nbmcw april 2013

66 NBM&CW APRIL 2013

Pavement Equipment

IntroductionThe Annual Transportation Research Board (TRB) meeting in the US is held every year in the month of January in Washington, DC. This meeting is very well attended, and most people who are involved in consulting work, teaching or research that are related to some aspects of transportation engineering, try to attend it. There are numerous parallel sessions spread out in three hotels, and the subjects include numerous topics ranging from administration and management, design, education and training, operations and trafc management materials, pavements, aviation and vehicles, and equipment. The number of papers/presentations has been growing steadily over the years and this year, there were more than 4,000 presentations in approximately 750 sessions, with a record attendance of approximately 12,000.

Apart from listening to speakers about latest research work in the transportation area, and participating in committee meetings to discuss ongoing work and future session

proposals and generate problem statements, most people enjoy the opportunity to meet and network with transportation professionals from other agencies and universities. Everyone who has been to this meeting agrees that it is an enlightening experience, and there are people who have been attending this meeting for decades they would not miss it for anything!

Probably the best part of the annual TRB meeting is receiving the compendium of research papers - this year there were 2,400 papers available. It is very critical for transportation professionals, and students and researchers to be aware of ongoing work, state-of-the-art and state of the practice in their respective

areas, and specications that are being implemented. A careful review of the relevant papers is a great way to stay abreast in the profession and many professionals and students do travel from other countries to attend the conference. However, in many cases, it may not be able for people to devote the time and/or money to travel to the meeting, specically from foreign countries. It will be helpful for these people to have a forum

for exchanging summaries of the important papers that are presented in this meeting.

The objective of this article is to make a humble attempt to summarize some of the important and relevant pavement engineering (specially asphalt/composite pavements) related papers for researchers and practitioners in India. Hopefully, this will help them, and more importantly, y for students, stimulate their interests in the pavement engineering eld.

FormatIn the following paragraphs, summaries of forty pavement engineering related papers are presented. These papers were selected on the basis of the

A Snapshot of Pavement Engineering Papers Presented at the 2013 Annual Transportation Research Board Meeting in Washington DC, USA

A. Veeraragavan and Rajib B. Mallick


Pavement Equipment

following criteria: 1. The topics are relevant for ongoing pavement engineering related work in India; 2. The papers present practical methods that can be useful in the near future; and 3. Topics include specications that can be implemented for improving pavement related work in India.

Rather than presenting summaries of each paper, extracts from relevant papers are grouped into several key topics, which correspond with the titles of the sessions in which the papers were presented. It is acknowledged that the authors choices are subjective and may not match with that of everyone the readers are requested to provide feedback, so that in future, if such an article is written, it will be of more relevance and help to the readers.

Cold In-Recycling of Asphalt PavementsThe Asphalt Recycling and Reclaiming Association (ARRA) is preparing a compilation of guidelines for mix design and construction of cold in-place recycling that will be available soon on their website (Cross, 2013). Some of the specications relate to calculation of theoretical maximum specic gravity of recycled mixes, compaction effort in the laboratory, curing protocol, use of ,moisture susceptibility and raveling tests. Of particular interest is the specication

for cold recycling in high temperature regions. The new approach is to consider the fact that relatively less recycling agent will be required in such recycling operations in warm climates, and the specications of tests to validate the effect of the reduced recycling agent content, with the help of relevant tests, such as the raveling test (ASTM D7196).

A signicant amount of both laboratory and eld research information pertaining to short- and long-term properties of foamed asphalt in-place recycled mixes were presented (Halles et al, 2013). Procedures for the determination of active ller (such as cement) and asphalt contents included checking changes in indirect tensile strength and resilient modulus, by keeping one factor constant while changing the other one, and vice versa. It was concluded that while the addition of cement helps in short-term strength, the asphalt content provides long-term durability, which can be evaluated with resilient modulus tests in both dry and wet cycles. The importance of providing adequate curing time was stressed to ensure the proper contribution of the asphalt (from the foamed asphalt) towards the durability of the mix. On the basis of a comparison of durability results from different countries (Greece, South Africa, Chile) as well as laboratory

results it was concluded that the use of a stress ratio (SR, maximum tensile stress divided by the tensile strength) could be used as an effective indicator or long-term durability, as follows: SR, 20%, constant stiffness, SR: 30%, decrease in long-term stiffness with constant rate, SR: 40%, decrease in long-term stiffness at increasing rate, and SR: 50% or above, failure in the long term performance. (long-term stiffness would be the same as that of granular materials) Accordingly, the concept of determination of an endurance limit (in terms of the SR) was proposed, and the relatively low contribution of a higher cement content at higher SR was mentioned. Caution was expressed regarding the importance of checking disabilities for foamed asphalt mixes with same mix design but with binders from different sources and different active llers.

