WorldWideScience

Sample records for pavement surface distress

  1. LDPE and CRMB Utilization in Bituminous Concrete Pavement Surfaces

    OpenAIRE

    Payal Bakshi

    2013-01-01

    The road traffic and the traffic intensity are also increasing. Thus the load bearing capacities of the road is to be increased. There are two types of roads - flexible pavements (bitumen roads) and rigid pavements (concrete roads). Flexible pavements (bitumen roads) comprise of the major portion of all surfaced roads. In India, bituminous surfaced flexible pavements comprise of majority of the roads. Distress symptoms, such as cracking, rutting, etc., are being increasingly caused earlier by...

  2. Surface Wave Testing of Pavements

    OpenAIRE

    Rydén, Nils

    2004-01-01

    A novel approach for surface wave testing of pavements is presented. It is a non-destructive testing (NDT) technique that can be used to obtain the thickness and stiffness properties of the different layers in a pavement. With this method structural properties of the pavement can be mapped as a function of time and space, providing a valuable tool in pavement design and management. The technical development is based on a theoretical study of wave propagation in pavement structures and on the ...

  3. Finite element analysis of surface wave radiation for pavement debonding

    Science.gov (United States)

    Lu, Yifeng; Cao, Yinghong; McDaniel, J. Gregory; Wang, Ming L.

    2010-04-01

    A large scale finite element model with high mesh resolution is established to simulate the ground truth of regular highway pavement structure with subsurface debonding defects. The simulation is motivated by non-destructive testing methods that derive information from the acoustic radiation of the surface wave. These NDT (Non-Destructive Testing) signals come from solid elastic wave propagation beneath pavement surface, which then couple with acoustic wave in air above the pavement surface. In this article, 2 main debonding phenomena, which are conventionally hidden below the pavement surface, are modeled and also compared with a healthy (perfectly intact) pavement structure model. Both the impact-response transient analysis and frequency spectrum analysis have been given to show a new opportunity to detect the subsurface debonding in pavement non-destructively through acoustic signals from heights above the pavement surface which are incorporated with ground truth information.

  4. Improving a pavement-watering method on the basis of pavement surface temperature measurements

    CERN Document Server

    Hendel, Martin; Diab, Youssef; Royon, Laurent

    2014-01-01

    Pavement-watering has been studied since the 1990's and is currently considered a promising tool for urban heat island reduction and climate change adaptation. However, possible future water resource availability problems require that water consumption be optimized. Although pavement heat flux can be studied to improve pavement-watering methods (frequency and water consumption), these measurements are costly and require invasive construction work to install appropriate sensors in a dense urban environment. Therefore, we analyzed measurements of pavement surface temperatures in search of alternative information relevant to this goal. It was found that high frequency surface temperature measurements (more than every 5 minutes) made by an infrared camera can provide enough information to optimize the watering frequency. Furthermore, if the water retaining capacity of the studied pavement is known, optimization of total water consumption is possible on the sole basis of surface temperature measurements.

  5. Performance of recycled asphalt concrete airport pavement surfaces

    Science.gov (United States)

    Cline, G. D.; Hironaka, M. C.

    1986-10-01

    The objective of this research was to make an assessment of the relative performance of recycled versus new asphalt concrete pavement surfaces constructed for airport facilities. To make this assessment, pavement condition index (PCI) surveys and tests on core samples from the hot-mix recycled pavements located on the airports at Needles, California, and Valley City, North Dakota were conducted. Both pavements have a condition rating of very good. The survey and test data were compared with those for recycled highway and virgin material Navy airfield pavements. The recycle pavement at Needles is performing as good as those Navy pavements constructed with virgin material. The recycled pavement at Valley City has a higher deterioration rate than the Navy pavements but this could be attributed to the harsh climate found in North Dakota. The results of this study show that hot-mix recycling was successful at these airports but additional studies are required to determine the applicability of Asphalt Concrete (AC) recycling for reconstruction at all airports.

  6. Durability of Ring-Road II asphalt pavement - Phase I report on forensic analysis of Ring-Road II pavement distresses

    OpenAIRE

    Pellinen, Terhi; Makowska, Michalina; Olmos, Pablo; Laukkanen, Olli-Ville

    2013-01-01

    This report presents findings from prematurely failed pavement of Ring-Road II (Kehä II) in Espoo, Finland. The road had excessive potholes, cracking, raveling and stripping only five years after construction. Core samples taken for this study revealed also that pavement layers were partially separated due to the lack of bonding. Research focus was to determine the causes of Stone Mastic Asphalt surface layer failure. Documentation of mix design, construction and material quality analysis, pr...

  7. Urban pavement surface temperature. Comparison of numerical and statistical approach

    Science.gov (United States)

    Marchetti, Mario; Khalifa, Abderrahmen; Bues, Michel; Bouilloud, Ludovic; Martin, Eric; Chancibaut, Katia

    2015-04-01

    The forecast of pavement surface temperature is very specific in the context of urban winter maintenance. to manage snow plowing and salting of roads. Such forecast mainly relies on numerical models based on a description of the energy balance between the atmosphere, the buildings and the pavement, with a canyon configuration. Nevertheless, there is a specific need in the physical description and the numerical implementation of the traffic in the energy flux balance. This traffic was originally considered as a constant. Many changes were performed in a numerical model to describe as accurately as possible the traffic effects on this urban energy balance, such as tires friction, pavement-air exchange coefficient, and infrared flux neat balance. Some experiments based on infrared thermography and radiometry were then conducted to quantify the effect fo traffic on urban pavement surface. Based on meteorological data, corresponding pavement temperature forecast were calculated and were compared with fiels measurements. Results indicated a good agreement between the forecast from the numerical model based on this energy balance approach. A complementary forecast approach based on principal component analysis (PCA) and partial least-square regression (PLS) was also developed, with data from thermal mapping usng infrared radiometry. The forecast of pavement surface temperature with air temperature was obtained in the specific case of urban configurtation, and considering traffic into measurements used for the statistical analysis. A comparison between results from the numerical model based on energy balance, and PCA/PLS was then conducted, indicating the advantages and limits of each approach.

  8. Asphalt pavement surfaces and asphalt mixtures. Transportation research record

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    The papers in this volume, which deal with asphalt pavement surfaces and asphalt mixtures, should be of interest to state and local construction, design, materials, and research engineers as well as contractors and material producers. The papers in Part 1 include discussions of pavement smoothness specifications and skidding characteristics. The first four papers in Part 2 were submitted in response to a call for papers for a session at the 75th Annual Meeting of the Transportation Research Board on low-temperature properties of hot-mix asphalt. The next eight are on the influence of volumetric and strength properties on the performance of hot-mix asphalt. In the following three papers, the topics covered are the complex modulus of asphalt concrete, cold in-place asphalt recycling, and polymer modification of asphalt pavements in Ontario. The last two papers were presented in a session on relationship of materials characterization to accelerated pavement performance testing.

  9. Propagation Mechanisms for Surface Initiated Crackingin Composite Pavements

    Directory of Open Access Journals (Sweden)

    Duraid Ali Al Khafagy

    2009-01-01

    Full Text Available The primary objective of this study was to identify the mechanisms for the development and propagation of longitudinal cracks that initiate at the surface of composite pavement. In this study the finite element program ANSYS version (5.4 was used and the model worked out using this program has the ability to analyze a composite pavement structure of different layer properties. Also, the aim of this study was modeling and analyzing of the composite pavement structure with the physical presence of crack induced in concrete underlying layer. The results obtained indicates that increasing the thickness of the asphalt layer tends to decrease the stress intensity factor, which may be attributed to the rapidly decrease of horizontal tensile stress in the asphalt layer. The cracks initiate at the surface due to high vertical stress and shear stress from wheel loads tends to propagate downward due tensile stress generated at the bottom of the asphalt layer or near crack tip, and the whole process occur at the same location of the existing cracks in underlying concrete layer rather than travel up from existing crack. As the load position varies from the crack zone, this result in tensile stresses or tension at the crack tip, leading to increase the stress intensity factor and intern result in crack propagation further into the depth of the pavement.

  10. Development and evaluation of the model for the surface pavement temperature prediction

    Directory of Open Access Journals (Sweden)

    B. Mati?

    2012-07-01

    Full Text Available This paper examines the existing models for predicting pavement temperatures and formulates a new one using a regression equation to predict the minimum and maximum pavement surface temperatures depending on the air temperature. Also, the paper presents a model for pavement temperature prediction according to the Superpave methodology and conducts the validation of the model for measured temperatures.

  11. Development and evaluation of the model for the surface pavement temperature prediction

    OpenAIRE

    B. Mati?; J. Tepi?; Sremac, S.; Radonjanin, V.; Mati?, D.; P. Jovanovi?

    2012-01-01

    This paper examines the existing models for predicting pavement temperatures and formulates a new one using a regression equation to predict the minimum and maximum pavement surface temperatures depending on the air temperature. Also, the paper presents a model for pavement temperature prediction according to the Superpave methodology and conducts the validation of the model for measured temperatures.

  12. Simulation of pavement surface runoff using the depth-averaged shallow water equations

    OpenAIRE

    Wolff, Anne

    2013-01-01

    Water on the pavement significantly affects traffic safety. Climate change will lead to a higher number of heavy rainstorms in Germany and the risk to have large amounts of water on the pavement will even increase. Therefore, it is important to have a tool which enables highway engineers to analyse existing and designed road sections concerning their drainage capability. In this work, a model is developed, which allows an integral simulation of pavement surface runoff. This includes features ...

  13. Laser Scanning on Road Pavements: A New Approach for Characterizing Surface Texture

    OpenAIRE

    Gabriele Bitelli; Andrea De Simone(SISSA, INFN); Fabrizio Girardi; Claudio Lantieri

    2012-01-01

    The surface layer of road pavement has a particular importance in relation to the satisfaction of the primary demands of locomotion, such as security and eco-compatibility. Among those pavement surface characteristics, the “texture” appears to be one of the most interesting with regard to the attainment of skid resistance. Specifications and regulations, providing a wide range of functional indicators, act as guidelines to satisfy the performance requirements. This paper describes an experime...

  14. Assessment of in-situ compaction degree of HMA pavement surface layers using GPR and novel dielectric properties-based algorithms

    Science.gov (United States)

    Georgiou, Panos; Loizos, Fokion

    2015-04-01

    Field compaction of asphalt pavements is ultimately conducted to achieve layer(s) with suitable mechanical stability. However, the achieved degree of compaction has a significant influence on the performance of asphalt pavements. Providing all desirable mixture design characteristics without adequate compaction could lead to premature permanent deformation, excessive aging, and moisture damage; these distresses reduce the useful life of asphalt pavements. Hence, proper construction of an asphalt pavement is necessary to develop a long lasting roadway that will help minimize future maintenance. This goal is achieved by verifying and confirming that design specifications, in this case density specifications are met through the use of Quality Assurance (QA) practices. With respect to in-situ compaction degree of hot mix asphalt (HMA) pavement surface layers, nearly all agencies specify either cored samples or nuclear/ non nuclear density gauges to provide density measurement of the constructed pavement. Typically, a small number of spot tests (with either cores or nuclear gauges) are run and a judgment about the density level of the entire roadway is made based on the results of this spot testing. Unfortunately, density measurement from a small number of spots may not be representative of the density of the pavement mat. Hence, full coverage evaluation of compaction quality of the pavement mat is needed. The Ground Penetrating Radar (GPR), as a Non Destructive Testing (NDT) technique, is an example of a non-intrusive technique that favors over the methods mentioned above for assessing compaction quality of asphalt pavements, since it allows measurement of all mat areas. Further, research studies in recent years have shown promising results with respect to its capability, coupled with the use of novel algorithms based on the dielectric properties of HMA, to predict the in-situ field density. In view of the above, field experimental surveys were conducted to assess the effectiveness of GPR methodology to estimate the in-situ compaction degree of several test sections. Moreover, considering also the field density results as obtained with traditional methods, comparative evaluation was conducted to assess the potential of using the GPR technique as a surrogate tool for pavement compaction quality purposes. Acknowledgements: This work has been inspired from publications of the COST action TU-1208 funded from EU.

  15. Vehicle-Pavement Interaction

    OpenAIRE

    Khavassefat, Parisa

    2014-01-01

    Several aspects of vehicle-pavement interaction have been studied and discussed in this thesis. Initially the pavement response is studied through a quasi-static and a dynamic computationally efficient framework under moving traffic loads. Subsequently, a non-stationary stochastic solution has been developed in order to account for the effect of pavement surface deterioration on pavement service life.The quasi-static procedure is based on a superposition principle and is computationally favou...

  16. Laser Scanning on Road Pavements: A New Approach for Characterizing Surface Texture

    Directory of Open Access Journals (Sweden)

    Gabriele Bitelli

    2012-07-01

    Full Text Available The surface layer of road pavement has a particular importance in relation to the satisfaction of the primary demands of locomotion, such as security and eco-compatibility. Among those pavement surface characteristics, the “texture” appears to be one of the most interesting with regard to the attainment of skid resistance. Specifications and regulations, providing a wide range of functional indicators, act as guidelines to satisfy the performance requirements. This paper describes an experiment on the use of laser scanner techniques on various types of asphalt for texture characterization. The use of high precision laser scanners, such as the triangulation types, is proposed to expand the analysis of road pavement from the commonly and currently used two-dimensional method to a three-dimensional one, with the aim of extending the range of the most important parameters for these kinds of applications. Laser scanners can be used in an innovative way to obtain information on areal surface layer through a single measurement, with data homogeneity and representativeness. The described experience highlights how the laser scanner is used for both laboratory experiments and tests in situ, with a particular attention paid to factors that could potentially affect the survey.

  17. A Hessian-based methodology for automatic surface crack detection and classification from pavement images

    Science.gov (United States)

    Ghanta, Sindhu; Shahini Shamsabadi, Salar; Dy, Jennifer; Wang, Ming; Birken, Ralf

    2015-04-01

    Around 3,000,000 million vehicle miles are annually traveled utilizing the US transportation systems alone. In addition to the road traffic safety, maintaining the road infrastructure in a sound condition promotes a more productive and competitive economy. Due to the significant amounts of financial and human resources required to detect surface cracks by visual inspection, detection of these surface defects are often delayed resulting in deferred maintenance operations. This paper introduces an automatic system for acquisition, detection, classification, and evaluation of pavement surface cracks by unsupervised analysis of images collected from a camera mounted on the rear of a moving vehicle. A Hessian-based multi-scale filter has been utilized to detect ridges in these images at various scales. Post-processing on the extracted features has been implemented to produce statistics of length, width, and area covered by cracks, which are crucial for roadway agencies to assess pavement quality. This process has been realized on three sets of roads with different pavement conditions in the city of Brockton, MA. A ground truth dataset labeled manually is made available to evaluate this algorithm and results rendered more than 90% segmentation accuracy demonstrating the feasibility of employing this approach at a larger scale.

  18. Analysis of Load Stress for Asphalt Pavement of Lean Concrete Base

    Science.gov (United States)

    Lijun, Suo; Xinwu, Wang

    The study revealed that whether it is early distresses in asphalt pavement or not depends largely on working performance of base. In the field of asphalt pavement, it is widely accepted that lean concrete base, compared with the general semi-rigid base, has better working performance, such as high strength and good eroding resistance. Problem of early distresses in asphalt pavement, which caused by more traffic loadings, can be settled effectively when lean concrete is used in asphalt pavement. Traffic loading is important parameter used in the analysis of the new pavement design. However, few studies have done extensive and intensive research on the load stress for asphalt pavement of lean concrete base. Because of that, it is necessary to study the load stress for the asphalt pavement. In the paper, first of all, three-dimension finite element model of the asphalt pavement is created for the aim of doing mechanical analysis for the asphalt pavement. And then, the two main objectives of this study are investigated. One is analysis for load stress of lean concrete base, and the other is analysis for load stress of asphalt surface. The results show that load stress of lean concrete base decreases, decrease and increase with increase of base's thickness, surface's thickness and ratio of base's modulus to foundation's modulus respectively. So far as the asphalt surface is concerned, maximum shearing stress, which is caused by load, is evident in asphalt surface which is located in transverse contraction joint of lean concrete base of asphalt pavement. Maximum shearing stress decrease, decrease, decrease and increase respectively with increase of the surface's modulus, the surface's thickness, base's thickness and ratio of base's modulus to foundation's modulus.

  19. EFFECTS OF PAVEMENT SURFACE TEMPERATURE ON THE MODIFICATION OF URBAN THERMAL ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    SARAT, Adebayo-Aminu

    2012-01-01

    Full Text Available Urban centres continue to experience escalating average summer temperature over the last fifty years. Temperature in the urban core cites have been rising due to rapid growth of urbanization in the latter half of the twentieth century (Akbari et al., 1989. Outdoor experiments were conducted to investigate the effects of different movement of materials on the urban thermal environment. Meteorological conditions such as air temperature, pavement surface temperature, Relative humidity and wind velocity were recorded to determine temperature differences among Asphalt/concrete, interlocking bricks and grass surfaces.

  20. A 3D study of the contact surface developed by the contact between the tires and the structural pavements

    Directory of Open Access Journals (Sweden)

    Alex Alves Bandeira

    2008-01-01

    Full Text Available The basic aim in this work is to present a new technique to analyze the contact surfaces developed by the contact between the tires and the structural pavements by numerical simulations, using 3D finite element formulations with contact mechanics. For this purpose, the Augmented Lagrangian method is used. This study is performed just putting the tires on the structural pavement. These tires and the structural pavement are discretized by finite elements under large 3D elastoplastic deformation. The real loads (of aircrafts, trucks or cars are applied directly on each tire and by contact mechanics procedures, the real contact area between the tires and the pavement surface is computed. The penetration conditions and the contact interfaces are investigated in details. Furthermore, the pressure developed at the contact surfaces is automatically calculated and transferred to the structural pavement by contact mechanics techniques. The purpose of this work research is to show that the contact area is not circular and the finite element techniques can calculate automatically the real contact area, the real geometry and its stresses and strains. In the end of this work, numerical resultsin terms of geometry, stress and strain are presented and compared to show the ability of the algorithm. These numerical results are also compared with the numerical results obtained by the commercial program ANSYS.

  1. Fast simulated annealing inversion of surface waves on pavement using phase-velocity spectra

    Science.gov (United States)

    Ryden, N.; Park, C.B.

    2006-01-01

    The conventional inversion of surface waves depends on modal identification of measured dispersion curves, which can be ambiguous. It is possible to avoid mode-number identification and extraction by inverting the complete phase-velocity spectrum obtained from a multichannel record. We use the fast simulated annealing (FSA) global search algorithm to minimize the difference between the measured phase-velocity spectrum and that calculated from a theoretical layer model, including the field setup geometry. Results show that this algorithm can help one avoid getting trapped in local minima while searching for the best-matching layer model. The entire procedure is demonstrated on synthetic and field data for asphalt pavement. The viscoelastic properties of the top asphalt layer are taken into account, and the inverted asphalt stiffness as a function of frequency compares well with laboratory tests on core samples. The thickness and shear-wave velocity of the deeper embedded layers are resolved within 10% deviation from those values measured separately during pavement construction. The proposed method may be equally applicable to normal soil site investigation and in the field of ultrasonic testing of materials. ?? 2006 Society of Exploration Geophysicists.

  2. Assessment of an action against environmental noise: Acoustic durability of a pavement surface with crumb rubber.

    Science.gov (United States)

    Vázquez, V F; Luong, J; Bueno, M; Terán, F; Paje, S E

    2016-01-15

    Environmental noise is a worldwide problem that has an adverse effect in the quality of life of urban population. Some work has shown that there is a correlation between environmental noise and health issues as sleep disturbance or annoyance. This study presents the time evolution of a test track fabricated with an asphalt mixture with 20% of crumb rubber by weight of bitumen, added by the wet process. A complete surface characterization has been performed by determining tire/pavement sound levels, road texture profiles, in-situ dynamic stiffness and sound absorption of compacted and extracted sample cores. Two measurement campaigns were performed: just after mixture laying and after 3years in service. This study confirms that the use of crumb rubber as a modifier of bituminous binders (CRMB) can improve the pavement characteristics: gap-graded mixtures with crumb rubber can be used in the action plans as urban rehabilitation measure to fight noise pollution. However, this noise reduction seems to decrease with age at a rate of approximately 0.15dB(A) per year. PMID:26519582

  3. A Study on Overlay Design of Repeatedly Deteriorating Flexible Pavement

    Directory of Open Access Journals (Sweden)

    Mahendrakar Kiran Kumar

    2015-06-01

    Full Text Available A factor, which causes further concern in India, is very high and very low pavement temperature in some parts of the country. Under these conditions, flexible pavements tend to become soft in summer and brittle in winter. Further increase in road traffic during the last one decade with an unduly low level of maintenance has contributed to accelerated deterioration of road surfacing. To prevent this deterioration process, several types of measures may be adopted effectively such as improved design, use of high performance materials and effective construction technologies. Over the last two decades, traffic volume and the percentage of heavy truck traffic have increased enormously on the National High Way No 18. This pavement is a Flexible pavement with bituminous surfacing. The high traffic intensity in terms of commercial vehicles, overloading of axles and significant variations in daily and seasonal temperature of the pavement have been always responsible for early development of distress symptoms like undulations, rutting, cracking, bleeding, raveling, shoving and potholing of bituminous surfacing.

  4. Some experience using noncontact sensors on airport pavements

    Science.gov (United States)

    Lenngren, Carl A.

    1996-11-01

    The Swedish National Road Administration has been using a laser based system for assessing pavement surface characteristics for over a decade. Typically, important distress data like roughness and rutting are being sampled at speeds up to 25 meters per second. Other parameters include textures and geometric data, such as cross slope and curvature. The Royal Swedish Fortifications Administration has just recently looked into these techniques for airfield pavements. The objectives are similar but not exactly the same as for highway pavements. A promising aspect is using data for building terrain models of the surface so that overlay design procedures can take place in a computerized environment. The objectives are similar but not exactly the same as for highway pavements. A promising aspect is using data for building terrain models of the surface so that overlay design procedures can take place in a computerized environment. Two different ways of treating the data for this purpose was tried. One model uses several parallel continuous longitudinal profiles. The other consists of snap-shot transverse profiles at five meter intervals. The former model yields good assessment of the volumetric needs of either filling or milling operations. The latter is better for identifying features on the surface. The present paper describes some of experiences obtained with the two methods. However, in both cases the most advantageous aspect of using the non-contact devices is the short time needed for collecting the data.

  5. Weak interlayers in flexible and semi-flexible road pavements: Part 1

    Scientific Electronic Library Online (English)

    F, Netterberg; M, de Beer.

    2012-04-01

    Full Text Available Weak layers, interlayers, laminations and/or interfaces in the upper structural layers of road pavements are specifically prohibited in most road-building specifications. However, such layers are extremely common and often lead to premature pavement distress. In Part 1 of this two-part set of papers [...] , it is shown that from experience with heavy vehicle simulator (HVS) and dynamic cone penetrometer (DCP) testing, the presence of such layers and/or conditions at any depth in the structural layers of a flexible or semi-flexible pavement is far more deleterious than is commonly appreciated. In Part 2 the effects of these weak layers are further modelled and discussed using various examples based an HVS testing and mechanistic pavement analyses. In particular, a weak upper base course of a cemented pavement under a thin bituminous surfacing may lead to severe surfacing (and upper base) failure within a matter of weeks to months after opening to traffic, not excluding failure even during construction. In this paper (Part 1), the causes of weak layers, interlayers, laminations and/or interfaces, together with simple methods for their detection during construction and analyses of their effects on the structural capacity of flexible and semi-rigid (cemented) road pavements, are briefly discussed.

  6. Weak interlayers in flexible and semi-flexible road pavements: Part 1

    Directory of Open Access Journals (Sweden)

    F Netterberg

    2012-04-01

    Full Text Available Weak layers, interlayers, laminations and/or interfaces in the upper structural layers of road pavements are specifically prohibited in most road-building specifications. However, such layers are extremely common and often lead to premature pavement distress. In Part 1 of this two-part set of papers, it is shown that from experience with heavy vehicle simulator (HVS and dynamic cone penetrometer (DCP testing, the presence of such layers and/or conditions at any depth in the structural layers of a flexible or semi-flexible pavement is far more deleterious than is commonly appreciated. In Part 2 the effects of these weak layers are further modelled and discussed using various examples based an HVS testing and mechanistic pavement analyses. In particular, a weak upper base course of a cemented pavement under a thin bituminous surfacing may lead to severe surfacing (and upper base failure within a matter of weeks to months after opening to traffic, not excluding failure even during construction. In this paper (Part 1, the causes of weak layers, interlayers, laminations and/or interfaces, together with simple methods for their detection during construction and analyses of their effects on the structural capacity of flexible and semi-rigid (cemented road pavements, are briefly discussed.

  7. Visual surveying platform for the automated detection of road surface distresses

    Science.gov (United States)

    Naidoo, Thegaran; Joubert, Deon; Chiwewe, Tapiwa; Tyatyantsi, Ayanda; Rancati, Bruno; Mbizeni, Asanda

    2014-06-01

    Road distresses, such as potholes and edge cracks, are not only a source of frustration to drivers but also negatively impact the economy due to damage to motor vehicles and costly ro6ad repairs. Regular and rapid pavement inspection and maintenance is vital to preventing pothole formation and growth. To improve the efficiency of maintenance and reduce the cost thereof, the Visual Surveying Platform (VSP) is being developed that will automatically detect and analyse road distresses. The VSP consists of a vehicle mounted sensor system, consisting of a high speed camera and a Global Positioning System (GPS) receiver, and an analysis and visualization software suite. The system extracts both a visual image and the coordinates of a detected road defect from recorded video and presents it in an interactive interface for use by technical experts and maintenance schedulers. The VSP automatically detects and classifies road distresses using a two-stage artificial neural network framework. Video frames first undergo hue, saturation and value (HSV) colour space conversion as well as a spatial frequency transformation before being used as inputs to the neural networks. A road detector neural network first classifies which section of the image contains the road, after which a distress detector neural network identifies those road regions containing defects. Although the VSP can be adapted to detect any type of road distress it has been trained to specifically detect potholes. An initial prototype of the VSP was designed and constructed. The prototype was also trained and tested on real-world data collected from provincial roads.

  8. Experimental pavement delineation treatments

    Science.gov (United States)

    Bryden, J. E.; Lorini, R. A.

    1981-06-01

    Visibility and durability of materials used to delineate shoulders and medians adjacent to asphalt pavements were evaluated. Materials evaluated were polysulfide and coal tar epoxies, one and two component polyesters, portland cement, acrylic paints, modified-alkyd traffic paint, preformed plastic tape, and thermoplastic markings. Neat applications, sand mortars, and surface treatments were installed in several geometric patterns including cross hatches, solid median treatments, and various widths of edge lines. Thermoplastic pavement markings generally performed very well, providing good visibility under adverse viewing conditions for at least 4 years. Thermoplastic 4 in. wide edge lines appear to provide adequate visibility for most conditions.

  9. Kinect, a Novel Cutting Edge Tool in Pavement Data Collection

    Science.gov (United States)

    Mahmoudzadeh, A.; Firoozi Yeganeh, S.; Golroo, A.

    2015-12-01

    Pavement roughness and surface distress detection is of interest of decision makers due to vehicle safety, user satisfaction, and cost saving. Data collection, as a core of pavement management systems, is required for these detections. There are two major types of data collection: traditional/manual data collection and automated/semi-automated data collection. This paper study different non-destructive tools in detecting cracks and potholes. For this purpose, automated data collection tools, which have been utilized recently are discussed and their applications are criticized. The main issue is the significant amount of money as a capital investment needed to buy the vehicle. The main scope of this paper is to study the approach and related tools that not only are cost-effective but also precise and accurate. The new sensor called Kinect has all of these specifications. It can capture both RGB images and depth which are of significant use in measuring cracks and potholes. This sensor is able to take image of surfaces with adequate resolution to detect cracks along with measurement of distance between sensor and obstacles in front of it which results in depth of defects. This technology has been very recently studied by few researchers in different fields of studies such as project management, biomedical engineering, etc. Pavement management has not paid enough attention to use of Kinect in monitoring and detecting distresses. This paper is aimed at providing a thorough literature review on usage of Kinect in pavement management and finally proposing the best approach which is cost-effective and precise.

  10. Determination of the heating temperature of potholes surface on road pavement in the process of repairs using hot asphalt concrete mixes

    Directory of Open Access Journals (Sweden)

    Giyasov Botir Iminzhonovich

    2014-12-01

    Full Text Available In the process of roads construction the necessary transport and operational characteristics should be achieved, which depend on the quality of the applied, material and technologies. Under the loads of transport means and the influence of weather conditions on the road pavement deformations and destructions occur, which lead to worsening of transport and operational characteristics, decrease of operational life of the road and they are often the reason of road accidents. According to the data of the Strategic Research Center of "Rosgosstrah" more than 20 % of road accidents in Russia occur due to bad quality of road pavement. One of the main directions in traffic security control and prolongation of operational life for road pavement of non-rigid type is road works, as a result of which defects of pavement are eliminated and in case of timely repairs of high quality the operational life of the road increases for several years. The most widely used material for non-rigid pavement repairs is hot road concrete mixes and in case of adherence to specifications they provide high quality of works. The authors investigate the problems of hot asphalt concrete mixes for repairs of road surfaces of non-rigid type. The results of the study hot asphalt concrete mix’s temperature regimes are offered in case of repair works considering the temperature delivered to the work site and the ambient temperature depending on the type of mix and class of bitumen.

  11. 76 FR 67018 - Notice to Manufacturers of Airport In-Pavement Stationary Runway Weather Information Systems

    Science.gov (United States)

    2011-10-28

    ...Manufacturers of Airport In-Pavement Stationary Runway...150/5220-30, Airport Winter Safety and...recommends that in-pavement runway sensor systems...become mandatory for airports using AIP grant funds, an in-pavement runway surface...

  12. Pavement Performance Modeling – A Case Study

    Directory of Open Access Journals (Sweden)

    Saranya Ullas

    2013-08-01

    Full Text Available Pavement deterioration is a complex process. It involves not only structural fatigue but also many functional distresses of pavement. It results from the interaction between traffic, climate, material and time. Deterioration is the term used to represent the change in pavement performance overtime. The ability of the road to satisfy the demands of traffic and environment over its design life is referred to as performance. Due to the great complexity of the road deterioration process, performance models are the best approximate predictors of expected conditions. In this study main distresses were identified from the selected road stretches. Regression models are then developed using SPSS (Statistical packages for social sciences package. T test is used to check the reliability of the model.

  13. Maintenance measures for preservation and recovery of permeable pavement surface infiltration rate - The effects of street sweeping, vacuum cleaning, high pressure washing, and milling.

    Science.gov (United States)

    Winston, Ryan J; Al-Rubaei, Ahmed M; Blecken, Godecke T; Viklander, Maria; Hunt, William F

    2016-03-15

    The surface infiltration rates (SIR) of permeable pavements decline with time as sediment and debris clog pore spaces. Effective maintenance techniques are needed to ensure the hydraulic functionality and water quality benefits of this stormwater control. Eight different small-scale and full-scale maintenance techniques aimed at recovering pavement permeability were evaluated at ten different permeable pavement sites in the USA and Sweden. Maintenance techniques included manual removal of the upper 2 cm of fill material, mechanical street sweeping, regenerative-air street sweeping, vacuum street sweeping, hand-held vacuuming, high pressure washing, and milling of porous asphalt. The removal of the upper 2 cm of clogging material did not significantly improve the SIR of concrete grid paves (CGP) and permeable interlocking concrete pavers (PICP) due to the inclusion of fines in the joint and bedding stone during construction, suggesting routine maintenance cannot overcome improper construction. For porous asphalt maintenance, industrial hand-held vacuum cleaning, pressure washing, and milling were increasingly successful at recovering the SIR. Milling to a depth of 2.5 cm nearly restored the SIR for a 21-year old porous asphalt pavement to like-new conditions. For PICP, street sweepers employing suction were shown to be preferable to mechanical sweepers; additionally, maintenance efforts may become more intensive over time to maintain a threshold SIR, as maintenance was not 100% effective at removing clogging material. PMID:26735865

  14. Pavement management and rehabilitation of portland cement concrete pavements

    Science.gov (United States)

    Zegeer, C. V.; Agent, K. R.; Rizenbergs, R. L.; Curtayne, P. C.; Scullion, T.; Pedigo, R. D.; Hudson, W. R.; Roberts, F. L.; Karan, M. A.; Haas, R.

    Pavement management and rehabilitation projects and techniques are discussed. The following topics are discussed: economic analyses and dynamic programming in resurfacing project selection; implementation of an urban pavement management system; pavement performance modeling for pavement management; illustration of pavement management: from data inventory to priority analysis; rehabilitation of concrete pavements by using portland cement concrete overlays; pavement management study: Illinois tollway pavement overlays; resurfacing of plain jointed-concrete pavements; design procedure for premium composite pavement; model study of anchored pavement; prestressed concrete overlay at O'Hare International Airport: in-service evaluation; and, bonded portland cement concrete resurfacing.

  15. Laboratory Characterization and Influence of Mineralogy and Grading on the Performance of Treated and Untreated Granular Materials Used as Surface Pavements in Unpaved Road

    OpenAIRE

    Pierre, P; Beaulieu, L.; J.-P. Bilodeau

    2010-01-01

    This paper presents the results of a laboratory study on the influence of grading and granular mineralogy sources (granitic gneiss, basalt and limestone) on the performance of treated and untreated granular materials used as surface pavements in unpaved roads. Results of bearing capacity, resilient modulus and compressive strength tests are discussed. Natural brine, calcium chloride, cement and a polymer emulsion treated samples were tested and compared to untreated samples. The combinations ...

  16. An experience on street pavement maintenance program in small region- (Bafq city

    Directory of Open Access Journals (Sweden)

    Khabiry Mehdi

    2009-05-01

    Full Text Available This paper reports an experience on Pavement Maintenance plan of the Research Team of the Islamic Azad University- Bafq Branch. The City of Bafq streets are failing at a growing rate, despite all the efforts of Pavement Management, improved efficiencies in street maintenance operations, contracted work and sharing equipment with other agencies. Pavements in this range show some form of distress or wear that requires more than a life extending achievement. In this group, a well-designed pavement will have served at least 75% of its life and the authority of the pavement has dropped by about 40%.

  17. Utilization of Advanced Diagnostic Methods for Texture and Rut Depth Analysis on a Testing Pavement Section

    Science.gov (United States)

    Slabej, Martin; Grin?, Michal; Kotek, Peter; Ková?, Matúš; Decký, Martin

    2015-05-01

    Qualitative characteristics of pavement in wide range reflects the pavement serviceability, which is a summary of the characteristics of the pavement, providing a fast, smooth, economical and especially safe driving of motor-vehicles. The target factor of pavement serviceability and safety of roads represents the quality of their surface properties. In the framework of research activities performed in the Research Centre founded under the auspices of University of Žilina, individual parameters of pavement serviceability were monitored by pavement surface scanning. This paper describes the creation of a 3D - road surface model and its analysis and evaluation from the viewpoint of two pavement serviceability parameters - the rut depth and texture. Measurements were performed on an experimental pavement section used contemporary in an Accelerated Pavement Testing experiment. The long-term goal is to ascertain functions predicting degradation of these two pavement serviceability parameters.

  18. Study on Flexible Pavement Failures in Soft Soil Tropical Regions

    Science.gov (United States)

    Jayakumar, M.; Chee Soon, Lee

    2015-04-01

    Road network system experienced rapid upgrowth since ages ago and it started developing in Malaysia during the colonization of British due to its significant impacts in transportation field. Flexible pavement, the major road network in Malaysia, has been deteriorating by various types of distresses which cause descending serviceability of the pavement structure. This paper discusses the pavement condition assessment carried out in Sarawak and Sabah, Malaysia to have design solutions for flexible pavement failures. Field tests were conducted to examine the subgrade strength of existing roads in Sarawak at various failure locations, to assess the impact of subgrade strength on pavement failures. Research outcomes from field condition assessment and subgrade testing showed that the critical causes of pavement failures are inadequate design and maintenance of drainage system and shoulder cross fall, along with inadequate pavement thickness provided by may be assuming the conservative value of soil strength at optimum moisture content, whereas the exiting and expected subgrade strengths at equilibrium moisture content are far below. Our further research shows that stabilized existing recycled asphalt and base materials to use as a sub-base along with bitumen stabilized open graded base in the pavement composition may be a viable solution for pavement failures.

  19. An Investigation into the Mechanics of Windblown Dust Entrainment from Nickel Slag Surfaces Resembling Armoured Desert Pavements

    Science.gov (United States)

    Sanderson, Robert Steven

    The purpose of this thesis is to investigate the dynamics of PM 10 emission from a nickel slag stockpile that closely resembles a desert pavement in physical characteristics. In the field, it was observed that slag surfaces develop by natural processes into a well-armoured surface over some period of time. The surface then consists of two distinct layers; a surficial armour layer containing only non-erodible gravel and cobble-sized clasts, and an underlying dust-laden layer, which contains a wide size range of slag particles, from clay-sized to cobble-sized. This surficial armour layer protects the underlying fines from wind entrainment, at least under typical wind conditions; however, particle emissions still do occur under high wind speeds. The dynamics of particle entrainment from within these surfaces are investigated herein. It is shown that the dynamics of the boundary layer flow over these lag surfaces are influenced by the inherent roughness and permeability of the surficial armour layer, such that the flow resembles those observed over and within vegetation canopies, and those associated with permeable gravel-bed river channels. Restriction of air flow within the permeable surface produces a high-pressure zone within the pore spaces, resulting in a Kelvin-Helmholtz shear instability, which triggers coherent motions in the form of repeating burst-sweep cycles. Using Laser Doppler Anemometry (LDA), it is demonstrated that the lower boundary layer is characterized by both Q4 sweeping motions and Q2 bursting motions, while the upper boundary layer is dominated by Q2 bursts. Pore air motions within the slag material were measured using buried pressure ports. It is shown that the mean pressure gradient which forms within the slag material results in net upward displacement of air, or wind pumping. However, this net upward motion is a result of rapid oscillatory motions which are directly driven by coherent boundary layer motions. It is also demonstrated that these coherent motions are able to penetrate at least 4 cm through the surficial armour layer, thereby transporting turbulent kinetic energy (TKE) downward to the dust-laden sub-surface layer. This represents a mechanism of momentum transfer that is able to reach the erodible material, while the wind pumping effect represents a mechanism for particle exhaustion.

  20. Monitoring the condition of roads pavement surfaces: proposal of methodology using hyperspectral images / Monitoramento das condições das superfícies de pavimentos rodoviários: proposta de metodologia utilizando imagens hiperespectrais

    Scientific Electronic Library Online (English)

    Marcos Ribeiro, Resende; Liedi Legi Bariani, Bernucci; José Alberto, Quintanilha.

    2014-04-01

    Full Text Available No atual sistema de concessões rodoviária do Brasil ambos, concessionárias e agências reguladoras têm a missão de melhorar a qualidade dos pavimentos rodoviários no País. Tal situação requer a pesquisa e a identificação de novas ferramentas que facilitem o levantamento das condições dos pavimentos r [...] odoviários num tempo e custos menores que os métodos usuais. Recentemente, se verificou um grande aumento da disponibilidade de imagens de sensoriamento remoto com alta resolução espacial, seguindo uma tendência do mercado de novos satélites de sensoriamento remoto, e de sensores aerotransportados. De forma similar, imagens multi e hiperespectrais estão disponíveis tanto comercialmente quanto para a pesquisa científica. O artigo apresenta uma nova metodologia para a identificação das condições do asfalto em superfícies pavimentadas e uma classificação dos tipos de defeitos identificáveis a partir de imagens hiperespectrais adquiridas por sensores aerotransportados. O objetivo do artigo é o de mostrar que índices das condições das superfícies dos pavimentos asfaltados gerados via imagens hiperespectrais podem ser comparados com os indicadores vigentes, utilizados pela agência reguladora nacional. Abstract in english With the current system of concession roads in Brazil, both concessionaires and regulatory agents have been charged with improving the quality of the pavement on Brazilian highways. This situation requires the search for new tools that can facilitate the survey of pavement conditions in less time an [...] d at a lower cost than traditional methods. Recently, an increasing number of high-resolution spatial images have become available on the world market following the development of new remote sensing satellites and airborne sensors. Similarly, multispectral images and even hyperspectral images are now available commercially and for scientific research. The paper presents a new methodology for the identification of asphalted pavement surfaces condition and the classification of the main types of asphalt defects using hyperspectral images from airborne digital sensors. The objective of this study was to generate indexes of pavement conditions from images that can be compared with the indicators of pavement surface conditions already used by national regulatory agencies.

