Matching Items (8)

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Feasibility Study of the Integration of Asphalt Heat Energy Power Generation for Heat Mitigation Purposes at Arizona State University

Description

The heat island effect has resulted in an observational increase in averave ambient as well as surface temperatures and current photovoltaic implementation do not migitate this effect. Thus, the feasibility

The heat island effect has resulted in an observational increase in averave ambient as well as surface temperatures and current photovoltaic implementation do not migitate this effect. Thus, the feasibility and performance of alternative solutions are explored and determined using theoretical, computational data.

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Created

Date Created
  • 2014-05

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Impact of forecasted freight trends on highway pavement infrastructure

Description

The major challenge for any pavement is the freight transport carried by the structure. This challenge is expected to increase in the coming years as freight movements are projected to

The major challenge for any pavement is the freight transport carried by the structure. This challenge is expected to increase in the coming years as freight movements are projected to grow and because these movements account for most of the load related distresses for the pavement. Substantial effort has been devoted to identifying the impacts of these future national freight trends with respect to the environment, economic growth, congestion, and reliability. These are all important aspects relating to the freight question, but an equally important and often overlooked aspect of this issue involves the impact of freight trends on the physical infrastructure. This study analyzes the impact of future freight traffic trends on 26 major interstates representing 68% of the total system mileage and carrying 80% of the total national roadway freight. The pavement segments were analyzed using the Mechanistic Empirical Pavement Design Guide software after collecting the relevant traffic, climate, structural, and material properties. Comparisons were drawn between the expected pavement performance using current design standards for traffic growth and performance predictions that incorporated more detailed freight projections which themselves considered job growth and six key drivers of freight movement. The differences in the resultant performance were used to generate maps that provide a bird’s eye view of locations that are especially vulnerable to future trends in freight movement. The analysis shows that the areas of greatest vulnerability include segments that are directly linked to the busiest ports, and surprisingly those from Atlantic and Central states that provide long distance connectivity, but do not currently carry the highest traffic volumes.

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Created

Date Created
  • 2016

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Safety of Earthen Stormwater Infiltration Best Management Practices (BMP) Adjacent to Highways

Description

The California Department of Transportation (Caltrans) is required to comply

with the National Pollution Discharge Elimination (NPDES) permit, which includes the infiltration of stormwater runoff from highways and implementing soil

The California Department of Transportation (Caltrans) is required to comply

with the National Pollution Discharge Elimination (NPDES) permit, which includes the infiltration of stormwater runoff from highways and implementing soil based best managements practices (BMPs). Stormwater BMPs are in place to prevent pollution in stormwater runoff as well as to facilitate the stormwater discharge from the road. Per this new permit, Caltrans is to install soil based BMPs that can absorb the 85th percentile of a 24-hour stormwater event. In order to absorb the stormwater runoff, the area used is the Clear Recovery Zone (CRZ), which are the road embankments/slopes located adjacent to the roadside. The CRZ must be traversable and recoverable in order to meet roadside traffic safety standards. A major concern for Caltrans is the uncertainty on how these BMPs will affect the safety of a vehicle, if a vehicle were to interact with the soft soils.

In order to provide an insight on the effects of the BMPs, the modeling and simulation of vehicle dynamics under certain interactions between the roadside, soil, and vehicle was completed. The research used computer simulations to quantify the probability of rollover accidents under several different vehicle, driving and ground conditions. The vehicles traversing typical archetype roadsides on soft soil are simulated using MsMac3D software. It was important to model the properties of the vehicle, roadside, mechanical and hydraulic properties of soils realistically in order to obtain an accurate representation of a real-world vehicle and soil interaction.

The outcome was a library of simulations that provided quantifiable data on the effect that soft soils have on the safety and rollover potential of a vehicle traversing the CRZ.