Results of over decade long research with foamed asphalt by California Department of transportation (DOT) were also presented (Jones, 2013). Several issues affecting the performance of foamed asphalt recycled mixes were discussed including moisture problem resulting from lling up of side drains by farmers, changes in gradation resulting from second pass (after pre-pulverization) and common equipment problems. The need for the continued presence of a trained technician (walking behind the


Pavement Equipment

recycling machine) was emphasized for quality control. Important points discussed included the need for proper distribution of cement (with depth and laterally, high localized cement content can lead to shrinkage cracking), need for proper compaction (to avoid premature cracking) with heavy rollers, specically for >200 mm thick recycled layers, expedited rolling in hot weather (to avoid setting up of cement before compaction), and the necessity of applying the hot mix asphalt layer right after curing (10-15 days). It was concluded that softer foamability of asphalt binder should be checked with proper consideration of expected pavement temperature (during construction), softer binders are better for foamed asphalt projects, and that upto 15% ller content is acceptable as long as the moisture sensitivity of the mix is checked properly however a higher ller content results in a higher design asphalt content. The need for the evaluation of the effect of ller plus the active ller was stressed. Currently, research is being conducted to develop input parameters for mechanistic empirical design of foamed asphalt recycled layers, and the effect of recycling layers with rubberized asphalt.

A case study on premature cracking of a foamed asphalt pavement on Peru-Brazil highway was presented (Menendez et al, 2013). The authors evaluated the mix design, construction process and the structural capacity of the pavement and concluded that the premature cracks were a result of a combination of poor curing process, low relative humidity, excessive nes and low structural capacity. They recommend an early curing process, quick application of a surface seal, and the adoption of specications for tolerable rage of nes, layer thickness and maximum deection.

Research results of evaluation of horizontal tensile strains at the bottoms of HMA layers and base layers granular and emulsion stabilized full depth reclaimed (SFDR) lying underneath, were discussed (Johanneck and Doi, 2013). Gages were utilized to measure strains under pavements in MnRoad test sections, under both FWD and truck trafc loading. The results indicated that the use of SFDR reduces the tensile strain in HMA layers signicantly, and that the strains are actually higher at the bottom of the SFDRs than at the bottom of the overlying HMA layers. Based on the eld data and modeling, the authors concluded that SFDR will provide greater structural benets and better performance than unstabilized FDR or granular base materials.

A study on cold in-place recycled (CIR) pavement in Brazil was presented (da Silva et al, 2013) in which the authors discussed the results of tests on eld course and Falling Weight Deectometer (FWD) testing. The results showed a decrease in modulus during rainy seasons and similarity (in terms of orders of magnitude) between laboratory resilient modulus and backcalculated modulus from FWD data. The authors recommend the application of light trafc immediately after compaction and the use of a

specic (14 day) curing period; they also concluded that the application of a relatively thicker HMA overlay (40 mm) gave better performance compared to a micro surfacing (over CIR layer) only.

Outcomes of a thorough evaluation of materials, construction and environmental related aspects of emulsion stabilized full depth reclamation (FDR) project were utilized to present a new laboratory mix design procedure and guidelines for construction of emulsion FDR projects (Nazarian et al, 2013). The authors recommend specications based on unconned strength and indirect tensile strength for laboratory mix design and guidelines for the use of the portable seismic pavement analyzer (PSPA) for eld quality control. The effects of the use of the new mix design tests were discussed with respect to eld projects in Texas.