  1. Measurement of the Cooling Efficiency of Pavement-Watering as an Urban Heat Island Mitigation Technique

    Directory of Open Access Journals (Sweden)

    Martin Hendel

    2015-03-01

    Pavement watering was found to lower pavement surface temperatures by several degrees for several hours after watering, while also strongly reducing its cooling rate a few hours before and after sunset. Heat flux and storage at a depth of 5 cm in the pavement were also found to have been significantly reduced, especially during direct sunlight exposure, but also when the pavement was in the shade. Uninterrupted watering appears necessary during direct sunlight exposure of the pavement to maximize efficiency.

  2. Modeling Deflection Basin Using Neurofuzzy in Backcaluculating Flexible Pavement Layer Moduli

    OpenAIRE

    Mehmet Saltan

    2002-01-01

    Flexible pavement surface condition date play a principle role in the evaluation of pavement structural capacity and in the design of pavement rehabilitation programs. Flexible pavements are affected by moving vehicles, climate and other environmental factors. As a result of these factors, the pavement starts to deteriorate. In order to prevent further deterioration, a maintenance program should be carried out at right time and right places. For the determination of the structural carrying ca...

  3. Pavement Testing Facility

    Data.gov (United States)

    Federal Laboratory Consortium — Comprehensive Environmental and Structural Analyses The ERDC Pavement Testing Facility, located on the ERDC Vicksburg campus, was originally constructed to provide...

  4. A Review Study of Urban Landfill Pavement Drainage System in Madhya Pradesh

    Directory of Open Access Journals (Sweden)

    Tapas Dasgupta,

    2015-10-01

    Full Text Available Urban Land fill pavement drainage is one of the key components which need to be considered along with other parameters for urban land fill pavement management system. In which various issues related with integrating the urban land fill pavement roadway drainage with Land fill pavement Management System. It highlights the major ingress and egress routes of water in land fill pavement structure, methods to measure moisture and approaches to control the water entry. This paper reviews different software's for designing the drainage system and techniques for modeling the drainage conditions in land fill pavement deterioration models. The effect of poor surface and subsurface drainage on land fill pavement performance and its life-cycle are also discussed. The measures to manage the poor land fill pavement roadway drainage conditions are also presented. The need for a detailed field and laboratory studies related to land fill pavements drainage systems has been demonstrated.

  5. Pavement Subgrade Performance Study

    DEFF Research Database (Denmark)

    Zhang, Wei; Ullidtz, Per; Macdonald, Robin

    1998-01-01

    The report describes the second test in the Danish Road Testing Machine (RTM) under the International Pavement Subgrade Performance Study. Pavement response was measured in different layers, and compared to different theroretical values. Performance in terms of plastic strains, rutting and...

  6. Fracture of highway and airport pavements

    Science.gov (United States)

    Ramsamooj, D. V.

    1993-03-01

    Existing solutions for the stresses in a cracked slab containing a crack and supported by an elastic foundation are extended to obtain the stress intensity factor (SIF) for a crack in a pavement subjected to moving vehicular loads. In the existing solutions the stresses can be obtained only for a uniform bending stress (before the crack occurs) along the crack surface. For pavements subjected to moving vehicular loads, the stress distribution along the crack surface is not uniform and the approximation of a uniform stress is often unsatisfactory. The present work extends the above solutions to cover more realistic loading of highway and airport pavements. This facilitates the application of the principles of fracture mechanics to the fatigue crack propagation and fracture of pavements. Beginning with a part-through semi-elliptical starter crack, the crack is assumed to grow under load and the SIF is presented at various stages of crack growth, from the starter crack into a short through-crack that eventually becomes a very long through-crack. Some examples of the fracture of typical rigid and flexible highway and airport pavements are presented to show the need to consider fracture in the design of pavements.

  7. Effect Of Geopathic Stress On Bituminous Pavement

    Directory of Open Access Journals (Sweden)

    B.H.CHAFEKAR

    2013-06-01

    Full Text Available This paper basically for the investigation of Geopathic Stress Zones along the road. Geopathic stress is detrimental energy emanating from the earth and leading to long-term harm to susceptible humans, animals and plants which are exposed to them in their environment. Detection of geopathic location has been done by Experimental investigations on road alignment of one KM, by performing distresses survey, dowsing and by magnetic field detector to investigate the Geopathic Stress. Due to such energies emitted by the earth distresses may occurs on road pavements. It is found that, where geopathic stress occurs a copper L rod gets deflected, also get abrupt changes in magnetic field where the distresses occurs.

  8. Hybrid green permeable pave with hexagonal modular pavement systems

    International Nuclear Information System (INIS)

    Modular permeable pavements are alternatives to the traditional impervious asphalt and concrete pavements. Pervious pore spaces in the surface allow for water to infiltrate into the pavement during rainfall events. As of their ability to allow water to quickly infiltrate through the surface, modular permeable pavements allow for reductions in runoff quantity and peak runoff rates. Even in areas where the underlying soil is not ideal for modular permeable pavements, the installation of under drains has still been shown to reflect these reductions. Modular permeable pavements have been regarded as an effective tool in helping with stormwater control. It also affects the water quality of stormwater runoff. Places using modular permeable pavement has been shown to cause a significant decrease in several heavy metal concentrations as well as suspended solids. Removal rates are dependent upon the material used for the pavers and sub-base material, as well as the surface void space. Most heavy metals are captured in the top layers of the void space fill media. Permeable pavements are now considered an effective BMP for reducing stormwater runoff volume and peak flow. This study examines the extent to which such combined pavement systems are capable of handling load from the vehicles. Experimental investigation were undertaken to quantify the compressive characteristics of the modular. Results shows impressive results of achieving high safety factor for daily life vehicles.

  9. FUEL CONSUMPTION & ENERGY DISSIPATION THROUGH ROAD PAVEMENT CHARACTERISTIC

    Directory of Open Access Journals (Sweden)

    Dipanjan Mukherjee

    2014-06-01

    Full Text Available This thesis estimates the effect of pavement characteristic on energy dissipation of a rolling vehicle tyre. On objective of this study is to compare the relative amount of energy dissipated in pavement by the rolling depending on the pavement materials surface condition & environmental condition also. The study also assesses the effect of the vertical deflection, induced by the tyre, on overall energy dissipation in pavement. A comprehensive literature was carried out to prove a wide background for the study. Field measures and laboratory tests were discussed to provide basis for analyses. Results indicate that energy dissipated in pavement significantly depend on the characteristic of pavement. An obvious influence of speed on energy dissipation can be found only when the stiffness in a low level.

  10. Vehicle dynamic response due to pavement roughness

    Scientific Electronic Library Online (English)

    Roberto Spinola, Barbosa.

    2011-09-01

    Full Text Available The goal of the present study is the development of a spectral method to obtain the frequency response of the half-vehicle subjected to a measured pavement roughness in the frequency domain. For this purpose, a half-vehicle dynamic model with a two-point delayed base excitation was developed to corr [...] elate with the spectral density function of the pavement roughness, to obtain the system spectral transfer function, in the frequency domain. The vertical pavement profile was measured along two roads sections. The surface roughness was here expressed in terms of the spectral density function of the measured vertical pavement profile with respect to the evenness wave number of the pavement roughness. A frequency response analysis was applied to obtain the vertical and angular modal vehicle dynamic response with the excitation of the power spectral density (PSD) of the pavement roughness. The results show that at low speed, the vehicle suspension mode is magnified due to the unpaved track signature. At 120 km/h in an undulated asphalted road, the first vehicle vibration mode has a significant motion amplification, which may cause passenger discomfort.

  11. Image Preprocessing Methods to Identify Micro-cracks of Road Pavement

    OpenAIRE

    Hui Wang; Zhang Chen; Lijun Sun

    2013-01-01

    Standards of highway conservation and maintenance are improved gradually following the improvement of requirements of road service. Before obvious damage such as obvious cracking (block?transverse, longitudinal ) and rutting emerge, inconspicuous distress (micro-cracks, polishing, pockmarked) is generated previously. These inconspicuous distresses may provide basis and criteria for pavement preventive maintenance. Currently most of preventive conservation measures are determined by experienc...

  12. Assessment of porous asphalt pavement performance: hydraulics and water quality

    Science.gov (United States)

    Briggs, J. F.; Ballestero, T. P.; Roseen, R. M.; Houle, J. J.

    2005-05-01

    The objective of this study is to focus on the water quality treatment and hydraulic performance of a porous asphalt pavement parking lot in Durham, New Hampshire. The site was constructed in October 2004 to assess the suitability of porous asphalt pavement for stormwater management in cold climates. The facility consists of a 4-inch asphalt open-graded friction course layer overlying a high porosity sand and gravel base. This base serves as a storage reservoir in-between storms that can slowly infiltrate groundwater. Details on the design, construction, and cost of the facility will be presented. The porous asphalt pavements is qualitatively monitored for signs of distress, especially those due to cold climate stresses like plowing, sanding, salting, and freeze-thaw cycles. Life cycle predictions are discussed. Surface infiltration rates are measured with a constant head device built specifically to test high infiltration capacity pavements. The test measures infiltration rates in a single 4-inch diameter column temporarily sealed to the pavement at its base. A surface inundation test, as described by Bean, is also conducted as a basis for comparison of results (Bean, 2004). These tests assess infiltration rates soon after installation, throughout the winter, during snowmelt, after a winter of salting, sanding, and plowing, and after vacuuming in the spring. Frost penetration into the subsurface reservoir is monitored with a frost gauge. Hydrologic effects of the system are evaluated. Water levels are monitored in the facility and in surrounding wells with continuously logging pressure transducers. The 6-inch underdrain pipe that conveys excess water in the subsurface reservoir to a riprap pad is also continuously monitored for flow. Since porous asphalt pavement systems infiltrate surface water into the subsurface, it is important to assess whether water quality treatment performance in the subsurface reservoir is adequate. The assumed influent water quality is derived from that which is entering the stormwater treatment system in the adjacent parking lot. Since the facility is new, parking has been less intensive here, and influent concentrations will be adjusted down accordingly. Several wells have been installed in and around the facility. Screened intervals are at two levels; in the reservoir and beneath the facility. One well in the facility is continually monitored for basic water quality parameters (temperature, specific conductivity, pH, dissolved oxygen) and level, and is also sampled with an automated refrigerated sampler. Grab samples are collected from the other wells as a basis for comparison. Water samples are collected during several storm events and during interstorm periods to assess water quality treatment performance. The samples are analyzed for nutrients, metals, petroleum hydrocarbons, and pathogens. The potential for leaching of pollutants from the asphalt binder will also be assessed during these storm events. Water quality treatment performance is compared to those of several other studies. Updates on spring 2005 data are also included in the presentation.

  13. Modeling the Pavement Present Serviceability Index of Flexible Highway Pavements Using Data Mining

    Directory of Open Access Journals (Sweden)

    Serdal Terzi

    2006-01-01

    Full Text Available The term present serviceability was adopted to represent the momentary ability of pavement to serve traffic and the performance of the pavement was represented by its serviceability history in conjunction with its load application history. Serviceability was found to be influenced by longitudinal and transverse profile as well as the extent of cracking and patching. The amount of weight to assign to each element in the determination of the over-all serviceability is a matter of subjective opinion. In the present study, a regression tree model has been presented for determining flexible pavement surface layer thickness. The model, RT was selected as estimating method. Results show that wearing course thickness of flexible pavement regression values of the regression tree model is better than that of the AASHO model. This approach can be easily and realistically performed to solve the optimization problems which do not have a formulation or function about the solution.

  14. PCC pavements: some findings from US-LTPP and Canadian case studies

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    This technical brief was developed with two objectives in mind: to provide a brief overview of the type of portland cement concrete pavements available, and to make known some of the performance results observed to date concerning portland cement pavements in the US Long-Term Pavement Performance (US-LTTP) experiment, as well as various Canadian case studies. The various types of pavements and concrete pavement products are discussed, along with the components of concrete pavements, surface texture and smoothness, the design of thickness, the production of concrete and curing and sealing operations. The effect of structural features towards performance are explained based on the experiences of the US-LTTP experiment. Some examples of Canadian concrete pavement projects such as Highway 407, (Ontario), Highway 104 (Nova Scotia), Autoroute 13 (Quebec) are also reviewed. It was concluded that concrete pavement products can provide innovative solutions in terms of both technical and cost efficiencies. 8 refs., 2 tabs., 5 figs.

  15. Field Evaluation of Nondestructive Tests in Measuring the Pavement Layers Density

    Directory of Open Access Journals (Sweden)

    H. Divandary

    2010-01-01

    Full Text Available The aim of this study was field evaluation of nondestructive devices in measuring the density of road layers. Density may be considered as a reliable criterion for evaluating pavement quality and has a high level of importance in that it can ensure the proper performance of pavement at least prior the period of life-time. At present time, the most current and also accurate method to determine in-situ density of asphalt mixture is core sample method, however it has some disadvantages. As well as being costly and time consuming, core sample method causes some distress on the pavement surface and it is not possible to repeat the test for a specific location. In view of this, some attempts were made to develop new methods as alternatives for core sample method. And as such, nondestructive tests have grown into a huge area over the last few years. These tests including nuclear and nonnuclear nondestructive tests do not have the limitations of core sample method. In this study, field evaluation in a new constructed part of a highway was conducted using pavement quality indicator (PQI301 and Troxler nuclear gauge (Model HS-5001EZ. According to the results of validation tests for nondestructive devices (PQI and Nuclear devices, PQI device has sufficient reliability to determine density of asphalt mixture layer but Nuclear device is not reliable to determine density. The obtained results from validation of nuclear device revealed that it has sufficient reliability to determine density of soil layers. Also it was found that the role of calibration procedure in obtaining correct readings From PQI device is highly critical.

  16. DRAINAGE AND FLEXIBLE PAVEMENT PERFORMANCE

    OpenAIRE

    SIDDHARTHA ROKADE; Agarwal, P.K.; RAJNISH SHRIVASTAVA

    2012-01-01

    Providing adequate drainage to a pavement system has been considered as an important design consideration to prevent premature failures due to water related problems such as pumping action, loss of support, and rutting, among others. Most water in pavements is due to rainfall infiltration into unsaturated pavement layers, throughjoints, cracks, shoulder edges, and various other defects, especially in older deteriorated pavements. Water also seep upward from a high groundwater table due to cap...

  17. Runway Operability under Cold Weather Conditions. Tire-pavement friction creation by sand particles on iced pavements, and non-contacting detection of sand particles on pavements

    OpenAIRE

    Klein-Paste, Alex

    2007-01-01

    Airports that operate under cold weather conditions face major challenges in ensuring that runways, taxiways and aprons provide sufficient tire-pavement friction to the operating aircraft. This thesis is motivated by two practical problems: (1) maintaining or improving the pavement surface conditions in an, for airline companies, acceptable state and (2) accurately reporting the actual surface conditions to the relevant actors (pilots, air traffic control, winter maintenance services). The pr...

  18. Pavement Snow Melting

    Energy Technology Data Exchange (ETDEWEB)

    Lund, John W.

    2005-01-01

    The design of pavement snow melting systems is presented based on criteria established by ASHRAE. The heating requirements depends on rate of snow fall, air temperature, relative humidity and wind velocity. Piping materials are either metal or plastic, however, due to corrosion problems, cross-linked polyethylene pipe is now generally used instead of iron. Geothermal energy is supplied to systems through the use of heat pipes, directly from circulating pipes, through a heat exchanger or by allowing water to flow directly over the pavement, by using solar thermal storage. Examples of systems in New Jersey, Wyoming, Virginia, Japan, Argentina, Switzerland and Oregon are presented. Key words: pavement snow melting, geothermal heating, heat pipes, solar storage, Wyoming, Virginia, Japan, Argentina, Klamath Falls.

  19. The impact of geology on the performance of a bituminous surfaced pavement—a case study from southeastern Nigeria

    Science.gov (United States)

    Okagbue, C. O.; Uma, K. O.

    One of the multi-million Naira dual carriageways in Nigeria, the Enugu-Port Harcourt expressway, has continued to experience failure at some sections, namely the stretches covering Lokpaukwu, Lokpanta, and Leru. This road section which, unlike others, does not respond to regular and routine maintenance, is concentrated on one geologic formation, the Eze Aku Shale which has been intruded by a dolerite sill. The emplacement of the dolerite sill had resulted in intense fracturing of the shales in the vicinity of the intrusions which includes portions of where the express road crosses. The road problem is most severe where the dolerite sill is traced right under and across the road. There is evidence from the study that the road problem is linked to the geological/hydrogeological conditions of the area. For example, the problematic section of the road is built on a considerably jointed, fractured and weathered shale formation as a subgrade. The subgrade ultimately has low bearing capacity. The road is almost at the foot of an escarpment where there is a concentration of natural groundwater discharge. Most of the discharge zones including natural water courses are now almost blocked resulting in increased groundwater storage and rise in water table under the highway pavement. This leads to fast deterioration of the base course materials. The dolerite sill, where it crosses the road, is less than 2 m below the grade level. It impedes vertical infiltration as well as lateral groundwater flow. Thus its position with respect to the highway grade elevation leads to an almost perpetual wetting of the base and sub-base materials.

  20. Road Edge of Pavement, Includeds payed road area, parking lots, gravel roads and other impervious surfaces, Published in unknown, Johnson County AIMS.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Road Edge of Pavement dataset, was produced all or in part from Orthoimagery information as of unknown. It is described as 'Includeds payed road area, parking...

  1. Some advances/results in monitoring road cracks from 2D pavement images within the scope of the collaborative FP7 TRIMM project

    Science.gov (United States)

    Baltazart, Vincent; Moliard, Jean-Marc; Amhaz, Rabih; Wright, Dean; Jethwa, Manish

    2015-04-01

    Monitoring road surface conditions is an important issue in many countries. Several projects have looked into this issue in recent years, including TRIMM 2011-2014. The objective of such projects has been to detect surface distresses, like cracking, raveling and water ponding, in order to plan effective road maintenance and to afford a better sustainability of the pavement. The monitoring of cracking conventionally focuses on open cracks on the surface of the pavement, as opposed to reflexive cracks embedded in the pavement materials. For monitoring surface condition, in situ human visual inspection has been gradually replaced by automatic image data collection at traffic speed. Off-line image processing techniques have been developed for monitoring surface condition in support of human visual control. Full automation of crack monitoring has been approached with caution, and depends on a proper manual assessment of the performance. This work firstly presents some aspects of the current state of monitoring that have been reported so far in the literature and in previous projects: imaging technology and image processing techniques. Then, the work presents the two image processing techniques that have been developed within the scope of the TRIMM project to automatically detect pavement cracking from images. The first technique is a heuristic approach (HA) based on the search for gradient within the image. It was originally developed to process pavement images from the French imaging device, Aigle-RN. The second technique, the Minimal Path Selection (MPS) method, has been developed within an ongoing PhD work at IFSTTAR. The proposed new technique provides a fine and accurate segmentation of the crack pattern along with the estimation of the crack width. HA has been assessed against the field data collection provided by Yotta and TRL with the imaging device Tempest 2. The performance assessment has been threefold: first it was performed against the reference data set including 130 km of pavement images over UK roads, second over a few selected short sections of contiguous pavement images, and finally over a few sample images as a case study. The performance of MPS has been assessed against an older image data base. Pixel-based PGT was available to provide the most sensitive performance assessment. MPS has shown its ability to provide a very accurate cracking pattern without reducing the image resolution on the segmented images. Thus, it allows measurement of the crack width; it is found to behave more robustly against the image texture and better matched for dealing with low contrast pavement images. The benchmarking of seven automatic segmentation techniques has been provided at both the pixel and the grid levels. The performance assessment includes three minimal path selection algorithms, namely MPS, Free Form Anisotropy (FFA), one geodesic contour with automatic selection of points of interests (GC-POI), HA, and two Markov-based methods. Among others, MPS approach reached the best performance at the pixel level while it is matched to the FFA approach at the grid level. Finally, the project has emphasized the need for a reliable ground truth data collection. Owing to its accuracy, MPS may serve as a reference benchmark for other methods to provide the automatic segmentation of pavement images at the pixel level and beyond. As a counterpart, MPS requires a reduction in the computing time. Keywords: cracking, automatic segmentation, image processing, pavement, surface distress, monitoring, DICE, performance

  2. Classificação híbrida: pixel a pixel e baseada em objetos para o monitoramento da condição da superfície dos pavimentos rodoviários / Hybrid classification: pixel by pixel and object based to monitor the surface conditions of road pavements

    Scientific Electronic Library Online (English)

    Marcos Ribeiro, Resende; Liedi Légi Barianni, Bernucci; José Alberto, Quintanilha.

    2012-09-01

    Full Text Available Monitorar a condição de uso de toda a extensão das rodovias brasileiras é tarefa dispendiosa e demorada. Este trabalho trata de novas técnicas que permitem o levantamento da condição da superfície dos pavimentos rodoviários de forma ágil utilizando imagens hiperespectrais de sensor digital aeroembar [...] cado. Nos últimos anos, um número crescente de imagens de alta resolução espacial tem surgido no mercado mundial com o aparecimento dos novos satélites e sensores aeroembarcados de sensoriamento remoto. Propõe-se uma metodologia para identificação dos pavimentos asfálticos e classificação das principais ocorrências dos defeitos na superfície do pavimento. A primeira etapa da metodologia é a identificação da superfície asfáltica na imagem, utilizando uma classificação híbrida baseada inicialmente em pixel e depois refinada por objetos. A segunda etapa da metodologia é a identificação e classificação das ocorrências dos principais defeitos nos pavimentos flexíveis que são observáveis nas imagens de alta resolução espacial. Esta última etapa faz uso intensivo das novas técnicas de classificação de imagens baseadas em objetos. O resultado final é a geração de índices da condição da superfície do pavimento a partir das imagens que possam ser comparados com os indicadores vigentes da condição da superfície do pavimento já normatizados pelos órgãos competentes no país. Abstract in english Monitoring every Brazilian road use condition is an expensive and time consuming task. This research deals with new techniques which will yield a quick survey of road surface pavement condition by using hyperspectral images from airborne remote sensing. Recently, an increasing number of images with [...] high spatial resolution has emerged on the world market with the advent of new remote sensing satellites and airborne sensors. Hyperspectral images from digital airborne sensor have been used in this work. A new identification methodology for a pavement surface and also for classification of the main defects of the surface has been devised. The first step of the methodology is the identification of the asphalt surface in the image, by using hybrid classification based on pixel initially and then improved by objects. The second step of the methodology is the identification and classification of the main defects of pavement surface that are observable in high spatial resolution imagery. This step makes intensive use of new techniques for classification of images based on objects. The goal is the generation of pavement surface condition index from the images which can be compared to quality index of pavement surface already managed by the regulatory agency in the country.

  3. Pavement Evaluation and Maintenance Decisions Based on Fuzzy Inference Systems

    Directory of Open Access Journals (Sweden)

    Beltrán-Calvo Gloria Inés

    2014-07-01

    Full Text Available The remaining service life and maintenance decisions of existing pavements are highly dependent on stiffness and deterioration conditions throughout their operation. A non-conventional fuzzy logic based methodology is proposed in this work to address the stiffness-deterioration condition and conservation decisions, by means of three Fuzzy Inference Systems. Analysis were conducted using a database gathered from field tests performed on three and four layer pavement systems, that included traditional layer structuring and pavements having a subbase stiffer than their granular base. Information about layer thicknesses, magnitude and severity of structural distresses, and parameters and indicators derived from deflection testing by impulse load devices were used. The developed systems, allowed representing expert knowledge and linguistic variables of subjective and qualitative nature, commonly used to describe the severity levels of deterioration; thus they can be involved into structural characterization of pavements. Results were also expressed linguistically, to facilitate their interpretation and understanding. Based on the high quality of results obtained, it seems reasonable to conclude that the proposed systems could be used confidently for assessing and making decisions about pavement conservation, with low computational cost.

  4. Analysis of the functional quality of pavements from texture measurements

    OpenAIRE

    Freitas, Elisabete F.; Pereira, Paulo A. A.

    2007-01-01

    The surface texture of a pavement, including uneveness, is largely determinant of drivers’safety and comfort. It is undoubtedly a major cause of road traffic accidents all over the world. Statistics show that one million killed and 50 million injured are reported every year by Competent Authorities. The effect of traffic noise has also become a critical public issue. On the road networking the surface characteristics of pavements also contributed to nearly 80-90% of roadway traffic nois...

  5. Improvement of the functional pavement quality with asphalt rubber mixtures

    OpenAIRE

    Fontes, Liseane P. T. L.; Pereira, Paulo A. A.; Pais, Jorge C.; Trichês, Glicério

    2006-01-01

    Skid resistance and texture are important safety characteristics which need to be considered in flexible pavement design, maintenance and rehabilitation. The main objective of this paper is to optimize surface texture characteristics in asphalt rubber pavements, mainly macrotexture to reduce splash, spray and hydroplaning and microtexture to increase friction at low and high speeds. The objective was accomplished by measuring the friction surface with two different tests: (i) B...

  6. The impact of material characteristics on tire pavement interaction noise for flexible pavements

    Science.gov (United States)

    Kocak, Salih

    Noise pollution has recently been one of the growing problems all over the world. While there are many sources of the noise, traffic noise is the main contributor to the total environmental noise. Although there are different sources for traffic noise, the tire pavement interaction noise is the most dominant component within most city and highway limits. One of the ways to reduce the tire pavement noise is to improve the material characteristics of the pavements such that they produce less noise. In this study, the relationship between basic material characteristics (e.g., Hot Mix Asphalt (HMA) volumetrics) and sound generation and absorption characteristics of flexible pavements was investigated. In addition, the effect of linear visco-elastic properties (e.g., dynamic modulus (|E*|) and phase angle (delta)) on sound absorption was studied. In order to focus only on impact of material characteristics and overshadow the effect of surface texture, a novel laboratory tire pavement noise measurement simulator (TIPANOS) was developed. The statistical analysis results showed that although the individual material characteristics do not have appreciable influence on sound absorption, there is a significant correlation between sound pressure levels (SPL) and combination of several material and linear visco-elastic parameters.

  7. Condition monitoring of airport pavements subjected to repeated dynamic aircraft loading

    OpenAIRE

    Gopalakrishnan, Kasthurirangan

    2006-01-01

    The Heavy Weight Deflectometer (HWD) is one of the most commonly used devices for monitoring the structural condition of airport pavement infrastructure systems on a routine basis in a rapid and non-destructive manner. The HWD measures pavement surface response (i e deflections) to an applied dynamic load that simulates a moving wheel of an aircraft at moderate speeds. The pavement surface deflection basins obtained by the HWD tests is frequently used as an indicator of the load-bearing capac...

  8. Modeling Deflection Basin Using Neurofuzzy in Backcaluculating Flexible Pavement Layer Moduli

    Directory of Open Access Journals (Sweden)

    Mehmet Saltan

    2002-01-01

    Full Text Available Flexible pavement surface condition date play a principle role in the evaluation of pavement structural capacity and in the design of pavement rehabilitation programs. Flexible pavements are affected by moving vehicles, climate and other environmental factors. As a result of these factors, the pavement starts to deteriorate. In order to prevent further deterioration, a maintenance program should be carried out at right time and right places. For the determination of the structural carrying capacity of the pavement, non-destructive testing equipments are used. In such a process, the most important thing is to analyse the collected data. A backcalculation procedure is carried out for back-calculation elastic modules for each layer effective in the pavement life. The input data are usually restricted to the pavement surface deflection or its basin obtained by Nondestructive testing as the Falling Weight Deflectometer (FWD. Generally, linear elastic and finite element based programs are used for back-calculating, but they are both time consuming. It is also important to simulate deflection basin realistically in backcalculating pavement layer moduli. For this purpose, NeuroFuzzy method is used for simulation deflection basin during the course of this study. Results indicate that the NeuroFuzzy can be used for backcalculation of flexible pavement layer moduli with great improvement and accuracy.

  9. A Study on Overlay Design of Repeatedly Deteriorating Flexible Pavement

    OpenAIRE

    Mahendrakar Kiran Kumar; D.Gouse Peera; Konge Praveen Kumar

    2015-01-01

    A factor, which causes further concern in India, is very high and very low pavement temperature in some parts of the country. Under these conditions, flexible pavements tend to become soft in summer and brittle in winter. Further increase in road traffic during the last one decade with an unduly low level of maintenance has contributed to accelerated deterioration of road surfacing. To prevent this deterioration process, several types of measures may be adopted effectively such as improved d...

  10. The study of road surface micro-texture's effects for the pavement's decontamination by high pressure water washing

    International Nuclear Information System (INIS)

    In the result of “decontamination technical demonstration project” by Ministry of the Environment, it has became clear that the effect variation is larger in high pressure water washing method, compared with others in road surface decontamination technology. In this study, we have hypothesized the fact at the difference of micro-texture of the road surface, by carrying out high pressure water washing method in different kinds of road surfaces and verified the relation between washing efficiency and micro-texture road surface. Positive correlation has admitted between the washing number of times and radiation reduction rate and the trend of primary regression equation (i.e. radiation reduction rate per washing time) is indicating that decreasing tendency of radiation carried by the increasing of micro-texture of the road surface. Here, we proposed the method to estimated essential washing number of times to achieve the targeted radiation reduction rate from the relation of that trend and micro-texture of the road surface. (author)

  11. Use of lime cement stabilized pavement construction

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, M.A.; Raju, G.V.R.P. [JNTU College of Engineering, Kakinada (India). Dept. of Civil Engineering

    2009-08-15

    Expansive clay is a major source of heave induced structural distress. Swelling of expansive soils causes serious problems and produce damages to many structures. Many research organizations are doing extensive work on waste materials concerning the feasibility and environmental suitability. Fly ash, a waste by product from coal burning in thermal power stations, is abundant in India causing severe health, environmental and disposal problems. Attempts are made to investigate the stabilization process with model test tracks over expansive subgrade in flexible pavements. Cyclic plate load tests are carried out on the tracks with chemicals like lime and cement introduced in fly ash subbase laid on sand and expansive subgrades. Test results show that maximum load carrying capacity is obtained for stabilized fly ash subbase compared to untreated fly ash subbase.

  12. Cloud Impacts on Pavement Temperature in Energy Balance Models

    Science.gov (United States)

    Walker, C. L.

    2013-12-01

    Forecast systems provide decision support for end-users ranging from the solar energy industry to municipalities concerned with road safety. Pavement temperature is an important variable when considering vehicle response to various weather conditions. A complex, yet direct relationship exists between tire and pavement temperatures. Literature has shown that as tire temperature increases, friction decreases which affects vehicle performance. Many forecast systems suffer from inaccurate radiation forecasts resulting in part from the inability to model different types of clouds and their influence on radiation. This research focused on forecast improvement by determining how cloud type impacts the amount of shortwave radiation reaching the surface and subsequent pavement temperatures. The study region was the Great Plains where surface solar radiation data were obtained from the High Plains Regional Climate Center's Automated Weather Data Network stations. Road pavement temperature data were obtained from the Meteorological Assimilation Data Ingest System. Cloud properties and radiative transfer quantities were obtained from the Clouds and Earth's Radiant Energy System mission via Aqua and Terra Moderate Resolution Imaging Spectroradiometer satellite products. An additional cloud data set was incorporated from the Naval Research Laboratory Cloud Classification algorithm. Statistical analyses using a modified nearest neighbor approach were first performed relating shortwave radiation variability with road pavement temperature fluctuations. Then statistical associations were determined between the shortwave radiation and cloud property data sets. Preliminary results suggest that substantial pavement forecasting improvement is possible with the inclusion of cloud-specific information. Future model sensitivity testing seeks to quantify the magnitude of forecast improvement.

  13. Pore-structure models of hydraulic conductivity for permeable pavement

    Science.gov (United States)

    Kuang, X.; Sansalone, J.; Ying, G.; Ranieri, V.

    2011-03-01

    SummaryPermeable pavement functions as a porous infrastructure interface allowing the infiltration and evaporation of rainfall-runoff while functioning as a relatively smooth load-bearing surface for vehicular transport. Hydraulic conductivity ( k) of permeable pavement is an important hydraulic property and is a function of the pore structure. This study examines k for a cementitious permeable pavement (CPP) through a series of pore-structure models. Measurements utilized include hydraulic head as well as total porosity, ( ? t), effective porosity ( ? e), tortuosity ( L e/ L) and pore size distribution (PSD) indices generated through X-ray tomography (XRT). XRT results indicate that the permeable pavement pore matrix is hetero-disperse, with high tortuosity and ? t ? ? e. Power law models of k- ? t and k- ? e relationships are developed for a CPP mix design. Results indicate that the Krüger, Fair-Hatch, Hazen, Slichter, Beyer and Terzaghi models based on simple pore-structure indices do not reproduce measured k values. The conventional Kozeny-Carman model (KCM), a more parameterized pore-structure model, did not reproduce measured k values. This study proposes a modified KCM utilizing ? e, specific surface area (SSA) pe and weighted tortuosity ( L e/ L) w. Results demonstrate that such permeable pavement pore-structure parameters with the modified KCM can predict k. The k results are combined with continuous simulation modeling using historical rainfall to provide nomographs examining permeable pavement as a low impact development (LID) infrastructure component.

  14. Subsurface defect detection in first layer of pavement structure and reinforced civil engineering structure by FRP bonding using active infrared thermography

    Science.gov (United States)

    Dumoulin, Jean; Ibos, Laurent

    2010-05-01

    In many countries road network ages while road traffic and maintenance costs increase. Nowadays, thousand and thousand kilometers of roads are each year submitted to surface distress survey. They generally lean on pavement surface imaging measurement techniques, mainly in the visible spectrum, coupled with visual inspection or image processing detection of emergent distresses. Nevertheless, optimisation of maintenance works and costs requires an early detection of defects within the pavement structure when they still are hidden from surface. Accordingly, alternative measurement techniques for pavement monitoring are currently under investigation (seismic methods, step frequency radar). On the other hand, strengthening or retrofitting of reinforced concrete structures by externally bonded Fiber Reinforced Polymer (FRP) systems is now a commonly accepted and widespread technique. However, the use of bonding techniques always implies following rigorous installing procedures. To ensure the durability and long-term performance of the FRP reinforcements, conformance checking through an in situ auscultation of the bonded FRP systems is then highly suitable. The quality-control program should involve a set of adequate inspections and tests. Visual inspection and acoustic sounding (hammer tap) are commonly used to detect delaminations (disbonds) but are unable to provide sufficient information about the depth (in case of multilayered composite) and width of debonded areas. Consequently, rapid and efficient inspection methods are also required. Among the non destructive methods under study, active infrared thermography was investigated both for pavement and civil engineering structures through experiments in laboratory and numerical simulations, because of its ability to be also used on field. Pulse Thermography (PT), Pulse Phase Thermography (PPT) and Principal Component Thermography (PCT) approaches have been tested onto pavement samples and CFRP bonding on concrete samples in laboratory. In parallel numerical simulations have been used to generate a set of time sequence of thermal maps for simulated samples with and without subsurface defect. Using this set of experimental and simulated data different approaches (thermal contrast, FFT analysis, polynomial interpolation, singular value decomposition…) for defect location have been studied and compared. Defect depth retrieval was also studied on such data using different thermal model coupled to a direct or an inverse approach. Trials were conducted both with an uncooled and cooled infrared camera with different measurement performances. Results obtained will be discussed and analysed in the paper we plan to present. Finally, combining numerical simulations and experiments allows us discussing on the sensitivity influence of the infrared camera used to detect subsurface defects.

  15. Impact of Vehicle Class and Tire Pressure on Pavement Performance in MEPDG

    Directory of Open Access Journals (Sweden)

    Mohamed I. E. Attia

    2014-10-01

    Full Text Available The new Mechanistic-Empirical Pavement Design Guide (MEPDG design and analysis procedures defines the exact traffic loading by defining the specific number of each vehicle class and the use of axle load distribution factors instead of the equivalent single axle load (ESAL. The number of traffic inputs (parameters in MEPDG was found to be 17024. This research aimed to evaluate the sensitivity of the predicted flexible pavement distress to vehicle class and tire pressure in MEPDG. To evaluate the impact of vehicle (truck class on pavement sections, different cases of loading were analyzed. For each case, the MEPDG Ver. 1.1 was used to evaluate the effect of tire pressure by solving each case for a tire pressure of 120 and 140 psi. The effect of the traffic parameters on asphalt pavement (AC rutting, base rutting, subgrade rutting, international roughness index (IRI, longitudinal cracking and fatigue (alligator cracking were investigated. It was found that vehicle class distribution (VCD would cause clear impact (comparable to the effect of AADTT level only if the major traffic is of specific class (very light or very heavy. If this is not the case, the vehicle class distribution will not be a significant factor that affects the final design because most of the trucks had similar impact on flexible pavement distresses. The impact of tire pressure is clear on longitudinal cracking, fatigue cracking and AC rutting, and have no significant impact on both base and subgrade rutting.

  16. Spills on Flat Inclined Pavements

    Energy Technology Data Exchange (ETDEWEB)

    Simmons, Carver S.; Keller, Jason M.; Hylden, Jeff L.

    2004-03-01

    This report describes the general spill phenomenology for liquid spills occurring on relatively impermeable surfaces such as concrete or asphalt pavement and the development and application of a model to describe the time evolution of such spills. The discussion assumes evaporation and degradation are negligible and a homogeneous surface. In such an instance, the inherent interfacial properties determine the spatial extent of liquid spreading with the initial flow being controlled by the release rate of the spill and by the liquids resistance to flow as characterized by its viscosity. A variety of spill scenarios were simulated and successful implementation of the model was achieved. A linear relationship between spill area and spill volume was confirmed. The simulations showed spill rate had little effect on the final spill area. Slope had an insignificant effect on the final spill area, but did modify spill shape considerably. However, a fluid sink on the edge of the simulation domain, representing a storm drain, resulted in a substantial decrease in spill area. A bona fide effort to determine the accuracy of the model and its calculations remain, but comparison against observations from a simple experiment showed the model to correctly determine the spill area and general shape under the conditions considered. Further model verification in the form of comparison against small scale spill experiments are needed to confirm the models validity.

  17. Techniques to Determine Maintenace Frequency of Permeable Pavement Systems with Time Domain Reflectometers (TDRs

    Science.gov (United States)

    As the surface clogs in permeable pavement systems, they lose effectiveness and require maintenance. There is limited direct guidance for determining when maintenance is needed to prevent surface runoff bypass. Research is being conducted using multiple time domain reflectomete...

  18. Use of Time Domain Reflectometers (TDRs) in Permeable Pavement Systems to Predict Maintenance Needs and Effectiveness

    Science.gov (United States)

    As the surface in permeable pavement systems clogs, infiltration capacity decreases, so maintenance is required to maintain hydrologic performance. There is limited direct guidance for determining when maintenance is needed to prevent surface runoff bypass. Research is being co...

  19. Stormwater quality of spring-summer-fall effluent from three partial-infiltration permeable pavement systems and conventional asphalt pavement.

    Science.gov (United States)

    Drake, Jennifer; Bradford, Andrea; Van Seters, Tim

    2014-06-15

    This study examined the spring, summer and fall water quality performance of three partial-infiltration permeable pavement (PP) systems and a conventional asphalt pavement in Ontario. The study, conducted between 2010 and 2012, compared the water quality of effluent from two Interlocking Permeable Concrete Pavements (AquaPave(®) and Eco-Optiloc(®)) and a Hydromedia(®) Pervious Concrete pavement with runoff from an Asphalt control pavement. The usage of permeable pavements can mitigate the impact of urbanization on receiving surface water systems through quantity control and stormwater treatment. The PP systems provided excellent stormwater treatment for petroleum hydrocarbons, total suspended solids, metals (copper, iron, manganese and zinc) and nutrients (total-nitrogen and total-phosphorus) by reducing event mean concentrations (EMC) as well as total pollutant loadings. The PPs significantly reduced the concentration and loading of ammonia (NH4(+)+NH3), nitrite (NO2(-)) and organic-nitrogen (Org-N) but increased the concentration and loading of nitrate (NO3(-)). The PP systems had mixed performances for the treatment of phosphate (PO4(3-)). The PP systems increased the concentration of sodium (Na) and chloride (Cl) but EMCs remained well below recommended levels for drinking water quality. Relative to the observed runoff, winter road salt was released more slowly from the PP systems resulting in elevated spring and early-summer Cl and Na concentrations in effluent. PP materials were found to introduce dissolved solids into the infiltrating stormwater. The release of these pollutants was verified by additional laboratory scale testing of the individual pavement and aggregate materials at the University of Guelph. Pollutant concentrations were greatest during the first few months after construction and declined rapidly over the course of the study. PMID:24681366

  20. Analysis of Pavement for National Highway-N.H.1

    Directory of Open Access Journals (Sweden)

    Arvind Dewangan

    2012-02-01

    Full Text Available Rigid pavements are those which posses note worthy flexural strength or flexural rigidity. The stresses are not transferred from grain to grain to the lower layers as in the ease of flexible pavements layers the rigid pavements are made of Portland cement concrete-either plain, reinforced or prestressed concrete[1]. This paper shows the required to evaluate the strength characteristics of the soil subgrade, this helps the designer to adopt the suitable values of the strength parameter for design purposes and in case this supporting layer does not come upto the expectations, the same is treated or conditioned to suit the requirementsThe plain cement concrete slabs are expected to take up about 40 kg/cm2 flexural stress. As the rigid pavements slab has tensile strength, tensile stresses are developed due to the bending of the slab under wheel load and temperature variations thus the type of stress develop and their distribution within the cement concrete slab are quit different. The rigid pavement does not get deformed to the shape of the lower surface as it can bridge the minor variation of lower layer[2].

