the material to achieve appropriate stiffness and strength: cool enough is good enough! (As an empirical indication one could consider the softening point of the bitumen). At this stage the pavement will be particularly sensible to high shear stresses, therefore one should be very careful when paving at intersections or short-radius curves (high shear stresses due to cornering tires). Afterwards, aging due to oxidation leads to increase of "consistency" of the binder: things get better! ("consistency" is not the exact technical term, please avoid it).
I was involved in a similar problem during the resurfacing of an airport pavement (https://www.researchgate.net/publication/267626200_Presentation_at_BCR2A_2009?ev=prf_pub). Paving was carried out in the night (runway closed) and trafficked in the morning (first landing at 7.00). This was an "extreme" case because shear forces due to breaking could be really high. I used a split-mastix-asphalt (SMA) produced with modified binders. We had a fire truck ready to flood the pavement (and cool it down) in case of delay of paving operations.
Good luck!
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rutting factor- G*/ Sin δ
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Whether you determine your rutting parameter |G*|/sind through a stress-controlled or a strain-controlled measurement, the resulting value should theoretically be the same provided, of course, the evaluation is done at identical values of stress and strain at an identical temperature and an identical pre-shear and measuring shear deformation history.  So in that sense, it should not matter whether this parameter, which is the inverse of the loss compliance, is obtained from a stress-controlled or a strain-controlled measurement.  However, what is difficult is to have identical shear deformation histories in the stress-controlled and the strain-controlled measurement.  Hence, the values of |G*|/sind obtained from the stress-controlled and the strain-controlled measurement could be different even when compared at identical temperatures. 
Strain-controlled measurement is the preferred one and rightly so, because it is more robust in its response, gives better repeatability, and the actual deformation (strain or strain rate) that the material is undergoing can be kept within realistic limit.  On the other hand, stress-controlled measurements can result in unrealistic deformations that the material does not see in reality and would not represent the true material behavior.  There is often the likelihood of obtaining values indiscreetly outside the range of significance through meaningless measurements just because the equipment is capable of producing the information.  A typical example is the multiple stress creep measurements under stress-controlled conditions wherein the response to the high levels of imposed stress create very unrealistic deformations that are well beyond any level of deformation that the material sees in practice. [Aroon Shenoy, Non-recovered compliance from dynamic oscillatory test vis-à-vis non-recovered compliance from multiple stress creep recovery test in the dynamic shear rheometer, The International J. of Pavement Engg., Vol. 9, No.5, pp. 329-341 (2008).]
It is important to bear in mind that the range of the response strain or stress must be within the appropriate levels that the material sees in actual practice independent of whether a stress-controlled or a strain-controlled measurement is done.  To get an idea of the relevance of getting rheological data within the appropriate applicability and correct sensitivity ranges, you could refer to any of the following books in case they are available in your library:
1. Aroon V. Shenoy, Rheology of Filled Polymer Systems, Kluwer Academic Publishers, Netherlands (1999).
2. Charles P. MacDermott and Aroon V. Shenoy, Selecting Thermoplastics for Engineering Applications, Marcel Dekker Inc., New York (1997).
3. A. V. Shenoy and D. R. Saini, Thermoplastic Melt Rheology and Processing, Marcel Dekker Inc., New York (1996).