Nondestructive Hot Mix Asphalt (HMA) TestingThe use of ground penetrating radar (GPR) for measuring density of compacted Hot Mix Asphalt (HMA) mat as a quality control tool was discussed (Shangguan et al. 2013). While measurement of thickness is possible, traditionally GPR is not used

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Pavement Equipment

for density measurement right after construction because of the effect of water that sprayed by rollers during compaction on the GPR signal. This research points out the relatively less signicant effect on the lower frequency components of the signal, and proposes the use of a lter (200-800 Mhz) for a 2GHz antenna signal to extract surface reection amplitude and processing. Validations of the proposed approach are presented or two sites and similarity of GPR density and nuclear gage density were demonstrated.

The effect of temperature and moisture on results obtained from non-nuclear density gages was presented in a paper (Timm et al, 2013). Comparison of results from tests with a nuclear density gage and two non-nuclear density ages, a PaveTracker (Troxler) and a PQI (Transtech) showed similar density measurements, and that aggregate mineralogy, nominal maximum size of aggregates, HMA type, absorption as well as pavement markings did not cause signicant effect on the non-nuclear density gage readings. Recommendations were made to use the nonnuclear density gages when the pavement temperature is equal or higher than 90oF and when the HMA is dry, to avoid signicant effects of temperature and moisture.

Guidelines for the use of Portable Seismic Pavement Analyzer (PSPA) were provided (Faheem et al,. 2013). The researchers recommended the use of PSPA as a quality control tool during pavement construction through the measurement of stiffness, as follows: 1. Conduct ve tests per test location and take the average after discarding the maximum and the minimum; 2. Conduct tests at two different temperature ranges to establish temperature dependency of stiffness; 3. Use a modulus

temperature relationship to normalize all measurements to a standard temperature of 130F; 4. Conduct tests away from shaded areas and joints; 5. Avoid testing at temperatures above 140F; 6. Randomize test locations in transverse ad longitudinal directions. The authors provide a correlations between eld modulus and laboratory mixture volumetric properties.

The description of a new nondestructive and nonintrusive pavement testing device, called the Total Pavement Acceptance Device (TAPD) was presented (Stokoe et al, 2013). The TAPD, developed in Texas, can measure pavement deections (with rolling dynamic deectometer), determine pavement thickness and subsurface conditions (with GPR), measure surface temperature and obtain digital video images (along with GPA data), while moving at 3-5 km/hr. The authors demonstrated the capability if the equipment with results of tests conducted on two pavements.

A newly developed equipment which combines an impact echo system and a spectral analysis of surface wave scanner, for detection of debonding between Hot MIx Asphalt (HMA) layers was described (Tinkey, 2013). The authors presented the background of the development of

the equipment and a case study of evaluation of the equipment on the National Center for Asphalt technology (NCAT) test section.

The relatively high variability in results of tests conducted with different nondestructive testing devices such as the light weight deectometer, seismic testers, impulse plate load testers and lector mechanical devices, when compared to results of tests with conventional density measuring devices were discussed (Mazari et al, 2013). The authors presented quantication of equipment and operator related variability in a systematic manner, and based on tests with eighteen spate test specimens the concluded that most devices produce repeatable and reproducible results provided the densities and moisture contents are controlled, and that most of the reported site specic variability are due to lack of process control during construction.

Pavement Preservation Practices, Patching Materials, Roller-Compacted Bike Paths, Determining Thickness of Concrete Pavement, and Other Recent AdvancesA review of current pavement preservation and maintenance practices in North America was presented (Tighe and Gransberg, 2013). The authors concluded the use of thin asphalt overlay is the most prevalent treatment for asphalt and composite pavements, diamond grinding and joint sealing are the most common techniques for concrete pavements, regrading and regraveling are the most common treatments for graveled roads, and chip seals for surface treated roads. The need for the development of an assessment system for environmental sustainability of pavement preservation


Pavement Equipment

and maintenance techniques was stressed.

The longevity of two common pavement preservation techniques, thin hot mix asphalt overlay and chipseals were presented (Liu and Gharaibeh, 2013). On the basis of analysis conducted with long term pavement performance (LTPP) data, the authors concluded that there is a wide range of life expectancy for the two treatments (500 2,000 KESALs for chip seals and 1,500-8,000 KESALs for thin HMA overlay), depending on the climatic condition of the project locations. Another paper (Dosa and Mamlouk, 2013) reported that the performance of chip seals were much better on pavements with greater initial smoothness.