  1. Recycling of asphalt pavements with asphalt rubber

    OpenAIRE

    Pais, Jorge; Pereira, Paulo; Minhoto, Manuel; Baptista, António

    2008-01-01

    Pavement recycling has been an important rehabilitation technique to deal with reclaimed materials from old pavements which are usually sent to landfills. The application of this technique contributes to: i) the accomplishment of the requirements defined by the European legislation for the amount of material sent to landfills; ii) the reduction in the use of new raw materials used to produce pavement layers. The reduction of materials to be used in pavement rehabilitation has also been possib...

  2. USE OF RECLAIMED ASPHALT PAVEMENT WITH MILLED ROAD PAVEMENT LAYERS

    Directory of Open Access Journals (Sweden)

    Andrzej Plewa

    2015-07-01

    Full Text Available The article presents the results of research on the functional properties of asphalt mixes using RAP obtained from milling asphalt road pavements. Asphalt concrete AC 22P with 0%, 10%, 15% and 20% addition of RAP used for base course of road pavements were designed. It was found that asphalt mixes with RAP characterized by comparable and in some cases better functional properties compared to the asphalt mixes without RAP (0%. One should notice the influence of RAP on the performance and durability of the asphalt mixtures, as compared to virgin asphalt mixtures (without RAP.

  3. Design of Rigid and Flexible Pavements by Various Methods & Their Cost Analysis of Each Method

    Directory of Open Access Journals (Sweden)

    Saurabh Jain

    2013-09-01

    Full Text Available Highway and pavement design plays an important role in the DPR projects. The satisfactory performance of the pavement will result in higher savings in terms of vehicle operating costs and travel time, which has a bearing on the overall economic feasibility of the project. This paper discusses about the design methods that are traditionally being followed and examines the “Design of rigid and flexible pavements by various methods & their cost analysis by each method”. Flexible pavement are preferred over cement concrete roads as they have a great advantage that these can be strengthened and improved in stages with the growth of traffic and also their surfaces can be milled and recycled for rehabilitation. The flexible pavements are less expensive also with regard to initial investment and maintenance. Although Rigid pavement is expensive but have less maintenance and having good design period. The economic part are carried out for the design pavement of a section by using the result obtain by design method and their corresponding component layer thickness. It can be done by drawing comparisons with the standard way and practical way. This total work includes collection of data analysis various flexible and rigid pavement designs and their estimation procedure are very much useful to engineer who deals with highways.

  4. Geo synthetic-reinforced Pavement systems

    International Nuclear Information System (INIS)

    Geo synthetics have been used as reinforcement inclusions to improve pavement performance. while there are clear field evidence of the benefit of using geo synthetic reinforcements, the specific conditions or mechanisms that govern the reinforcement of pavements are, at best, unclear and have remained largely unmeasured. Significant research has been recently conducted with the objectives of: (i) determining the relevant properties of geo synthetics that contribute to the enhanced performance of pavement systems, (ii) developing appropriate analytical, laboratory and field methods capable of quantifying the pavement performance, and (iii) enabling the prediction of pavement performance as a function of the properties of the various types of geo synthetics. (Author)

  5. Use of noncontact sensors for paving operations on airport pavements

    Science.gov (United States)

    Lenngren, Carl A.

    1999-01-01

    The Swedish National Road Administration has been using a laser range finder system for assessing longitudinal and transversa profiles of pavements for a number of years. The Civil Administration has expressed interest in trying automated methods for surveying airfield runways. Regardless of sampling method, the data re used as input for computer aided design of new pavement surfaces. Typically, the output will consist of tables and maps of where to pave and mill the old pavement surface. Adjusting an old surface to perfectly smooth standards may require continuously changing the new pavement layer thickness. Traditionally, this was often carried out with mechanical devices, usually in direct touch with a wire. Some manufacturers now offer non-contact devices for pavers such as ultra sound sensors as an alternative to the mechanical sensors thus eliminating the need for setting up sires. The method was tested in late 1997 after the output data were converted for a design to be read directly by a paver control unit. A larger test was done in the summer of 1998. The results were promising and the Royal Swedish Fortifications Administration decided to try the method on a taxiway in 1999. The present paper describes some of the experiences obtained with this method and computer controlled equipment in general.

  6. The Concrete and Pavement Challenge

    Science.gov (United States)

    Roman, Harry T.

    2012-01-01

    The modern world is characterized by the extensive use of concrete and asphalt pavement. Periodically, these materials are replaced and the old materials disposed of. In this challenge, students will be asked to develop ways to reuse the old materials. It is important for students to understand how concrete and asphalt are made and applied, as…

  7. Natural Airfield Pavements, Load-Carrying Capacities There Of, Principles Of Construction And Operational Use

    Directory of Open Access Journals (Sweden)

    Nita Piotr

    2015-09-01

    Full Text Available The paper has been intended to present analytically derived relationships for aircraft wheels that move through the soil medium. The analyses have been conducted for both the rigid wheel and the pneumatic whell. The most fundamental principles of constructing natural(soil and sod/grass airfield pavements have been diccussed. Characteristic of soils typical of such pavements /surfaces have been defined. Proped are criteria for the evaluation of load-carring capacities of such pavements. The most essential principles that goven the operational use there of follow.

  8. Effect of Pavement Conditions on Rolling Resistance

    Directory of Open Access Journals (Sweden)

    Mr.Dipanjan Mukherjee

    2014-07-01

    Full Text Available Rolling resistance is the force acting on a vehicle over a full journey. It is generated by the hysteresis of tyre and pavement. Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body (such as a ball, tire, or wheel rolls on a surface. It is mainly caused by non-elastic effects; that is, not all the energy needed for deformation (or movement of the wheel, roadbed, etc. is recovered when the pressure is removed. A hysteresis phenomenon can be observed when viscoelastic materials undergo a load-then-unload process. A typical hysteresis curve of viscoelastic material can be found. The shadow area enclosed by the hysteresis loop represents energy loss. A characteristic of a deformable material such that the energy of deformation is greater than the energy of recovery. The rubber compound in a tire exhibits hysteresis. As the tire rotates under the weight of the vehicle, it experiences repeated cycles of deformation and recovery, and it dissipates the hysteresis energy loss as heat. Hysteresis is the main cause of energy loss associated with rolling resistance and is attributed to the viscoelastic characteristics of the rubber. Materials that have a large hysteresis effect, such as rubber, which bounce back slowly, exhibit more rolling resistance than materials with a small hysteresis effect that bounce back more quickly and more completely, such as steel or silica. Low rolling resistance tires typically incorporate silica in place of carbon black in their tread compounds to reduce low-frequency hysteresis without compromising traction. Note that railroads also have hysteresis in the roadbed structure. Like the fuel consumption, rolling resistance also has a significant relationship with velocity. experiment has shown that, for a 32-tonn goods vehicle, rolling resistance contributes about 70% of total drag when driven at 50km/h and about 37% at 100km/h. An important issue which should not be overlooked is that rolling resistance is affected by the characteristics of the pavement surface. Rolling resistance varies between different pavement surfaces. Hard and smooth surfaces produce lower rolling resistance than soft and rough surfaces. Rolling resistance is affected by both tyre and ambient temperature.

  9. Effectiveness of pavement-solar energy system – An experimental study

    International Nuclear Information System (INIS)

    Highlights: • We built a small-scale pilot project of pavement-solar energy utilization. • Design an automatic monitoring system to record the operating data. • The average heat absorptivity of pavement-solar energy is 37%. • The average thermal storage effectiveness of the system is 17%. - Abstract: A small-scale pilot project was built for the pavement-solar energy utilization in this paper. An automatic data acquisition system was designed to measure the effectiveness of the pavement solar energy system based on the operation data of 24 h a day in both summer and winter. Through 69 days (1656 h) of operation in summer, 2821 kW h of heat energy were stored in soil underground. In the transitional season, 4598 kW h of heat energy were taken out from soil during 104 days (2496 h) of operation in winter. The analysis showed that in summer, solar heat collection of asphalt pavement could effectively reduce 7 °C of its temperature. Under conditions of natural radiation, the average heat absorptivity of pavement was 37% and the average thermal storage effectiveness of the system was 17%. The electrical energy consumed by the system is only 11% of stored heat. During the winter, the asphalt pavement absorbs heat from underground soil which effectively increases its temperature, cutting 32% days of surface temperature below the freezing point. This not only save the energy for ice/snow removal but also mitigate associated safety risks

  10. The use of reflective and permeable pavements as a potential practice for heat island mitigation and stormwater management

    International Nuclear Information System (INIS)

    To help address the built environmental issues of both heat island and stormwater runoff, strategies that make pavements cooler and permeable have been investigated through measurements and modeling of a set of pavement test sections. The investigation included the hydraulic and thermal performance of the pavements. The permeability results showed that permeable interlocking concrete pavers have the highest permeability (or infiltration rate, ?0.5 cm s?1). The two permeable asphalt pavements showed the lowest permeability, but still had an infiltration rate of ?0.1 cm s?1, which is adequate to drain rainwater without generating surface runoff during most typical rain events in central California. An increase in albedo can significantly reduce the daytime high surface temperature in summer. Permeable pavements under wet conditions could give lower surface temperatures than impermeable pavements. The cooling effect highly depends on the availability of moisture near the surface layer and the evaporation rate. The peak cooling effect of watering for the test sections was approximately 15–35?°C on the pavement surface temperature in the early afternoon during summer in central California. The evaporative cooling effect on the pavement surface temperature at 4:00 pm on the third day (25 h after watering) was still 2–7?°C lower compared to that on the second day, without considering the higher air temperature on the third day. A separate and related simulation study performed by UCPRC showed that full depth permeable pavements, if designed properly, can carry both light-duty traffic and certain heavy-duty vehicles while retaining the runoff volume captured from an average California storm event. These preliminarily results indicated the technical feasibility of combined reflective and permeable pavements for addressing the built environment issues related to both heat island mitigation and stormwater runoff management. (letter)

  11. Representative volume element of asphalt pavement for electromagnetic measurements

    Directory of Open Access Journals (Sweden)

    Terhi Pellinen

    2015-02-01

    Full Text Available The motivation for this study was to investigate the representative volume element (RVE needed to correlate the nondestructive electromagnetic (EM measurements with the conventional destructive asphalt pavement quality control measurements. A large pavement rehabilitation contract was used as the test site for the experiment. Pavement cores were drilled from the same locations where the stationary and continuous Ground Penetrating Radar (GPR measurements were obtained. Laboratory measurements included testing the bulk density of cores using two methods, the surface-saturated dry method and determining bulk density by dimensions. Also, Vector Network Analyzer (VNA and the through specimen transmission configuration were employed at microwave frequencies to measure the reference dielectric constant of cores using two different footprint areas and therefore volume elements. The RVE for EM measurements turns out to be frequency dependent; therefore in addition to being dependent on asphalt mixture type and method of obtaining bulk density, it is dependent on the resolution of the EM method used. Then, although the average bulk property results agreed with theoretical formulations of higher core air void content giving a lower dielectric constant, for the individual cores there was no correlation for the VNA measurements because the volume element seizes deviated. Similarly, GPR technique was unable to capture the spatial variation of pavement air voids measured from the 150-mm drill cores. More research is needed to determine the usable RVE for asphalt.

  12. A simplified modelling for cracking in pavements

    OpenAIRE

    TRAN, QD; CHABOT, A; EHRLACHER, A; TAMAGNY, P

    2004-01-01

    The French pavement design method uses the 2D axi-symmetric structural analysis of Burmister's model. This model calculates almost analytically and efficiently a multilayer on a solid half space soil subjected to a circular load. However, to take into account pavement degradations as cracks in the structure, for concrete and bituminous pavements, the design method requires other models. They can be modelled by using 3D finite element methods, but such calculations can be very time-consuming. ...

  13. Enhancing pavements for thermal applications

    OpenAIRE

    Keikhaei Dehdezi, Pejman

    2012-01-01

    Renewable energy combined with energy efficiency can offer a viable and influential solution to minimise the harmful consequences of both fossil fuel depletion and increases in the cost of power generation. However, in most cases renewable energy technologies require high initial investments that may deter potential users. Pavement Energy Systems (PES) potentially offer a low-cost solution to sustainable and clean energy generation by utilising the thermo-physical properties and design featur...

  14. Generation mechanisms of tire-pavement noise

    Science.gov (United States)

    Dare, Tyler P.

    Tire-pavement noise is the dominant source of traffic noise at highway speeds. It is the result of a combination of several noise generation mechanisms, including tire carcass vibration and tread block vibration. Because multiple mechanisms are involved, it is difficult to predict the effects of changes in pavement parameters on tire-pavement noise. In this research, a set of experimental techniques were developed to decompose a measured tire-pavement noise spectrum into a set of constituent spectra relating to each generation mechanism. Three principal mechanisms were identified: treadband vibration, sidewall vibration, and tangential tread block vibration. By combining the constituent spectra associated with these mechanisms, it was possible to accurately predict the total tire-pavement noise spectrum. The constituent spectra were fit to tire-pavement noise data measured on asphalt and concrete pavements at highway speeds. It was found that the constituent spectra fit the measured data well, and a two-parameter model was developed to predict tire-pavement noise levels from pavement texture data.

  15. Superfícies estriadas no embasamento granítico e vestígio de pavimento de clastos neopaleozóicos na região de Salto, SP Neopaleozoic striated surfaces in the granitic basement and clast pavement remains of Salto, SP

    Directory of Open Access Journals (Sweden)

    Annabel Pérez-Aguilar

    2009-03-01

    Full Text Available Nas proximidades da Cerâmica Guaraú, localizada a sudoeste da cidade de Salto, Estado de São Paulo, dois afloramentos de granito, distantes algumas dezenas de metros um do outro, exibem superfícies estriadas neopaleozóicas. Essas superfícies estão em contato com diamictitos do Subgrupo Itararé. As estrias correspondem a sulcos subparalelos com espaçamento e profundidade milimétrica, possuindo uma direção média de N48°W e mergulhos variando entre 12° e 42° para SE. As feições observadas e a sua associação com diamictitos indicam uma origem por abrasão glacial devido ao movimento de massas de gelo de sudeste para noroeste. A aproximadamente 1,8 km a este da cidade de Salto foi encontrado, no topo de afloramentos de granito, material inconsolidado contendo abundantes clastos de quartzito facetados e estriados. Esses clastos foram interpretados como vestígios de um pavimento de castos.Near Guaraú Ceramic, localized southwest of Salto city in the State of São Paulo, two granite outcrops, distant some tens of meters from each other, display Neopaleozoic striated surfaces. These surfaces are in contact with diamictites from the Itararé Subgroup. The striae correspond to sub parallel grooves with millimetric spacing and depth, oriented about N48E and dipping 12° to 42° towards SE. Observed features and association with diamictites indicate an origin by glacial abrasion due to ice movement from southeast towards northwest. About 1.8 km east of Salto, unconsolidated material containing flat-iron-shaped and striated clasts was found on top of granite outcrops, interpreted as clast pavement remains.

  16. Cooler reflective pavements give benefits beyond energy savings: durability and illumination

    Energy Technology Data Exchange (ETDEWEB)

    Pomerantz, Melvin; Akbari, Hashem; Harvey, John T.

    2000-06-01

    City streets are usually paved with asphalt concrete because this material gives good service and is relatively inexpensive to construct and maintain. We show that making asphalt pavements cooler, by increasing their reflection of sunlight, may lead to longer lifetime of the pavement, lower initial costs of the asphalt binder, and savings on street lighting and signs. Excessive glare due to the whiter surface is not likely to be a problem.

  17. A study of ageing and degradation of asphalt pavements on low volume roads

    OpenAIRE

    Lerfald, Bjørn Ove

    2000-01-01

    An important objective with this research work has been to get more knowledge about mix design and maintenance of low volume roads with asphalt pavements in Norway. A literature review on bitumen, filler, rheology and ageing has been carried out. This has been focused on bitumen and filler because of their importance in the asphalt mixture. Bitumen as the binder in the asphalt pavement, and filler because of its relatively large surface area compared to the rest of the aggregates. Filler will...

  18. Characterization of pavement texture by means of height difference correlation and relation to wet skid resistance

    Directory of Open Access Journals (Sweden)

    Stefan Torbruegge

    2015-04-01

    We deduce within this article the correlation between classical surface roughness parameters and the parameter set of self-affine surfaces. These parameters allow for a detailed understanding of the relationship between pavement texture and its wet skid resistance. We present wet skid resistance measurements with the British pendulum and a linear friction tester device on different pavement textures. We demonstrate that the so-called estimated texture depth does not correlate to the surface skid resistance measured with the British pendulum. Finally, we deduce a dependency of wet skid resistance on pavement texture which is supported by current models for hysteresis friction.

  19. Preliminary evaluation of the lifecycle costs and market barriers of reflective pavements; TOPICAL

    International Nuclear Information System (INIS)

    The objective of this study is to evaluate the life cycle costs and market barriers associated with using reflective paving materials in streets and parking lots as a way to reduce the urban heat island effect. We calculated and compared the life cycle costs of conventional asphalt concrete (AC) pavements to those of other existing pavement technologies with higher reflectivity-portland cement concrete (PCC), porous pavements, resin pavements, AC pavements using light-colored chip seals, and AC pavements using light-colored asphalt emulsion additives. We found that for streets and parking lots, PCC can provide a cost-effective alternative to conventional AC when severely damaged pavements must be completely reconstructed. We also found that rehabilitating damaged AC streets and intersections with thin overlays of PCC (ultra-thin white topping) can often provide a cost-effective alternative to standard rehabilitation techniques using conventional AC. Chip sealing is a common maintenance treatment for low-volume streets which, when applied using light-colored chips, could provide a reflective pavement surface. If the incremental cost of using light-colored chips is low, this chip sealing method could also be cost-effective, but the incremental costs of light-colored chips are as of yet uncertain and expected to vary. Porous pavements were found to have higher life cycle costs than conventional AC in parking lots, but several cost-saving features of porous pavements fell outside the boundaries of this study. Resin pavements were found to be only slightly more expensive than conventional AC, but the uncertainties in the cost and performance data were large. The use of light-colored additives in asphalt emulsion seal coats for parking lot pavements was found to be significantly more expensive than conventional AC, reflecting its current niche market of decorative applications. We also proposed two additional approaches to increasing the reflectivity of conventional AC, which we call the chipping and aggregate methods, and calculated their potential life cycle costs. By analyzing the potential for increased pavement durability resulting from these conceptual approaches, we then estimated the incremental costs that would allow them to be cost-effective compared to conventional AC. For our example case of Los Angeles, we found that those allowable incremental costs range from less than dollar 1 to more than dollar 11 per square yard (dollar 1 to dollar 13 per square meter) depending on street type and the condition of the original pavement. Finally, we evaluated the main actors in the pavement market and the existing and potential market barriers associated with reflective pavements. Apart from situations where lifecycle costs are high compared to conventional AC, all reflective paving technologies face a cultural barrier based on the belief that black is better. For PCC, high first costs were found to be the most significant economic barrier, particularly where agencies are cons trained by first cost. Lack of developer standards was found to be a significant institutional barrier to PCC since developers are often not held accountable for the long-term maintenance of roads after initial construction, which creates a misplaced incentive to build low first-cost pavements. PCC also faces site-specific barriers such as poorly compacted base soils and proximity to areas of frequent utility cutting

  20. Preliminary evaluation of the lifecycle costs and market barriers of reflective pavements

    Energy Technology Data Exchange (ETDEWEB)

    Ting, M.; Koomey, J.G.; Pomerantz, M.

    2001-11-21

    The objective of this study is to evaluate the life cycle costs and market barriers associated with using reflective paving materials in streets and parking lots as a way to reduce the urban heat island effect. We calculated and compared the life cycle costs of conventional asphalt concrete (AC) pavements to those of other existing pavement technologies with higher reflectivity-portland cement concrete (PCC), porous pavements, resin pavements, AC pavements using light-colored chip seals, and AC pavements using light-colored asphalt emulsion additives. We found that for streets and parking lots, PCC can provide a cost-effective alternative to conventional AC when severely damaged pavements must be completely reconstructed. We also found that rehabilitating damaged AC streets and intersections with thin overlays of PCC (ultra-thin white topping) can often provide a cost-effective alternative to standard rehabilitation techniques using conventional AC. Chip sealing is a common maintenance treatment for low-volume streets which, when applied using light-colored chips, could provide a reflective pavement surface. If the incremental cost of using light-colored chips is low, this chip sealing method could also be cost-effective, but the incremental costs of light-colored chips are as of yet uncertain and expected to vary. Porous pavements were found to have higher life cycle costs than conventional AC in parking lots, but several cost-saving features of porous pavements fell outside the boundaries of this study. Resin pavements were found to be only slightly more expensive than conventional AC, but the uncertainties in the cost and performance data were large. The use of light-colored additives in asphalt emulsion seal coats for parking lot pavements was found to be significantly more expensive than conventional AC, reflecting its current niche market of decorative applications. We also proposed two additional approaches to increasing the reflectivity of conventional AC, which we call the chipping and aggregate methods, and calculated their potential life cycle costs. By analyzing the potential for increased pavement durability resulting from these conceptual approaches, we then estimated the incremental costs that would allow them to be cost-effective compared to conventional AC. For our example case of Los Angeles, we found that those allowable incremental costs range from less than dollar 1 to more than dollar 11 per square yard (dollar 1 to dollar 13 per square meter) depending on street type and the condition of the original pavement. Finally, we evaluated the main actors in the pavement market and the existing and potential market barriers associated with reflective pavements. Apart from situations where lifecycle costs are high compared to conventional AC, all reflective paving technologies face a cultural barrier based on the belief that black is better. For PCC, high first costs were found to be the most significant economic barrier, particularly where agencies are cons trained by first cost. Lack of developer standards was found to be a significant institutional barrier to PCC since developers are often not held accountable for the long-term maintenance of roads after initial construction, which creates a misplaced incentive to build low first-cost pavements. PCC also faces site-specific barriers such as poorly compacted base soils and proximity to areas of frequent utility cutting.

  1. Response of desert pavement to seismic shaking, Hector Mine earthquake, California, 1999

    Science.gov (United States)

    Haff, P. K.

    2005-06-01

    The October 1999 Mw 7.1 Hector Mine earthquake in the Mojave Desert, California, generated characteristic surface disturbances on nearby desert pavements. These disturbances included (1) zones of wholesale gravel displacement interspersed with zones of intact pavement, (2) displaced and rotated cobbles, (3) moats around loosened, embedded boulders, (4) filling of abandoned cobble sockets, boulder moats, and other depressions with gravel, and (5) formation of narrow, subparallel, linear strips of exposed fine-grained subpavement matrix (matrix lineations). Clasts displaced from matrix lineations and from cobble sockets tended to move downslope. Sharp boundaries of matrix lineations and slope-controlled displacement directions on slopes of only a few degrees indicated that clasts remained close to the pavement surface during shaking. The regular, few decimeter spacing of matrix lineations suggests the presence of standing waves during seismic shaking. Boulder moats probably have good preservation potential and, at some desert pavement locations, might provide information on paleoseismic shaking. Although readily produced by coseismic shaking, displaced cobbles are unreliable indicators of past earthquake activity because of potential multiple origins. For an assumed earthquake recurrence interval of 10 ka, seismically driven sediment fluxes similar to those generated by the Hector Mine earthquake at the Lavic Siding pavement study site may be marginally competitive with aseismic smoothing mechanisms driven by bioturbation, rainbeat, and wash. For a 1 ka recurrence interval, seismic smoothing is likely to play a significant role in pavement evolution.

  2. Adaptive road crack detection system by pavement classification.

    Science.gov (United States)

    Gavilán, Miguel; Balcones, David; Marcos, Oscar; Llorca, David F; Sotelo, Miguel A; Parra, Ignacio; Ocaña, Manuel; Aliseda, Pedro; Yarza, Pedro; Amírola, Alejandro

    2011-01-01

    This paper presents a road distress detection system involving the phases needed to properly deal with fully automatic road distress assessment. A vehicle equipped with line scan cameras, laser illumination and acquisition HW-SW is used to storage the digital images that will be further processed to identify road cracks. Pre-processing is firstly carried out to both smooth the texture and enhance the linear features. Non-crack features detection is then applied to mask areas of the images with joints, sealed cracks and white painting, that usually generate false positive cracking. A seed-based approach is proposed to deal with road crack detection, combining Multiple Directional Non-Minimum Suppression (MDNMS) with a symmetry check. Seeds are linked by computing the paths with the lowest cost that meet the symmetry restrictions. The whole detection process involves the use of several parameters. A correct setting becomes essential to get optimal results without manual intervention. A fully automatic approach by means of a linear SVM-based classifier ensemble able to distinguish between up to 10 different types of pavement that appear in the Spanish roads is proposed. The optimal feature vector includes different texture-based features. The parameters are then tuned depending on the output provided by the classifier. Regarding non-crack features detection, results show that the introduction of such module reduces the impact of false positives due to non-crack features up to a factor of 2. In addition, the observed performance of the crack detection system is significantly boosted by adapting the parameters to the type of pavement. PMID:22163717

  3. Runoff on Pavements of Soil-Cement Blocks – an Experimental Boarding

    Directory of Open Access Journals (Sweden)

    Zegarra-Tarqui Jorge Luis

    2015-01-01

    Full Text Available The article evaluates the reduction of runoff in pavements constructed with rectangular blocks of soil-cement. The tests were conducted in a pilot pavement built with soil-cement blocks, seated in a metal box of 50 cm × 50 cm (area = 2500 cm2, with declivities of 1%, 3% and 5%. Mean intensities of 76.9 mm / I 117.7 mm / h were used, values close to the intensities calculated by intensity-frequency-duration (i-f- -d equation of the city of Salvador, Brazil, for return periods of 2 and 5 years, respectively. The medium runoff coefficient was C = 0.61, this value is close to the coefficient of pavement with rectangular blocks (C = 0.6 and it has a lower value than the coefficient for concrete block pavement (C = 0.78. On the other hand, considering that areas with more than 2500 cm2 are constituted by coupling of area units of 50 cm × 50 cm, the splash losses are part of the runoff, obtaining the coefficient Csuperficial + splashing, which showed values in the 0.74 to 0.89 range, these values were found close to the coefficient of concrete block pavement (C = 0.78 and below the concrete pavement (C = 0.95, respectively, but factors such as displacement time of runoff on surface, depressions on the surface, roughness of pavement, evaporation and others, should reduce this value. Then, the pavement of soil-cement blocks can be considered in the category of semi-permeable for the area size used.

  4. The Road Traffic Noise Reduction on the Drainage Pavement

    OpenAIRE

    Ali, Nur; Hustim, Muralia; Zubair, Achmad; Zakaria, Rasdiana

    2013-01-01

    The drainage pavement or porous asphalt has open structure of its gradation. Therefore, the porous asphalt can reduce noise level from road traffic, as well as drains water from the road surface. These behaviors lead to the porous asphalt contribution on road traffic noise reduction and environment. This paper provides an artificial simulation on the road traffic noise reduction when the porous asphalt is applied an urban expressway. The simulation using and adapting ASJ RTN-2008 Model approa...

  5. Mathematical failure-theory (MFT methodology in pavement management system for rehabilitation and repair methods selection

    Directory of Open Access Journals (Sweden)

    Fereidoon Moghadas Nejad

    2009-04-01

    Full Text Available Pavement rehabilitation and repair methods selection is one of the key issues many road organizations and researchers have occupied. Not only road management cost but also road user’s cost and cost for inhabitants and community should be included in the life cycle cost in order to help infrastructure investment judgment. Thus in estimating life cycle cost, Pavement rehabilitation and repair methods selection is essential even if technological capabilities of evaluation are not sufficient. In order for Pavement Management Systems (PMS to be effective, they must be based on a reliable, statistically sound means for the rehabilitation and repair methods that are present on the system. To make sensible life cycle cost decisions in design and rehabilitation, pavement engineers must be able to account for distress phenomena and repair methods. This paper will present a Mathematical Failure-Theory (MFT methodology for incorporating statistical and probabilistically Factors into life cycle cost analysis and PMS. This approach gives the engineer the ability to statistically and probability consider different rehabilitation and repair method and statistically and probability factors in computing the life cycle costs for rehabilitation and repair methods selection.

  6. Superfícies estriadas no embasamento granítico e vestígio de pavimento de clastos neopaleozóicos na região de Salto, SP / Neopaleozoic striated surfaces in the granitic basement and clast pavement remains of Salto, SP

    Scientific Electronic Library Online (English)

    Annabel, Pérez-Aguilar; Setembrino, Petri; Rafhael, Hypólito; Sibele, Ezaki; Paulo Alves de, Souza; Caetano, Juliani; Lena V.S., Monteiro; Francisco A., Moschini.

    2009-03-01

    Full Text Available Nas proximidades da Cerâmica Guaraú, localizada a sudoeste da cidade de Salto, Estado de São Paulo, dois afloramentos de granito, distantes algumas dezenas de metros um do outro, exibem superfícies estriadas neopaleozóicas. Essas superfícies estão em contato com diamictitos do Subgrupo Itararé. As e [...] strias correspondem a sulcos subparalelos com espaçamento e profundidade milimétrica, possuindo uma direção média de N48°W e mergulhos variando entre 12° e 42° para SE. As feições observadas e a sua associação com diamictitos indicam uma origem por abrasão glacial devido ao movimento de massas de gelo de sudeste para noroeste. A aproximadamente 1,8 km a este da cidade de Salto foi encontrado, no topo de afloramentos de granito, material inconsolidado contendo abundantes clastos de quartzito facetados e estriados. Esses clastos foram interpretados como vestígios de um pavimento de castos. Abstract in english Near Guaraú Ceramic, localized southwest of Salto city in the State of São Paulo, two granite outcrops, distant some tens of meters from each other, display Neopaleozoic striated surfaces. These surfaces are in contact with diamictites from the Itararé Subgroup. The striae correspond to sub parallel [...] grooves with millimetric spacing and depth, oriented about N48E and dipping 12° to 42° towards SE. Observed features and association with diamictites indicate an origin by glacial abrasion due to ice movement from southeast towards northwest. About 1.8 km east of Salto, unconsolidated material containing flat-iron-shaped and striated clasts was found on top of granite outcrops, interpreted as clast pavement remains.

  7. Dust accretion under stone pavements: A complementary environmental archive in arid environments

    Science.gov (United States)

    Dietze, Michael; Fuchs, Markus; Kleber, Arno

    2014-05-01

    Stone pavements are widespread surface covers in arid environments. They form predominantly by the trapping of aeolian dust, which trickles below the surficial clast layer, where it forms a continuous layer of fine-grained material with a prominent foamy structure: the vesicular horizon (Av). Successive accretion of dust leads to a thickening of the aeolian mantle and detaches clasts from bedrock. Since this process is dependent on environmental conditions, stone pavement-covered accretionary sections can be used as palaeoenvironmental archive. In the eastern Mojave Desert, correlation of six sediment sections on a 560 ka old basalt flow yield a standard section, comprising at least three distinct units of pulsed aeolian sediment input, interrupted by phases of stone pavement formation, their burial and subsequent pedogenetic alteration. Formation and subsequent burial of stone pavements requires lateral re-formation processes. Two such processes - clast drag by unconcentrated overland flow and clast creep by air release from the soil - are presented, along with their environmental boundary conditions. The different sedimentary units under stone pavements in the eastern Mojave Desert must be interpreted in the light of both, the prominent climatic changes during the Pleistocene/Holocene and the young drainage system in this region. Accretionary dust sections under stone pavements receive their sediment predominantly from modern playas. However, they typically start trapping sediment and thus environmental information when the lake level drops and the lacustrine archive deceases. Hence, they appear to be complementary archives with a the potential to fill the stratigraphic gaps in lacustrine records.

  8. Global warming potential of pavements

    International Nuclear Information System (INIS)

    Pavements comprise an essential and vast infrastructure system supporting our transportation network, yet their impact on the environment is largely unquantified. Previous life-cycle assessments have only included a limited number of the applicable life-cycle components in their analysis. This research expands the current view to include eight different components: materials extraction and production, transportation, onsite equipment, traffic delay, carbonation, lighting, albedo, and rolling resistance. Using global warming potential as the environmental indicator, ranges of potential impact for each component are calculated and compared based on the information uncovered in the existing research. The relative impacts between components are found to be orders of magnitude different in some cases. Context-related factors, such as traffic level and location, are also important elements affecting the impacts of a given component. A strategic method for lowering the global warming potential of a pavement is developed based on the concept that environmental performance is improved most effectively by focusing on components with high impact potentials. This system takes advantage of the fact that small changes in high-impact components will have more effect than large changes in low-impact components.

  9. Global warming potential of pavements

    Energy Technology Data Exchange (ETDEWEB)

    Santero, Nicholas J [Department of Civil and Environmental Engineering, 407 McLaughlin Hall, University of California, Berkeley, CA 94720-1712 (United States); Horvath, Arpad, E-mail: njsantero@cal.berkeley.ed, E-mail: horvath@ce.berkeley.ed [Department of Civil and Environmental Engineering, 215B McLaughlin Hall, University of California, Berkeley, CA 94720-1712 (United States)

    2009-09-15

    Pavements comprise an essential and vast infrastructure system supporting our transportation network, yet their impact on the environment is largely unquantified. Previous life-cycle assessments have only included a limited number of the applicable life-cycle components in their analysis. This research expands the current view to include eight different components: materials extraction and production, transportation, onsite equipment, traffic delay, carbonation, lighting, albedo, and rolling resistance. Using global warming potential as the environmental indicator, ranges of potential impact for each component are calculated and compared based on the information uncovered in the existing research. The relative impacts between components are found to be orders of magnitude different in some cases. Context-related factors, such as traffic level and location, are also important elements affecting the impacts of a given component. A strategic method for lowering the global warming potential of a pavement is developed based on the concept that environmental performance is improved most effectively by focusing on components with high impact potentials. This system takes advantage of the fact that small changes in high-impact components will have more effect than large changes in low-impact components.

  10. In place recycling of granular bases of asphalt pavements

    Directory of Open Access Journals (Sweden)

    Taís Sachet

    2008-04-01

    Full Text Available This work presents the results of a study intended the obtaining and introduction of the auxiliary elements to assure the road pavements technological control of rehabilitation which involves the recycling in place of granular bases. This verification was made using two techniques, the CBR in place verification, through the use of DCP (Dynamic Cone Penetrometer, and the granulometric framing, through the curve of Talbot, for recycled materials. The investigations were accomplished starting from practical applications in roads which involved, in an experimental way, the pavements rehabilitation through the base course recycling, incorporating the surface layer. Through the data processing obtained in the tests, it was possible the elaboration of the technical specification proposal of the granular bases recycling.

  11. Effective flow resistivity of highway pavements.

    Science.gov (United States)

    Rochat, Judith L; Read, David R

    2013-12-01

    In the case of highway traffic noise, propagating sound is influenced by the ground over which it travels, whether it is the pavement itself or the ground between the highway and nearby communities. Properly accounting for ground type in modeling can increase accuracy in noise impact determinations and noise abatement design. Pavement-specific effective flow resistivity values are being investigated for inclusion in the Federal Highway Administration Traffic Noise Model, which uses these values in the sound propagation algorithms and currently applies a single effective flow resistivity value to all pavement. Pavement-specific effective flow resistivity values were obtained by applying a modified version of the American National Standards Institute S1.18 standard. The data analysis process was tailored to allow for increased sensitivity and extraction of effective flow resistivity values for a broad range of pavements (sound absorptive to reflective). For porous pavements (sound absorptive), it was determined that examination of the measured data can reveal influence from an underlying structure. Use of such techniques can aid in the design of quieter pavements. PMID:25669283

  12. Assessment of highway pavements using GPR

    Science.gov (United States)

    Plati, Christina; Loizos, Andreas

    2015-04-01

    Highway infrastructure is a prerequisite for a functioning economy and social life. Highways, often prone to congestion and disruption, are one of the aspects of a modern transport network that require maximum efficiency if an integrated transport network, and sustainable mobility, is to be achieved. Assessing the condition of highway structures, to plan subsequent maintenance, is essential to allow the long-term functioning of a road network. Optimizing the methods used for such assessment will lead to better information being obtained about the road and underlying ground conditions. The condition of highway structures will be affected by a number of factors, including the properties of the highway pavement, the supporting sub-base and the subgrade (natural ground), and the ability to obtain good information about the entire road structure, from pavement to subgrade, allows appropriate maintenance programs to be planned. The maintenance of highway pavements causes considerable cost and in many cases obstruction to traffic flow. In this situation, methods that provide information on the present condition of pavement structure non-destructively and economically are of great interest. It has been shown that Ground-Penetrating-Radar (GPR), which is a Non Destructive Technique (NDT), can deliver information that is useful for the planning of pavement maintenance activities. More specifically GPR is used by pavement engineers in order to determine physical properties and characteristics of the pavement structure, information that is valuable for the assessment of pavement condition. This work gives an overview on the practical application of GPR using examples from highway asphalt pavements monitoring. The presented individual applications of GPR pavement diagnostics concern structure homogeneity, thickness of pavement layers, dielectric properties of asphalt materials etc. It is worthwhile mentioning that a number of applications are standard procedures, either separately or in combination with other NDT methods, but even for them there is still a room for improvement and there is still need to set stricter regulations Comparisons between radar results and ground truth data produce evidence in support of the statement that the accuracy and reliability of radar results is sufficient for facing many issues related to the evaluation of asphalt pavements. Thus, benefits and limits of this method are shown and recommendations for GPR inspections are presented. Acknowledgments: This work benefited from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar."

  13. Thermal Stability Analysis under Embankment with Asphalt Pavement and Cement Pavement in Permafrost Regions

    OpenAIRE

    Zhang Junwei; Li Jinping; Quan Xiaojuan

    2013-01-01

    The permafrost degradation is the fundamental cause generating embankment diseases and pavement diseases in permafrost region while the permafrost degradation is related with temperature. Based on the field monitoring results of ground temperature along G214 Highway in high temperature permafrost regions, both the ground temperatures in superficial layer and the annual average temperatures under the embankment were discussed, respectively, for concrete pavements and asphalt pavements. The max...

  14. Road Asphalt Pavements Analyzed by Airborne Thermal Remote Sensing: Preliminary Results of the Venice Highway

    Directory of Open Access Journals (Sweden)

    Rosa Cavalli

    2008-02-01

    Full Text Available This paper describes a fast procedure for evaluating asphalt pavement surface defects using airborne emissivity data. To develop this procedure, we used airborne multispectral emissivity data covering an urban test area close to Venice (Italy.For this study, we first identify and select the roads’ asphalt pavements on Multispectral Infrared Visible Imaging Spectrometer (MIVIS imagery using a segmentation procedure. Next, since in asphalt pavements the surface defects are strictly related to the decrease of oily components that cause an increase of the abundance of surfacing limestone, the diagnostic absorption emissivity peak at 11.2μm of the limestone was used for retrieving from MIVIS emissivity data the areas exhibiting defects on asphalt pavements surface.The results showed that MIVIS emissivity allows establishing a threshold that points out those asphalt road sites on which a check for a maintenance intervention is required. Therefore, this technique can supply local government authorities an efficient, rapid and repeatable road mapping procedure providing the location of the asphalt pavements to be checked.

  15. Wet Night Visibility of Pavement Markings

    OpenAIRE

    Gibbons, Ronald B. (Ronald Bruce); Hankey, Jonathan M.; Pashaj, Irena

    2004-01-01

    This report describes an investigation into the performance of pavement markings in wet night conditions. The performance of a typical pavement marking will degrade when it gets wet. This is a result of the flooding of the marking optics, thereby reducing retroreflectivity. Several technologies are available to improve wet marking performance. In this project, six technologies were tested using both standard measurement methods and participant evaluations. The results show that two of the mar...

  16. Pavement-marking materials: New York's experience

    Science.gov (United States)

    Bryden, J. E.; Gurney, G. F.