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Created

Date Created
  • 2019

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Asphalt Binder Parameters and their Relationship to the Linear Viscoelastic and Failure Properties of Asphalt Mixtures

Description

Asphalt concrete is a non-homogenous viscoelastic material; its behavior depends on the properties of the asphalt binder and the aggregate skeleton. The two major distresses in flexible pavements, fatigue cracking

Asphalt concrete is a non-homogenous viscoelastic material; its behavior depends on the properties of the asphalt binder and the aggregate skeleton. The two major distresses in flexible pavements, fatigue cracking and rutting, have different mechanisms in that the way binders and mixtures behavior are related differ. Further complicating the issues is that distresses in asphalt pavement are dependent on climate, pavement structure, and traffic loads, in addition to factors such as properties of the asphalt mixture itself. Hence, to characterize the multiscale mechanics associated with binder to mixture behaviors, researchers characterized the fatigue and rutting resistance of asphalt binders and mixtures in the laboratory, and established specifications related to how asphalt mixtures would perform in the field.

This dissertation tackles the linkages across length scales with respect to rutting and cracking. Through the literature reviewed, studies regarding the linear and non-linear viscoelastic properties of asphalt mixture and the corresponding bitumen were identified. There was a wealth of data in this area. In addition, the relationship between the laboratory mixture short-term aging and the binder aging conditions were studied, characterized and analyzed.

The literature review showed that there exists a shortage of knowledge that directly examines the relationships between the binder nonlinear viscoelastic damage behaviors and mixture performance. Addressing this knowledge gap is the basic objective of this research. Specifically, the relationships between the non-recoverable creep compliance at 3.2 kPa (Jnr3.2) and the percent of elastic recovery (R3.2) from the multiple stress creep and recovery (MSCR) test and mixture rutting; and between mixture fatigue and binder linear amplitude sweep (LAS) were studied.

Finally, an aging study was performed to ensure that the binder tests properties reflect the condition of the binder during the mixture test when evaluating binder-to-mixture properties. The propensity to oxidize measured by calculating the aging ratio of various aged conditions (RTFO, PAV, and STOA) were gathered and analyzed.

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Created

Date Created
  • 2019

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Investigation of Subgrade Moisture Flow Caused by Hydro-Thermal Gradients In Airfield Pavements

Description

Recent research efforts have been directed to improve the quality of pavement design procedures by considering the transient nature of soil properties due to environmental and aging effects on pavement

Recent research efforts have been directed to improve the quality of pavement design procedures by considering the transient nature of soil properties due to environmental and aging effects on pavement performance. The main purpose of this research study was to investigate the existence of subgrade soil moisture changes that may have arisen due to thermal and hydraulic gradients at the Atlantic City NAPTF and to evaluate their effect on the material stiffness and the California Bearing Ratio (CBR) strength parameter of the clay subgrade materials. Laboratory data showed that at the same water content, matric suction decreases with increasing temperature; and at the same suction, hydraulic conductivity increases with increasing temperature. Models developed, together with moisture/temperature data collected from 30 sensors installed in the test facility, yielded a maximum variation of suction in field of 155 psi and changes in hydraulic conductivity from 2.9E-9 m/s at 100% saturation to 8.1E-12 at 93% saturation. The maximum variation in temperature was found to be 20.8oC at the shallower depth and decreased with depth; while a maximum variation in moisture content was found to be 3.7% for Dupont clay and 4.4% for County clay. Models developed that predicts CBR as a function of dry density and moisture content yielded a maximum variation of CBR of 2.4 for Dupont clay and 2.9 for County clay. Additionally, models were developed relating the temperature with the bulk stress and octahedral stress applied on the subgrade for dual gear, dual tandem and triple tandem gear types for different tire loads. It was found that as the temperature increases the stresses increase. A Modified Cary and Zapata model was used for predicting the resilient modulus(Mr) of the subgrade. Using the models developed and the temperature/moisture changes observed in the field, the variation of suction, bulk and octahedral stresses were estimated, along with the resilient modulus for three different gear types. Results indicated that changes in Mr as large as 9 ksi occur in the soils studied due to the combined effect of external loads and environmental condition changes.