Relative advantages of worst-st (W-F) and benet-cost analysis (BCA) approach for maintenance and rehabilitation (M&R) was discussed in a paper (Menendez et al, 2013). They analyzed data from pavement management database of a district in East-Central Texas and concluded that the W-F approach is less effective in reducing backlog and improving the condition of the roadway network when M&R share a single common DOT budget; however if the budgets are separated, then the disadvantages of W-F approach are less signicant.

A discussion on differences in concrete pavement thickness as measured by probing and from cores was presented (Whited et al, 2013). It was concluded that the differences are less than 3/8 inch, and recommendations were made regarding the required sample size to identify differences of inch, 1/8th inch and 3/8 inch.

The performance of partial-depth repair (PDR) materials for concrete material in a eld research project in Canada was discussed

(Soliman and Shalaby, 2013(1)). Repair materials were evaluated on the basis of a number of criteria, such as presence of cracks, spalling, separation between materials and concrete slab and deterioration of the repair materials. On the basis of the results, the authors recommend set of specications for evaluating partial depth repairing materials. In a companion paper, the authors (Soliman and Shalaby, 2013(2)) present laboratory methods for the evaluations of the PDR materials on the basis of bond between the material and the concrete and substrate and the change in the bond due to wet-dry and freeze-thaw cycling.

The concept of using roller compacted concrete (RCC) for the construction of bike paths was presented (Lee et al, 2013). The authors conducted both laboratory and eld experiments for mechanical strength, durability and rideability. They suggest appropriate cement content, water content and compaction ratio for attaining proper performance.

Results of a study carried out to evaluate the structural capacity of pervious concrete pavements constructed over virgin aggregate base, recycled concrete aggregate base and cellular lightweight permeable concrete (CLPC) (Armaghani, 2013). Based on the results of tests conducted with a Falling Weight Deectometer (FWD), the conclusions were that pervious concrete pavements are capable of handling moderate truck trafc on streets and low volume roads, and that the strengths were higher for the ones with the virgin aggregate and the CLPC than on the recycled concrete aggregate base.

Flexible Pavements Design A research on the comparative effect of the use of dynamic modulus data from indirect tensile strength tests and uniaxial compression tests on the rutting and fatigue cracking of asphalt pavements, as predicted by the Mechanistic Empirical Pavement Design Guide (MEPDG) software was reported (Guercio et al, 2013). Comparisons were also made between dynamic modulus data from laboratory reheated and plant and eld compacted specimens. The authors concluded that the results, for both different test and sample types were identical, and that agencies can select any of the two test methods and either laboratory reheated of plant/eld compacted samples they should expect similar levels of distresses that are predicted by the MEPDG software.

A paper presented the results of a comparison between a conventional (10 inch) and a perpetual (14 inch) asphalt pavement that were subjected to accelerated trafc loading in the National Center for Asphalt technology (NCAT) test track (Shakhaeifar et al, 2013). The life cycle costs of the two sections were evaluated with RealCost software and compared. The authors conclude that the conventional pavements failed by bottom up fatigue cracking, perpetual pavement has a signicant lower life cycle cost as well as better serviceability. The use of

NBM&CW APRIL 2013 75

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high-polymer mix was demonstrated as better alternative to rehabilitate failed pavements compared to the use of conventional mix in mill and ll construction.

A paper reported the performance of stone interlayers between cements stabilized base and asphalt mix layers, in Lousiana (Xingwei Chen et al, 2013). The authors reported the results of a eld evaluation of eleven test sections with and without stone interlayers, and concluded that the section with stone interlayer showed superior performance compared to the one without, and the performance of the other nine sections with stone layer were very good over a range of 2.5 to 12 years of service.

Results of analysis with 3-dimensional viscoelastic nite element method were presented to demonstrate the effects of non uniform tire contact pressure and

thermal gradients on the potential of cracking in asphalt pavements (Wang et al, 2013). The authors conclude that signicant tensile stresses present at the edge of tires may lead to top down cracking and negative thermal gradient (surface cooler than deep layers) increases its potential, while positive thermal gradient increases the potential of top down cracking.