    1984-04-01

    A wide range of stripping materials is available for pavement-marking programs. The four basic systems; traffic paint, thermoplastic, preformed tape, and field-reacted materials are described, as well as the various materials used in each system, including cost, durability, methods of installation and mantenance, visibility, and handling safety. New York State's pavement marking policies are described. Information on stripping costs, material usage, and results of durability studies is provided, based on New York's experience with most currently available marking materials.

  17. Generating Infrastructure Funds Through Innovative Pavement Management

    OpenAIRE

    Ponce, Javier; Overton, Patrick; Cunagin, Wiley

    2015-01-01

    The American Society of Civil Engineers (ASCE) estimates that there will be a need for $3.6 trillion in infrastructure investment by 2020. A portion of this need can be made available through judicious management of the Nation's pavement systems. The Florida Department of Transportation (FDOT) has made significant progress in meeting this objective by continuously improving the performance of its materials, processes, construction methods and management, and pavement management technology. On...

  18. Modelación del envejecimiento de los pavimentos asfálticos con la metodología de la superficie de respuesta / Pavement Aging Model by Response Surface Modeling

    Scientific Electronic Library Online (English)

    L.E., Chávez-Valencia; C, Hernández-Barriga; A, Manzano-Ramírez.

    2011-12-01

    Full Text Available En la presente investigación se realizó la modelación del envejecimiento de una carpeta asfáltica por medio de la Metodología de Superficie de Respuesta (MSR). Se elaboraron muestras cilíndricas tipo Marshall, que fueron colocadas en un horno bajo las condiciones de tiempo y temperatura establecidos [...] por las condiciones ambientales de la región geográfica donde se construyen pavimentos asfálticos con el AC-20 de la Refinería Ing. Antonio M. Amor, los cuales fueron codificados en la MSR, con esto se determinaron los modelos que predicen el cambio de la estabilidad Marshall (?L) y del flujo (?F), así como la volatilización del material (VM). Además, se extrajeron muestras cilíndricas de una carpeta asfáltica piloto para determinar el error de modelación, observando que el material volatilizado predicho por el modelo VM fue muy cercano al real, no así para los modelos de ?Ly ?F, posiblemente asociado a los factores ambientales que no fueron considerados al inicio de la investigación. Abstract in english In this work, surface course aging was modeled by Response Surface Methodology (RSM). The Marshall specimens were placed in a conventional oven for time and temperature conditions established on the basis of the environment factors of the region where the surface course is constructed by AC-20 from [...] the Ing. Antonio M. Amor refinery. Volatilized material (VM), load resistance increment (?L) and flow resistance increment (?F) models were developed by the RSM. Cylindrical specimens with real aging were extracted from the surface course pilot to evaluate the error of the models. The VM model was adequate, in contrast (?L) and (?F) models were almost adequate with an error of 20 %, that was associated with the other environmental factors, which were not considered at the beginning of the research.

  19. Volatilization of polycyclic aromatic hydrocarbons from coal-tar-sealed pavement

    Science.gov (United States)

    Van Metre, Peter C.; Majewski, Michael S.; Mahler, Barbara J.; Foreman, William T.; Braun, Christopher L.; Wilson, Jennifer T.; Burbank, Teresa L.

    2012-01-01

    Coal-tar-based pavement sealants, a major source of PAHs to urban water bodies, are a potential source of volatile PAHs to the atmosphere. An initial assessment of volatilization of PAHs from coal-tar-sealed pavement is presented here in which we measured summertime gas-phase PAH concentrations 0.03 m and 1.28 m above the pavement surface of seven sealed (six with coal-tar-based sealant and one with asphalt-based sealant) and three unsealed (two asphalt and one concrete) parking lots in central Texas. PAHs also were measured in parking lot dust. The geometric mean concentration of the sum of eight frequently detected PAHs (?PAH8) in the 0.03-m samples above sealed lots (1320 ng m-3) during the hottest part of the day was 20 times greater than that above unsealed lots (66.5 ng m-3). The geometric mean concentration in the 1.28-m samples above sealed lots (138 ng m-3) was five times greater than above unsealed lots (26.0 ng m-3). Estimated PAH flux from the sealed lots was 60 times greater than that from unsealed lots (geometric means of 88 and 1.4 ?g m-2 h-1, respectively). Although the data set presented here is small, the much higher estimated fluxes from sealed pavement than from unsealed pavement indicate that coal-tar-based sealants are emitting PAHs to urban air at high rates compared to other paved surfaces.

  20. LOW-NOISE PAVEMENT AS A WAY OF LIMITATION OF TRAFFIC NOISE LEVEL

    Directory of Open Access Journals (Sweden)

    W?adys?aw Gardziejczyk

    2014-11-01

    Full Text Available Road surface can significantlyreduce the trafficnoise level. Depending on the characteristic of the upper surface layers the differences between the maximum rolling noise levels from passing vehicles to reach values about 10 dB (A. A special group is low-noise pavements characterized by the presence of voids above 15%. Application the porous asphalt layers or asphalt mixture type BBTM affects a significantreduction the width of land surrounded the roads where permissible equivalent sound level is exceeded. Such solutions in some cases can replace acoustic barriers. Road pavements with a higher content of voids require proper maintenance because their acoustic performances are reduced during operation.

  1. Comparison Between 2-D and 3-D Stiffness Matrix Model Simulation of Sasw Inversion for Pavement Structure

    OpenAIRE

    Sri Atmaja P. Rosidi

    2007-01-01

    The Spectral Analysis of Surface Wave (SASW) method is a non-destructive in situ seismic technique used to assess and evaluate the material stiffness (dynamic elastic modulus) and thickness of pavement layers at low strains. These values can be used analytically to calculate load capacities in order to predict the performance of pavement system. The SASW method is based on the dispersion phenomena of Rayleigh waves in layered media. In order to get the actual shear wave velocities, 2-D and 3-...

  2. Investigation of antenna frequency impact on assessing voids of asphalt pavements using GPR

    Science.gov (United States)

    Plati, C.; Georgouli, K.; Loizos, A.

    2012-04-01

    Ground Penetrating Radar (GPR) is a Non Destructive Testing (NDT) technique that has been developed and improved upon over the past 30 years. The technique is frequently utilized in order to evaluate and assess pavement structures. GPR, for pavement evaluation purposes, can be described as a remote sensing system that emits a short pulse, of electromagnetic energy, into the pavement, with a central frequency varying from 10 MHz up to 2.5GHz. The two most commonly utilized setups are air-coupled and ground-coupled antenna systems. For air-coupled systems, the antennas are suspended above the pavement surface and can operate at normal traffic speeds (up to ~ 80 Km/h). The major drawback of the air-coupled antenna is that penetration depth is limited. On the other hand, for ground-coupled systems the antennas are in direct contact with the pavement surface, providing for better signal penetration into the pavement structure; however ground coupled systems can achieve only limited operational speeds. As a generalized rule, increasing the GPR central operating frequency, increases the investigation resolution, while decreasing the overall depth of investigation In the light of the above, air-coupled systems have become increasingly popular for the evaluation of the part of the pavement structure, especially for the asphalt layers, while ground-coupled systems are utilized mostly in order to gather information from the entire pavement structure (up to ~ 3 m depth). The majority of GPR pavement studies are carried out with air-coupled horn antennas, as they can be implemented at driving speeds without need for road closures. For instance, the 1 GHz air-coupled horn antenna is commonly used for the estimation of pavement layer thickness. However signals generated by horn antenna systems must have sufficient quality to allow the performance of automated signal processing and qualitative data analysis, especially when pavement data more sensitive to the analysis parameters, such voids or moisture, is concerned. The implementation of the horn antenna method is dependent upon, amongst others, the resolution of the antenna in use. The present research work investigates the application of the GPR sensor technique to assess voids within the asphalt layers, with a focus on the air-coupled antenna penetration depth and resolution. For this purpose the dielectric properties of asphalt layer materials were estimated and related voids contents were evaluated based on data collected by an air-coupled GPR system, operating at a 1 GHz and alternatively a 2 GHz central frequency. The collected data is analyzed comparatively for the two antennas. Comparison results indicate differences between the voids determined from the 1 GHz and 2GHz antennas. These differences are further analyzed and evaluated for pavement quality control purposes. The indication of a relationship between the measured voids is also evaluated, while ground truth data is used for the validation of the GPR data analysis results. The above is presented and discussed thoroughly with the aim to assist pavement quality assurance systems

  3. Evaluation of airport pavements using NDT approaches

    Science.gov (United States)

    Avdelidis, N. P.; Moropoulou, A.

    2007-04-01

    Corrosion of airport pavements is a major problem involved with materials engineering and transportation engineering. Airport pavements frequently start to deteriorate slowly primarily, gradually progressing to failure. Such failure can be expensive in terms of both money and lives, but can also be prevented. For that reason, intelligent techniques should be suggested, with the intention of examining the condition of such engineering structures. IR thermography and ground penetrating radar are two NDT (non-destructive testing) techniques that have the ability to inspect effectively substantial areas, such as airport pavements. In this work, two different airport pavements located at the International Airport of Athens, in Greece, were investigated by the use of the above two mentioned techniques. Successful detection of cracks, voids and other imperfections appearing either from the aging of the materials or due to poor workmanship was attained. Furthermore, this paper describes the problem of deteriorated airport pavements, shows the process and the apparatus used for the in situ tests, and finally presents results obtained from the investigations.

  4. Calculation method for permanent deformation of unbound pavement materials

    OpenAIRE

    Korkiala-Tanttu, Leena

    2009-01-01

    An analytical-mechanistic method for the calculation of permanent deformations of pavements has been developed at the Technical Research Centre of Finland (VTT) over some years by the author. The calculation method is needed in the analytical design procedure of pavements. This research concentrated on the calculation method for permanent deformations in unbound pavement materials. The calculation method was generated based on the results of full-scale accelerated pavement tests along with th...

  5. Benefits of including hot mix recycled materials in pavement design

    OpenAIRE

    Oliveira, Joel; Pereira, Paulo A. A.; Pais, Jorge C.; Santos, Luís Picado

    2005-01-01

    Pavement recycling is becoming more acceptable among the available techniques for pavement maintenance/rehabilitation. It is based on sustainable development, by reusing materials reclaimed from the pavements and reducing the disposal of asphalt materials. Based on the results obtained from laboratory tests carried out on two bituminous mixtures, one of which including 50% of recycled asphalt, some simulations were made for the design of a pavement where those mixtures would be used as a bitu...

  6. Quantifying the Benefits of Good Pavement Asset Management

    OpenAIRE

    Hudson, W. Ronald; Haas, Ralph

    2015-01-01

    In the 1970s it became clear that pavements could not actually be designed for 30-50 year life; and that they had to be managed. It was found necessary to consider construction, maintenance, rehabilitation, and even reconstruction in the life of pavements, not just a design. The concept of pavement management was thus born. The authors have jointly about 8 decades of experience in pavement management, and, with others have seen many agencies and engineers realize the qualitative benefits of p...

  7. Friction evaluation of concrete paver blocks for airport pavement applications

    Science.gov (United States)

    Yager, Thomas J.

    1992-01-01

    The development and use of concrete paver blocks is reviewed and some general specifications for application of this type of pavement surface at airport facilities are given. Two different shapes of interlocking concrete paver blocks installed in the track surface at NASA Langley's Aircraft Landing Dynamics Facility (ALDF) are described. Preliminary cornering performance results from testing of 40 x 14 radial-belted and bias-ply aircraft tires are reviewed. These tire tests are part of a larger, ongoing joint NASA/FAA/Industry Surface Traction and Radial Tire (START) Program involving several different tire sizes. Both dry and wet surface conditions were evaluated on the two concrete paver block test surfaces and a conventional, nongrooved Portland cement concrete surface. Future test plans involving evaluation of other concrete paver block designs at the ALDF are indicated.

  8. Full scale accelerated testing of bituminous road pavement mixtures

    OpenAIRE

    Gilchrist, M. D.; Hartman, Anton M.; Owende, Philip; et al.,

    2001-01-01

    The in-service behaviour of a standard Irish Dense Base Coarse Macadam mixture (DBC) was evaluated by using the material to overlay a road section, which was based upon a weak pavement structure. The response of the layer under a fully laden dual axle truck was examined using a series of pressure cells and asphalt strain gauges that were embedded in the test section. The section was traversed repeatedly until a network of fatigue cracks was observed on the road surface. The transverse horizon...

  9. The effect of cracking on the deflection basin of flexible pavements

    Science.gov (United States)

    Omar, Hadi Mohamed

    Because of the rapid development of hardware and software during the past decade, it is now possible to use an analytical-empirical (or mechanistic) method of structural pavement evaluation on a routine basis. One reason for using this approach is the increased need for pavement maintenance and rehabilitation. To make the right choice from many potentially feasible maintenance and rehabilitation measures, the engineer must base his decision on a rational evaluation of the mechanical properties of the materials in the existing pavement structure. One of the parameters in terms of pavement response are the deflections; these are of interest to this particular study. The Falling Weight Deflectometer (FWD) has been developed specifically for the purpose of obtaining deflection measurements in order to determine the in-situ elastic moduli. The profile of the deflection at the surface of the pavement is known as the deflection basin, because it resembles a bowl-shaped depression. The magnitude of the deflections and the basin shape are functions of the number of layers making up the pavement cross section, their thicknesses, and their moduli values. A variety of multi-layered linear elastic pavement models are available for use at this present time. A general-purpose finite-element program called ANSYS developed by Swanson Analysis System is very powerful and is capable of solving a layered system such as the pavement. A finite element model was developed to study the effect of the crack on the predicted deflection bowls. A general-purpose finite-element program was used in this study due to its ability to solve this problem and because of the availability of the program. A hypothetical crack problem was assumed and modeled in different ways. The crack depth, crack width, and distance of the crack from the loading point were among the many parameters that were investigated. Considering the shape of the deflection basin, it is very important to study the effect of the crack on this bowl, when and where the cracks can be ignored, and when they would not play a significant effect. This study also addresses the importance of the field data and how the observed deflection basins compare with the predicted ones especially in aged pavements. This study has concluded that the location of a crack from the loading point is very significant to the deflection basin.

  10. Design of airport pavements for expansive soils

    Science.gov (United States)

    McKeen, R. G.

    1981-01-01

    Expansive soil subgrades exhibit volume changes with variation in moisture condition. These changes result in differential movement of airport pavements resting on these soils. Special design procedures must be used to account for the expansive soil activity during equilibration. In addition, special precautions are required to protect the subgrade from moisture variation with climate. Measurement of soil suction is a key step in quantifying moisture-induced soil behavior. Procedures are outlined for suction characterization of the soil and for estimating the in situ differential movement likely to occur under the pavement. Once the wavelength and amplitude characteristics of the differential movement are obtained, design calculations to select the thickness and materials for the pavement may proceed.

  11. The development and geometry of shape change in Arabidopsis thaliana cotyledon pavement cells

    Directory of Open Access Journals (Sweden)

    Halsey Leah E

    2011-02-01

    Full Text Available Abstract Background The leaf epidermis is an important architectural control element that influences the growth properties of underlying tissues and the overall form of the organ. In dicots, interdigitated pavement cells are the building blocks of the tissue, and their morphogenesis includes the assembly of specialized cell walls that surround the apical, basal, and lateral (anticlinal cell surfaces. The microtubule and actin cytoskeletons are highly polarized along the cortex of the anticlinal wall; however, the relationships between these arrays and cell morphogenesis are unclear. Results We developed new quantitative tools to compare population-level growth statistics with time-lapse imaging of cotyledon pavement cells in an intact tissue. The analysis revealed alternating waves of lobe initiation and a phase of lateral isotropic expansion that persisted for days. During lateral isotropic diffuse growth, microtubule organization varied greatly between cell surfaces. Parallel microtubule bundles were distributed unevenly along the anticlinal surface, with subsets marking stable cortical domains at cell indentations and others clearly populating the cortex within convex cell protrusions. Conclusions Pavement cell morphogenesis is discontinuous, and includes punctuated phases of lobe initiation and lateral isotropic expansion. In the epidermis, lateral isotropic growth is independent of pavement cell size and shape. Cortical microtubules along the upper cell surface and stable cortical patches of anticlinal microtubules may coordinate the growth behaviors of orthogonal cell walls. This work illustrates the importance of directly linking protein localization data to the growth behavior of leaf epidermal cells.

  12. Breast Cancer Distress in Childhood

    Medline Plus

    Full Text Available ... Videos & Tools You Are Here: Home ? Latest Health News ? Breast Cancer Distress in Childhood URL of this page: https://www.nlm.nih.gov/medlineplus/videos/news/Cancer_Distress_101915.html Breast Cancer Distress in ...

  13. Analysis of Asphalt Pavement under Nonuniform Tire-pavement Contact Stress using Finite Element Method

    Directory of Open Access Journals (Sweden)

    A.K. Ariffin

    2011-01-01

    Full Text Available Tire-pavement contact stress is traditionally assumed to be uniformly distributed over a circular contact area. In this study, the tire-pavement contact pressure has been modeled to be nonuniform. A new tire model is developed for the analysis based on the geometry of the tire footprint because the contact area between the tire and the pavement is not exactly rectangular or circular. The objective of this study is to develop a finite element model based on viscoplastic theory for simulating the laboratory testing of asphalt mixes in Hamburg Wheel Rut Tester (HWRT for rutting and to model in-situ pavement performance. The creep parameters C1, C2 and C2 are developed from the triaxial repeated load creep test at 50C and at frequency of 1 Hz. Viscoplastic model (creep model is adopted and a commercially available Finite Element (FE program, ANSYS, is used in this study, in order to predict the rutting for in-situ pavement under nonuniform contact pressure. In the simulation, the used element has an eight-node with a three degrees of freedom per node translations in the nodal x, y and z directions. Dual wheel system of a standard axle load of 80 kN is used in the 2D pavement in-situ performance analysis. Reasonable agreement has been obtained between the predicted rut depths and the measured one. Moreover, it is found that creep model parameter C1, strongly influences rutting than the parameter C3. Finally it can be concluded that creep model based on finite element method can be used as an effective tools to analyze rutting of asphalt pavements.

  14. Inspection of airport runways and asphalt pavements using long-wave infrared thermography

    Science.gov (United States)

    Moropoulou, Antonia; Koui, Maria; Avdelidis, Nicolas P.; Kakaras, Kostas

    2000-03-01

    The deterioration of asphalt pavements and airport runways is one of the most serious problems concerned with materials engineering, transport engineering and transportation in general. Usually, this is done to the lack of knowledge or even in the lack of commitment, the maintaining such structures. When failure occurs in an airport runway or in an asphalt pavement, reconstruction is expensive. Therefore, cost-effective ways must be suggested, in order to see how badly deteriorated the investigated structure is. One of these cost-effective ways is the infrared thermography technique. This technique is used successfully in the detection of cracks, surface voids and other anomalies appearing from the aging of such materials. In this research work, by using an infrared thermographic system (AVIO TVS 2000 Mk II LW, wavelength 8 - 12 micrometers ), and with the aid of liquid diffusion, an investigation of asphalt pavements and airport runways situated in Greece was performed. The results of this investigation have led to the design of a monitoring and control NDT system for the inspection of the defected areas of the airport runways and asphalt pavements and consequently the appropriateness of distinctive engineering structures.

  15. Predicting Financial Distress and the Performance of Distressed Stocks

    OpenAIRE

    Campbell, John Y.; Hilscher, Jens Dietrich; Szilagyi, Jan

    2011-01-01

    In this paper, we consider the measurement and pricing of distress risk.We present a model of corporate failure in which accounting and market-based measures forecast the likelihood of future financial distress. Our best model is more accurate than leading alternative measures of corporate failure risk.We use our measure of financial distress to examine the performance of distressed stocks from 1981 to 2008. We find that distressed stocks have high stock return volatility and high market beta...

  16. Orientation patterns of stone pavements as a result of modern geomorphologic processes

    Science.gov (United States)

    Dietze, Michael; Kleber, Arno

    2010-05-01

    Stone pavements are typical surface features of climate-sensitive, arid environments. They form a tightly interlocking mosaic of clasts, covering virtually stone-free aeolian material. However, this mosaic does not generally exhibit random orientation of its constituents. Rather, there are systematic unimodal to bimodal distributions of stone length axes present. These orientation patterns may be the result of active geomorphologic processes, implying the unstable and fragile nature of this landform as well as a dominant lateral geomorphologic component, not considered in existing models of stone pavement formation. Responsible processes should be controlled by relief properties and may thus be described by topographic attributes. From three study areas (Laguna Salada, Mexico, eastern Mojave Desert and southern Sevier Basin, USA) we present measurements of pavement stone orientations and their relationship to landscape parameters. From 1 by 1 m sized plots azimuthal digital images were taken, corrected, georeferenced and length as well as orientation angle of the a- and b-axes of at least 100 stones were digitised. Subsequently, statistical parameters of circular data were calculated. From a digital elevation model relief attributes were derived to test their influence on pavement patterns. Three general types of orientation patterns were identified from all study areas: unimodal, bimodal and unoriented. These types are clustered together and may change within small lateral distance. The type of pattern is not influenced by stone dimensions or the formation character of the site (i.e. basalt flow vs. alluvial fan). Relief properties (e.g. slope length, specific catchment, inclination), controlling lateral geomorphologic processes appear to play a major role in generating orientation patterns in stone pavement surfaces. Hence, from pattern analysis the dynamic nature of these features can be drawn.

  17. A study of tire/pavement interaction noise using near- field acoustical holography

    Science.gov (United States)

    Ruhala, Richard James

    1999-12-01

    In this thesis, Nearfield Acoustical Holography (NAH) is applied as a tool to study the mechanisms of tire/pavement interaction noise-a major contributor to highway noise. NAH is a technique that reconstructs the three-dimensional acoustic field from a two- dimensional measurement of the complex pressure. Since NAH measurements are conducted in the acoustic nearfield, areas of maximum radiation from the tire may be localized with a much finer resolution than with conventional measurements. Not only can acoustic pressure be reconstructed, but also sound intensity vectors and sound power. To extend NAH from controlled, laboratory experiments to harsh realistic conditions of a rolling tire, NAH is modified to incorporate the effects of a moving medium and multiple partially coherent sources. Tire/pavement interaction noise is composed of several sources, e.g. interactions of the leading and trailing edges of the tire with the pavement, and sidewall vibration. Therefore, NAH is modified to improve separation of acoustic fields associated with multiple partially coherent sources. These techniques are used to visualize the acoustic field of a rolling tire on real pavements. A scanning mechanism is attached to an automobile trailer for measurements of tire noise under realistic conditions. Several types of tires are evaluated, including a blank tire, a tire with equally spaced transverse grooves, a tire with only circumferential grooves, and two commercial passenger car tire. The tires are tested on both smooth and rough pavements, and at two speeds (56 km/hr and 80 km/hr). Wavenumber spectra of the tire and pavement surfaces are computed when possible to quantify the roughness levels. Although the measurements were made along a plane 10 cm from the tire sidewall, sound pressure and intensity are reconstructed along a plane touching the surface of the tire to localize noise source. In addition to the side plane, front and rear planes were evaluated for two configurations to enhance the study of leading and trailing edge noise generation. Finally, sound power for each configuration was calculated to evaluate global trends. These results provide further insight into the sources and mechanisms of tire/pavement interaction noise.

  18. The career distress scale

    DEFF Research Database (Denmark)

    Creed, Peter; Hood, Michelle; Praskova, Anna; Makransky, Guido

    2016-01-01

    Career distress is a common and painful outcome of many negative career experiences, such as career indecision, career compromise, and discovering career barriers. However, there are very few scales devised to assess career distress, and the two existing scales identified have psychometric...... weaknesses. The absence of a practical, validated scale to assess this construct restricts research related to career distress and limits practitioners who need to assess and treat it. Using a sample of 226 young adults (mean age 20.5 years), we employed item response theory to assess 12 existing career......, which we combined into a scale labelled the Career Distress Scale, demonstrated excellent psychometric properties, meaning that both researchers and practitioners can use it with confidence, although continued validation is required, including testing its relationship to other nomological net variables...

  19. Evaluation of Road Pavement Density Using Ground Penetrating Radar

    OpenAIRE

    RSA Raja Abdullah; H. Zulhaidi M. Shafri; R. Mardeni; Sabira Khatun; R. Muniandy

    2009-01-01

    This study describes an analysis of Ground Penetrating Radar (GPR) measurements at frequency range of 1.7-2.6 GHz to get a relationship between attenuation and density for nine road pavements slabs with different densities. There are about four different frequencies had been tested. The method is simple, fast, non-destructive and accurate way to determine the density of road pavement. Density is a one of the important parameter in order to determine the compressive strength of road pavement f...

  20. Pervious Concrete: New Era For Rural Road Pavement

    OpenAIRE

    Darshan S. Shah 1 , Prof. Jayeshkumar Pitroda2Prof.J.J.Bhavsar

    2013-01-01

    Pervious concrete is a relatively new concept for rural road pavement, with increase into the problems in rural areas related to the low ground water level, agricultural problem. Pervious concrete has introduced in rural road as a road pavement material. Pervious concrete as a paving material has seen renewed interest due to its ability to allow waterto flow through itself to recharge groundwater level and minimize storm water runoff. This introduction topervious concrete pavements reviews it...

  1. An Airport Pavement Traffic Simulation Based on CPN

    OpenAIRE

    Heng Hong-jun; Yang Jue

    2014-01-01

    According to the characteristics of airport pavement traffic, we discuss a method of building an airport pavement traffic model which is based on CPN theory and simulate a practical situation as well. The method overcomes the shortage of modelling with normal Petri Net theory, solves the difficult problems of airport pavement traffic such as complex traffic nets, frequent road changing, etc., refines the process of the model, and will be good for the model’s analysis and simulation.

  2. Utilize Cementitious High Carbon Fly Ash (CHCFA) to Stabilize Cold In-Place Recycled (CIR) Asphalt Pavement as Base Coarse

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Haifang; Li, Xiaojun; Edil, Tuncer; O' Donnell, Jonathan; Danda, Swapna

    2011-02-05

    The purpose of this study was to evaluate the performance of cementitious high carbon fly ash (CHCFA) stabilized recycled asphalt pavement as a base course material in a real world setting. Three test road cells were built at MnROAD facility in Minnesota. These cells have the same asphalt surface layers, subbases, and subgrades, but three different base courses: conventional crushed aggregates, untreated recycled pavement materials (RPM), and CHCFA stabilized RPM materials. During and after the construction of the three cells, laboratory and field tests were carried out to characterize the material properties. The test results were used in the mechanistic-empirical pavement design guide (MEPDG) to predict the pavement performance. Based on the performance prediction, the life cycle analyses of cost, energy consumption, and greenhouse gasses were performed. The leaching impacts of these three types of base materials were compared. The laboratory and field tests showed that fly ash stabilized RPM had higher modulus than crushed aggregate and RPM did. Based on the MEPDG performance prediction, the service life of the Cell 79 containing fly ash stabilized RPM, is 23.5 years, which is about twice the service life (11 years) of the Cell 77 with RPM base, and about three times the service life (7.5 years) of the Cell 78 with crushed aggregate base. The life cycle analysis indicated that the usage of the fly ash stabilized RPM as the base of the flexible pavement can significantly reduce the life cycle cost, the energy consumption, the greenhouse gases emission. Concentrations of many trace elements, particularly those with relatively low water quality standards, diminish over time as water flows through the pavement profile. For many elements, concentrations below US water drinking water quality standards are attained at the bottom of the pavement profile within 2-4 pore volumes of flow.

  3. Practical applications of nondestructive evaluation for airport pavement analysis

    Science.gov (United States)

    McQueen, Roy D.; Guo, Edward

    1995-07-01

    This paper discusses the equipment and methodologies currently used for nondestructive testing (NDT) and nondestructive evaluation (NDE) of the structural capacity of military and civil airport pavements, including: (1) commonly used equipment and test methods for measuring pavement response to dynamic loads; (2) qualitative and quantitative evaluation of NDT data; (3) methods for back-calculating layer properties from NDT data; (4) layered elastic methods for evaluating pavement performance using processed NDT data; and (5) application of analytical results for developing pavement rehabilitation and management strategies.

  4. A study of bituminous pavements to determine a correlation between pavement structure designs and tripping of asphalt cement

    Science.gov (United States)

    Barton, B. R.

    1984-03-01

    After detecting a few cases of stripping of asphalt cement from the aggregate in bituminous pavement, there was concern that stripping might be a widespread problem in the state. It is agreed that water is the cause of stripping, and it was the opinion of some that pavements on granular bases would be less likely to strip because of supposedly better drainage characteristics. Differently designed pavement structures in all areas of the state were investigated to determine if there is a correlation between base and pavement design and stripping. Stripping was not as widespread as had been feared and there was less stripping in fulldepth bituminous base and pavement constructed over a lime-treated subgrade than in pavements constructed oer granular bases. This was contrary to what some had theorized.

  5. Pavement technology for mega transportation projects

    Energy Technology Data Exchange (ETDEWEB)

    Emery, J. [John Emery Geotechnical Engineering Ltd., Toronto, ON (Canada)

    2001-07-01

    This paper described the use of asphalt and concrete pavement technology for mega projects such as the Duarte Highway in the Dominican Republic, the Colombia Bogota El Dorado International Airport, Highway 407 Express Toll Route north of Toronto, the Cobequid Pass Highway in Nova Scotia and the Fredericton-Moncton Highway in New Brunswick. A mega transportation project is considered to involve more than $100 million in construction costs and use an alternative delivery method such as design-build. It must also include life cycle costing for technology evaluation, fast track construction and total quality management. This paper showed that the durability, flexibility and structural capacity of hot-mix asphalt and PCC concrete make it possible to provide economic, smooth, safe pavements for highways, airports and for heavy traffic conditions under both normal and severe operating environments. In particular, the paper focused on the practical concepts of the pavement technology and the role of contractors in meeting the fast-track technical quality requirements for mega paving projects. The paper emphasized the fact that it is possible to develop sustainable paving projects that integrate transportation infrastructure development with communities and the environment while maintaining safety and performance. 8 refs., 4 tabs., 8 figs.

  6. Airport pavement NDE research at CQEFP

    Science.gov (United States)

    Popovics, John S.; Achenbach, Jan D.

    1996-11-01

    The Center for Quality Engineering and Failure Prevention (CQEFP) at Northwestern University is actively involved in the development of new stress-wave based non-destructive evaluation techniques for airport pavements. This paper summarizes recent accomplishments and outlines current research directions. The development of a new stress-wave source is detailed first. The stress-wave generating technique allows for a high degree of control of the input stress wave while at the same time enabling the generation of significant wave amplitudes. Experimental results on concrete specimens demonstrate the controllability and penetrating ability of the developed stress wave generation technique. Its performance is compared to that of an impact source. Experimental results from an existing stress-wave based NDE technique, the impact-echo method, are presented and limitations of that approach are demonstrated. Finally, directions of future airport pavement NDE research at CQEFP, which focus upon application of the developed stress wave generation technique to pavement NDE problems, are outlined.

  7. Assessment of flexible airfield pavements using Heavy Weight Deflectometers. Development of a FEM dynamical time-domain analysis for the backcalculation of structural properties.

    OpenAIRE

    Broutin, Michaël

    2010-01-01

    Evolved from the French “déflectomètre à boulet”, the Heavy Weight Deflectometer (HWD) is today viewed worldwide as the most appropriate device to assess the bearing capacity of airport pavements. Its principle consists in applying a transient impulsive load simulating the weight effect of an aircraft rolling wheel, onto a stationary load plate placed over the pavement, through a buffer system, and studying the surface deflections induced by this dynamic loading. The latter are continuously m...

  8. Pavement Sealcoat, PAHs, and Water Quality of Urban Water Bodies: An Overview

    Science.gov (United States)

    Mahler, B. J.; Van Metre, P. C.; Ingersoll, C.; Kunz, J. L.; Kienzler, A.; Devaux, A.; Bony, S.

    2014-12-01

    Coal-tar-based (CT) sealcoat is used to protect and beautify the asphalt pavement of driveways and parking lots primarily in the central, southern, and northeastern U.S. and in Canada. CT sealcoat typically is 20 to 35 percent crude coal tar or coal-tar pitch and contains from 50,000 to 100,000 mg/kg PAHs, about 1,000 times more than asphalt-based (AS) sealcoat or asphalt itself. Tires and snowplows abrade the friable sealcoat surface into fine particles—PAH concentrations in fine particles (dust) from CT-sealcoated pavement are about 1,000 times higher than in dust from AS-sealcoated pavement (median total PAH concentrations 2,200 and 2.1 mg/kg, respectively). Use of CT sealcoat has several implications for urban streams and lakes. Source apportionment modeling has indicated that, in regions where CT sealcoat is prevalent, particles from sealcoated pavement are contributing the majority of the PAHs to recently deposited lake sediment, with implications for ecological health. Acute 2-d toxicity of runoff from CT-sealcoated pavement to stream biota, demonstrated for a cladoceran (Ceriodaphnia dubia) and fathead minnows (Pimephales promelas), continues for samples collected as long as weeks or months following sealcoat application. Using the fish-liver cell line RGL-W1, runoff collected as much as 36 days following CT-sealcoat application has been demonstrated to cause DNA damage and impair DNA repair capacity. These results demonstrate that CT runoff is a potential hazard to aquatic ecosystems for at least several weeks after sealant application, and that exposure to sunlight can enhance toxicity and genetic damage. Recent research has provided direct evidence that restricting use of CT sealcoat in a watershed can lead to a substantial reduction in PAH concentrations in receiving water bodies.

  9. Comparison Between 2-D and 3-D Stiffness Matrix Model Simulation of Sasw Inversion for Pavement Structure

    Directory of Open Access Journals (Sweden)

    Sri Atmaja P. Rosidi

    2007-01-01

    Full Text Available The Spectral Analysis of Surface Wave (SASW method is a non-destructive in situ seismic technique used to assess and evaluate the material stiffness (dynamic elastic modulus and thickness of pavement layers at low strains. These values can be used analytically to calculate load capacities in order to predict the performance of pavement system. The SASW method is based on the dispersion phenomena of Rayleigh waves in layered media. In order to get the actual shear wave velocities, 2-D and 3-D models are used in the simulation of the inversion process for best fitting between theoretical and empirical dispersion curves. The objective of this study is to simulate and compare the 2-D and 3-D model of SASW analysis in the construction of the theoretical dispersion curve for pavement structure evaluation. The result showed that the dispersion curve from the 3-D model was similar with the dispersion curve of the actual pavement profile compared to the 2-D model. The wave velocity profiles also showed that the 3-D model used in the SASW analysis is able to detect all the distinct layers of flexible pavement units.

  10. Application of CalME incremental-recursive method to the evaluation of the structural condition as asphalt pavements

    International Nuclear Information System (INIS)

    CalME procedure represents one of the most advanced tools for the design, of flexible pavements world-wide. IT is an incremental-recursive method, which means that pavements service life must be divided into many time intervals where both structural integrity and environmental conditions can be regarded as constants. It also means that the damage calculated at the end of each interval must be considered as initial condition for the next one. The goal of this type of models is the prediction of the evolution of the different distress mechanisms. The advantages of incremental-recursive procedures versus classical analytical design are shown in this paper. Advantages are shown not only in terms of design, but also as a tool in order to support structural evaluation. In particular, the potential of asphalt fatigue model incorporated in CalME is presented. this model is initially calibrated in the laboratory, and it is then re-calibrated based on the actual performance observed from field deflection testing. The model provides a reliable prediction of the future evolution of the damage of the asphalt mixture. Fatigue model validation has been conducted based on the performance from several flexible sections evaluated in CEDEX full-scale pavements test track. (Author) 14 refs.

  11. Relationships between laboratory measured HMA material and mixture properties and pavement performance at WesTrack

    Science.gov (United States)

    Hand, Adam J. T.

    For years researchers and practitioners alike in the pavements and materials industry have attempted to establish relationships between laboratory measured material and mixture properties and actual pavement performance. The ultimate goal of any highway agency is to have performance related specifications, which require such relationships. This sounds simple enough, but in reality such a task is not so simple due to the extremely complex behavior of hot mix asphalt. Due to the fact that it takes many years to evaluate new materials and methodologies, the use of accelerated loading facilities such as WesTrack for evaluation purposes becomes very advantageous. The research presented here produces multiple permanent deformation performance relationships for the WesTrack project, some of which may be extended to other environments. An attempt to develop similar fatigue performance relationships was unsuccessful due partially to the lack of fatigue distress at WesTrack to date. Additionally, mix design and some quality control data summaries are presented for the project along with an investigation into a potential cause of the premature rutting of coarse Superpave mixes. The investigation resulted in the development of precision statements for the ASTM D5821-95 coarse aggregate angularity test method and a better understanding of the sensitivity of coarse Superpave mixtures.

  12. INVESTIGATION OF SKID RESISTANCE PROPERTIES OF AGGREGATES USED IN AFYONKARAHISAR CITY PAVEMENTS

    Directory of Open Access Journals (Sweden)

    Cahit GÜRER

    2007-02-01

    Full Text Available For a safe driving, pavement surface aggregates must have superior physical and mechanical properties. Although high rate of accidents is mainly due to drivers errors, pavement surface properties affect significantly occurance of traffic accidents. The most important factor in the highways leading to traffic accidents are the skid resistance. In this study, adherence test with Vialit plate, Nicholson stripping test, accelerated polishing test (PSV were carried out on four aggregate samples which were used in seal coats and hot mix asphalt in Afyonkarahisar City. Results were compared with values of specification limits. The results showed that particularly limestone aggregates polishing stone values are poorer than volcanic aggregates sample. Especially, use of aggregates having a good polishing resistance, will be an important factor increasing driving safety.

  13. An analysis of pavement heat flux to optimize the water efficiency of a pavement-watering method

    International Nuclear Information System (INIS)

    Pavement-watering as a technique of cooling dense urban areas and reducing the urban heat island effect has been studied since the 1990's. The method is currently considered as a potential tool for and climate change adaptation against increasing heat wave intensity and frequency. However, although water consumption necessary to implement this technique is an important aspect for decision makers, optimization of possible watering methods has only rarely been conducted. An analysis of pavement heat flux at a depth of 5 cm and solar irradiance measurements is proposed to attempt to optimize the watering period, cycle frequency and water consumption rate of a pavement-watering method applied in Paris over the summer of 2013. While fine-tuning of the frequency can be conducted on the basis of pavement heat flux observations, the watering rate requires a heat transfer analysis based on a relation established between pavement heat flux and solar irradiance during pavement insolation. From this, it was found that watering conducted during pavement insolation could be optimized to 30-min cycles and water consumption could be reduced by more than 80% while reducing the cooling effect by less than 13%. - Highlights: • The thermal effects of pavement-watering were investigated in Paris, France. • Pavement-watering was found to significantly affect pavement heat flux 5 cm deep. • When insolated, a linear relation was found between heat flux and solar radiation. • Pavement-watering did not alter its slope, but introduced a negative intercept. • Subsequent improvements of the watering period, frequency and rate are proposed

  14. Global Cooling: Policies to Cool the World and Offset Global Warming from CO2 Using Reflective Roofs and Pavements

    Energy Technology Data Exchange (ETDEWEB)

    Akbari, Hashem; Levinson, Ronnen; Rosenfeld, Arthur; Elliot, Matthew

    2009-08-28

    Increasing the solar reflectance of the urban surface reduce its solar heat gain, lowers its temperatures, and decreases its outflow of thermal infrared radiation into the atmosphere. This process of 'negative radiative forcing' can help counter the effects of global warming. In addition, cool roofs reduce cooling-energy use in air conditioned buildings and increase comfort in unconditioned buildings; and cool roofs and cool pavements mitigate summer urban heat islands, improving outdoor air quality and comfort. Installing cool roofs and cool pavements in cities worldwide is a compelling win-win-win activity that can be undertaken immediately, outside of international negotiations to cap CO{sub 2} emissions. We propose an international campaign to use solar reflective materials when roofs and pavements are built or resurfaced in temperate and tropical regions.

  15. MaNIAC-UAV - a methodology for automatic pavement defects detection using images obtained by Unmanned Aerial Vehicles

    Science.gov (United States)

    Henrique Castelo Branco, Luiz; César Lima Segantine, Paulo

    2015-09-01

    Intelligent Transportation Systems - ITS is a set of integrated technologies (Remote Sensing, Image Processing, Communications Systems and others) that aim to offer services and advanced traffic management for the several transportation modes (road, air and rail). Collect data on the characteristics and conditions of the road surface and keep them update is an important and difficult task that needs to be currently managed in order to reduce accidents and vehicle maintenance costs. Nowadays several roads and highways are paved, but usually there is insufficient updated data about current condition and status. There are different types of pavement defects on the roads and to keep them in good condition they should be constantly monitored and maintained according to pavement management strategy. This paper presents a methodology to obtain, automatically, information about the conditions of the highway asphalt pavement. Data collection was done through remote sensing using an UAV (Unmanned Aerial Vehicle) and the image processing and pattern recognition techniques through Geographic Information System.