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Created

Date Created
  • 2017

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Properties of activated crumb rubber

Description

ABSTRACT Pre-treated crumb rubber technologies are emerging as a new method to produce asphalt rubber mixtures in the field. A new crumb rubber modifier industrially known as "RuBind" is one

ABSTRACT Pre-treated crumb rubber technologies are emerging as a new method to produce asphalt rubber mixtures in the field. A new crumb rubber modifier industrially known as "RuBind" is one such technology. RuBindTM is a "Reacted and Activated Rubber" (RAR) that acts like an elastomeric asphalt extender to improve the engineering properties of the binder and mixtures. It is intended to be used in a dry mixing process with the purpose of simplifying mixing at the asphalt plant. The objectives of this research study were to evaluate the rheological and aging properties of binders modified with RuBindTM and its compatibility with warm mix technology. Two binders were used for this study: Performance Grade (PG) 70-10 and PG 64-22, both modified with 25% by weight of asphalt binder. Laboratory test included: penetration, softening point, viscosity, Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR). Tests were conducted under original, short and long -term aging conditions. Observations from the test results indicated that there is a better improvement when RuBindTM is added to a softer binder, in this case a PG 64-22. For short-term aging, the modified binder showed a similar aging index compared to the control. However, long term aging was favorable for the modified binders. The DSR results showed that the PG 64-22 binder high temperature would increase to 82 °C, and PG 70-10 would be increased to 76 °C, both favorable results. The intermediate temperatures also showed an improvement in fatigue resistance (as measured by the Superpave PG grading parameter |G*|sinä). Test results at low temperatures did not show a substantial improvement, but the results were favorable showing reduced stiffness with the addition of RuBindTM. The evaluation of warm mix additive using EvothermTM confirmed the manufacturer information that the product should have no negative effects on the binder properties; that is the modified binder can be used in a warm mix process. These results were encouraging and the recommendation was to continue with a follow up study with mixture tests using the RuBindTM modified binders.

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Created

Date Created
  • 2014

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Use of micro-mechanical models to study the mastic level structure of asphalt concretes containing reclaimed asphalt pavement

Description

This study investigates the mastic level structure of asphalt concrete containing RAP materials. Locally sourced RAP material was screened and sieved to separate the coated fines (passing #200) from the

This study investigates the mastic level structure of asphalt concrete containing RAP materials. Locally sourced RAP material was screened and sieved to separate the coated fines (passing #200) from the remaining sizes. These binder coated fines were mixed with virgin filler at proportions commensurate with 0%, 10%, 30%, 50% and 100% RAP dosage levels. Mastics were prepared with these blended fillers and a PG 64-22 binder at a filler content of 27% by volume. Rheological experiments were conducted on the resulting composites as well as the constituents, virgin binder, solvent extracted RAP binder. The results from the dynamic modulus experiments showed an expected increase in stiffness with increase in dosage levels. These results were used to model the hypothesized structure of the composite. The study presented discusses the different micromechanical models employed, their applicability and suitability to correctly predict the blended mastic composite. The percentage of blending between virgin and RAP binder estimated using Herve and Zaoui model decreased with increase in RAP content.

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Created

Date Created
  • 2014

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Development of paint stripe testing protocol

Description

Nighttime visibility of pavement markings is provided by glass beads embedded into the striping surface. The glass beads take light from the vehicle headlamps and reflect it back to the

Nighttime visibility of pavement markings is provided by glass beads embedded into the striping surface. The glass beads take light from the vehicle headlamps and reflect it back to the driver. This phenomenon is known as retroreflection. Literature suggests that the amount of the bead embedded into the striping surface has a profound impact on the intensity of the retroreflected light. In order to gain insight into how the glass beads provide retroreflection, an experiment was carried out to produce paint stripes with glass beads and measure the retroreflection. Samples were created at various application rates and embedment depths, in an attempt to verify the optimal embedment and observe the effect of application rate on retroreflection. The experiment was conducted using large, airport quality beads and small, road quality beads. Image analysis was used to calculate the degree to which beads were embedded and in an attempt to quantify bead distribution on the stripe surface. The results from the large beads showed that retroreflection was maximized when the beads were embedded approximately seventy percent by bead volume. The results also showed that as the application rate increased, the retroreflection increased, up to a point and then decreased. A model was developed to estimate the retroreflectivity given the amount of beads, bead spacing, and distribution of bead embedment. Results from the small beads were less conclusive, but did demonstrate that the larger beads are better at providing retroreflection. Avenues for future work in this area were identified as the experiment was conducted.

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Created

Date Created
  • 2014