A study on the effect of changes in groundwater level and moisture content on the various layers of a exible pavement as presented (Salour et al, 2013). In this eld study on a hill side road in Sweden, the subsurface drainage system was intentionally clogged to raise the ground water level and hence the moisture content in the pavement. From tests with Falling Weight Deectometer (FWD) conducted at different loads, the authors determined that as a result of rise in groundwater level, the stiffness

of the overall pavement decreased (with an increase in moisture content), the unbound layers showed stress dependent behavior, the subgrade showed stress-softening response in unsaturated and stress-independent behavior in saturated state, and the granular layer showed stress-hardening behavior. The authors concluded that the k1 parameter in the extended k- model decreased with an increase in moisture content for both unbound granular layers and unsaturated ne grained subgrade materials.

The concept of the use of high modulus asphalt binders to reduce the thickness of HMA layers was evaluated and conrmed in a paper (Geng et al, 2013). The authors considered different types of high modulus asphalt binders (HMABs) and tested mixes in terms of workability, viscosity, frequency sweep elastic recovery and bending beam


Pavement Equipment

rheometer tests. The properties were utilized in the MEPDG to estimate the permanent deformation potential of mixes with and without HMABs. The authors concluded that asphalt layer thickness could be reduced by 9 to 28% with HMAB, and that those with HMAB showed slightly less bottom up cracking; however they cautioned about the decrease in low temperature grading with the use of HMAB.

A comparison of load pulse duration from FWD drop and truck loadings were made with data obtained from instrumented section at the NCAT test track (Leiva-Villacorta and Timm, 2013) The authors concluded that load pulse durations from FWD range between 0.03 and 0.05 seconds, which were two to three times less than the pulse duration from trucks moving at 45 mph. Based on an analysis with a model, the authors concluded that the FWD pulse durations matched these from 120 mph trafc, and point out the signicant effect of overestimation of asphalt mix modulus for an underestimation of load duration.

Hot Mix Recycling, Environmental ImpactsEffectiveness of rejuvenators in recycling mixes with 100% RAP were discussed (Zaumanis et al, 2013). Nine different rejuvenators, including plant oils, waste derived oils, engineered products and renery base oils were evaluated at two dosages, with the help of asphalt tests (penetration and viscosity) and low temperature mix tests (creep compliance and tensile strength). The test results were utilized to rank the rejuvenators four of which were successful in restoring the desirable properties of the RAP mixes for effective recycling.

The rheological properties of asphalts prepared by blending RAP extracted asphalts (15 and 50%)

and new asphalts were discussed in a paper (Huang and Turner, 2013). The blended binders were subjected to oven aging, and an evaluation of their properties with the dynamic shear rheometer showed that there is a linear relationship between rheological, log* versus phase angle plot and RAP content for long term oxidative aging (regardless of RAP source), and the increase in stiffness with aging time is signicant initially and then levels off - similar to that of chemical aging kinetic model.

Crumb rubber modied asphalt is being increasingly used in exible pavements. A paper was presented that discussed the results of tests of zinc concentration on water leaching out of permeable friction courses with and without crumb rubber (Barrett and Larsen, 2013). Zinc concentrations were found to be signicantly higher in PFC with tire they offer the explanation that the zinc present in tires leaches out through rain water. This observation points out how the choice of stable road materials can affect stormwater quality, which can affect (negatively) many natural things such as aquatic life.

A new tool for determination of emissions during roadway construction projects was presented (Mukherjee and Stawowy, 2013). This web based software (Project Emission Estimator, PE-2) uses existing life cycle analysis assessment methods and inventories, and helps in the determination of emissions resulting from raw material acquisition and production, and the pavement construction phase.

A comparison of environmental impact of four projects using conventional hot mix asphalt (CHMA), dense and open graded crumb rubber modied HMA (ARDG and ARGG) and polymer modied HMA (PM-SBS) was discussed (Martinez-Arguelles et al, 2013). Ecoindicator 99 software was

used as life cycle analysis tool along with estimation of energy consumption and global warming potential The authors concluded that ARGG was the most eco-efcient, and ARDG and PMSBS had similar environmental load. They estimated that 5-65% of the environmental impact as from the production of materials and 29% of it was from the heating of aggregates.