  16. Development of Improved Mechanistic Deterioration Models for Flexible Pavements

    DEFF Research Database (Denmark)

    Ullidtz, Per; Ertman, Hans Larsen

    The paper describes a pilot study in Denmark with the main objective of developing improved mechanistic deterioration models for flexible pavements based on an accelerated full scale test on an instrumented pavement in the Danish Road Tessting Machine. The study was the first in "International...

  17. Comparative Study of French and Chinese Asphalt Pavement Design Methods

    Directory of Open Access Journals (Sweden)

    Pierre Guy Atangana Njock

    2015-01-01

    Full Text Available This study deals with the comparison of French and Chinese approaches for the design of flexible pavement. The Finite Element Analysis (FEA using ANSYS was used to compute and compare the mechanical responses in four typical pavement structures used in France and China, for respective axle type and loads. The study concluded that the maximum deflection in typical structure of stabilized asphalt pavement in China is greater than that obtained in the typical treated bases asphalt pavement in France. Therefore, the high modulus materials used in the French method allows the structure to have a high rutting resistance compared to Chinese pavement structures whose the values of the elastic modulus of materials are relatively lower. The results also shown that, the Chinese methodology is advantageous for the design of semi-rigid asphalt pavement, in terms of the mechanical response at the bottom of treated base layer. There are considerable differences between the equivalent axle load conversion methods and the reference axles loads used in France and in China and both methodologies pavement design indexes are established on the criterion of fatigue at the bottom of asphaltic concrete layer for acceptable pavement performance at the end of the design period (i.e., acceptable levels of rutting, fatigue cracking and thermal cracking.

  18. Lichen colonization of the Roman pavement at Baelo Claudia ( Cadiz, Spain): biodeterioration vs. bioprotection

    OpenAIRE

    Ariño, Xavier; Ortega Calvo, J.J.; Gómez Bolea, A.; Sáiz-Jiménez, Cesáreo

    1995-01-01

    This paper describes the effect of lichen colonization on the first century A.D. pavement of the forum at Baelo Claudia, a Roman city located in southern Spain. Lichen colonization is scarce, covering only 13% of the total surface. The rest of the flagstones are mostly uncovered but show strong physico-chemical weathering. The flagstones colonized by lichens do not show weathering. The distribution of the species is influenced by environmental factors, confirming the role of lichens as bioind...

  19. The use of Deflection Measurements in Pavement Management of the Primary Road Network of Wallonia, Belgium

    OpenAIRE

    Van Geem, Carl; Nigro, Pierre; Berlémont, Bruno

    2015-01-01

    The road authorities of the primary road network of motorways and main roads in Wallonia (Belgium) determined the priorities for road maintenance from surface characteristics such as roughness, skid resistance and rutting. Recently, they added the structural health (and primarily the bearing capacity) as a criterion for pavement management. The structural health of the road sections is estimated from deflection measurements obtained with Falling Weight Deflectometer and Curviameter. This pape...

  20. Pervious Concrete: New Era For Rural Road Pavement

    Directory of Open Access Journals (Sweden)

    Darshan S. Shah 1 , Prof. Jayeshkumar Pitroda2Prof.J.J.Bhavsar

    2013-08-01

    Full Text Available Pervious concrete is a relatively new concept for rural road pavement, with increase into the problems in rural areas related to the low ground water level, agricultural problem. Pervious concrete has introduced in rural road as a road pavement material. Pervious concrete as a paving material has seen renewed interest due to its ability to allow waterto flow through itself to recharge groundwater level and minimize storm water runoff. This introduction topervious concrete pavements reviews its applications and engineering properties, including environmentalbenefits, structural properties, and durability.In rural area cost consideration is the primary factor which must be kept in mind. So that in rural areas costly storm water management practices is not applicable. Pervious concrete pavement is unique and effective means to meet growing environmental demands. By capturing rainwater and allowing it to seep into the ground. This pavement technology createsmore efficient land use by eliminating the need for retention ponds, swell, and other costly stormwater management devices.

  1. Modeling of energy dissipation processes in a pavement – vehicle system

    Directory of Open Access Journals (Sweden)

    A.M. Kirillov

    2015-09-01

    Full Text Available The law of conservation of energy for a ‘pavement – vehicle’ system manifests itself primarily in the fact that for any temperature and operating conditions of a road asphalt concrete pavement the potential energy of gravity and the kinetic energy of a vehicle are partially transformed upon contact with the road pavement into elastic deformation energy or thermal energy, while a part of the energy dissipates. These types of energy are to some extent transformed into the internal energy of the road pavement, altering its energy balance and causing destructive processes. The initial level of the internal pavement energy changes while the road is used, on the one hand, through regular contributions from vehicles and from solar raditation, and, on the other hand, from compensating for viscoelastic deformation. Understanding these changes will allow to develop new and more efficient methods for monitoring the pavement condition, as well as a scientifically valid system of scheduling the repairs. In this article, we have assessed the level and the significance of the contribution of the work done by the moving vehicles over the pavement, and of the thermal radiation to the internal pavement energy gain. We have constructed a physical and mathematical model of energy dissipation and storage in the ‘pavement – vehicle’ system accounting for viscoelastic deformation and thermal radiation. We have designed an algorithm allowing to determine a scientifically based repair interval for asphalt concrete pavement. It is shown that the maximum plasticity for some ranges of speeds and transport weights may serve as a criterion of the recommended operating conditions of the road.

  2. Pavement structure mechanics response of flexible on semi-flexible overlay that based on the old cement concrete pavement damage

    Directory of Open Access Journals (Sweden)

    Jiang Ruinan

    2015-01-01

    Full Text Available The old cement pavement damage status directly affect the design of the paving renovation. Based on the state of the old road investigation, combined with the research data at home and abroad, use the control index that average deflection, deflection value and CBR value to determine the reasonable time to overlay. Draw up the typical pavement structure according to the principle of combination of old cement pavement overlay structure design, and calculated that the tensile stress and shear stress in asphalt layer ,semi-flexible layer and the tensile in the old cement pavement adopting BISA3.0 statics finite element analysis model when modulus in the old road was diminishing. Use the computed result to analyses the influence of old road damage condition the influence of pavement structure.

  3. The Implications of Financial Distress

    OpenAIRE

    Nevalainen, Riku

    2010-01-01

    PURPOSE OF THE STUDY This thesis aims to be the first paper to study comprehensively the full implications of financial distress and its indirect costs. Specifically, I investigate whether financially distressed companies operationally underperform their more conservatively financed counterparts and whether the distressed companies engage in inefficient asset sales. This is the first paper to study the effects of financial distress as the earlier literature concentrates purely on the e...

  4. Multiresolution texture analysis applied to road surface inspection

    Science.gov (United States)

    Paquis, Stephane; Legeay, Vincent; Konik, Hubert; Charrier, Jean

    1999-03-01

    Technological advances provide now the opportunity to automate the pavement distress assessment. This paper deals with an approach for achieving an automatic vision system for road surface classification. Road surfaces are composed of aggregates, which have a particular grain size distribution and a mortar matrix. From various physical properties and visual aspects, four road families are generated. We present here a tool using a pyramidal process with the assumption that regions or objects in an image rise up because of their uniform texture. Note that the aim is not to compute another statistical parameter but to include usual criteria in our method. In fact, the road surface classification uses a multiresolution cooccurrence matrix and a hierarchical process through an original intensity pyramid, where a father pixel takes the minimum gray level value of its directly linked children pixels. More precisely, only matrix diagonal is taken into account and analyzed along the pyramidal structure, which allows the classification to be made.

  5. Intra Partum Foetal Distress

    OpenAIRE

    J Kubheka

    1985-01-01

    The occurrence of neonatal asphyxia at Baragwanath Hospital is a daily problem. The question was raised as to whether intra partum foetal distress, apgar scoring at birth and the biochemical analysis of blood acid base status from the chorionic arteries can predict any short-term neurological defects.

  6. Adult respiratory distress syndrome

    International Nuclear Information System (INIS)

    Our present-day knowledge concerning the clinico-chemical and radiological findings in adult respiratory distress syndrome are described. Three typical case histories have been selected to illustrate this condition; they were due to multiple trauma or sepsis. It is stressed that radiology is in a key position for making the diagnosis and for observing the course of the illness. (orig)

  7. Breast Cancer Distress in Childhood

    Medline Plus

    Full Text Available ... medlineplus/videos/news/Cancer_Distress_101915.html Breast Cancer Distress in Childhood HealthDay News Video - October 20, ... this page, please enable JavaScript. Play video: Breast Cancer Distress in Childhood For closed captioning, click the ...

  8. Breast Cancer Distress in Childhood

    Medline Plus

    Full Text Available ... gov/medlineplus/videos/news/Cancer_Distress_101915.html Breast Cancer Distress in Childhood HealthDay News Video - October 20, ... on this page, please enable JavaScript. Play video: Breast Cancer Distress in Childhood For closed captioning, click the ...

  9. Breast Cancer Distress in Childhood

    Science.gov (United States)

    ... gov/medlineplus/videos/news/Cancer_Distress_101915.html Breast Cancer Distress in Childhood HealthDay News Video - October 20, ... on this page, please enable JavaScript. Play video: Breast Cancer Distress in Childhood For closed captioning, click the ...

  10. Evaluation of flexible pavement performance life in Florida. Final research report, October 1993--June 1998

    Energy Technology Data Exchange (ETDEWEB)

    Ping, W.V.; He, Y.

    1998-06-01

    The pavement performance life provides information on how long a particular pavement type will typically last before it needs rehabilitation. This study presents the research effort to estimate the average flexible pavement performance life in Florida. Two data files of Pavement Condition Survey (PCS) and Work Program Administration (WPA) were used for this study. SAS programs were applied to analyze and manipulate these two data files. The pavement performance condition curves were developed for a large sample size of pavement sections based on the polynomial model. The average pavement performance lives were evaluated for each pavement group based on the performance curves. The results of the evaluation showed that the primary system had longer average performance life than the interstate system. Generally, the polynomial model performed well in fitting the data. The pavement performance curve indicates that if M and R are performed while the pavement is still in the `slow rate of deterioration` phase, life cycle cost may be reduced.

  11. Desempeño de pavimentos estabilizado con asfalto espumado en una prueba de pavimentos a escala real y carga acelerada Performance of foamed bitumen pavements in accelerated testing facility

    Directory of Open Access Journals (Sweden)

    Alvaro Gonzalez

    2012-08-01

    Full Text Available Uno de los objetivos claves de la gestión de pavimentos es desarrollar e implementar una estrategia de construcción y mantenimiento rentables, con el fin de alcanzar niveles requeridos de servicio y desempeño. Una técnica rentable y sustentable para la rehabilitación de pavimentos es la de estabilización o reciclado con asfalto espumado (AE. Este artículo presenta un estudio sobre el desempeño de pavimentos estabilizados con asfalto espumado en el Canterbury Accelerated Pavement Testing Indoor Facility CAPTIF. CAPTIF es un laboratorio a escala real para pavimentos ubicado en Nueva Zelandia, que permite aplicar un gran número de cargas de tráfico en un breve período de tiempo. Seis secciones de pavimentos con distintos contenidos de asfalto y cemento fueron ensayadas en CAPTIF. Los resultados del experimento mostraron que las deflexiones disminuyen en las secciones con mayor contenido de asfalto espumado. Luego de aplicar más de un millón de ciclos de carga, las secciones estabilizadas sólo con cemento, sólo con asfalto y la sección sin estabilizar mostraron un deterioro significativo en forma de ahuellamiento. Por otro lado, las secciones que fueron estabilizadas con AE y cemento mostraron un buen desempeño, demostrando que el cemento y el AE juntos mejoran significativamente el desempeño del pavimento. Los resultados de ahuellamiento fueron empleados para desarrollar modelos y describir el deterioro estable y acelerado de los pavimentos en estudio, lo que puede ser utilizado para una mejor gestión de los pavimentos estabilizados con asfalto espumado.One of the key principal goals of pavement asset management is to develop and implement cost-effective pavement construction and maintenance strategies that achieve the required levels of service and performance. A sustainable, cost-effective technique for rehabilitating pavements is foamed bitumen stabilization. This paper presents a study on the performance of foamed bitumen pavements tested in the Canterbury Accelerated Pavement Testing indoor Facility (CAPTiF, for full scale testing of pavements. Six pavement sections were tested; the variables were bitumen and cement content; one control section with the untreated unbound material was tested. Results showed that surface deflections decreased at sections with higher bitumen contents. After the application of 5,710,000 Equivalent Standard Axles (ESAs, the sections stabilised with cement only, bitumen only, and the control section all showed large amounts of rutting. Conversely, little rutting was observed in the three sections stabilised with foamed bitumen and 1.0% cement, showing that cement and FB together significantly improve pavement performance. The rutting results were used to develop models to describe the stable and unstable performance of the tested pavements. The paper concludes by outlining some of the practical benefits of utilising this technology in pavement asset management.

  12. Desempeño de pavimentos estabilizado con asfalto espumado en una prueba de pavimentos a escala real y carga acelerada / Performance of foamed bitumen pavements in accelerated testing facility

    Scientific Electronic Library Online (English)

    Alvaro, Gonzalez; Misko, Cubrinovski; Bryan, Pidwerbesky; David, Alabaster.

    2012-08-01

    Full Text Available Uno de los objetivos claves de la gestión de pavimentos es desarrollar e implementar una estrategia de construcción y mantenimiento rentables, con el fin de alcanzar niveles requeridos de servicio y desempeño. Una técnica rentable y sustentable para la rehabilitación de pavimentos es la de estabiliz [...] ación o reciclado con asfalto espumado (AE). Este artículo presenta un estudio sobre el desempeño de pavimentos estabilizados con asfalto espumado en el Canterbury Accelerated Pavement Testing Indoor Facility CAPTIF. CAPTIF es un laboratorio a escala real para pavimentos ubicado en Nueva Zelandia, que permite aplicar un gran número de cargas de tráfico en un breve período de tiempo. Seis secciones de pavimentos con distintos contenidos de asfalto y cemento fueron ensayadas en CAPTIF. Los resultados del experimento mostraron que las deflexiones disminuyen en las secciones con mayor contenido de asfalto espumado. Luego de aplicar más de un millón de ciclos de carga, las secciones estabilizadas sólo con cemento, sólo con asfalto y la sección sin estabilizar mostraron un deterioro significativo en forma de ahuellamiento. Por otro lado, las secciones que fueron estabilizadas con AE y cemento mostraron un buen desempeño, demostrando que el cemento y el AE juntos mejoran significativamente el desempeño del pavimento. Los resultados de ahuellamiento fueron empleados para desarrollar modelos y describir el deterioro estable y acelerado de los pavimentos en estudio, lo que puede ser utilizado para una mejor gestión de los pavimentos estabilizados con asfalto espumado. Abstract in english One of the key principal goals of pavement asset management is to develop and implement cost-effective pavement construction and maintenance strategies that achieve the required levels of service and performance. A sustainable, cost-effective technique for rehabilitating pavements is foamed bitumen [...] stabilization. This paper presents a study on the performance of foamed bitumen pavements tested in the Canterbury Accelerated Pavement Testing indoor Facility (CAPTiF), for full scale testing of pavements. Six pavement sections were tested; the variables were bitumen and cement content; one control section with the untreated unbound material was tested. Results showed that surface deflections decreased at sections with higher bitumen contents. After the application of 5,710,000 Equivalent Standard Axles (ESAs), the sections stabilised with cement only, bitumen only, and the control section all showed large amounts of rutting. Conversely, little rutting was observed in the three sections stabilised with foamed bitumen and 1.0% cement, showing that cement and FB together significantly improve pavement performance. The rutting results were used to develop models to describe the stable and unstable performance of the tested pavements. The paper concludes by outlining some of the practical benefits of utilising this technology in pavement asset management.

  13. Climate change, energy, sustainability and pavements

    International Nuclear Information System (INIS)

    Provides an integrated perspective on understanding the impacts of climate change, energy and sustainable development on transportation infrastructure systems. Presents recent technological innovations and emerging concepts in the field of green and sustainable transportation infrastructure systems with a special focus on highway and airport pavements. Written by leading experts in the field. Climate change, energy production and consumption, and the need to improve the sustainability of all aspects of human activity are key inter-related issues for which solutions must be found and implemented quickly and efficiently. To be successfully implemented, solutions must recognize the rapidly changing socio-techno-political environment and multi-dimensional constraints presented by today's interconnected world. As part of this global effort, considerations of climate change impacts, energy demands, and incorporation of sustainability concepts have increasing importance in the design, construction, and maintenance of highway and airport pavement systems. To prepare the human capacity to develop and implement these solutions, many educators, policy-makers and practitioners have stressed the paramount importance of formally incorporating sustainability concepts in the civil engineering curriculum to educate and train future civil engineers well-equipped to address our current and future sustainability challenges. This book will prove a valuable resource in the hands of researchers, educators and future engineering leaders, most of whom will be working in multidisciplinary environments to address a host of next-generation sustainable transportation infrastructure challenges.

  14. Work flow of signal processing data of ground penetrating radar case of rigid pavement measurements

    International Nuclear Information System (INIS)

    The signal processing of Ground Penetrating Radar (GPR) requires a certain work flow to obtain good results. Even though the Ground Penetrating Radar data looks similar with seismic reflection data, but the GPR data has particular signatures that the seismic reflection data does not have. This is something to do with coupling between antennae and the ground surface. Because of this, the GPR data should be treated differently from the seismic signal data processing work flow. Even though most of the processing steps still follow the same work flow of seismic reflection data such as: filtering, predictive deconvolution etc. This paper presents the work flow of GPR processing data on rigid pavement measurements. The processing steps start from raw data, de-Wow process, remove DC and continue with the standard process to get rid of noises i.e. filtering process. Some radargram particular features of rigid pavement along with pile foundations are presented

  15. Work flow of signal processing data of ground penetrating radar case of rigid pavement measurements

    Energy Technology Data Exchange (ETDEWEB)

    Handayani, Gunawan [The Earth Physics and Complex Systems Research Group (Jl. Ganesa 10 Bandung Indonesia) gunawanhandayani@gmail.com (Indonesia)

    2015-04-16

    The signal processing of Ground Penetrating Radar (GPR) requires a certain work flow to obtain good results. Even though the Ground Penetrating Radar data looks similar with seismic reflection data, but the GPR data has particular signatures that the seismic reflection data does not have. This is something to do with coupling between antennae and the ground surface. Because of this, the GPR data should be treated differently from the seismic signal data processing work flow. Even though most of the processing steps still follow the same work flow of seismic reflection data such as: filtering, predictive deconvolution etc. This paper presents the work flow of GPR processing data on rigid pavement measurements. The processing steps start from raw data, de-Wow process, remove DC and continue with the standard process to get rid of noises i.e. filtering process. Some radargram particular features of rigid pavement along with pile foundations are presented.

  16. Developing a Network-Level Structural Capacity Index for Structural Evaluation of Pavements

    OpenAIRE

    Bryce, James M.; Flintsch, Gerardo W.; Katicha, Samer; Diefenderfer, Brian K.

    2013-01-01

    The objective of this project was to develop a structural index for use in network-level pavement evaluation to facilitate the inclusion of the pavement's structural condition in pavement management applications. The primary goal of network-level pavement management is to provide the best service to the users for the available, often limited, resources. Pavement condition can be described in terms of functional and structural condition. The current widespread practice of network-level pavemen...

  17. An Innovative Strategy for Maintenance of Highway Pavement

    Directory of Open Access Journals (Sweden)

    Sandeep Choudhary, Dr. P. K. Agarwal

    2013-05-01

    Full Text Available Highway pavement are deteriorating fast due to lack of timely maintenance, leading to higher vehicle operating costs, increasing number of accidents etc. Thus, timely maintenance of the highway pavement is essential. Because, once pavements start to deteriorate; they deteriorate rapidly beyond the point where maintenance is effective. Thus, there is an urgent need to develop a strategy for maintenance of pavement in a huge highway network. In this study, an innovative strategy for maintenance of highway pavement is proposed. A two stage maintenance strategy is proposed. In stage I, it is proposed to determine priority of highway sections. In Stage II, priority of various maintenance activities to be carried out on various sections will be determined. Maintenance priority of the pavement is based on importance of the road sections, present road conditions, and future road conditions. The methodology proposed in this study is illustrated with the help of example of some hypothetical highway network consisting of 4 sections. Analysis results indicated that the proposed strategy is considered to be more rational, innovative & logical. Some strategies for maintenance of urban roads are also presented in this study. Therefore, it is expected that this study will be useful for maintenance of huge highway network in India and thus will be useful for preserving huge asset of pavement infrastructure.

  18. Evaluation of a highway pavement using non destructive tests: Falling Weight Deflectometer and Ground Penetrating Radar

    Science.gov (United States)

    Marecos, Vania; Fontul, Simona; de Lurdes Antunes, Maria

    2015-04-01

    This paper presents the results of the application of Falling Weight Deflectometer (FWD) and Ground Penetrating Radar (GPR) to assess the bearing capacity of a rehabilitated flexible highway pavement that began to show the occurrence of cracks in the surface layer, about one year after the improvement works. A visual inspection of the surface of the pavement was performed to identify and characterize the cracks. Several core drills were done to analyse the cracks propagation in depth, these cores were also used for GPR data calibration. From the visual inspection it was concluded that the development of the cracks were top-down and that the cracks were located predominantly in the wheel paths. To determine the thickness of the bituminous and granular layers GPR tests were carried out using two horn antennas of 1,0 GHz and 1,8 GHz and a radar control unit SIR-20, both from GSSI. FWD load tests were performed on the wheel paths and structural models were established, based on the deflections measured, through back calculation. The deformation modulus of the layers was calculated and the bearing capacity of the pavement was determined. Summing up, within this study the GPR was used to continuously detect the layer thickness and the GPR survey data was calibrated with core drills. The results showed variations in the bituminous layer thickness in comparison to project data. From the load tests it was concluded that the deformation modulus of the bituminous layers were also vary variable. Limitations on the pavement bearing capacity were detected in the areas with the lower deformation modulus. This abstract is of interest for COST Action TU1208 Civil Engineering Applications of Ground Penetrating Radar.

  19. Adaptation of AASHTO Pavement Design Guide for Local Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hajek, J.J. [Applied Research Associates Inc., Toronto, ON (Canada)

    2001-07-01

    The methodology used to adapt the 1993 AASHTO Guide for Design of Pavement Structures to Ontario conditions was described. The guide expresses the effect of traffic loads on pavement performance using the concept of axle Load Equivalency Factors (LEF). LEF is regarded as a pavement damage factor assigned to each specific load and axle configuration. The size of LEF is related to the damage that is expected to occur from a standard load of 80 kN carried by a single axle with dual tires. The factors are summarized to yield the number of Equivalent Single Axle Loads (ESALs) a pavement is expected to sustain during its life. A summary was also provided of the additional work done to prepare for the transition to the proposed mechanistically-based 2002 AASHTO Guide. The paper focused only on the design of flexible pavements in terms of load characterization using equivalent single axle loads along with axle load spectra, below grade and material characterization, plus initial and terminal serviceability and reliability. The AASHTO Guide uses two parameters to deal with design reliability: design reliability level and overall standard deviation. Data collected on Ontario highway pavements and materials was used for assessing the design inputs. Other data was also collected from research and development studies, laboratory experiments, and from a survey of experienced pavement design engineers. The end result was a new grouping of Ontario soils for pavement design, recommended values for the resilient modulus of below grade soils, recommendations for structural layer coefficients for Ontario pavement materials and recommendations for the initial pavement serviceability based on Ontario smoothness specifications. Results of calibration and verification processes indicate that for new flexible pavements, the AASHTO-Ontario model is in good agreement with the observed results. It was recommended that the calibration and verification of the AASHTO-Ontario model should be a continuous process and that the quality and quantity of the database should be improved to serve the needs of the 2002 Guide. It was also recommended that a study be conducted on Ontario below grade characteristics of soil and that the existing procedures for estimating traffic loads for pavement design should be updated using information from the 1999 Commercial Vehicle Surveys. 9 refs., 6 figs., 6 tabs.

  20. Development of Mechanistic-Empirical Flexible Pavement Design in Iran

    Directory of Open Access Journals (Sweden)

    M. Ameri

    2009-01-01

    Full Text Available Recent advances in flexible pavement design have prompted agencies to move toward the development and use of Mechanistic-Empirical (M-E design procedures. Mechanistic-Empirical (M-E design combine the elements of mechanical modeling and performance observation in determining the required pavement thickness for a set of design condition. In this study, a Mechanistic-Empirical (M-E design procedures and algorithm based on KENLAYER software with regard to Iran climatic and traffic conditions is developed. This study also explores present relationships and diagrams based on effective variable on pavement design to facilitate design process.

  1. Numerical study on the curling and warping of hardened rigid pavement slabs

    Science.gov (United States)

    Qin, Yinghong

    In-service hardened concrete pavement suffers from environmental loadings caused by curling and warping of the slab. Traditionally, these loadings are computed on the basis of treating the slab as an elastic material, and of evaluating separately the curling and warping components. This dissertation simulates temperature distribution and moisture distribution through the slabs by use of a developed numerical model that couples the heat transfer and moisture transport. The computation of environmental loadings treats the slab as an elastic-viscous material, which considers the relaxation behavior and Pickett effect of the concrete. The heat transfer model considers the impacts of solar radiation, wind speed, air temperature, pavement slab albedo, etc. on the pavement temperature distribution. This dissertation assesses the difference between documented models that aim to predict pavement temperature, highlighting their pros and cons. The moisture transport model is unique for the documented models; it mimics the wetting and drying events occurring at the slab surface. These events are estimated by a proposed statistical algorithm, which is verified by field rainfall data. Analysis of the predicted results examines on the roles of the local air RH (relative humidity), wind speed, rainy pattern in the moisture distribution through the slab. The findings reveal that seasonal air RH plays a decisive role on the slab's moisture distribution; but wind speed and its daily variation, daily RH variation, and seasonal rainfall pattern plays only a secondary role. This dissertation sheds light on the computation of environmental loadings that in-service pavement slabs suffer from. Analysis of the computed stresses centers on the stress relaxation near the surface, stress evolution after the curing ends, and the impact of construction season on the stress's magnitude. An unexpected finding is that the total environmental loadings at the cyclically-stable state divert from the thermal stresses. At such a state, the total stress at the daytime is roughly equal to the thermal stress; whereas the total stress during the nighttime is far greater than the thermal stress. An explanation for this phenomenon is that during the night hours, the decline of the slab's near-surface temperature leads to a drop of the near-surface RH. This RH drop results in contraction therein and develops additional tensile stresses. The dissertation thus argues that estimating the environmental loadings by solely computing the thermally-induced stresses may reach delusive results. It recommends that the total environmental loadings of in-service slabs should be estimated by a sophisticated model coupling both moisture component and temperature component.

  2. Flexible pavements and climate change: impact of climate change on the performance, maintenance, and life-cycle costs of flexible pavements

    OpenAIRE

    Qiao, Yaning

    2015-01-01

    Flexible pavements are environmentally sensitive elements of infrastructure and their performance can be influenced by climate. Climate change poses a challenge to design and management of flexible pavements in the future. Climate change can occur worldwide and thus all flexible pavements can be exposed to the impact. However, an assessment framework is not available to evaluate the impact of climate change on flexible pavements in terms of performance, maintenance decision-making and the sub...

  3. Development of New Bituminous Pavement Design Method

    DEFF Research Database (Denmark)

    Ullidtz, Per

    The report and work of COST Action 333 sets in place the foundation for a coherent, cost-effective and harmonised European pavement design method. In order to do this, the work programme focused on information gathering, identification of requirements and the selection of the necessary design...... elements for such a European design method. During the course of the Action, 20 countries signed the Memorandum of Understanding and participated in the work, thus showing a very high level of interest in the work programme and results.The document contains a very thorough review of the position in Europe...... at the present time and identifies the basic framework for a design method. It then clearly shows the necessary steps to be taken in the future in order to arrive at a method based on current best practice in the shorter term, and then to move to improved versions....

  4. On-site inspections of pavement damages evolution using GPR

    Science.gov (United States)

    Tosti, Fabio; D'Amico, Fabrizio; Calvi, Alessandro; Benedetto, Andrea

    2014-05-01

    Ground-penetrating radar (GPR) is being increasingly used for pavements maintenance due to the wide range of applications spanning from physical to geometrical inspections, thereby allowing for a reliable diagnosis of the main causes of road structural damages. In this work, an off-ground GPR system was used to investigate a large-scale rural road network. Two sets of surveys were carried out in different time periods, with the main goals to i) localize the most critical sections; ii) monitor the evolution of previous damages and localize newborn deep faults, although not revealed at the pavement surface level; iii) analyze the causes of both evolution and emergence of faults by considering environmental and human factors. A 1-GHz GPR air-launched antenna was linked to an instrumented van for collecting data at traffic speed. Other support techniques (e.g. GPS data logger, odometer, HD video camera) were used for cross-checking,. Such centre frequency of investigation along with a 25-ns time window allow for a signal penetration of 900 mm, consistent with the deepest layer interfaces. The bottom of the array was 400 mm over the surface, with a minimum distance of 1200 mm from the van body. Scan length of maximum 10 km were provided for avoiding heavy computational loads. The rural road network was located in the District of Rieti, 100 km north from Rome, Italy, and mostly develops in a hilly and mountainous landscape. In most of the investigated roads, the carriageway consists in two lanes of 3.75 meters wide and two shoulders of 0.50 meters wide. A typical road section includes a HMA layer (65 mm average thickness), a base layer (100 mm average thickness), and a subbase layer (300 mm average thickness), as described by pavement design charts. The first set of surveys was carried out in two days at the beginning of spring in moderately dry conditions. Overall, 320-km-long inspections were performed in both travel directions, thereby showing a productivity of approximately 160 km/day at 40 km/h speed, on the average. After processing and first-checking, GPR profiles were divided into homogeneous sections according to the combination of different parameters (e.g. route analyzed, long distance conditions of regularity/irregularity in layers arrangement). In such context, a high consistency between surface damages, mismatches from the GPR scans, and boundary environmental conditions was demonstrated. In addition, deep mismatches were detected even for early-stage or unrevealed faults. The second set of surveys was carried out in autumn in high humidity conditions, due to recent rainfalls. 160 km of relevant routes from the same road network were investigated. Results showed a high consistency with those collected during the first-stage of surveys. Minor changes were found in those sections with low traffic loads (e.g. farther away from the biggest town of Rieti), whereas major mismatches were detected in wetlands (e.g. close to rivers), work zones, and nearby those sections already deeply damaged in the past. This work benefited from networking activities carried out within the EU funded COST Action TU1208 'Civil Engineering Applications of Ground Penetrating Radar'.

  5. Nondestructive evaluation of load transfer at rigid airport pavement joints

    Science.gov (United States)

    Hammons, Michael I.

    1995-07-01

    Current design criteria for rigid pavements for commercial and military airfields assume that 25% of the load applied to an edge of a slab is transferred through the joint to an adjacent unloaded slab. A nondestructive testing technique using a falling weight deflectometer (FWD) was used to conduct field testing at a number of sites. A transfer function, developed from an analytical study, was used to estimate load transfer from the measured joint efficiency as a function of the loaded area and the radius of relative stiffness of the pavement. This procedure, although analytically sound, lacks actual field verification at an instrumented pavement site. This procedure was used to estimate load transfer at a number of commercial and military airfields for a variety of joint types, climate conditions, and pavement structures. The results of these tests indicate that the assumption of load transfer as a constant value of 25% appears to be unconservative, especially during the winter months.

  6. FEM analysis of dynamic behavior of asphalt pavement structure weakened by grassroots with account of hydraulic and vehicle load coupling effects

    Science.gov (United States)

    Huang, J.; Pan, X.; Dai, S. B.; Cai, Y.

    2015-12-01

    This paper establishes the finite element model of saturated asphalt pavement with ANSYS. The thickness and elastic modulus of pavement surface layers and grassroots are taken as influencing factors to analyze the influence of these factors’ change on the pavement mechanical behavior. The results indicate that the increase of surface thickness leads to the shear stress's decrease that may relieve the internal shear stress concentrated phenomenon effectively. The increase of elastic modulus of surface makes the pore pressure decrease, and result in the shear stress's increase. The grassroots thickness has no obvious effect on the pore- water pressure and shear stress; the grassroots elastic modulus’ increase may increase the internal shear stress and decrease the pore pressure.

  7. Moral Distress among Iranian Nurses.

    Directory of Open Access Journals (Sweden)

    Mohammad Hosein Vaziri

    2015-03-01

    Full Text Available The purpose of this study was to describe the moral distress among Iranian registered nurses.This was a descriptive -analytic study, in which 264 out of 1000 nurses were randomly selected as a sample group and completed the questionnaire. The nurses' moral distress was assessed using Corley's 30-item Moral Distress Scale adapted for use in an Iranian population. The collected data were analyzed by SPSS version 19.In this study, no correlation was found between the level of moral distress and any of the demographic data. The mean moral distress score ranged from 3.56 to 5.83, indicating moderate to high levels of moral distress. The item with the highest mean score was "working with unsafe levels of nurse staffing". The item with the lowest mean score was "giving medication intravenously to a patient who has refused to take it". Nurses working in EMS and NICU units had the highest levels of moral distress.A higher degree of moral distress is observed among nurses who work in health care systems. The results of this study highly recommend practical and research-oriented evaluation of moral distress in the medical society in Iran. Our findings suggest that Iranian version of MDS is a reliable instrument to measure moral distress in nurses.

  8. Wet night visibility of pavement markings :executive summary

    OpenAIRE

    Gibbons, Ronald B. (Ronald Bruce); Hankey, Jonathan M.; Pashaj, Irena

    2004-01-01

    This executive summary describes an investigation into the performance of pavement markings in wet night conditions. The performance of a typical pavement marking will degrade when it gets wet. This is a result of the flooding of the marking optics, thereby reducing retroreflectivity. Several technologies are available to improve wet marking performance. In this project, six technologies were tested using both standard measurement methods and participant evaluations. The results show that two...

  9. Fatigue resistance of bituminous layers incorporating reclaimed asphalt pavement

    OpenAIRE

    Tabakovic, Amir, (Thesis); Gibney, Amanda; Gilchrist, M. D.; McNALLY, Ciaran

    2006-01-01

    This paper presents the results of an investigation into the fatigue performance of a 20mm Binder Course Asphalt Pavement Mix incorporating Recycled Asphalt Pavement (RAP). For the study, a series of binder course mixes were designed containing varying percentages of RAP. A mix made only from virgin material, was selected as the control mix for the investigation. A Circular Wheel Tracker (CWT) was developed in order to simulate the dynamic loading conditions of a rolling wheel and to st...

  10. Investigation of asphalt concrete pavement quality of Lithuanian highways

    OpenAIRE

    Petkevi?ius, Evaldas; Petkevi?ius, Rolandas; Babickas, Rimantas

    2006-01-01

    Planning of road building and repair sectors requires evaluation of the actual state of the road pavement. The available methods of evaluation of the condition and construction of pavement have serious shortcomings: some of them are lacking precision and reliability, others are too sophisticated. For this reason they are not very helpful in practice. Based on analysis of previous works and on the experimental results, a sufficiently accurate and simple method for evaluation of the state of as...

  11. Shear Fatigue Behaviour of Tack Coats in Pavements

    OpenAIRE

    Diakhaté, Malick; Phelipot-Mardelé, Annabelle; Millien, Anne; Petit, Christophe

    2006-01-01

    For many years, pavement engineers use mechanistic design methods that are based on algorithms to compute stresses, strains and displacements in a flexible pavement structure, or in a multi-layered structure in general. Most of these methods assume, to ease the modelling of the structure and the computation process, that the layers are fully bonded or completely unbounded to each other. Moreover, determining the effectiveness of the bonding between two layers is difficult since there is no st...

  12. Technical-economical evaluation of pavement recycling alternatives

    OpenAIRE

    Pereira, Paulo A. A.; Santos, Luís Picado

    2006-01-01

    Pavement recycling is becoming an increasingly important alternative worldwide for maintenance of highways, once sustainability and environmental issues have continued to receive more attention. The reference point is that of considering the use of road materials in a closed cycle, in which a natural material, previously used in road construction, should not be rejected in the following life-cycle. The objective of this paper is that of analysing flexible pavement recycling alternatives techn...

  13. Evaluation of Common Maintenance Methods for Flexible Pavements

    OpenAIRE

    Asma T. Ibraheem; Suda M. Gani

    2011-01-01

    Problem statement: With the increasing use and awareness of pavement management systems and the growing emphasis on asset management of pavement infrastructure, it is important to strengthen the maintenance components of these systems and particularly the preventive maintenance component. Iraqi Roads don?t receive an effective and proper maintenance during their service life until they reach the state of major failure that requires rehabilitation. Roads in Iraq are being lost. Approach: In th...

  14. Psychological distress among homeless adults.

    Science.gov (United States)

    Gelberg, L; Linn, L S

    1989-05-01

    Recent studies have reported a high prevalence of mental illness among the homeless. As part of a community-based survey of 529 homeless adults, we developed and tested a model to increase our understanding of the factors related to their psychological distress. Using a previously validated and reliable scale of perceived psychological distress, we found that homeless adults were more likely to report psychological distress than the general population (80% vs. 49%). Distress levels were not associated with most demographic or homeless characteristics or general appearance. However, distress was related to unemployment, greater cigarette and alcohol use, worse physical health, fewer social supports, and perceived barriers to obtaining needed medical care. Since mental, physical, and social health are strongly related among homeless adults, alleviating distress among them may be most effectively done by implementing a broad-based health services package coupled with employment programs provided in an accessible service delivery setting. PMID:2785158

  15. Time series observations of marsh recovery and pavement persistence at three Metula spill sites after 30.5 years

    International Nuclear Information System (INIS)

    In 1974, the oil tanker Metula ran aground in the Strait of Magellan, Chile and spilled about 50,000 tons of light Arabian crude and 2,000 tons of Bunker C fuel. No attempt was made to recover or treat the stranded oil and the coast was left to recover by natural attenuation. Field visits to the coastal sites affected by the spill were conducted 30 years after the incident. The survey in 2005 repeated observations and measurements made in 1998 in the heavily affected Punta Espora area that documented salt marsh recovery at 2 sites, and changes in asphalt pavement at a third site. The 1998 survey also indicated that tilling was responsible for a significant increase in the number of plants that recolonized the area. A comparison of the plant counts between 1998 and 2005 showed that the number of plants in tilled plots was reduced because of fewer larger plants. A comparison of oil distribution in the west marsh from 1998 to 2005 showed that recolonization was evident. A large 550 m-long asphalt pavement on a mixed sediment beach showed very little changes in pavement area in the aftermath of the spill. However, the upper edge of the pavement showed signs of erosion by backwash action of waves during high-tide. The presence of surface oil cover continues to dominate the physical character of the upper intertidal and supratidal zones. 11 refs., 6 tabs., 3 figs

  16. In-situ infiltration performance of different permeable pavements in a employee used parking lot - A four-year study.

    Science.gov (United States)

    Kumar, Kuldip; Kozak, Joseph; Hundal, Lakhwinder; Cox, Albert; Zhang, Heng; Granato, Thomas

    2016-02-01

    Permeable pavements are being adopted as a green solution in many parts of the world to manage urban stormwater quantity and quality. This paper reports on the measured in-situ infiltration performance over a four-year period since construction and use of three permeable parking sections (permeable pavers, permeable concrete and permeable asphalt) of an employee car parking lot. There was only a marginal decline in infiltration rates of all three pavements after one year of use. However, between years two to four, the infiltration rates declined significantly due to clogging of pores either by dry deposition of particles and/or shear stress of vehicles driving and degrading the permeable surfaces; during the last two years, a greater decline was also observed in driving areas of the parking lots compared to parking slots, where minimal wear and tear are expected. Maintenance strategies were employed to reclaim some of the lost infiltration rate of the permeable pavements to limited success. Despite this decline, the infiltration rates were still four to five times higher than average rainstorm intensity in the region. Thus, these permeable pavement parking lots may have significant ecological importance due to their ability to infiltrate rainwater quickly, reduce the runoff in the catchment area, and also dampen runoff peak flows that could otherwise enter the collection system for treatment in a combined sewer area. PMID:26606196

  17. "Comparison of some Structural Analyses Methods used for the Test Pavement in the Danish Road Testing Machine

    DEFF Research Database (Denmark)

    Baltzer, S.; Zhang, W.

    1998-01-01

    A flexible test pavement, instrumented to measure stresses and strains in the three primary axes with the upper 400 mm of the subgrade, has been constructed and load tested in the Danish Road Testing Machine (RTM). One objective of this research, which is part of the International Pavement Subgrade Performance Study, is to develop an improved mechanistic subgrade failure criterion.Simulated traffic loads were applied between June and December 1997 by a dual tyre loading cart within a climate chamber maintained at a constant temperature. Three load levels (40 kN, 50 kN and 60 kN) were applied. In all three test series, 50000 load repetitions were applied at each load level, and the test chamber temperature was maintained at approximately 25 degree C.Instruments installed in the test pavement included: Strain measuring sensors (LVDT Soil Strain Deformation Transducers and Asphalt Strain Gauges), Soil Pressure Cells, Thermistors and Pore Pressure Sensors. Routine monitoring of instrument responses and surface profiles with a Profilometer and FWD/LWD structural testing were undertaken at regular intervals during the construction and load testing programmes.This paper compares various structural analysis methods used for the RTM test pavement with data from FWD testing undertaken after the construction and loading programmes. Multilayer linear elastic forward and backcalculation methods, a finite element program and MS Excel spreadsheet based methods are compared.

  18. Automatic Detection and Classification of Defect on road Pavement using Anisotropy Measure

    OpenAIRE

    Nguyen, Tien Sy; Avila, Manuel; Begot, Stéphane

    2009-01-01

    Automatic pavement cracking detection is a part of road maintenance and rehabilitation strategies. Cracks detec-tion is one of the main features used by road authorities to manage efficiently its networks. Road surface is made using aggregates which can have different sizes, organized randomly. Scanned pictures of theses surfaces appear has random distribution of a re-duced set of gray levels. Cracks or defaults can't be ex-tracted by a simple threshold. In this paper, we introduce a measure ...

  19. Effects of rejuvenator seal and fog seal on performance of open-graded friction course pavement

    OpenAIRE

    Nadeem A. Qureshi

    2013-01-01

    An open-graded friction course (OGFC) is a special-purpose surface layer of hot-mix asphalt (HMA) pavement that is increasingly being used around the world. Owing to its numerous benefits, OGFC is being regularly used as a final riding surface on interstate and high-traffic expressways by different highway agencies in the United States. However, some OGFC sections have experienced premature failure due to ravelling only after 6-8 years of service life. To maintain an effective, longer service...

  20. Targeting distress in rheumatic diseases

    OpenAIRE

    Vriezekolk, J.E.|info:eu-repo/dai/nl/282985646

    2011-01-01

    Psychological distress is highly prevalent in patients with rheumatic diseases. It is associated with a variety of negative outcomes, including pain, fatigue, disability, and maladaptive cognitive behavioural coping strategies. In this thesis, psychological distress was studied both as an outcome measure and as a therapeutic target in the context of multidisciplinary rehabilitation. The longitudinal role of coping in psychological distress was systematically reviewed, a questionnaire to asses...

  1. Effect Of Geopathic Stress On Bituminous Pavement

    OpenAIRE

    B.H.CHAFEKAR; G.P.JARAD; S.S.PIMPLIKAR; A.G.KHARAT; N.P.DHARMADHIKARI; R.R.SORATE

    2013-01-01

    This paper basically for the investigation of Geopathic Stress Zones along the road. Geopathic stress is detrimental energy emanating from the earth and leading to long-term harm to susceptible humans, animals and plants which are exposed to them in their environment. Detection of geopathic location has been done by Experimental investigations on road alignment of one KM, by performing distresses survey, dowsing and by magnetic field detector to investigate the Geopathic Stress. Due to such e...

  2. Breast Cancer Distress in Childhood

    Medline Plus

    Full Text Available ... not. The researchers rated their levels of anxiety, depression, hyperactivity, aggression and social stress. Breast cancer-specific distress was also evaluated. Growing up in ...

  3. Acute Respiratory Distress Syndrome (ARDS)

    Science.gov (United States)

    ... the philanthropic arm of the American College of Chest Physicians. Blank Section Header Lung Disease Lookup Acute Respiratory Distress Syndrome (ARDS) Learn About ARDS ARDS Symptoms, Causes & Risk ...

  4. 47 CFR 80.324 - Transmission of distress message by station not itself in distress.

    Science.gov (United States)

    2010-10-01

    ...2010-10-01 false Transmission of distress message by station not itself in distress. ...§ 80.324 Transmission of distress message by station not itself in distress. ...is in distress must transmit a distress message in any of the following cases:...

  5. Leaching of organic contaminants from storage of reclaimed asphalt pavement.

    Science.gov (United States)

    Norin, Malin; Strömvall, A M

    2004-03-01

    Recycling of asphalt has been promoted by rapid increases in both the use and price of petroleum-based bitumen. Semi-volatile organic compounds in leachates from reclaimed asphalt pavement, measured in field samples and in laboratory column test, were analysed through a GC/MS screen-test methodology. Sixteen PAH (polyaromatic hydrocarbons) were also analysed in leachates from the column study. The highest concentrations of semi-volatile compounds, approximately 400 microg l(-1), were measured in field samples from the scarified stockpile. Naphthalene, butylated hydroxytoluene (BHT) and dibutyl phthalate (DBP) were the most dominant of the identified semi-volatiles. The occurrence of these compounds in urban groundwater, also indicate high emission rates and persistent structures of the compounds, making them potentially hazardous. Car exhausts, rubber tires and the asphalt material itself are all probable emission sources, determined from the organic contaminants released from the stockpiles. The major leaching mechanism indicated was dissolution of organic contaminants from the surface of the asphalt gravels. In the laboratory column test, the release of high-molecular weight and more toxic PAH was higher in the leachates after two years than at the commencement of storage. The concentrations of semi-volatiles in leachates, were also several times lower than those from the field stockpile. These results demonstrate the need to follow up laboratory column test with real field measurements. PMID:15176747

  6. Asphalt Pavement Material Improvement: A Review

    Directory of Open Access Journals (Sweden)

    Mohamed Sulyman

    2014-10-01

    Full Text Available The recycling of solid industrial wastes (SIW such as waste rubber tires and plastics will not only solve the global environmental problem of these SIW but also act as very promising modifiers for the improvement of engineering characteristics of the asphalt pavement material. The present work was concerned with assisting the interested readers to be familiarized with the paving material asphalt-modifiers obtained from SIW by providing historical perspective on its first invention and development. The paper has also provided highlights on common processes of asphalt mixture production. It was also worth mentioning that there are two asphalt production technologies: the warm mix asphalt (WMA and hot mix asphalt (HMA technologies, and the various advantages of using each one. Additionally, the paper has provided the reader with an overview of a number of case studies which were conducted by scientists and researchers for serious attempting to reach development and capturing significant properties of incorporating SIWs in civil engineering represented by scarp tires in form of crumb rubber (CR, plastics (polymers in their different forms.

  7. Evaluation of Road Pavement Density Using Ground Penetrating Radar

    Directory of Open Access Journals (Sweden)

    RSA Raja Abdullah

    2009-01-01

    Full Text Available This study describes an analysis of Ground Penetrating Radar (GPR measurements at frequency range of 1.7-2.6 GHz to get a relationship between attenuation and density for nine road pavements slabs with different densities. There are about four different frequencies had been tested. The method is simple, fast, non-destructive and accurate way to determine the density of road pavement. Density is a one of the important parameter in order to determine the compressive strength of road pavement for road user safety. In laboratory, the measurement system consists of a signal generator (250 kHz-3 GHz as a source, spectrum analyzer (100 Hz-8 GHz, directional coupler with adapter and horn antenna. The first part of the measurement system setup is to determine the amplitude of transmitted wave (received signal strength. A few of received signal strength and attenuation for nine road pavement slab samples were taken at four different frequencies. An instantaneous method for measuring the density of road pavement was developed by using microwave reflection technique and free space method. The MATLAB software is used to analyze the measurement data and also for the graphs comparisons. At the end of this study, it is found that density plays an important factor in causing a major in the recorded signal strength as well as the differences of attenuation of the GPR signal.

  8. Coal-tar based pavement sealant toxicity to freshwater macroinvertebrates

    International Nuclear Information System (INIS)

    Non-point-source pollution is a major source of ecological impairment in urban stream systems. Recent work suggests that coal-tar pavement sealants, used extensively to protect parking areas, may be contributing a large portion of the polycyclic aromatic hydrocarbon (PAH) loading seen in urban stream sediments. The hypothesis that dried coal-tar pavement sealant flake could alter the macroinvertebrate communities native to streams in Austin, TX was tested using a controlled outdoor laboratory type approach. The treatment groups were: control, low, medium, and high with total PAH concentrations (TPAH = sum of 16 EPA priority pollutant PAHs) of 0.1, 7.5, 18.4, and 300 mg/kg respectively. The low, medium, and high treatments were created via the addition of dried coal-tar pavement sealant to a sterile soil. At the start of the 24-day exposure, sediment from a minimally impacted local reference site containing a community of live sediment-dwelling benthic macroinvertebrates was added to each replicate. An exposure-dependent response was found for several stream health measures and for several individual taxa. There were community differences in abundance (P = 0.0004) and richness (P < 0.0001) between treatments in addition to specific taxa responses, displaying a clear negative relationship with the amount of coal-tar sealant flake. These results support the hypothesis that coal-tar pavement sealants contain bioavailable PAHs that may harm aquatic environments. - Coal-tar pavement sealants degrade stream invertebrate communities.

  9. Moisture Influence on Structural Behaviour of Pavements : Field and Laboratory Investigations

    OpenAIRE

    Salour, Farhad

    2015-01-01

    The structural behaviour of pavements in cold regions can considerably be affected by seasonal variation in environmental factors such as temperature and moisture content. Along with the destructive effect of heavy traffic loads, climatic and environmental factors can considerably contribute to pavement deterioration. These factors can influence the structural and functional capacity of the pavement structures which, as a result, can trigger and accelerate pavement deterioration mechanisms. S...

  10. Deterioration Forecasting in Flexible Pavements Due to Floods and Snow Storms

    OpenAIRE

    Shahini Shamsabadi, Salar; Hashemi Tari, Yasamin Sadat; Birken, Ralf; Wang, Ming

    2014-01-01

    Roadway agencies and state DOTs utilize Pavement Management Systems (PMS) to implement cost-effective maintenance strategies. A reliable yet easily applicable model for deterioration process of pavements is an integral part of any Pavement Management System. As pavement condition grows to be one of the crucial problems facing our nation, the reliability of these deterioration prediction models becomes more important. While numerous endevours have been made to capture the effect of the environ...

  11. Analysis of the Evolution of Flexible Pavement Condition Based on LTPP SPS-5 Sections

    OpenAIRE

    Azevedo, Joana; Capitão, Silvino; Rasteiro, Deolinda; Picado-Santos, Luís

    2015-01-01

    The American LTPP program has one of the greatest amounts of stored information regarding pavement characteristics and the evolution of their condition on a network. This is a valuable tool to support decision-making in what concerns maintenance and rehabilitation of pavements carried out by highway infrastructure agencies. This paper presents a study carried out to analyze the evolution of pavement conditions of several SPS-5 test sections, which were included in pavement rehabilitation stud...

  12. Design of Rigid and Flexible Pavements by Various Methods & Their Cost Analysis of Each Method

    OpenAIRE

    Saurabh Jain

    2013-01-01

    Highway and pavement design plays an important role in the DPR projects. The satisfactory performance of the pavement will result in higher savings in terms of vehicle operating costs and travel time, which has a bearing on the overall economic feasibility of the project. This paper discusses about the design methods that are traditionally being followed and examines the “Design of rigid and flexible pavements by various methods & their cost analysis by each method”. Flexible pavement are pre...

  13. Effects of rejuvenator seal and fog seal on performance of open-graded friction course pavement

    Directory of Open Access Journals (Sweden)

    Nadeem A. Qureshi

    2013-05-01

    Full Text Available An open-graded friction course (OGFC is a special-purpose surface layer of hot-mix asphalt (HMA pavement that is increasingly being used around the world. Owing to its numerous benefits, OGFC is being regularly used as a final riding surface on interstate and high-traffic expressways by different highway agencies in the United States. However, some OGFC sections have experienced premature failure due to ravelling only after 6-8 years of service life. To maintain an effective, longer service life and enhanced performance of OGFC, preventive maintenance has been considered essential. There are several approaches to maintaining OGFC, one of which is the application of a fog seal and rejuvenator seal. A fog seal can reduce ravelling and extend the service life of OGFC while a rejuvenator seal can revitalise the existing aged asphalt binder in the top OGFC layer. This research focuses on optimising the fog and rejuvenator seal application rates by evaluating their effectiveness in terms of surface friction and durability. Three types of seal material were evaluated: Pavegaard (PG and Pavepreserve (PP asphalt rejuvenators and a cationic slow-setting asphalt emulsion (CSS-1H as a fog seal. Improvement in abrasion resistance of OGFC pavement was observed on application of fog and rejuvenator seals but surface friction was reduced to some extent. Hamburg test clearly shows a trend that the medium application rate of 0.10 gallon/square yard is better in enhancing resistance to rutting/moisture susceptibility of OGFC.

  14. Water quality and quantity assessment of pervious pavements performance in experimental car park areas.

    Science.gov (United States)

    Sañudo-Fontaneda, Luis A; Charlesworth, Susanne M; Castro-Fresno, Daniel; Andres-Valeri, Valerio C A; Rodriguez-Hernandez, Jorge

    2014-01-01

    Pervious pavements have become one of the most used sustainable urban drainage system (SUDS) techniques in car parks. This research paper presents the results of monitoring water quality from several experimental car park areas designed and constructed in Spain with bays made of interlocking concrete block pavement, porous asphalt, polymer-modified porous concrete and reinforced grass with plastic and concrete cells. Moreover, two different sub-base materials were used (limestone aggregates and basic oxygen furnace slag). This study therefore encompasses the majority of the materials used as permeable surfaces and sub-base layers all over the world. Effluent from the test bays was monitored for dissolved oxygen, pH, electric conductivity, total suspended solids, turbidity and total petroleum hydrocarbons in order to analyze the behaviour shown by each combination of surface and sub-base materials. In addition, permeability tests were undertaken in all car parks using the 'Laboratorio Caminos Santander' permeameter and the Cantabrian Portable Infiltrometer. All results are presented together with the influence of surface and sub-base materials on water quality indicators using bivariate correlation statistical analysis at a confidence level of 95%. The polymer-modified porous concrete surface course in combination with limestone aggregate sub-base presented the best performance. PMID:24718346

  15. PAH volatilization following application of coal-tar-based pavement sealant

    Science.gov (United States)

    Van Metre, Peter C.; Majewski, Michael S.; Mahler, Barbara J.; Foreman, William T.; Braun, Christopher L.; Wilson, Jennifer T.; Burbank, Teresa L.

    2012-05-01

    Coal-tar-based pavement sealants, a major source of PAHs to urban water bodies, have recently been identified as a source of volatile PAHs to the atmosphere. We tracked the volatilization of PAHs for 1 year after application of a coal-tar-based pavement sealant by measuring gas-phase PAH concentrations above the pavement surface and solid-phase PAH concentrations in sealant scraped from the surface. Gas-phase concentrations at two heights (0.03 and 1.28 m) and wind speed were used to estimate volatilization flux. The sum of the concentrations of eight frequently detected PAHs (?PAH8) in the 0.03-m sample 1.6 h after application (297,000 ng m-3) was about 5000 times greater than that previously reported for the same height above unsealed parking lots (66 ng m-3). Flux at 1.6 h after application was estimated at 45,000 ?g m-2 h-1 and decreased rapidly during the 45 days after application to 160 ?g m-2 h-1. Loss of PAHs from the adhered sealant also was rapid, with about a 50% decrease in solid-phase ?PAH8 concentration over the 45 days after application. There was general agreement, given the uncertainties, in the estimated mass of ?PAH8 lost to the atmosphere on the basis of air sampling (2-3 g m-2) and adhered sealant sampling (6 g m-2) during the first 16 days after application, translating to a loss to the atmosphere of one-quarter to one-half of the PAHs in the sealcoat product. Combining the estimated mass of ?PAH8 released to the atmosphere with a national-use estimate of coal-tar-based sealant suggests that PAH emissions from new coal-tar-based sealcoat applications each year (˜1000 Mg) are larger than annual vehicle emissions of PAHs for the United States.

  16. An algorithm for pavement crack detection based on multiscale space

    Science.gov (United States)

    Liu, Xiang-long; Li, Qing-quan

    2006-10-01

    Conventional human-visual and manual field pavement crack detection method and approaches are very costly, time-consuming, dangerous, labor-intensive and subjective. They possess various drawbacks such as having a high degree of variability of the measure results, being unable to provide meaningful quantitative information and almost always leading to inconsistencies in crack details over space and across evaluation, and with long-periodic measurement. With the development of the public transportation and the growth of the Material Flow System, the conventional method can far from meet the demands of it, thereby, the automatic pavement state data gathering and data analyzing system come to the focus of the vocation's attention, and developments in computer technology, digital image acquisition, image processing and multi-sensors technology made the system possible, but the complexity of the image processing always made the data processing and data analyzing come to the bottle-neck of the whole system. According to the above description, a robust and high-efficient parallel pavement crack detection algorithm based on Multi-Scale Space is proposed in this paper. The proposed method is based on the facts that: (1) the crack pixels in pavement images are darker than their surroundings and continuous; (2) the threshold values of gray-level pavement images are strongly related with the mean value and standard deviation of the pixel-grey intensities. The Multi-Scale Space method is used to improve the data processing speed and minimize the effectiveness caused by image noise. Experiment results demonstrate that the advantages are remarkable: (1) it can correctly discover tiny cracks, even from very noise pavement image; (2) the efficiency and accuracy of the proposed algorithm are superior; (3) its application-dependent nature can simplify the design of the entire system.

  17. Evaluation of Common Maintenance Methods for Flexible Pavements

    Directory of Open Access Journals (Sweden)

    Asma T. Ibraheem

    2011-01-01

    Full Text Available Problem statement: With the increasing use and awareness of pavement management systems and the growing emphasis on asset management of pavement infrastructure, it is important to strengthen the maintenance components of these systems and particularly the preventive maintenance component. Iraqi Roads don’t receive an effective and proper maintenance during their service life until they reach the state of major failure that requires rehabilitation. Roads in Iraq are being lost. Approach: In this study, a study of the status of maintenance methods for road pavements in Iraq with special reference to flexible pavements is presented. For this purpose, open and closed questionnaires were executed in Baghdad to investigate the status of road pavement maintenance in Iraq. Road maintenance offices as (Ministry of construction and Housing, State Corporation for Roads and Bridges, Amanat Baghdad, Project office, were included in the questionnaire to arrive at the level of maintenance and techniques followed to maintain paved road in Iraq. Results: The interviews carried out reveal that maintenance in Iraq has secondary importance, apparently with no special budget allocated for such important works. In addition the maintenance methods and techniques followed do not comply the developments and modern techniques. Conclusion/Recommendations: Poor and miss-management of maintenance works and activities leading to delays and accumulation of failure in the highway network that require unusual expenditures to repair and maintain the accumulated damages. Also shortages in resources allocated for maintenance works and this leads to the diversion of significant portion of the allocated fund for maintenance works toward purchasing of new, or additional equipment to be used for the construction of new roads. It is strongly recommended to design a planning system for management pavement maintenance of road network in Iraq and develop a particular failure criterion for roads in Iraq.

  18. Diurnal Thermal Behavior of Pavements, Vegetation, and Water Pond in a Hot-Humid City

    Directory of Open Access Journals (Sweden)

    Xiaoshan Yang

    2015-12-01

    Full Text Available This study investigated the diurnal thermal behavior of several urban surfaces and landscape components, including pavements, vegetation, and a water pond. The field experiment was conducted in a university campus of Guangzhou, South China, which is characterized by a hot and humid summer. The temperature of ground surface and grass leaves and the air temperature and humidity from 0.1 to 1.5 m heights were measured for a period of 24 h under hot summer conditions. The results showed that the concrete and granite slab pavements elevated the temperature of the air above them throughout the day. In contrast, the trees and the pond lowered the air temperature near ground during the daytime but produced a slight warming effect during the nighttime. The influence of vegetation on air temperature and humidity is affected by the configurations of greenery. Compared to the open lawn, the grass shaded by trees was more effective in cooling and the mixture of shrub and grass created a stronger cooling effect during the nighttime. The knowledge of thermal behavior of various urban surfaces and landscape components is an important tool for planners and designers. If utilized properly, it can lead to climatic rehabilitation in urban areas and an improvement of the outdoor thermal environment.

  19. Geo synthetic-reinforced Pavement systems; Sistemas de pavimentos reforzados con geosinteticos

    Energy Technology Data Exchange (ETDEWEB)

    Zornberg, J. G.

    2014-02-01

    Geo synthetics have been used as reinforcement inclusions to improve pavement performance. while there are clear field evidence of the benefit of using geo synthetic reinforcements, the specific conditions or mechanisms that govern the reinforcement of pavements are, at best, unclear and have remained largely unmeasured. Significant research has been recently conducted with the objectives of: (i) determining the relevant properties of geo synthetics that contribute to the enhanced performance of pavement systems, (ii) developing appropriate analytical, laboratory and field methods capable of quantifying the pavement performance, and (iii) enabling the prediction of pavement performance as a function of the properties of the various types of geo synthetics. (Author)

  20. Mechanistic-empirical pavement design guide: features and distinctive elements / Mechanistic-empirical pavement design guide: características y elementos distintivos

    Scientific Electronic Library Online (English)

    Margarita, Martínez Díaz; Ignacio, Pérez.

    2015-04-01

    Full Text Available El objetivo de este artículo es describir los rasgos más característicos del método de diseño de firmes conocido como Mechanistic-Empirical Pavement Design Guide, así como compararlo con otras metodologías de renombre, destacando sus ventajas y desventajas. El MEPDG puede predecir con precisión la e [...] volución de los deterioros, ayudando por tanto a elegir el diseño más adecuado para el caso de firmes de nueva construcción, o a programar la conservación de los ya existentes. Tras analizar diferentes métodos de diseño y gestión de firmes, el MEPDG destaca como el más completo al ser el que tiene en cuenta un mayor número de factores que afectan al firme. Por ello algunos países fuera de EEUU ya han importado y calibrado este método, lo que al mismo tiempo permite a la comunidad científica llevar a cabo estudios comparativos y mejorar sus pequeñas deficiencias. Abstract in english This paper is aimed at describing the most distinctive features of the pavement design method known as Mechanistic-Empirical Pavement Design Guide and to compare it with other renowned methodologies, while emphasizing its advantages and disadvantages. The MEPDG can accurately predict damage evolutio [...] n, thus helping to choose the most appropriate design for new pavements or to schedule the conservation of the already existing ones. After analyzing different pavement design and management methods, the MEPDG stands out as the most comprehensive one as it takes into account and properly combines the greatest number of factors that affect the pavement. Therefore, some countries outside the USA have already imported and calibrated this method, what, at the same time, allows the scientific community to carry out comparative studies and improve its small deficiencies.

  1. Stormwater quality performance of a macro-pervious pavement car park installation equipped with channel drain based oil and silt retention devices.

    Science.gov (United States)

    Newman, Alan Paul; Aitken, Douglas; Antizar-Ladislao, Blanca

    2013-12-15

    This paper reports the results of a two year field monitoring exercise intended to investigate the pollution abatement capabilities of a novel system which offers an alternative to the, now well established, pervious pavement system as a source control device for stormwater management. The aim of this study was to determine the effectiveness of a live installation of a macro-pervious pavement system (MPPS) (operated as a visitors' car park at a prison in Central Scotland) in retaining and treating a range of pollutants which originate from automobile use or become concentrated on the parking surface from the wider environment. The MPPS is a sub-class of pervious pavement system where the vast majority of the surface is impermeable. It directs stormwater into a pervious sub surface storage/attenuation zone through a series of distinct infiltration points fast enough to prevent flooding during the design storm. In the particular system studied here the infiltration points consist of a network of oil/silt separation devices with extensive further pollutant retention/degradation provided during the passage of stormwater through the sub surface zone. Approximately 12 months after the car park was completed a sampling regime was instigated in which grab samples were collected at intervals from each of the three sub catchments whilst, simultaneously, samples were collected directly from the, pollutant retaining, infiltration devices. Through investigation of samples collected at the upstream end of the system, the retention of significant amounts of hydrocarbons and heavy metals in the initial collection devices has been illustrated and the analysis of effluent samples collected at the outlet points indicate that the system is capable of producing effluent which is of a standard comparable to that expected from a traditional pervious pavement system and is acceptable for direct release into a surface water receptor. The system offers the opportunity to accrue the benefits of a pervious pavement when the use of traditional paving surfaces is the preferred option. PMID:23954068

  2. Breast Cancer Distress in Childhood

    Medline Plus

    Full Text Available ... cancer or a known genetic risk for the disease. The other half did not. The researchers rated their levels of anxiety, depression, hyperactivity, aggression and social stress. Breast cancer-specific distress was also evaluated. Growing ...

  3. Adult respiratory distress syndrome

    International Nuclear Information System (INIS)

    Due to improved emergency resuscitation procedures, and with advancing medical technology in the field of critical care, an increasing number of patients survive the acute phase of shock and catastrophic trauma. Patients who previously died of massive sepsis, hypovolemic or hypotensive shock, multiple fractures, aspiration, toxic inhalation, and massive embolism are now surviving long enough to develop previously unsuspected and unrecognized secondary effects. With increasing frequency, clinicians are recognizing the clinical and radiographic manifestations of pathologic changes in the lungs occurring secondary to various types of massive insult. This paper gives a list of diseases that have been shown to precipitate or predispose to diffuse lung damage. Various terms have been used to describe the lung damage and respiratory failure secondary to these conditions. The term adult respiratory distress syndrome (ARDS) is applied to several cases of sudden respiratory failure in patients with previously healthy lungs following various types of trauma or shock. Numerous investigations and experiments have studied the pathologic changes in ARDS, and, while there is still no clear indication of why it develops, there is now some correlation of the sequential pathologic developments with the clinical and radiographic changes

  4. Acute Respiratory Distress Syndrome.

    Science.gov (United States)

    Yadam, Suman; Bihler, Eric; Balaan, Marvin

    2016-01-01

    Acute respiratory distress syndrome (ARDS) is a serious inflammatory disorder with high mortality. Its main pathologic mechanism seems to result from increased alveolar permeability. Its definition has also changed since first being described according to the Berlin definition, which now classifies ARDS on a severity scale based on PaO2 (partial pressure of oxygen, arterial)/FIO2 (fraction of inspired oxygen) ratio. The cornerstone of therapy was found to be a low tidal volume strategy featuring volumes of 6 to 8 mL per kg of ideal body weight that has been shown to have decreased mortality as proven by the ARDSnet trials. There are other areas of treatment right now that include extracorporeal membrane oxygenation, as well for severe refractory hypoxemia. Other methods that include prone positioning for ventilation have also shown improvements in oxygenation. Positive end-expiratory pressure with lung recruitment maneuvers has also been found to be helpful. Other therapies that include vasodilators and neuromuscular agents are still being explored and need further studies to define their role in ARDS. PMID:26919679

  5. Deterioration modeling for condition assessment of flexible pavements considering extreme weather events

    Science.gov (United States)

    Hashemi Tari, Yasamin; Shahini Shamsabadi, Salar; Birken, Ralf; Wang, Ming

    2015-04-01

    Accurate pavement management systems are essential for states' Department Of Transportation and roadway agencies to plan for cost-effective maintenance and repair (M and R) strategies. Pavement deterioration model is an imperative component of any pavement management system since the future budget and M and R plans would be developed based on the predicted pavement performance measures. It is crucial for the pavement deterioration models to consider the factors that significantly aggravate the pavement condition. While many studies have highlighted the impact of different environmental, load, and pavement's structure on the life cycle of the pavement, effect of extreme weather events such as Floods and Snow Storms have often been overlooked. In this study, a pavement deterioration model is proposed which would consider the effect of traffic loads, climate conditions, and extreme weather events. Climate, load and performance data has been compiled for over twenty years and for eight states using the Long Term Pavement Performance (LTPP) and National Oceanic and Atmospheric Administration (NOAA) databases. A stepwise regression approach is undertaken to quantify the effect of the extreme weather events, along with other influential factors on pavement performance in terms of International Roughness Index (IRI). Final results rendered more than 90% correlation with the quantified impact values of extreme weather events.

  6. Artificial intelligence modeling to evaluate field performance of photocatalytic asphalt pavement for ambient air purification.

    Science.gov (United States)

    Asadi, Somayeh; Hassan, Marwa; Nadiri, Ataallah; Dylla, Heather

    2014-01-01

    In recent years, the application of titanium dioxide (TiO?) as a photocatalyst in asphalt pavement has received considerable attention for purifying ambient air from traffic-emitted pollutants via photocatalytic processes. In order to control the increasing deterioration of ambient air quality, urgent and proper risk assessment tools are deemed necessary. However, in practice, monitoring all process parameters for various operating conditions is difficult due to the complex and non-linear nature of air pollution-based problems. Therefore, the development of models to predict air pollutant concentrations is very useful because it can provide early warnings to the population and also reduce the number of measuring sites. This study used artificial neural network (ANN) and neuro-fuzzy (NF) models to predict NOx concentration in the air as a function of traffic count (Tr) and climatic conditions including humidity (H), temperature (T), solar radiation (S), and wind speed (W) before and after the application of TiO? on the pavement surface. These models are useful for modeling because of their ability to be trained using historical data and because of their capability for modeling highly non-linear relationships. To build these models, data were collected from a field study where an aqueous nano TiO? solution was sprayed on a 0.2-mile of asphalt pavement in Baton Rouge, LA. Results of this study showed that the NF model provided a better fitting to NOx measurements than the ANN model in the training, validation, and test steps. Results of a parametric study indicated that traffic level, relative humidity, and solar radiation had the most influence on photocatalytic efficiency. PMID:24699867

  7. Platelet surface glycoproteins. Studies on resting and activated platelets and platelet membrane microparticles in normal subjects, and observations in patients during adult respiratory distress syndrome and cardiac surgery.

    OpenAIRE

    George, J N; Pickett, E B; Saucerman, S; McEver, R P; Kunicki, T J; Kieffer, N; Newman, P J

    1986-01-01

    The accurate definition of surface glycoprotein abnormalities in circulating platelets may provide better understanding of bleeding and thrombotic disorders. Platelet surface glycoproteins were measured on intact platelets in whole blood and platelet membrane microparticles were assayed in cell-free plasma using 125I-monoclonal antibodies. The glycoproteins (GP) studied were: GP Ib and GP IIb-IIIa, two of the major intrinsic plasma membrane glycoproteins; GMP-140, an alpha-granule membrane gl...

  8. Functionality Enhancement of Industrialized Optical Fiber Sensors and System Developed for Full-Scale Pavement Monitoring

    Directory of Open Access Journals (Sweden)

    Huaping Wang

    2014-05-01

    Full Text Available Pavements always play a predominant role in transportation. Health monitoring of pavements is becoming more and more significant, as frequently suffering from cracks, rutting, and slippage renders them prematurely out of service. Effective and reliable sensing elements are thus in high demand to make prognosis on the mechanical properties and occurrence of damage to pavements. Therefore, in this paper, various types of functionality enhancement of industrialized optical fiber sensors for pavement monitoring are developed, with the corresponding operational principles clarified in theory and the performance double checked by basic experiments. Furthermore, a self-healing optical fiber sensing network system is adopted to accomplish full-scale monitoring of pavements. The application of optical fiber sensors assembly and self-healing network system in pavement has been carried out to validate the feasibility. It has been proved that the research in this article provides a valuable method and meaningful guidance for the integrity monitoring of civil structures, especially pavements.

  9. Underwater observations of dolphin reactions to a distressed conspecific.

    Science.gov (United States)

    Kuczaj, Stan A; Frick, Erin E; Jones, Brittany L; Lea, James S E; Beecham, Dan; Schnöller, Fabrice

    2015-09-01

    This report describes the epimeletic (or "caregiving") behavior produced by members of a group of Atlantic bottlenose dolphins (Tursiops truncatus) and the possible role of the ailing animal's distress call in eliciting such behavior. Epimeletic behavior in cetaceans most typically involves forms of support provided to a distressed, injured, or dying animal (Caldwell & Caldwell, 1966). Analyses of underwater video and corresponding acoustic recordings revealed a distressed dolphin (the DD) that frequently produced what are most likely distress calls, often paired with the emission of long bubble streams. The frequency of her whistle production was positively correlated with the frequency of the supporting behaviors the DD received from other dolphins. These helping behaviors included raft formations, lifts, and stimulating pushes that were predominantly directed toward the upper third of the DD's body, all of which appeared to be directed towards bringing the DD toward the surface so that she could breathe. This is the first documented underwater account of multiple wild bottlenose dolphins providing epimeletic care to a distressed conspecific, and highlights the possible role of distress calls in such scenarios. PMID:25898942

  10. A Detailed Study of Cbr Method for Flexible Pavement Design

    Directory of Open Access Journals (Sweden)

    Er. Devendra Kumar Choudhary

    2014-06-01

    Full Text Available As per IRC recommendation, California Bearing Ratio (CBR value of subgrade is used for design of flexible pavements. California Bearing Ratio (CBR value is an important soil parameter for design of flexible pavements and runway of air fields. It can also be used for determination of sub grade reaction of soil by using correlation. It is one of the most important engineering properties of soil for design of sub grade of roads. CBR value of soil may depends on many factors like maximum dry density (MDD, optimum moisture content (OMC, liquid limit (LL, plastic limit (PL, plasticity index (PI, type of soil, permeability of soil etc. Besides, soaked or unsoaked condition of soil also affects the value. These tests can easily be performed in the laboratory. the estimation of the CBR could be done on the basis of these tests which are quick to perform, less time consuming and cheap, then it will be easy to get the information about the strength of subgrade over the length of roads, By considering this aspect, a number of investigators in the past made their investigations in this field and designed different pavements by determining the CBR value on the basis of results of low cost, less time consuming and easy to perform tests. In this study, attempts have been made to seek the values of CBR of different soil samples and correlate their CBR values for the design purpose of flexible pavement as per guidelines of IRC: SP: 37-2001.

  11. Exploring pavement crack evaluation with bidimensional empirical mode decomposition

    Science.gov (United States)

    Ayenu-Prah, Albert; Attoh-Okine, Nii

    2007-04-01

    Crack evaluation is essential for effective classification of pavement cracks. Digital images of pavement cracks have been analyzed using techniques such as fuzzy set theory and neural networks. Bidimensional empirical mode decomposition (BEMD), a new image analysis method recently developed, can potentially be used for pavement crack evaluation. BEMD is an extension of the empirical mode decomposition (EMD), which can decompose non-linear and non-stationary signals into basis functions called intrinsic mode functions (IMF). IMFs are monocomponent functions that have well defined instantaneous frequencies. EMD is a sifting process that is non-parametric and data-driven; it does not depend on an a priori basis set. It is able to remove noise from signals without complicated convolution processes. BEMD decomposes an image into two-dimensional IMFs. The present paper explores pavement crack detection using BEMD together with the Sobel edge detector. A number of images are filtered with BEMD to remove noise, and the residual image analyzed with the Sobel edge detector for crack detection. The results are compared with results from the Canny edge detector, which uses a Gaussian filter for image smoothing before performing edge detection. The objective is to qualitatively explore how well BEMD is able to smooth an image for more effective and speedier edge detection with the Sobel method.

  12. Use of seismic pavement analyzer in forensic studies

    Science.gov (United States)

    Yuan, Deren; Nazarian, Soheil; Baker, Mark R.

    1999-02-01

    Seismic nondestructive testing technology as used for pavement evaluation has been incorporated in two devices: the Seismic Pavement Analyzer (SPA) and the Portable Seismic Pavement Analyzer (PSPA). A few short-term projects were conducted to learn when and where the use of seismic methods is feasible. The usefulness of the test methods involved in the SPA and PSPA has been to some extent evaluated. In their present states, the SPA and PSPA seem to be emerging as valuable tools in forensic studies and the day-to-day operations of state highway agencies. The devices have been useful in understanding some of the complex mechanisms encountered in a few projects. More experience is needed to fully understand the potential and weaknesses of the devices, and further development of their software is needed. This paper presents a summary of efforts put forth to improve the SPA and PSPA for their incorporation into the activities of the highway community in maintenance, rehabilitation and construction of pavements. Several case studies that demonstrate the usefulness and shortcomings of the two devices and the methodology involved in them are presented.

  13. Coal-tar based pavement sealant toxicity to freshwater macroinvertebrates

    Energy Technology Data Exchange (ETDEWEB)

    Bryer, P.J.; Scoggins, M.; McClintock, N.L. [Lamar University, Beaumont, TX (United States). Dept. of Biology

    2010-05-15

    Non-point-source pollution is a major source of ecological impairment in urban stream systems. Recent work suggests that coal-tar pavement sealants, used extensively to protect parking areas, may be contributing a large portion of the polycyclic aromatic hydrocarbon (PAH) loading seen in urban stream sediments. The hypothesis that dried coal-tar pavement sealant flake could alter the macroinvertebrate communities native to streams in Austin, TX was tested using a controlled outdoor laboratory type approach. The treatment groups were: control, low, medium, and high with total PAH concentrations (TPAH = sum of 16 EPA priority pollutant PAHs) of 0.1, 7.5, 18.4, & 300 mg/kg respectively. The low, medium, and high treatments were created via the addition of dried coal-tar pavement sealant to a sterile soil. At the start of the 24-day exposure, sediment from a minimally impacted local reference site containing a community of live sediment-dwelling benthic macroinvertebrates was added to each replicate. An exposure-dependent response was found for several stream health measures and for several individual taxa. There were community differences in abundance (P = 0.0004) and richness (P < 0.0001) between treatments in addition to specific taxa responses, displaying a clear negative relationship with the amount of coal-tar sealant flake. These results support the hypothesis that coal-tar pavement sealants contain bioavailable PAHs that may harm aquatic environments.

  14. Evaluating Pavement Cracks with Bidimensional Empirical Mode Decomposition

    Directory of Open Access Journals (Sweden)

    Nii Attoh-Okine

    2008-05-01

    Full Text Available Crack evaluation is essential for effective classification of pavement cracks. Digital images of pavement cracks have been analyzed using techniques such as fuzzy set theory and neural networks. Bidimensional empirical mode decomposition (BEMD, a new image analysis method recently developed, can potentially be used for pavement crack evaluation. BEMD is an extension of the empirical mode decomposition (EMD, which can decompose nonlinear and nonstationary signals into basis functions called intrinsic mode functions (IMFs. IMFs are monocomponent functions that have well-defined instantaneous frequencies. EMD is a sifting process that is nonparametric and data driven; it does not depend on an a priori basis set. It is able to remove noise from signals without complicated convolution processes. BEMD decomposes an image into two-dimensional IMFs. The present paper explores pavement crack detection using BEMD together with the Sobel edge detector. A number of images are filtered with BEMD to remove noise, and the residual image analyzed with the Sobel edge detector for crack detection. The results are compared with results from the Canny edge detector, which uses a Gaussian filter for image smoothing before performing edge detection. The objective is to qualitatively explore how well BEMD is able to smooth an image for more effective edge detection with the Sobel method.

  15. Some experience using a rolling weight deflectometer on airport pavements

    Science.gov (United States)

    Lenngren, Carl A.

    1995-07-01

    A laser based deflection tester is being developed by the Swedish National Road Administration. Forty sensors are mounted on a heavy truck to determine two transverse profiles. One profile constitutes an unloaded case. The other profile just behind the rear wheels of the vehicle constitutes the loaded case. The high sampling rate is adequate for filtering the macro texture of the pavement.

  16. Alternative aircraft loading index for pavement structural analysis

    Energy Technology Data Exchange (ETDEWEB)

    Loizos, A.; Charonitis, G. [National Technical Univ. of Athens (Greece)

    1999-05-01

    The most common practical way to simplify the structural analysis of airfield pavements is the use of equivalent single wheel load models instead of the actual gear of the aircrafts. As the accuracy and reliability of these models strongly affects the design and evaluation of airfield pavements, there is considerable need to investigate both system approaches. The first one, which uses a constant value for the pressure while the radius is variable, is currently under use by the aircraft classification number-pavement classification number method of the International Civil Aviation Organization, but despite this fact it proved to be inadequate to express the aircraft loading in many situations. On the contrary, according to this study, the second model, which has a constant value for the radius while the pressure varies, is more reliable, and it can be an interesting alternative. Thus, based on this model, an aircraft loading index is introduced, which aims to be a simple and reliable factor for expressing the severity of the loading of the aircrafts and a utility for several matters related to the airfield pavement applications.