Granular layers, Cement Stabilized Layers, Geosynthetics and GeocellsA comparison of stresses and performance pavements with aggregate base course, cements stabilized material and geosynthetic reinforcement in subgrade were presented (Cowell et al, 2013). The authors found out that inspite of higher stresses the geosynthetic reinforced sections showed better performance in terms of permanent deformation, compared to cements stabilized sections and aggregate base courses.

A combined laboratory experiment-numerical simulation study of geocell reinforced aggregates over soft subgrade was presented (Saride et al, 2013). The authors tested the response of geocell reinforcement in a test tank and simulated the behavior, and concluded that the height of the geocell has a signicant effect on the bearing capacity of the soil whereas the stiffness of the soft clay subgrade was found to affect the performance of the geocell signicantly. The authors conrmed the validity of using 3D nite difference code in modeling geocell reinforced aggregate and recommended the optimum height of the geocell reinforced aggregate as 0.8B.

Results of testing of a foamed asphalt recycled project in Kolkata was presented (Reddy et al, 2013). Mixes were compacted and tested


Pavement Equipment

in the laboratory whereas structural improvements after recycling were evaluated with Falling Weight Deectometer (FWD) tests. The authors suggest representative modulus values of foamed asphalt mix layers, and concluded that the recycling proves did improve the surface as well as the structural strength of the roads.

A comparison of response of pavements with granular material and recycled PCC aggregates and RAP aggregates recycled with cement was made (Soares, et al, 2013). The comparison was made with the help of a 3-D non-linear orthotropic computational road model. The authors demonstrated the signicantly reduced edge shear strains when reclaimed PCC and reclaimed asphalt aggregates with cements were used as base layers, in comparison to granular base layers.

Discussions on the use of a Clegg Impact Value (CIV) for using a Clegg impact soil tester to determine the opening time (for early trafc, before application of overlay) for cement stabilized base layers were made (Reese and Guthrie, 2013). The authors conducted a eld tests in several states across the US, relating rut depths and CIVs, and recommended an equation relating the critical CIV with the 7 day unconned strength of cement stabilized material for regular use.

In one of the papers, the benets of research with Accelerated Pavement Testing (APT), specically related to the development of innovations in heavy duty pavement, were presented (Plessis et al, 2013). This paper studied the performance benets and economic impacts of research and the results of implementation of the research. The paper highlights

the importance of sensitivity analysis (instead of single estimates of savings and benet cost ratio) and reported savings ranging from $1.13 to $121 million in the state of California.

SummaryA wide range of pavement engineering related topics were presented at the 2013 Annual meeting of the Transportation Research Board (TRB), USA. Of the many topics on asphalt pavements, recycling, particularly cold recycling, probably stood out as the most discussed one. There was also much emphasis on nondestructive testing and development of specications for such tests, for both structural design and quality control. There were presentations on pavement preservations techniques as well such as chip seals and their performances. And nally, there was a signicant amount of emphasis on the need for the consideration of unavoidable variability in pavement materials and construction during analysis and prediction of pavement performance. At the end of the ve-day long meeting it seemed that the pavement research community is adopting a holistic and comprehensive approach towards new concepts, tools, materials and methods the importance on life cycle cost analysis has now been superseded by that on environmental loading or costs,

and comparison of technologies on the basis of environmental impact is expected to become routine in the next few years. At the same time, there is a signicant amount of growth of high performance products, such as binders, that are being used to reduce thickness of pavements, increased consideration of the pavement structure as a whole (instead of studying it layer by layer) and extensive use of data from accelerated testing facilities for improving analysis and design of pavements, and determining long term performance.

The need for continuous research to develop better, smarter and more cost effective materials and techniques was once again highlighted in the meeting there is no alternative to hard work! And overall, the need for properly educated and trained personnel in the civil engineering community in general and pavement engineering in particular, was emphasized directly and indirectly.