  17. Nutrient infiltrate concentrations from three permeable pavement types.

    Science.gov (United States)

    Brown, Robert A; Borst, Michael

    2015-12-01

    While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types have on nutrient concentrations present in stormwater runoff are limited. In 2009, the U.S. EPA constructed a 0.4-ha parking lot in Edison, New Jersey, that incorporated permeable interlocking concrete pavement (PICP), pervious concrete (PC), and porous asphalt (PA). Each permeable pavement type has four, 54.9-m(2), lined sections that direct all infiltrate into 5.7-m(3) tanks enabling complete volume collection and sampling. This paper highlights the results from a 12-month period when samples were collected from 13 rainfall/runoff events and analyzed for nitrogen species, orthophosphate, and organic carbon. Differences in infiltrate concentrations among the three permeable pavement types were assessed and compared with concentrations in rainwater samples and impervious asphalt runoff samples, which were collected as controls. Contrary to expectations based on the literature, the PA infiltrate had significantly larger total nitrogen (TN) concentrations than runoff and infiltrate from the other two permeable pavement types, indicating that nitrogen leached from materials in the PA strata. There was no significant difference in TN concentration between runoff and infiltrate from either PICP or PC, but TN in runoff was significantly larger than in the rainwater, suggesting meaningful inter-event dry deposition. Similar to other permeable pavement studies, nitrate was the dominant nitrogen species in the infiltrate. The PA infiltrate had significantly larger nitrite and ammonia concentrations than PICP and PC, and this was presumably linked to unexpectedly high pH in the PA infiltrate that greatly exceeded the optimal pH range for nitrifying bacteria. Contrary to the nitrogen results, the PA infiltrate had significantly smaller orthophosphate concentrations than in rainwater, runoff, and infiltrate from PICP and PC, and this was attributed to the high pH in PA infiltrate possibly causing rapid precipitation of orthophosphate with metal cations. Orthophosphate was exported from the PICP and PC, as evidenced by the significantly larger infiltrate concentrations compared with influent sources of rainwater and runoff. PMID:26348134

  18. Filtration and clogging of permeable pavement loaded by urban drainage.

    Science.gov (United States)

    Sansalone, J; Kuang, X; Ying, G; Ranieri, V

    2012-12-15

    Permeable pavement, as a sustainable infrastructure material can promote hydrologic restoration, particulate matter (PM) and solute control. However, filtration and commensurate clogging are two aspects of continued interest and discussion. This study quantifies filtration and clogging of cementitious permeable pavement (CPP) for loadings from 50 to 200 mg/L of hetero-disperse sandy-silt PM. The CPP mix design provides a hetero-disperse pore size distribution (PSD)(pore), effective porosity (?(e)) of 24% and median pore size of 658 ?m with a standard deviation of 457 ?m. The PM mass separation across the entire particle size distribution (PSD)(PM) exceeds 80%; with complete separation for PM greater than 300 ?m and 50% separation for suspended PM. Turbidity is reduced (42-95%), and effluent is below 10 NTU in the first quartile of a loading period. Permeable pavement illustrates reductions in initial (clean-bed) hydraulic conductivity (k(0)) with loading time. For all PM loadings, k(0) (3.1 × 10(-1) mm/s) was reduced to 10(-4) mm/s for runoff loading durations from 100 to 250 h, respectively. Temporal hydraulic conductivity (k) follows exponential profiles. Maintenance by vacuuming and sonication illustrate that 96-99% of k(0) is recovered. Permeable pavement constitutive properties integrated with measured PM loads and a year of continuous rainfall-runoff simulation illustrate k reduction with historical loadings. Study results measure and model filtration and hydraulic conductivity phenomena as well as maintenance requirements of permeable pavement directly loaded by urban drainage. PMID:22123518

  19. Mechanistic modelling of weak interlayers in flexible and semi-flexible road pavements: Part 2

    Scientific Electronic Library Online (English)

    M, de Beer; J W, Maina; F, Netterberg.

    2012-04-01

    Full Text Available This paper (Part 2 of a two-part set of papers) discusses models and illustrates the adverse effects of weak layers, interlayers, laminations and/or weak interfaces in flexible and semi-flexible pavements, also incorporating lightly cemented layers. The modelling is based on mechanistic analyses for [...] pavement design and evaluation. In Part 1, the effects of these relatively weak layers, interlayers, laminations and/or weak interfaces were discussed. It was shown that methodologies are available to detect and investigate the existence of these weak layers in cemented pavement layers. In Part 2, several cases of the above conditions for different road pavement types are discussed, with field examples. Mechanistic analyses were done on a typical hot mix asphalt (HMA), several cases of a cemented base pavement and a granular base pavement, with and without these weak layers and interface conditions to demonstrate their adverse effects. The analyses focus on the strain energy of distortion (SED) as a pavement response parameter to indicate the potential for structural damage expected within the pavement structure or layer. Generally, the higher the SED, the higher the potential damage in the pavement layer. SED shows some potential for quantifying the relative effects of these weak layers, interlayers, laminations and/or weak interfaces within flexible and semi-flexible pavements.

  20. Riding Quality Model for Asphalt Pavement Monitoring Using Phase Array Type L-band Synthetic Aperture Radar (PALSAR

    Directory of Open Access Journals (Sweden)

    Kamiya Yoshikazu

    2010-11-01

    Full Text Available There are difficulties associated with near-real time or frequent pavement monitoring, because it is time consuming and costly. This study aimed to develop a binary logit model for the evaluation of highway riding quality, which could be used to monitor pavement conditions. The model was applied to investigate the influence of backscattering values of Phase Array type L-band Synthetic Aperture Radar (PALSAR. Training data obtained during 3–7 May 2007 was used in the development process, together with actual international roughness index (IRI values collected along a highway in Ayutthaya province, Thailand. The analysis showed that an increase in the backscattering value in the HH or the VV polarization indicated the poor condition of the pavement surface and, of the two, the HH polarization is more suitable for developing riding quality evaluation. The model developed was applied to analyze highway number 3467, to demonstrate its capability. It was found that the assessment accuracy of the prediction of the highway level of service was 97.00%. This is a preliminary study of the proposed technique and more intensive investigation must be carried out using ALOS/PALSAR images in various seasons.

  1. Acute toxicity of runoff from sealcoated pavement to Ceriodaphnia dubia and Pimephales promelas.

    Science.gov (United States)

    Mahler, Barbara J; Ingersoll, Christopher G; Van Metre, Peter C; Kunz, James L; Little, Edward E

    2015-04-21

    Runoff from coal-tar-based (CT) sealcoated pavement is a source of polycyclic aromatic hydrocarbons (PAHs) and N-heterocycles to surface waters. We investigated acute toxicity of simulated runoff collected from 5 h to 111 days after application of CT sealcoat and from 4 h to 36 days after application of asphalt-based sealcoat containing about 7% CT sealcoat (AS/CT-blend). Ceriodaphnia dubia (cladocerans) and Pimephales promelas (fathead minnows) were exposed in the laboratory to undiluted and 1:10 diluted runoff for 48 h, then transferred to control water and exposed to 4 h of ultraviolet radiation (UVR). Mortality following exposure to undiluted runoff from unsealed asphalt pavement and UVR was ?10% in all treatments. Test organisms exposed to undiluted CT runoff samples collected during the 3 days (C. dubia) or 36 days (P. promelas) following sealcoat application experienced 100% mortality prior to UVR exposure; with UVR exposure, mortality was 100% for runoff collected across the entire sampling period. Phototoxic-equivalent PAH concentrations and mortality demonstrated an exposure-response relation. The results indicate that runoff remains acutely toxic for weeks to months after CT sealcoat application. PMID:25860716

  2. ROP GTPase-mediated auxin signaling regulates pavement cell interdigitation in Arabidopsis thaliana.

    Science.gov (United States)

    Lin, Deshu; Ren, Huibo; Fu, Ying

    2015-01-01

    In multicellular plant organs, cell shape formation depends on molecular switches to transduce developmental or environmental signals and to coordinate cell-to-cell communication. Plants have a specific subfamily of the Rho GTPase family, usually called Rho of Plants (ROP), which serve as a critical signal transducer involved in many cellular processes. In the last decade, important advances in the ROP-mediated regulation of plant cell morphogenesis have been made by using Arabidopsis thaliana leaf and cotyledon pavement cells. Especially, the auxin-ROP signaling networks have been demonstrated to control interdigitated growth of pavement cells to form jigsaw-puzzle shapes. Here, we review findings related to the discovery of this novel auxin-signaling mechanism at the cell surface. This signaling pathway is to a large extent independent of the well-known Transport Inhibitor Response (TIR)-Auxin Signaling F-Box (AFB) pathway, and instead requires Auxin Binding Protein 1 (ABP1) interaction with the plasma membrane-localized, transmembrane kinase (TMK) receptor-like kinase to regulate ROP proteins. Once activated, ROP influences cytoskeletal organization and inhibits endocytosis of the auxin transporter PIN1. The present review focuses on ROP signaling and its self-organizing feature allowing ROP proteins to serve as a bustling signal decoder and integrator for plant cell morphogenesis. PMID:25168157

  3. Stress and distress.

    Science.gov (United States)

    Selye, H

    1975-12-01

    I must ask the reader's indulgence for this article's concern with applications of the stress concept, which are distinct from, although related to clinical medicine. It has not been my object to deal with the way physicians have been aided by stress research in the practice of medicine--that information is already widely available. Rather, I have attempted to sketch briefly the history of the stress theory and to demonstrate how this information can help anyone, physician or layman, lead a more complete and satisfying life. The applications of the stress theory have been dealt with at length elsewhere. I believe that we can find within scientifically verified observations the basis of a code of behavior suited to our century. The great laws of nature that regulate the defenses of living beings against stress of any kind are essentially the same at all levels of life, from individual cells to entire complex human organisms and societies. It helps a great deal to understand the fundamental advantages and disadvantages of catatoxic and syntoxic attitudes by studying the biologic basis of self-preservation as reflected in syntoxic and catatoxic chemical mechanisms. When applied to everyday problems, this understanding should lead to choices most likely to provide us the pleasant eustress (from the Greek eu meaning good, as in euphoria) involved in achieving fulfillment and victory, thereby avoiding the self-destructive distress of frustration and failure. So the translation of the laws governing resistance of cells and organs to a code of behavior comes down to three basic precepts: 1. Find your own natural stress level. People differ with regard to the amount and kind of work they consider worth doing to meet the exigencies of daily life and to assure their future security and happiness. In this respect, all of us are influenced by hereditary predispositions and the expectations of our society. Only through planned self-analysis can we establish what we really want; too many people suffer all their lives because they are too conservative to risk a radical change by breaking with hiabits or traditions. 2. Altruistic egoism. The selfish (i.e., self-interested) hoarding of the goodwill, respect, esteem, support, and love of our neighbors is the most efficient way to give vent to our pent-up energy and to create a more enjoyable, beautiful, or useful environment.3. Earn thy neighbor's love. This motto--which is merely a rewording of the command to "love thy neighbor as thyself"--is compatible with man's natural structure, and although it is based on altruistic egoism, it could hardly be attacked as unethical. Who would blame the man who wants to assure his own homeostasis and happiness only by accumulating the treasure of other poeple's benevolence and love? Yet this makes him virtually unassailable, for nobody wants to attack and destroy those upon whom he depends. PMID:1222562

  4. Evaluación de pavimentos y decisiones de conservación con base en sistemas de inferencia difusos / Pavement Evaluation and Maintenance Decisions Based on Fuzzy Inference Systems

    Scientific Electronic Library Online (English)

    Gloria Inés, Beltrán-Calvo; Miguel Pedro, Romo-Organista.

    2014-09-01

    Full Text Available Las decisiones de conservación y la vida remanente de pavimentos en servicio, dependen en buena parte de la condición estructural que exhiben durante su operación. Con el ánimo de proveer una metodología que permita caracterizar el pavimento de manera rápida, con los niveles de detalle que se deseen [...] , en este trabajo se plantean tres sistemas basados en la lógica difusa, para inferir la condición de rigidez y deterioro, así como las decisiones de conservación. Para esos fines, se utilizaron datos de auscultación no destructiva registrados en sistemas de pavimento de tres y cuatro capas, incluyendo estructuras tradicionales y estructuras invertidas (con capa de sub-base rigidizada). Las bases de datos incluyen información sobre magnitud y severidad de daños estructurales y parámetros e indicadores de rigidez, derivados de pruebas de deflexión por impacto. Los sistemas desarrollados, permitieron integrar directamente en la caracterización estructural de los pavimentos, tanto el conocimiento y criterios de expertos, como las variables de carácter subjetivo y cualitativo, que se utilizan comúnmente para describir los niveles de severidad del deterioro. Asimismo, permitieron expresar los resultados mediante palabras o adjetivos cuantificadores del lenguaje, facilitando su interpretación y comprensión. En virtud de los resultados alcanzados, resulta razonable concluir que los sistemas propuestos pueden utilizarse con confianza para evaluaciones rápidas y toma de decisiones a nivel global o detallado en corredores viales. Abstract in english The remaining service life and maintenance decisions of existing pavements are highly dependent on stiffness and deterioration conditions throughout their operation. A non-conventional fuzzy logic based methodology is proposed in this work to address the stiffness-deterioration condition and conserv [...] ation decisions, by means of three Fuzzy Inference Systems. Analysis were conducted using a database gathered from field tests performed on three and four layer pavement systems, that included traditional layer structuring and pavements having a subbase stiffer than their granular base. Information about layer thicknesses, magnitude and severity of structural distresses, and parameters and indicators derived from deflection testing by impulse load devices were used. The developed systems, allowed representing expert knowledge and linguistic variables of subjective and qualitative nature, commonly used to describe the severity levels of deterioration; thus they can be involved into structural characterization of pavements. Results were also expressed linguistically, to facilitate their interpretation and understanding. Based on the high quality of results obtained, it seems reasonable to conclude that the proposed systems could be used confidently for assessing and making decisions about pavement conservation, with low computational cost.

  5. Research on the characteristics of temperature field of asphalt pavement in seasonal frozen region

    Science.gov (United States)

    Qiao, Jiangang; Liu, Weizheng

    2014-08-01

    The characteristics of climate in seasonal frozen area are low temperature and a large range of temperature variation between day and night in winter. These characteristics often lead to problems of asphalt pavement, especially transverse cracks. To reduce the problems of asphalt pavement, it is necessary to examine the distribution of the temperature range of asphalt pavement. A three-dimensional finite element model was used, taking the SMA asphalt pavement as an example with solid70 and plane55 unit features of ANSYS software. It can obtain the relationship between temperature gradient and time and the relationship between temperature gradient and depth. In addition, a function relation model of stress and time was also established. It can provide a theoretical basis for the prevention and treatment of problems of asphalt pavement in seasonal frozen area. Moreover, it has an important significance for improving asphalt pavement design.

  6. Design Methodologies of Asphalt Pavement Used in China and Mozambique

    Directory of Open Access Journals (Sweden)

    Jose Francisco Rufino Diogo

    2007-01-01

    Full Text Available This study discusses and compares Asphalt Concrete (AC pavement design methodologies used in China and Mozambique (based on South African Transportation and Communication Commission (SATCC methodologies. The SATCC design methodologies use California Bearing Ratio (CBR and catalogues methods. The South African catalogues are basically used for roads with traffic less than 30 million ESAs. The design catalogues method give small thickness than CBR and Chinese methods. The Chinese and the South African design methods give nearly the same thickness; this study concludes that these methods can be used in both countries; China and Mozambique. The results also show that the strong point of Chinese method is verifying the tensile stress and allowable displacement on the pavement calculated from computer program APDS.

  7. AN OPTIMAL MAINTENANCE MANAGEMENT MODEL FOR AIRPORT CONCRETE PAVEMENT

    Science.gov (United States)

    Shimomura, Taizo; Fujimori, Yuji; Kaito, Kiyoyuki; Obama, Kengo; Kobayashi, Kiyoshi

    In this paper, an optimal management model is formulated for the performance-based rehabilitation/maintenance contract for airport concrete pavement, whereby two types of life cycle cost risks, i.e., ground consolidation risk and concrete depreciation risk, are explicitly considered. The non-homogenous Markov chain model is formulated to represent the deterioration processes of concrete pavement which are conditional upon the ground consolidation processes. The optimal non-homogenous Markov decision model with multiple types of risk is presented to design the optimal rehabilitation/maintenance plans. And the methodology to revise the optimal rehabilitation/maintenance plans based upon the monitoring data by the Bayesian up-to-dating rules. The validity of the methodology presented in this paper is examined based upon the case studies carried out for the H airport.

  8. A methodological framework for pavement damage estimation considering simulated axle load spectra

    OpenAIRE

    Almeida, Arminda Maria Marques

    2014-01-01

    Despite being crucial to the economic and social development of any country or region, road freight transport is one of the players responsible for environmental impact of transport increasing in the last decades. In order to minimise these impacts, heavy vehicles have been evolving. Consequently, road pavement design must keep up with it since a road pavement is designed for a foreseeable heavy traffic flow that will pass on the pavement during its considered life time. The current pavem...

  9. Asphalt Materials Characterization in Support of Implementation of the Proposed Mechanistic-Empirical Pavement Design Guide

    OpenAIRE

    Flintsch, Gerardo W.; Loulizi, Amara; Diefenderfer, Stacey D.; Galal, Khaled A.; Diefenderfer, Brian K.

    2007-01-01

    The proposed Mechanistic-Empirical Pavement Design Guide (MEPDG) procedure is an improved methodology for pavement design and evaluation of paving materials. Since this new procedure depends heavily on the characterization of the fundamental engineering properties of paving materials, a thorough material characterization of mixes used in Virginia is needed to use the MEPDG to design new and rehabilitated flexible pavements. The primary objective of this project was to perform a full hot-mix a...

  10. Socio-economic aspects of the Byzantine mosaic pavements of Phoenicia and northern Palestine

    OpenAIRE

    Merrony, Mark W.; Dr Claudine Dauphin, Dr Julian Raby

    2002-01-01

    ?The present thesis analyzes the Byzantine mosaic pavements of Phoenicia and Northern Palcatine from a socio-economic perspective, primarily by examining the laying of pavements including technical aspects and bedding, the quality of decoration, the distribution of pavements in time and space, as well as inscriptions which provide names of donors and artists as well as dates. The approach adopted represents a novel alternative and complement to typical interpretations of mosaic floor decorati...

  11. Characterising the Deformation Behaviour of Unbound Granular Materials in Pavement Structures

    OpenAIRE

    Rahman, Mohammad Shafiqur

    2015-01-01

    Unbound granular materials (UGMs) used in the base and sub-base layers of flexible pavements play a significant role in the overall performance of the structure. Proper understanding and characterization of the deformation behaviour of UGMs in pavement structures are, therefore, vital for the design and maintenance of flexible pavements. In this study, the resilient deformation (RD) and the permanent deformation (PD) behaviour of UGMs were investigated for the better understanding and improve...

  12. Effect of Bituminous Pavement Structures on the Rolling Resistance

    OpenAIRE

    CHUPIN, Olivier; Piau, Jean Michel; CHABOT, Armelle

    2010-01-01

    For environmental reasons, the energy consumption of road traffic is an overwhelming question and so is the subsequent quantification of the power dissipation of a vehicle-road system. Among several sources of dissipation occurring at different levels of this system (aerodynamic forces, internal friction in the engine, etc), the present paper focuses on the power dissipation induced by the pavement itself, and more specifically by its constitutive behavior. As a matter of fact, the type of...

  13. Performance of waste tyre rubber on model flexible pavement

    OpenAIRE

    D. S. V. Prasad; G.V.R. Prasada Raju

    2009-01-01

    This paper investigates the performance of flexible pavement on expansive soil subgrade using gravel/flyash as subbase course with waste tyre rubber as a reinforcing material. It was observed that from the laboratory test results of direct shear and CBR, the gravel subbase shows better performance as compared to flyash subbase with different percentages of waste tyre rubber as reinforcing material. Cyclic load tests are also carried out in the laboratory by placing a circular metal plate on t...

  14. DYNAMIC JOINT LOAD TRANSFER EFFICIENCY OF RIGID PAVEMENT

    Directory of Open Access Journals (Sweden)

    YU Xinhua

    2011-02-01

    Full Text Available the mechanistic analysis presented in this paper is only the beginning of new approach for understanding the real joint load transfer capability on airport and highway concrete pavements. It gives up the two major assumptions those have been popularly adopted by hundreds of published papers: the load is transferred under a wheel with zero speed and with fixed position. The real load transfer in field is always under wheels with non-zero speed and with varied position at any moment. The objective of this study focuses on quantifying the dynamic effects of a moving wheel while it is crossing a joint on a pavement. The analysis is conducted using a model of two-slab system on Kelvin foundation under a moving wheel with variable speed v, different pavement damping Cs, foundation reaction modulus k and foundation damping Ck. The dynamic joint load transfer efficiency is temporarily and empirically defined by the peak strain ratio LTE(S on the two sides of a joint. The primary findings include: (1 The higher speed of a moving wheel leads to the higher LTE(S;(2 The larger the pavement damping Cs leads to the higher LTE(S;(3 The numerical ratio c(=LTE(Sdynamic/ LTE(Sstatic varies in the range 1 to 2 mainly depending on speed v and damping Cs;(4 The LTE(Sdynamic is not sensitive to foundation reaction modulus k and foundation damping Ck. Further researches are needed for appropriate applications of the new model in practice.

  15. Cytokinin signaling regulates pavement cell morphogenesis in Arabidopsis

    OpenAIRE

    Li H.; Xu T.; Lin D.; Wen M; Xie M; Duclercq J; Bielach A.; Kim J; Reddy GV; Zuo J.; Benkov\\xe1 E.; Friml J.; Guo H; Yang Z.

    2012-01-01

    The puzzle piece-shaped Arabidopsis leaf pavement cells (PCs) with interdigitated lobes and indents is a good model system to investigate the mechanisms that coordinate cell polarity and shape formation within a tissue. Auxin has been shown to coordinate the interdigitation by activating ROP GTPase-dependent signaling pathways. To identify additional components or mechanisms, we screened for mutants with abnormal PC morphogenesis and found that cytokinin signaling regulates the PC interdigita...

  16. Use of Recycled Aggregate and Fly Ash in Concrete Pavement

    OpenAIRE

    Myle N. James; Wonchang Choi; Taher Abu-Lebdeh

    2011-01-01

    Problem statement: Recycled materials aggregate from the demolished concrete structures and fly ash from burning coal shows the possible application as structural and non structural components in concrete structures. This research aims to evaluate the feasibility of using concrete containing recycled concrete aggregate and fly ash in concrete pavement. Approach: Two water cement ratio (0.45 and 0.55) the compressive strength, modulus of electricity and flexural streng...

  17. Identification and conversion of foundation parameters for airport pavement

    Science.gov (United States)

    Shang, Shiying; Wang, Shangwen

    1993-01-01

    The least squares method has been employed to fit measured and theoretical curves for the deflection of airport pavements, with the aim of identifying modulus of resilience E0 and of reaction K. Using these moduli results in errors generally no larger than 10 percent. A more accurate method of converting E0 into K and vice versa is proposed. The error is generally about 1 percent with maximum error not exceeding 2.7 percent.

  18. Road Performance of Fiber Reinforced Asphalt Concrete Bridge Deck Pavement

    OpenAIRE

    Xiu Liu; Zhaojie Sun; Decheng Feng; Yixiang Cao

    2013-01-01

    As the problem of asphalt concrete bridge deck pavement is becoming more and more serious, how to improve its road performance has become the focus of the study. Considering fiber is widely used in road engineering, wheel tracking test, flexural test, immersion marshall test and freeze-thaw splitting test were carried out to study road performance of asphalt mixture with different fiber contents, analyzing the function mechanism of fiber reinforced asphalt ...

  19. Accounting for distress in bank mergers

    OpenAIRE

    Koetter, Michael; Bos, Jaap W.B.; Heid, Frank; Kool, Clemens J.M.; Kolari, James W.; Porath, Daniel

    2005-01-01

    The inability of most bank merger studies to control for hidden bailouts may lead to biased results. In this study, we employ a unique data set of approximately 1,000 mergers to analyze the determinants of bank mergers. We use data on the regulatory intervention history to distinguish between distressed and non-distressed mergers. We find that, among merging banks, distressed banks had the worst profiles and acquirers perform somewhat better than targets. However, both distressed and non-dist...

  20. Perfectionism, Procrastination, and Psychological Distress

    Science.gov (United States)

    Rice, Kenneth G.; Richardson, Clarissa M. E.; Clark, Dustin

    2012-01-01

    Using a cross-panel design and data from 2 successive cohorts of college students ( N = 357), we examined the stability of maladaptive perfectionism, procrastination, and psychological distress across 3 time points within a college semester. Each construct was substantially stable over time, with procrastination being especially stable. We also…

  1. Breast Cancer Distress in Childhood

    Medline Plus

    Full Text Available ... researchers rated their levels of anxiety, depression, hyperactivity, aggression and social stress. Breast cancer-specific distress was ... Health Topics Breast Cancer Cancer--Living with Cancer Child Mental Health About MedlinePlus Site Map FAQs Contact ...

  2. Breast Cancer Distress in Childhood

    Medline Plus

    Full Text Available ... About MedlinePlus Site Map FAQs Contact Us Health Topics Drugs & Supplements Videos & Tools You Are Here: Home ? Latest Health News ? Breast Cancer Distress in Childhood URL of this page: https://www.nlm.nih.gov/medlineplus/videos/news/ ...

  3. Breast Cancer Distress in Childhood

    Medline Plus

    Full Text Available ... levels of anxiety, depression, hyperactivity, aggression and social stress. Breast cancer-specific distress was also evaluated. Growing ... Health Topics Breast Cancer Cancer--Living with Cancer Child Mental Health About MedlinePlus Site Map FAQs Contact ...

  4. Breast Cancer Distress in Childhood

    Medline Plus

    Full Text Available ... might help reduce distress and promote healthy psychosocial development. I’m Dr. Cindy Haines of HealthDay TV with the health news for you and your family. Related MedlinePlus Health Topics Breast Cancer Cancer--Living with Cancer Child Mental Health About MedlinePlus Site Map FAQs Contact ...

  5. Numerical Simulation of Moving Load on Concrete Pavements

    Directory of Open Access Journals (Sweden)

    Laj?áková Gabriela

    2015-06-01

    Full Text Available The knowledge of the development with time of the strain and stress states in pavement structures is needed in the solution of various engineering tasks as the design fatigue lifetime reliability maintenance and structure development. The space computing model of the truck TATRA 815 is introduced. The pavement computing model is created in the sense of Kirchhof theory of the thin slab on elastic foundation. The goal of the calculation is to obtain the vertical deflection in the middle of the slab and the time courses of vertical tire forces. The equations of motion are derived in the form of differential equations. The assumption about the shape of the slab deflection area is adopted. The equations of the motion are solved numerically in the environment of program system MATLAB. The dependences following the influence of various parameters (speed of vehicle motion, stiffness of subgrade, slab thickness, road profile on the pavement vertical deflections and the vertical tire forces are introduced. The results obtained from the plate computing model are compared with the results obtained by the FEM analysis. The outputs of the numerical solution in the time domain can be transformed into a frequency domain and subsequently used to solve various engineering tasks.

  6. EVALUATION OF TIRE RUBBER DISPOSAL IN CONCRETE FOR PAVEMENTS

    Directory of Open Access Journals (Sweden)

    Rosa Cristina Cecche Lintz

    2009-12-01

    Full Text Available The production of waste by the tire industry has been a growing problem, indicating the need for its reuse. More than thirty million tires are discharged per year in Brazil, where regulation for the environment states that for each four new tires, five unusable ones must be adequately disposed by manufacturers and importers. Paving consumes an extremely large quantity of materials, which can be the source of rational application of waste and rejected materials. Research shows that tire rubber can be added to asphalt, which increases its durability and improves pavement quality and safety conditions by absorbing the rubber elastic properties, and also be used for architectural applications, among others. This study deals with the addition of rubber fibers from tire crushing in concrete for roadway pavements in order to provide proper indication about the alternative material disposal through an evaluation of the mechanical behavior of the modified concrete. Different concrete mixes were produced, within which, part of fine aggregates were substituted by tire rubber and mechanical experiment tests were performed, which show that, due to great resistance losses, the disposal of this alternative material in concrete should be considered for light traffic pavements, with the addition of rubber ranging up to 10% in mass.

  7. Stratified soils under stone pavements as tools for palaeoenvironment reconstruction

    Science.gov (United States)

    Dietze, M.; Kleber, A.

    2009-04-01

    Stone pavements in climate-sensitive arid environments are often genetically associated with their underlying soil. Such soils are in general accretionary but also show features of stratification, resulting from changing environmental conditions, as well as alteration by pedogenesis. We thus regard soil-sediment profiles under stone pavements as distinctive archives of past geomorphic and pedologic processes. Deciphering the evolution allows reconstruction of landscape dynamics. Cima Volcanic Field, eastern Mojave Desert, California, has been in the focus of several studies. However, a detailed stratigraphic investigation of soils developed on basaltic lava flows of known age has not been conducted. We present descriptions of pedologic, stratigraphic and mineralogic properties of a sequence of soil profiles situated on a basaltic lava flow of middle Pleistocene age. We infer several phases of aeolian, fluvial, mass movement and pedologic activity of different nature. The archive reveals a complex evolution that can be attributed to specific environmental conditions in this climate-sensitive region, though numerical dating is preliminary. However, stratified, cumulic soils associated with desert pavements can be regarded as a unique type of archive, recording processes not traced in any other proxy record.

  8. Reliability-based performance simulation for optimized pavement maintenance

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Jui-Sheng, E-mail: jschou@mail.ntust.edu.tw [Department of Construction Engineering, National Taiwan University of Science and Technology (Taiwan Tech), 43 Sec. 4, Keelung Rd., Taipei 106, Taiwan (China); Le, Thanh-Son [Department of Construction Engineering, National Taiwan University of Science and Technology (Taiwan Tech), 43 Sec. 4, Keelung Rd., Taipei 106, Taiwan (China)

    2011-10-15

    Roadway pavement maintenance is essential for driver safety and highway infrastructure efficiency. However, regular preventive maintenance and rehabilitation (M and R) activities are extremely costly. Unfortunately, the funds available for the M and R of highway pavement are often given lower priority compared to other national development policies, therefore, available funds must be allocated wisely. Maintenance strategies are typically implemented by optimizing only the cost whilst the reliability of facility performance is neglected. This study proposes a novel algorithm using multi-objective particle swarm optimization (MOPSO) technique to evaluate the cost-reliability tradeoff in a flexible maintenance strategy based on non-dominant solutions. Moreover, a probabilistic model for regression parameters is employed to assess reliability-based performance. A numerical example of a highway pavement project is illustrated to demonstrate the efficacy of the proposed MOPSO algorithms. The analytical results show that the proposed approach can help decision makers to optimize roadway maintenance plans. - Highlights: > A novel algorithm using multi-objective particle swarm optimization technique. > Evaluation of the cost-reliability tradeoff in a flexible maintenance strategy. > A probabilistic model for regression parameters is employed to assess reliability-based performance. > The proposed approach can help decision makers to optimize roadway maintenance plans.

  9. Reliability-based performance simulation for optimized pavement maintenance

    International Nuclear Information System (INIS)

    Roadway pavement maintenance is essential for driver safety and highway infrastructure efficiency. However, regular preventive maintenance and rehabilitation (M and R) activities are extremely costly. Unfortunately, the funds available for the M and R of highway pavement are often given lower priority compared to other national development policies, therefore, available funds must be allocated wisely. Maintenance strategies are typically implemented by optimizing only the cost whilst the reliability of facility performance is neglected. This study proposes a novel algorithm using multi-objective particle swarm optimization (MOPSO) technique to evaluate the cost-reliability tradeoff in a flexible maintenance strategy based on non-dominant solutions. Moreover, a probabilistic model for regression parameters is employed to assess reliability-based performance. A numerical example of a highway pavement project is illustrated to demonstrate the efficacy of the proposed MOPSO algorithms. The analytical results show that the proposed approach can help decision makers to optimize roadway maintenance plans. - Highlights: ?A novel algorithm using multi-objective particle swarm optimization technique. ? Evaluation of the cost-reliability tradeoff in a flexible maintenance strategy. ? A probabilistic model for regression parameters is employed to assess reliability-based performance. ? The proposed approach can help decision makers to optimize roadway maintenance plans.

  10. An analysis of pavement heat flux to optimize the water efficiency of a pavement-watering method

    OpenAIRE

    Hendel, Martin; Colombert, Morgane; Diab, Youssef; Royon, Laurent

    2014-01-01

    Pavement-watering as a technique of cooling dense urban areas and reducing the urban heat island effect has been studied since the 1990's. The method is currently considered as a potential tool for and climate change adaptation against increasing heat wave intensity and frequency. However, although water consumption necessary to implement this technique is an important aspect for decision makers, optimization of possible watering methods has only rarely been conducted. We propose an analysis ...

  11. GPR used in combination with other NDT methods for assessing pavements in PPP projects

    Science.gov (United States)

    Loizos, Andreas; Plati, Christina

    2014-05-01

    In the recent decades, Public-Private Partnerships (PPP) has been adopted for highway infrastructure procurement in many countries. PPP projects typically take the form of a section of highway and connecting roadways which are to be construction and managed for a given concession period. Over the course of the highway concession period, the private agency takes over the pavement maintenance and rehabilitation duties. On this purpose, it is critical to find the most cost effective way to maintain the infrastructure in compliance with the agreed upon performance measures and a Pavement Management Systems (PMS) is critical to the success of this process. For the prosperous operation of a PMS it is necessary to have appropriate procedures for pavement monitoring and evaluation, which is important in many areas of pavement engineering. Non Destructive Testing (NDT) has played a major role in pavement condition monitoring, assessments and evaluation accomplishing continuous and quick collection of pavement data. The analysis of this data can lead to indicators related to trigger values (criteria) that define the pavement condition based on which the pavement "health" is perceived helping decide whether there is the need or not to intervene in the pavement. The accomplished perception appoints required management activities for preserving pavements in favor not only of the involved highway/road agencies but also of users' service. Amongst NDT methods Ground Penetrating Radar (GPR) seems to be a very powerful toll, as it provides a range of condition and construction pavement information. It can support effectively the implementation of PMS activities in the framework of pavement monitoring and evaluation. Given that, the present work aims to the development and adaptation of a protocol for the use of GPR in combination with other NDT methods, such as Falling Weight Deflectometer (FWD), for assessing pavements in PPP projects. It is based on the experience of Laboratory of Pavement Engineering of National Technical University of Athens (NTUA) gained through its research activities in various Greek PPP projects as well its involvement in several related European and International scientific actions. It is suggested that the implementation of such protocol could support the pavement management activities with respect to the needs of a PPP project. This is accomplished through the resulted advantages that include simplicity in application, economic benefits and familiarity that are very important factors towards the optimization of the resources and the utilization of the available information; both of them are required for the orderly operation of a PPP project. Acknowledgments: This work benefited from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar."

  12. Desert pavement development on the lake shorelines of Lake Eyre (South), South Australia

    Science.gov (United States)

    Al-Farraj, Asma

    2008-08-01

    To the southwest of Lake Eyre (South), South Australia, silcrete boulders exposed by the erosion of the surrounding fine sediments undergo mechanical weathering to form desert pavement. Successive palaeoshorelines of Lake Eyre have exposed an age-related sequence of different stages in the weathering of the boulders. This study investigates desert pavement development in this saline environment. In addition, it attempts to develop a model for the development of desert pavement following exposure of the silcrete boulders, based on palaeo-lake shorelines dated from previous studies. Seven stages can be recognised corresponding to stages of soil and pavement development. Prior to stage one is the actual exposure of the boulder as the result of erosion by wave action at the lake shoreline or by erosion as the lake level falls during desiccation. At stage-1 the upper surface of the boulder breaks up through mechanical weathering (salt weathering), while the rest of the boulder is still buried. At stage-2 the surface fragments fall to the edge of the stone and expose more of the stone, which continues to break-up. There is no soil development in stages 1 and 2. By stage-3 most of the stone is exposed and broken up, making a mini-hill. At this stage soil development begins with the accumulation of sandy soil between the rock fragments. At stage-4 the stones form small cones and the soil is more developed. It is sandy with a typical of colour 10 YR 6/6. At stage-5 the stones forming the small cone are completely fragmented. Stone fragments at the centre are very angular but smoother at the edges of the mini-hill as the result of weathering (etching by chemical processes?). Soil texture is silty/sand and soil colour is 7.5 YR 6/6. At stage-6 the surface is nearly flat. The soil is sandy/silt and soil colour is between 7.5 YR 5/6 and 7.5 YR 5/8. Stage-7a is the gibber plain phase, composed of small well rounded stones, as a result of continued etching of the edges of the fragmented stones. The soil is silty, and the soil colour is between 5 YR 5/6 and 5 YR 5/8. Stage-7b is also gibber plain, with small well rounded stone fragments but where the soil has been replaced by crystalline gypsum. This sequence differs from sequences described in other areas, especially on alluvial fan or terrace surfaces. This may be partly due to the different origin of the clasts, as "pre-weathered" silcrete boulders, and partly due to the importance of chemical weathering by "etching" in this salt-rich environment.

  13. Application of CalME incremental-recursive method to the evaluation of the structural condition as asphalt pavements; Aplicacion del metodo recursivo-incremental CalME a la evaluacion del estado estructural de los pavimentos bituminosas

    Energy Technology Data Exchange (ETDEWEB)

    Mateos Moreno, A.; Perez Ayuso, J.; Cadavid Jauregui, B.; Marron Fernandez, J. O.

    2011-07-01

    CalME procedure represents one of the most advanced tools for the design, of flexible pavements world-wide. It is an incremental-recursive method, which means that pavements service life must be divided into many time intervals where both structural integrity and environmental conditions can be regarded as constants. It also means that the damage calculated at the end of each interval must be considered as initial condition for the next one. The goal of this type of models is the prediction of the evolution of the different distress mechanisms. The advantages of incremental-recursive procedures versus classical analytical design are shown in this paper. Advantages are shown not only in terms of design, but also as a tool in order to support structural evaluation. In particular, the potential of asphalt fatigue model incorporated in CalME is presented. this model is initially calibrated in the laboratory, and it is then re-calibrated based on the actual performance observed from field deflection testing. The model provides a reliable prediction of the future evolution of the damage of the asphalt mixture. Fatigue model validation has been conducted based on the performance from several flexible sections evaluated in CEDEX full-scale pavements test track. (Author) 14 refs.

  14. Surfactant alteration and replacement in acute respiratory distress syndrome

    OpenAIRE

    Walmrath Dieter; Grimminger Friedrich; Markart Philipp; Schmidt Reinhold; Ruppert Clemens; Günther Andreas; Seeger Werner

    2001-01-01

    Abstract The acute respiratory distress syndrome (ARDS) is a frequent, life-threatening disease in which a marked increase in alveolar surface tension has been repeatedly observed. It is caused by factors including a lack of surface-active compounds, changes in the phospholipid, fatty acid, neutral lipid, and surfactant apoprotein composition, imbalance of the extracellular surfactant subtype distribution, inhibition of surfactant function by plasma protein leakage, incorporation of surfactan...

  15. The acute respiratory distress syndrome

    OpenAIRE

    Matthay, Michael A.; Ware, Lorraine B.; Zimmerman, Guy A

    2012-01-01

    The acute respiratory distress syndrome (ARDS) is an important cause of acute respiratory failure that is often associated with multiple organ failure. Several clinical disorders can precipitate ARDS, including pneumonia, sepsis, aspiration of gastric contents, and major trauma. Physiologically, ARDS is characterized by increased permeability pulmonary edema, severe arterial hypoxemia, and impaired carbon dioxide excretion. Based on both experimental and clinical studies, progress has been ma...

  16. In search of distress risk

    OpenAIRE

    Szilagyi, Jan; Hilscher, Jens; Campbell, John

    2005-01-01

    This paper explores the determinants of corporate failure and the pricing of financially distressed stocks using US data over the period 1963 to 2003. Firms with higher leverage, lower profitability, lower market capitalization, lower past stock returns, more volatile past stock returns, lower cash holdings, higher market-book ratios, and lower prices per share are more likely to file for bankruptcy, be delisted, or receive a D rating. When predicting failure at longer horizons, the most pers...

  17. The adult respiratory distress syndrome.

    OpenAIRE

    Biondi, J. W.; Hines, R. L.; Barash, P. G.; Baker, C. C.; Matthay, M A; Matthay, R A

    1986-01-01

    The adult respiratory distress syndrome (ARDS) represents a common denominator of acute lung injury leading to alveolar flooding, decreased lung compliance, and altered gas transport. In the absence of specific etiology and therapy, the management of ARDS remains largely supportive. Ubiquitous use of intermittent positive-pressure ventilation with positive end-expiratory pressure (PEEP) improves arterial oxygenation but with some risk of pulmonary barotrauma and decreased cardiac output. The ...

  18. Assessment of an Impulse GPR Antenna Abilities in Investigation of Transversal Cracks of the Bituminous Pavement

    Science.gov (United States)

    Krysi?ski, L.; Sudyka, J.