References1. Cross, Stephen. Oklahoma State University,

Progress on Cold In-Place Recycling Mix Design. 2. Halles, Felipe., Thenoux, Guillermo, Gonzlez,

lvaro V, Stiffness Evolution of Granular Materials Stabilized with Foamed Bitumen and Cement

3. Jones, David, Pavement Testing, and Field Studies of Full-Depth Reclamation to Rene Guidelines and Project and Long-term Performance Models

4. Shangguan, P., Al-Qadi, I. L., Leng, Z., Schmitt, R., and Faheem, A. An Innovative Approach for Asphalt Pavement Compaction Monitoring Using Ground Penetrating Radar

5. Timm, Anthony. Wen, Haifang, Sharma, Sunil, Rose, Mark. Evaluation of Non-nuclear Density Gauges for Measuring In-place Density of Hot Mix Asphalt

6. Faheem Ahmed F., Schmitt, Robert, Al-Qadi, Imad. Portable Seismic Pavement Analyzer for Paving Quality Assurance

7. Tighe, Susan and Gransberg, Douglas Sustainable Pavement Maintenance and Preservation Practices: A Review of Current Practice.

8. Liu, Litao and Gharaibeh Nasir G. Survival Analysis of Thin Overlay and Chip Seal Treatments Using the Long-Term Pavement Performance Data

9. Dosa, Matild and Mamlouk, Michael S. Relative Benet of Chip Seal In Different Climatic Conditions Based On Initial Pavement Roughness

10. Menendez, Jose Rafael, Siabil Salar Zabihi, Narciso Paul and Gharaibeh, Nasir G Evaluating Worst-First and Benet-Cost Analysis Approaches for Prioritizing Infrastructure Maintenance and Rehabilitation Activities under Various Budgetary Scenarios

11 Whited. Gary C., Stenhaug Benjamin A., Loh Wei-Yin, Wisconsins Method of Probing Portland Cement Concrete Pavement for Thickness Determination: Six-Year Statistical Review

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12. Soliman Haithem, Ahmed, Shalaby. Performance-Based Evaluation Criteria for Cementitious Partial-Depth Repair Materials in Cold Climates, I: Field Performance

13. Soliman Haithem, Ahmed Shalaby. Performance-Based Evaluation Criteria for Cementitious Partial-Depth Repair Materials in Cold Climates, II: Laboratory Performance

14. Lee, Seung Woo, Park, Cheolwoo, Cho., Yoon-Ho, Lee, Hyun Jong, Kim, In-Tai. Application of Roller Compacted Concrete for Bike Road Pavement: Mechanical Performance, Durability and Ride-ability

15. Guercio, Maria Chiara., McCarthy, Leslie Myers., Bennert, Thomas. A and DeJarnette, Van. Analysis of Impacts of Specimen Type on Dynamic Modulus and Predicted Pavement Performance

16. Sakhaeifar, Maryam., Brown, E. Ray Tran, Nam., Dean, Jeff. Evaluation of Long-Lasting Perpetual Asphalt Pavement Using Life-Cycle Cost Analysis

17. Chen, Xingwei., Zhang, Zhongjie., Lambert, Jeff. Field Performance Evaluation of Stone Interlayer Pavement in Louisiana

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24. Geng, Han., Clopotel., Cristian S., Bahia, Hussain U. Effects of High Modulus Asphalt Binders on Performance of Typical Asphalt Pavement Structures

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28. da Silva, Amanda Helena Marcandali., Vasconcelos, Kamilla L. Aranha, Ana Luisa., Bernucci, Liedi Lgi Bariani., Chaves, Jos Mario, Laboratory and Field Evaluation of Cold In-Place RAP Recycling.

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34. Reese, G. Benjamin., Guthrie, W. Spencer., Development Of Clegg Impact Value Thresholds For Minimizing Rutting Of Cement-Treated Base Material Under Early Trafcking

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37. Martinez-Arguelles Gilberto., Crispino, Maurizio., Giustozzi, Filippo,., Flintsch, Gerardo W. Environmental Analysis on asphalt pavement maintenance using modied binders in Developing Countries: Bogot Case Study

38. Plessis L du, Nokes WA, Mahdavi M, Burmas N, Holland TJ, Harvey J Case Study For Evaluating Benets of Pavement Research: Final Results

39. Nazarian Soheil Yuan Deren Franco Samuel Moss Steven Phillip Design and Constructability of Emulsion Stabilized Bases for Full-Depth Reclamation.

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