    2012-04-01

    Ground Penetrating Radar (GPR) technique is commonly used for detection of internal singularities of construction structure. The method is particularly efficient in the case of linear horizontal objects when profile scanning is being performed in the direction perpendicular to object elongation and polarization of the electric field is parallel to the elongation. Then the singular object manifests itself in the echogram as a scattering hyperbola. Similar response is generated by an object having shape close to a vertical half plane with horizontal edge, when the edge acts like the scattering linear object. The use of GPR technique for investigation of transversal cracks in the bituminous pavement would seem to be promising, but numerous paradoxes occur just at the beginning tests. Even well visible cracks of more than ten millimeters thickness doesn't generate noticeable GPR response, while thinner ones sometimes can produce strong response but in the deeper interior of the pavement. Thus arise a more general question: what the GPR technique can tell us about the cracks? Trying to study this problem some laboratory tests were performed to estimate efficiency of signal generation by structures simulating idealized cracks' shapes. Next long-term (several years) visual observation and repeated GPR scanning was performed on the three road sections (each one of several hundred meters length) with heavy traffic, where ongoing cracking process occurs. The preliminary measurements were directed to obtain the proper way of scanning. The main aim of the analysis was to find GPR characteristics of cracks that can be noticed on echograms. It was performed by detailed correlation of the visually observed cracks position with echograms using decimeter precision. These efforts provided a list of diagnostic GPR characteristics of cracks and some provisional scale of their intensity. In several cases the cracks were probed by drillings to recognize structures responsible for signal generation or to explain reasons of lacking signal. The three field cases represent different types of bituminous pavement and different degrees of cracking process progress, what showed first of all a large diversity GPR responses types and existence of specific masking effect related possibly to large-size granulation of the asphalt mixture. These examples show that the strong signals are frequently related to advanced deterioration in lower, older layers and confirm difficulty of cracks detection in a new cover. But on other hand long term observation showed that numerous new cracks appear on the surface in places, where some structural singularities were noticed earlier inside the new construction.

  19. Incidence of respiratory distress syndrome

    International Nuclear Information System (INIS)

    Objective: To determine the incidence of respiratory distress syndrome (RDS) in hospital born babies. Subjects and Methods: All live born infants delivered at the hospital and who fulfilled the diagnostic criteria of respiratory distress syndrome (RDS) were included in the study. Results: Ninety-four neonates developed RDS. Out of these, 88 (93.61%) were preterm and 06 (6.38%) were term infants. There was a male preponderance (65.95%). RDS was documented in 1.72% of total live births. 37.28% of preterm and 0.11% of term neonates born at the hospital. The incidence of RDS was 100% at 26 or less weeks of gestation, 57.14% at 32 weeks, and 3.70% at 36 weeks. The mortality with RDS was 41 (43.61%). Conclusion: RDS is the commonest cause of respiratory distress in the newborn, particularly, in preterm infants. It carries a high mortality rate and the incidence is more than that documented in the Western world. (author)

  20. Effects of reclaimed asphalt pavement on indirect tensile strength test of conditioned foamed asphalt mix

    International Nuclear Information System (INIS)

    This paper presents the results of Indirect Tensile Strength (ITS) Test for samples prepared with reclaimed asphalt pavement (RAP). Samples were conditioned in water at 25°C for 24 hours prior to testing. Results show that recycled aggregate from reclaimed asphalt pavement performs as well as virgin aggregate.

  1. Implementation of interactive Web-based training tools in pavement engineering

    OpenAIRE

    Steyn, Wynand J.vdM.

    2010-01-01

    Pavement Interactive, an online pavement community built on an open-source wiki platform, is a novel and possible approach to giving distance training to South African and southern African roads professionals in various aspects of road construction, maintenance and management.

  2. 23 CFR 970.208 - Federal lands pavement management system (PMS).

    Science.gov (United States)

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Federal lands pavement management system (PMS). 970.208... Federal lands pavement management system (PMS). In addition to the requirements provided in § 970.204, the PMS must meet the following requirements: (a) The NPS shall have PMS coverage of all paved park...

  3. 23 CFR 971.208 - Federal lands pavement management system (PMS).

    Science.gov (United States)

    2010-04-01

    ...,” AASHTO, 2001, is available for inspection as prescribed at 49 CFR part 7. It is also available from the... 23 Highways 1 2010-04-01 2010-04-01 false Federal lands pavement management system (PMS). 971.208... lands pavement management system (PMS). In addition to the requirements provided in § 971.204, the...

  4. 23 CFR 973.208 - Indian lands pavement management system (PMS).

    Science.gov (United States)

    2010-04-01

    ..., 2001, is available for inspection as prescribed at 49 CFR part 7. It is also available from the... 23 Highways 1 2010-04-01 2010-04-01 false Indian lands pavement management system (PMS). 973.208... PROGRAM Bureau of Indian Affairs Management Systems § 973.208 Indian lands pavement management system...

  5. High-speed texture measurement of pavements

    OpenAIRE

    McGhee, Kevin K.; Flintsch, Gerardo W.

    2003-01-01

    This study was conducted to validate high-speed texture measuring equipment for use in highway applications. The evaluation included two high-speed systems and a new static referencing device. Tests were conducted on 22 runway and taxiway test sections from the National Aeronautics and Space Administration's Wallops Flight Facility and 7 surfaces from Virginia's Smart Road. Texture estimates recorded with the high-speed (dynamic) equipment correlated extremely well with estimates made with st...

  6. Road Edge of Pavement, RoadPavement; polygon, Published in 2010, 1:1200 (1in=100ft) scale, Athens-Clarke County Planning Department.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Road Edge of Pavement dataset, published at 1:1200 (1in=100ft) scale, was produced all or in part from Orthoimagery information as of 2010. It is described as...

  7. Impact of the variation in dynamic vehicle load on flexible pavement responses

    Science.gov (United States)

    Ahsanuzzaman, Md

    The purpose of this research was to evaluate the dynamic variation in asphalt pavement critical responses due to dynamic tire load variations. An attempt was also made to develop generalized regression equations to predict the dynamic response variation in flexible pavement under various dynamic load conditions. The study used an extensive database of computed pavement response histories for five different types of sites (smooth, rough, medium rough, very rough and severely rough), two different asphalt pavement structures (thin and thick) at two temperatures (70 °F and 104 °F), subjected to a tandem axle dual tire at three speeds 25, 37 and 50 mph (40, 60 and 80 km/h). All pavement responses were determined using the 3D-Move Analysis program (Version 1.2) developed by University of Nevada, Reno. A new term called Dynamic Response Coefficient (DRC) was introduced in this study to address the variation in critical pavement responses due to dynamic loads as traditionally measured by the Dynamic Load Coefficient (DLC). While DLC represents the additional varying component of the tire load, DRC represents the additional varying component of the response value (standard deviation divided by mean response). In this study, DRC was compared with DLC for five different sites based on the roughness condition of the sites. Previous studies showed that DLC varies with vehicle speed and suspension types, and assumes a constant value for the whole pavement structure (lateral and vertical directions). On the other hand, in this study, DRC was found to be significantly varied with the asphalt pavement and function of pavement structure, road roughness conditions, temperatures, vehicle speeds, suspension types, and locations of the point of interest in the pavement. A major contribution of the study is that the variation of pavement responses due to dynamic load in a flexible pavement system can be predicted with generalized regression equations. Fitting parameters (R2) in the rage of 0.60 to 0.87 were observed the DRC predictive equations. In addition, verification of those generalized equations was evaluated using different sets of asphalt pavement structures and pavement materials. The differences between calculated and predicted values were found to be within +/-20% for the maximum tensile strain and +/-30% for the maximum compressive strain in the asphalt layer.

  8. PECULIAR FEATURES OF HEAT-HUMIDITY MODE PERTAINING TO POROUS LAYERS OF ASPHALT CONCRETE PAVEMENTS

    Directory of Open Access Journals (Sweden)

    V. Verenko

    2014-10-01

    Full Text Available The paper presents results of experimental investigations and points out the fact that conventional approaches to design and calculations of road pavements that presuppose application of porous asphalt concrete on compact bedding can cause some deformations and destructions initiated due to humidity migration in large internal material pores and lead to material destruction during warm season of the year when water is characterized by high activity. Such processes result in bitumen washing-out, white spot occurrence on the pavement and quick destruction of the pavement.The paper proposes to reconsider existing approaches to design and calculation of road pavements, estimation of reliability and service-ability levels of the applied construction materials. In particular it is necessary to calculate a road pavement with respect to thermo-physical action while excluding condensate and humidity accumulation in porous materials. 

  9. Use of Ground Penetrating Radar at the FAA's National Airport Pavement Test Facility

    Science.gov (United States)

    Injun, Song

    2015-04-01

    The Federal Aviation Administration (FAA) in the United States has used a ground-coupled Ground Penetrating Radar (GPR) at the National Airport Pavement Test Facility (NAPTF) since 2005. One of the primary objectives of the testing at the facility is to provide full-scale pavement response and failure information for use in airplane landing gear design and configuration studies. During the traffic testing at the facility, a GSSI GPR system was used to develop new procedures for monitoring Hot Mix Asphalt (HMA) pavement density changes that is directly related to pavement failure. After reviewing current setups for data acquisition software and procedures for identifying different pavement layers, dielectric constant and pavement thickness were selected as dominant parameters controlling HMA properties provided by GPR. A new methodology showing HMA density changes in terms of dielectric constant variations, called dielectric sweep test, was developed and applied in full-scale pavement test. The dielectric constant changes were successfully monitored with increasing airplane traffic numbers. The changes were compared to pavement performance data (permanent deformation). The measured dielectric constants based on the known HMA thicknesses were also compared with computed dielectric constants using an equation from ASTM D4748-98 Standard Test Method for Determining the Thickness of Bound Pavement Layers Using Short-Pulse Radar. Six inches diameter cylindrical cores were taken after construction and traffic testing for the HMA layer bulk specific gravity. The measured bulk specific gravity was also compared to monitor HMA density changes caused by aircraft traffic conditions. Additionally this presentation will review the applications of the FAA's ground-coupled GPR on embedded rebar identification in concrete pavement, sewer pipes in soil, and gage identifications in 3D plots.

  10. Reducing psychological distress in patients undergoing chemotherapy.

    Science.gov (United States)

    Milanti, Ariesta; Metsälä, Eija; Hannula, Leena

    2016-02-25

    Psychological distress is a common problem among patients with cancer, yet it mostly goes unreported and untreated. This study examined the association of a psycho-educational intervention with the psychological distress levels of breast cancer and cervical cancer patients undergoing chemotherapy. The design of the study was quasi-experimental, pretest-posttest design with a comparison group. One hundred patients at a cancer hospital in Jakarta, Indonesia, completed Distress Thermometer screening before and after chemotherapy. Fifty patients in the intervention group were given a psycho-educational video with positive reappraisal, education and relaxation contents, while receiving chemotherapy. Patients who received the psycho-educational intervention had significantly lower distress levels compared with those in the control group. Routine distress screening, followed by distress management and outcome assessment, is needed to improve the wellbeing of cancer patients. PMID:26911178

  11. Factors relating to emotional distress after stroke

    OpenAIRE

    Thomas, Shirley Ann

    2006-01-01

    Emotional distress is common after stroke and has a negative impact on rehabilitation outcome. The aim of this thesis was to identify factors relating to emotional distress after stroke to inform future interventions. This thesis developed a theoretical framework to guide the study of emotional distress and included stroke and demographic characteristics, background information, disability (personal and extended activities of daily living and aphasia) and psychosocial factors (coping, locus o...

  12. A "wreckers theory" of financial distress

    OpenAIRE

    von Kalckreuth, Ulf

    2005-01-01

    In recent years, a number of papers have established a new empirical regularity. Stocks of distressed firms vastly underperform those of financially healthy firms. It is not necessary to attribute the negative excess returns of distressed firms to inefficient or irrational markets. We show that negative excess returns are the equilibrium outcome when a subset of participants is able to draw returns "in kind" from distressed companies. For firms close to bankruptcy, non-cash returns to ownersh...

  13. Moral Distress in Medical Education and Training

    OpenAIRE

    Berger, Jeffrey T

    2013-01-01

    Moral distress is the experience of cognitive-emotional dissonance that arises when one feels compelled to act contrary to one’s moral requirements. Moral distress is common, but under-recognized in medical education and training, and this relative inattention may undermine educators’ efforts to promote empathy, ethical practice, and professionalism. Moral distress should be recognized as a feature of the clinical landscape, and addressed in conjunction with the related concerns of negative r...

  14. DISTRESS AND JOB PERFORMANCE OF INDUSTRIAL WORKERS

    OpenAIRE

    Samanta, C.R.; Singh, Avneesh

    1993-01-01

    The present study aims at the investigation of the relationship between distress and job performance of industrial workers. The sample consisted of 500 workers of public and private sectors. CMI Health Questionnaire and Performance Appraisal Scale (PAS) were used to measure the level of distress and quality of performance at job, respectively. Results showed that physical, menial and overall distress correlated significantly and negatively with workers ?performance as appraised Furthermore, l...

  15. 47 CFR 80.324 - Transmission of distress message by station not itself in distress.

    Science.gov (United States)

    2010-10-01

    ... station not itself in distress. (a) A mobile station or a land station which learns that a mobile station... has not been acknowledged. When a mobile station transmits such a distress message, it must notify...

  16. NOTRA - noise trailer in pavement evolution measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sainio, P.

    2003-07-01

    Reduction of noise emission has become more important issue among automotive industry and road construction. There are lot of different means to affect traffic noise by automotive engineering, road construction and maintenance. Perhaps the most effective means can be found during land use planning but practically in most cases a road and the houses already does exists. Changes in the built environment are always compromises and there is demand to have reliable information about the effect of different noise prevention means and their effects. Reduction of noise means new challenges and at the same time gives new business opportunities. Today the major source of traffic noise is tyre-road interaction. Tyre is a trade off between very complex and also emotionally loaded values like safety features, recycling questions, style (fashion) and noise. This offers opportunities to co-operation in research between automotive and road engineers and national road administrations. The full name of the project is {sup E}volution of road surface and noise from tyre-road interaction{sup .} The HUT NOTRA stands for Helsinki University of Technology, Noise Trailer. The part of NOTRA became the name of the trailer itself and so turned to be also the name of the whole project. It is today a registered trade mark for this kind of trailer. This project was under the umbrella of VTT (Technical Research Centre of Finland) coordinated Mobile 2-project by the support of Finnish Road Administration and Nokian Tyres plc.

  17. Financial Distress Comparison Across Three Global Regions

    Directory of Open Access Journals (Sweden)

    Harlan D. Platt

    2008-12-01

    Full Text Available Globalization has precipitated movement of output and employment between regions. We examine factors related to corporate financial distress across three continents. Using a multidimensional definition of financial distress we test three hypotheses to explain financial distress using historical financial data. A null hypothesis of a single global model was rejected in favor of a fully relaxed model which created individual financial distress models for each region. This result suggests that despite other indications of worldwide convergence, international differences in accounting rules, lending practices, managements skill levels, and legal requirements among others has kept corporate decline from becoming commoditized.

  18. An Overview Of Pavement Management System For Industrial Areas

    Science.gov (United States)

    Hokam, Vivek S.

    2012-03-01

    ACT With the current surge in national economy the industrial traffic has increased many folds in terms of quantity of load and traffic volume. This results in early deterioration of the roads. Also the serviceability reduces hampering the industry's supply of raw material and transport of finished goods. An efficient road transportation system is of vitally important for smooth operations of industrial units. Construction of new roads needs an enormous investment. However, once constructed the road network system requires huge resources to maintain serviceability and to ensure safe passage at an appropriate speed and with low VOC (Vehicle Operating Cost). Road maintenance is therefore an essential function and should be carried out on a timely basis. The cost of providing and maintaining the roads for the industrial areas at an acceptable serviceability level is quite high. It is therefore essential for a transportation engineer to attempt establishing an acceptable pavement condition level from economic, safety and environmental point of view. In today's economic environment of constrained budgets, as the existing road infrastructure has aged, a more systematic approach towards determining maintenance and rehabilitation needs is necessary. The efficient pavement management system shall provide objective information and useful analysis to ensure consistent and cost effective decisions related to preservation of existing industrial road network in healthy condition.

  19. Sustainable Drainage Practices in Spain, Specially Focused on Pervious Pavements

    Directory of Open Access Journals (Sweden)

    Jorge Rodriguez-Hernandez

    2013-01-01

    Full Text Available The Spanish climate is full of contrasts, with torrential rains and long droughts; under these conditions, appropriate water management is essential. In Spain, until the end of the twentieth century, water management and legislative development lagged behind other more developed countries. Nowadays, great efforts are being made to reverse this situation and improve both water management and legislation in order to control the two main problems related to stormwater management in cities: floods and diffuse pollution. In this context, Sustainable Urban Drainage Systems (SUDS were developed as the main solution to these problems. The study of these techniques started in the 1970s in the USA, but they were not studied in Spain until 1993 when the University of Cantabria and CLABSA started to look into solutions for stormwater management. After 20 years of research and application, sustainable drainage in Spain is still behind other countries in spite of the efforts to change this situation, notably by the University of Cantabria with 10 years of experience in these techniques, mainly regarding pervious pavements, where more than 13 related research projects have been carried out. The future challenges focus on the application of pervious pavements for Urban Hydrological Rehabilitation.

  20. Finite Element Investigation of the Deterioration of Doweled Rigid Pavements

    CERN Document Server

    Ghauch, Ziad G

    2011-01-01

    The purpose of this study is to describe the failure of concrete around dowel bars in jointed rigid pavements, and the resulting effect on the pavement performance. In fact, under repetitive vehicle loading, concrete in contact with the dowel bar deteriorates, particularly at the joint face. The degradation of concrete around the dowel negatively affects the latter's performance in terms of transferring wheel loads through vertical shear action. In this context, a nonlinear 3D Finite Element analysis was performed using the commercial FE code Abaqus (v-6.11). The FE model was validated with classical analytical solutions of shear and moment along the dowel. A concrete damaged plasticity model was used for the PCC slab to model the degradation of concrete matrix around the dowels under incremental loading. Results obtained show, among other things, that the degradation of concrete matrix around the dowel was found to initiate at the face of the joint and propagate towards the interior of the dowel. Also, resul...

  1. Thickness and air voids measurement on asphalt concrete pavements using ground-penetrating radar

    Science.gov (United States)

    Dhakal, Sharad Raj

    Layer thickness and air voids are important parameters in quality assurance of newly paved hot mix asphalt (HMA) pavements. A non-destructive testing (NDT) technique was used to collect layer thickness information. The thicknesses estimated by the technique were compared with core thicknesses. Ground penetrating radar (GPR) system with air coupled antennas was used for on-site pavement data collection. Two application softwares - RADAN and ROAD DOCTOR - were used to process the field data for estimating layer thicknesses and air voids along the scanned pavements. 150 mm diameter cores taken from random locations on the pavements were tested in the laboratory to determine layer thickness and air voids. Statistical analyses were conducted to compare thicknesses and generate a regression equation relating air voids and dielectric constant of the pavement material. No significant differences were found between thickness estimates from RADAN and ROAD DOCTOR softwares when compared to the core measurements. However, RADAN and ROAD DOCTOR results are marginally significantly different from each other. ROAD DOCTOR software was used to generate air voids for the pavements scanned. Laboratory results from cores were utilized to determine calibration factors for the air voids -- dielectric equation. A relationship between air voids and dielectric constant is presented. It is concluded that GPR system with air coupled antennas used alongside a reduced core testing has a potential for quality control of newly paved hot mixed asphalt pavements.

  2. 47 CFR 80.1115 - Transmission of a distress alert by a station not itself in distress.

    Science.gov (United States)

    2010-10-01

    ... of a distress alert by a station not itself in distress. (a) A station in the mobile or mobile-satellite service which learns that a mobile unit is in distress must initiate and transmit a distress alert relay in any of the following cases: (1) When the mobile unit in distress is not itself in a position...

  3. [Moral distress in nursing care].

    Science.gov (United States)

    Negrisolo, Adriana; Brugnaro, Luca

    2012-01-01

    In nursing practice, the ability to make decisions regarding patients and to act on them is considered to be an expression of the professional nursing role. Problems may arise when a nurses would like to perform an action they believe morally correct but which are conflictual with the habits, organization or politics of the health structure in which they work. This inevitably produces moral distress in nurses who feel impotent to act as they feel they should. Although a certain amount of moral distress is part and parcel of the nursing profession , when it is excessive or prolonged it may become unacceptable and culminate in burn-out and the relative consequences. The aim of the study was to compare the level of moral stress in 111 Italian nurses working in different Operative Units to identify those clinical situations significantly associated with moral stress using the MDS scale. Similarly to studies performed in the USA, the level of moral stress in the 3 different work contexts was moderate, although some clinical situations were related to significant stress levels. PMID:23121881

  4. 3-D cohesive finite element model for application in structural analysis of heavy duty composite pavements

    DEFF Research Database (Denmark)

    Skar, Asmus; Poulsen, Peter Noe

    2015-01-01

    paper presents a numerical analysis of the fracture behaviour of cement bound granular mixtures in composite concrete block pavement systems applying a cohesive model. The functionality of the proposed model is compared to experimental investigations of beam bending tests. The pavement is modelled as a...... can be shown that adequately good prediction of the structural response of composite pavements is obtained for monotonic loading without significant computational cost, making the model applicable for engineering design purpose. It is envisaged that the methodology implemented in this study can be...

  5. Pollutant load removal efficiency of pervious pavements: is clogging an issue?

    Science.gov (United States)

    Kadurupokune, N; Jayasuriya, N

    2009-01-01

    Pervious pavements in car parks and driveways reduce the peak runoff rate and the quantity of runoff discharged into urban drains as well as improve the stormwater quality by trapping the sediments in the infiltrated water. The paper focuses on presenting results from the laboratory tests carried out to evaluate water quality improvements and effects of long-term decrease in infiltration rates with time due to sediments trapping (clogging) within the pavement pores. Clogging was not found to be a major factor affecting pervious pavement performance after simulating 17 years of stormwater quality samples. PMID:19809141

  6. 46 CFR 169.553 - Pyrotechnic distress signals.

    Science.gov (United States)

    2010-10-01

    ... Lifesaving and Firefighting Equipment Additional Lifesaving Equipment § 169.553 Pyrotechnic distress signals... signals: (1) 6 hand red flare distress signals, and 6 hand orange smoke distress signals; or, (2) 12...

  7. 47 CFR 80.325 - Control of distress traffic.

    Science.gov (United States)

    2010-10-01

    ... 2010-10-01 false Control of distress traffic. 80.325 Section 80.325 Telecommunication...Safety Procedures § 80.325 Control of distress traffic. (a) Distress traffic consists of all messages relating to the...

  8. Psychological Distress Among Young Norwegian Health Professionals

    Directory of Open Access Journals (Sweden)

    Per Nerdrum

    2014-03-01

    Full Text Available In this study, we present longitudinal data on psychological distress among 169 young Norwegian health professionals. Psychological distress was measured at the end of their studies, and three years later on, when being professional nurses, physiotherapists and occupational therapists. Psychological distress was assessed by applying the 12-item version of the General Health Questionnaire (GHQ 12. Twenty-seven percent of the nursing students scored higher than the GHQ 12 case score at the end of the study, but as nurses, they became significantly less distressed three years later (13 percent. The other two professions showed relatively small and non-significant reductions in psychological distress during the first three years as a professional. Hierarchical multiple analyses showed that the level of psychological distress when finishing the study, the young professionals’ experience of personal support from colleagues, the experience of work-home conflicts and the experience of methodological coping at work were significant predictors of psychological distress three years after working as young health professionals. These four predictors explained together 29 percent in the variance in GHQ 12 three years after graduation. Belonging to any of the three professions did not contribute to the explained variance in psychological distress three years after graduation.

  9. Escurrimiento en pavimentos de bloques de suelo-cemento: un abordaje experimental / Runoff on Pavements of Soil-Cement Blocks - an Experimental Boarding

    Scientific Electronic Library Online (English)

    Jorge Luis, Zegarra-Tarqui; Jeferson, Santos-De Brito; Miriam, De Fátima-Carvalho.

    2015-03-01

    Full Text Available El artículo evalúa la reducción del escurrimiento superficial en pavimentos construidos con bloques rectangulares de suelo-cemento. Los ensayos fueron realizados en un pavimento piloto con bloques de suelo-cemento, asentados en una caja metálica de 50 cm × 50 cm (área = 2500 cm²), con pendientes de [...] 1, 3 y 5%. Se utilizaron intensidades medias de 76.9 mm/h y 117.7 mm/h, valores próximos a las intensidades calculadas por la curva intensidad-duración-frecuencia (i-d-f) de la ciudad del Salvador, Brasil, para tiempo de retorno de 2 y 5 años, respectivamente. El coeficiente de escurrimiento medio fue C = 0.61, este valor es cercano al coeficiente de pavimento con bloques rectangulares (C = 0.6) y es inferior al valor del coeficiente de pavimento de bloque de concreto (C = 0.78). Por otro lado, si consideramos que las áreas mayores que 2500 cm² son compuestas por el acoplamiento de unidades de área de 50 × 50 centímetros, entonces, las pérdidas por salpicamiento forman parte del escurrimiento superficial, obteniendo el coeficiente Csuperficial+salpicamiento, el cual presentó valores en la faja de 0.74 a 0.89; estos valores se encuentran cerca del coeficiente de pavimento de bloque de cemento (C = 0.78) y son inferiores al de pavimento de concreto (C = 0.95), pero considerando factores como tiempo de desplazamiento del escurrimiento sobre la superficie, depresiones en la superficie, evaporación y rugosidad del pavimento, entre otros, este valor debe disminuir. Entonces, el pavimento de bloques de suelo-cemento puede considerarse dentro de la categoría de semipermeable para las dimensiones de área utilizadas. Abstract in english The article evaluates the reduction of runoff in pavements constructed with rectangular blocks of soil-cement. The tests were conducted in a pilot pavement built with soil-cement blocks, seated in a metal box of 50 cm × 50 cm (area = 2500 cm²), with declivities of 1%, 3% and 5%. Mean intensities of [...] 76.9 mm / I 117.7 mm / h were used, values close to the intensities calculated by intensity-frequency-duration (i-f-d) equation of the city of Salvador, Brazil, for return periods of 2 and 5 years, respectively. The medium runoff coefficient was C = 0.61, this value is close to the coefficient of pavement with rectangular blocks (C = 0.6) and it has a lower value than the coefficient for concrete block pavement (C = 0.78). On the other hand, considering that areas with more than 2500 cm² are constituted by coupling of area units of 50 cm × 50 cm, the splash losses are part of the runoff, obtaining the coefficient Csuperficial + splashing, which showed values in the 0.74 to 0.89 range, these values were found close to the coefficient of concrete block pavement (C = 0.78) and below the concrete pavement (C = 0.95), respectively, but factors such as displacement time of runoff on surface, depressions on the surface, roughness of pavement, evaporation and others, should reduce this value. Then, the pavement of soil-cement blocks can be considered in the category of semi-permeable for the area size used.

  10. Proportioning of Steel Fibre Reinforced Concrete Mixes for Pavement Construction and Their Impact on Environment and Cost

    Directory of Open Access Journals (Sweden)

    Stelios Kallis

    2011-07-01

    Full Text Available Steel fibre reinforced concrete (SFRC is a construction material investigated for more than 40 years including for pavement applications. A number of studies have demonstrated the technical merits of SFRC pavements over conventional concrete pavements; however little work has been carried out on the environmental and economical impact of SFRC during the pavement’s life cycle. Therefore, extended research was undertaken within the framework of the EU funded project “EcoLanes” to estimate the environmental and economical loadings of SFRC pavements. The innovative concept of the project is the use of recycled steel tyre-cord wire as concrete fibre reinforcement, which provides additional environmental benefits for tyre recycling over landfilling. Within the project framework a demonstration of a steel-fibre-reinforced roller-compacted concrete (SFR-RCC pavement was constructed in a rural area in Cyprus. In order to assess the economical and environmental picture of the demonstration pavement, life cycle cost analysis (LCCA and life cycle assessment (LCA studies were undertaken, which also compared the under study pavement design with four conventional alternatives. The main output of the studies is that SFR-RCC is more environmentally and economically sustainable than others. In addition, various concrete mix designs were investigated by considering parameters such as fibre type and dosage, cement type, and transportation distances to the construction site. Fibre dosage has been highlighted as a crucial factor compared with economical and environmental loadings in SFR-RCC pavement construction.

  11. Liquidity Risk and Distressed Equity

    DEFF Research Database (Denmark)

    Medhat, Mamdouh

    I show theoretically and empirically that cash holdings can help rationalize the low returns to distressed equity. In my model, levered firms with financing constraints optimally choose their cash holdings to eliminate liquidity risk and optimally default when insolvent. Using data on solvency, liquidity, and returns for US firms, I find evidence consistent with the model’s predictions: (1) In all solvency levels, the average firm holds enough liquid assets to cover its short-term liabilities; less solvent firms have (2) a higher fraction of their total assets in liquid assets and therefore (3) lower conditional betas and (4) lower returns; (5) the profits of long-short solvency strategies are highest among firms with low liquidity; and (6) the profits of long-short liquidity strategies are highest among firms with low solvency.

  12. Study of Sand Characteristics as Bearing and Filler in Joint of Inter-locking Concrete Block Pavement

    Directory of Open Access Journals (Sweden)

    Rosli Hainin

    2009-09-01

    Full Text Available The use of interlocking concrete block pavement as a road surface has increased in the road constructionrecently. This study was conducted to envisage the problems occur particularly for the bedding and joint filling sand of the interlocking concrete block pavement. Moreover, the effect of the moisture on the bedding sandwas also studied. Two type of additives namely as palm oil fly ash (POFA and silica fume, which carry thepozzolanic behaviour, were mixed with joint filling sand in order to improve its quality. These materials areindustrial waste compound which can be easily found in Malaysia. Two types of permeability experiments,the constant and falling head tests were conducted to evaluate the permeability of the joint filling sands withthe percentage additives used of 2%, 4%, 6%, 8% and 10%. A physical model was developed to investigatethe degree of compaction and water absorption via sand in joints. Water absorption test was also conductedonto the model with the addition of additives of 0%, 5% and 10% with the joint filling sand for 5 and 10days. Study shown that the incorporation of additives reduced the permeability of joint filling sand withthe optimum values obtained for both POFA and silica fume mixtures both were at 2% respectively.

  13. Airport pavement roughness evaluation based on aircraft response

    Science.gov (United States)

    Dong, Qinxi; Hachiya, Yoshitaka; Endo, Katsura; Himeno, Kenji; Kawamura, Akira; Matsui, Kunihito

    2004-07-01

    Runway roughness affects primarily ride quality and dynamic wheel loads. The forces applied onto the airport pavement by aircraft vary instantaneously above and blow the static weight, which in turn increase the runway roughness. One method to effectively assess the ride quality of the airport runway is to measure its longitudinal profile and numerical simulate aircraft response performing a takeoff, landing or taxiing on that profile data. In this study the aircraft responses excited as the aircraft accelerates or moves at a constant speed on the runway during takeoff and taxi are computed by using the improved computer program TAXI. This procedure is capable of taking into account both the effects of discrete runway bumps and runway roughness. Thus, sections of significant dynamic response can be determined, and the maintenance and rehabilitation works for airport runways will be conducted.

  14. 23 CFR 973.208 - Indian lands pavement management system (PMS).

    Science.gov (United States)

    2010-04-01

    ...BIA's or tribes' goals, policies, criteria...or historic data is difficult to establish, it... (ii) A pavement performance analysis that includes present and predicted performance and an estimate of...remaining service life (performance and remaining...

  15. 23 CFR 972.208 - Federal lands pavement management system (PMS).

    Science.gov (United States)

    2010-04-01

    ...designed to fit the FWS goals, policies, criteria...or historic data are difficult to establish, it... (ii) A pavement performance analysis that includes present and predicted performance and an estimate of...remaining service life (performance and remaining...

  16. 23 CFR 971.208 - Federal lands pavement management system (PMS).

    Science.gov (United States)

    2010-04-01

    ...fit the FH program goals, policies, criteria...or historic data is difficult to establish, it... (ii) A pavement performance analysis that includes present and predicted performance and an estimate of...remaining service life. Performance and remaining...

  17. 23 CFR 970.208 - Federal lands pavement management system (PMS).

    Science.gov (United States)

    2010-04-01

    ...designed to fit the NPS goals, policies, criteria...or historic data is difficult to establish, it may... (ii) A pavement performance analysis that includes present and predicted performance and an estimate of...remaining service life (performance and remaining...

  18. Contributions of performance-graded asphalt to low temperature cracking resistance of pavements. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Loh, S.W.; Olek, J.

    1999-05-01

    The purpose of this research was to study and evaluate the role that asphalt cracking. As part of the Strategic Highway Research Program (SHRP) new specifications for asphalt binders were developed that are based on the performance of the material. The asphalt binder graded and specified according to these new performance-based specifications is called PG binder. These new specifications are commonly referred to as Superpave (Superior Performing Asphalt Pavement) binder specifications. A section of Interstate 64 in southern Indiana was experiencing severe low temperature cracking before it was reconstructed over the summers of 1995 and 1996. The binder used in the new pavement mixes was PG material. Dynamic Shear Rheometer (DSR) tests, Bending Beam Rheometer (BBR) tests, and viscosity tests were performed on this binder. Comparisons were made between test results obtained from the binders in the old pavement and the new pavement. All tests and comparisons were based on the Superpave binder specifications.

  19. Stress Analysis and Determination of Effective k-value for Rigid Pavement

    Directory of Open Access Journals (Sweden)

    Kundan Meshram

    2013-03-01

    Full Text Available EverFE is a user-friendly 3D finite-element analysis tool for simulating the response of jointed plain concrete pavement (JPCP systems to axle loads and environmental effects. EverFE is useful for both concrete pavement researchers and designers who must perform either complex nonlinear or simple linear stress analyses of JPCP.With help of this develop any type of model of rigid pavement considering practical condition thus getting more accurate and advance analysis for rigid pavement. It can also determine effective k-values for different combination of granular sub-base and dry lean concrete. A comparative study is done for two types of loading i.e. single and tandem axle. Edge and Corner stresses are also calculated for Class-AA of loading. Also calculate moment and shear force transfer by dowel bar by EverFE.

  20. Development of Knowledge-Based Expert System for Flexible Pavement Design

    Directory of Open Access Journals (Sweden)

    Deprizon

    2009-01-01

    Full Text Available In this study, the knowledge-based expert system approach was used to design a programmer using shell expert system of KAPPA PC Version 2.4 that is object oriented and displaying higher graphic resolutions. The flexible pavement design based on the accumulation of knowledge from several experts, books and journals results in a modular approach. Normally, the process of flexible pavement design is done by experts. The process was computerized and apply artificial intelligent that is a new technology in providing a system that can design and give the suggestion for user to choices the best and economy of the thickness of pavement layers. The expert system was tested using several design calculation samples. From the test, the success is 100% for pavement design. The expert system has revealed satisfactorily findings in a faster layers design.

  1. Integration and road tests of a self-sensing CNT concrete pavement system for traffic detection

    International Nuclear Information System (INIS)

    In this paper, a self-sensing carbon nanotube (CNT) concrete pavement system for traffic detection is proposed and tested in a roadway. Pre-cast and cast-in-place self-sensing CNT concrete sensors were simultaneously integrated into a controlled pavement test section at the Minnesota Road Research Facility (MnROAD), USA. Road tests of the system were conducted by using an MnROAD five-axle semi-trailer tractor truck and a van, respectively, both in the winter and summer. Test results show that the proposed self-sensing pavement system can accurately detect the passing of different vehicles under different vehicular speeds and test environments. These findings indicate that the developed self-sensing CNT concrete pavement system can achieve real-time vehicle flow detection with a high detection rate and a low false-alarm rate. (paper)

  2. Assessment of Clogging Dynamics in Permeable Pavement Systems with Time Domain Reflectometers

    Science.gov (United States)

    Infiltration is a primary functional mechanism in green infrastructure stormwater controls. This study used time domain reflectometers (TDRs) to measure spatial infiltration and assess clogging dynamics of permeable pavement systems in Edison, NJ, and Louisville, KY. In 2009, t...

  3. Innovative low noise surfaces : comparison of damping and absorption

    OpenAIRE

    Freitas, Elisabete F., ed. lit.; Rodrigues, José Dias; Rocha, Jorge de Araújo; Silva, Hugo Manuel Ribeiro Dias da

    2014-01-01

    While sound absorption is an acoustic related property reasonably well known and currently used to characterize low noise surfaces, damping is a property commonly used in other domains to define the energy dissipation of a material but rarely used to characterize this important mechanism in road pavements. This paper compares noise related properties such as damping and absorption of five road pavement surfaces. Two of which are innovative and therefore expected to be low noise since they hav...

  4. Evaluation of Runway Pavement Design Software and Application of Modified Asphalt Overlay on Airfields

    OpenAIRE

    M. Reza Yavari; Ardalan Balali

    2015-01-01

    Different software has been offered by aviation administrations and investigation institutions to facilitate runway pavement designs. In this paper, four generic runway design software including LEDFAA 1.3, PCASE 2.09, FAARFIELD 1.305 and TKUAPAV were aimed. Hereon, communal layer structures with particular characteristics along with a sample airport containing wide-body commercial and military aircrafts were introduced to each software and the thickness of the pavement was obtain...

  5. The Upper Eocene crustose coralline algal pavement in the Colli Berici, north-eastern Italy

    OpenAIRE

    Davide Bassi

    2005-01-01

    A crustose coralline algal pavement, identified in Upper Eocene (Priabonian) shallow water, middleramp carbonates in north-eastern Italy (Colli Berici, Southern Alps), represents a rare example of this facies.The crustose pavement consists of a coralline crust bindstone with a wackestone-packstone matrix, and is characterised by the dominance of crustose coralline thalli composed primarily of melobesioids (Lithothamnion and Mesophyllum) and mastophoroids (Spongites, Lithoporella, Neogoniolith...

  6. An approach for the definition of construction and maintenance strategies for flexible pavements

    OpenAIRE

    Sousa, Jorge B.; Pais, Jorge C.; Eckmann, Bernard

    1998-01-01

    Design, Build, Finance and Operate contracts to develop a road network require a re-evaluation of the strategic decisions towards the design and maintenance strategies of flexible pavements. Probabilistic analysis, based on the variability of pavement material properties and layer thickness as well as on traffic variability is required and needed as a cost effective basis for the many possible design and maintenance strategies. The NOAH software was used to combine hundreds of possibl...

  7. Characterization and modelling of self healing of bituminous materials towards durable asphalt pavement:

    OpenAIRE

    J. Qiu; Van de Ven, M.F.C.; Schlangen, H.E.J.G.; Wu, S.; Molenaar, A.A.A.

    2012-01-01

    The traffic volume and the number of heavy vehicles are growing enormously nowadays. There is a need for designing a durable asphalt pavement with innovative technologies. Pavement structures and materials with self healing and self repairing capability are believed to be very useful in such a system. This paper is aiming to understand the self healing behaviour through mechanical testing and finite element modelling. Instead of a complex and time consuming fatigue involved self healing inves...

  8. Towards a Uniform Fracture Mechanics-Based Framework for Flexible Pavement Design

    OpenAIRE

    Das, Prabir

    2009-01-01

    Cracking is an important potential failure mechanism for pavement structures. By combining a strain energy-based fracture criterion with conventional fracture mechanics based on the Energy Ratio (ER) concept, crack growth in asphalt can be investigated, and a low temperature Thermal Cracking model (TCMODEL) can be introduced. This thesis presents the implementation of the Florida cracking model into a Mechanistic-Empirical (ME) flexible pavement design framework. An improved analysis procedur...

  9. Development Of A Pavement Condition Assessment Method For The Interstate Highway System

    OpenAIRE

    Simpson, A.; Groeger, J.; Rada, Gonzalo R.; Guerre, J

    2012-01-01

    As part of a project conducted by the United States Department of Transportation (US DOT) Federal Highway Administration (FHWA), methods are being developed to assess infrastructure condition and health with a focus on pavements on the Interstate Highway System. The project scope includes development of prototype tools to provide FHWA and State DOTs ready access to key information on pavement and bridge performance based on these methods for assessing condition and health. These tools are des...

  10. Influence of Subsoil Conditionson the Design and Performance of Flexible Pavements

    OpenAIRE

    Yesuf, Girum Yimer

    2014-01-01

    The effect of subsoil conditions is one of the prominent factors that control both the design and performance of flexible pavement structures. Despite having a wide range of empirical methods from measurements and experience, the quantification of the short-term and long-term physical processes of geo-materials in roads is not yet fully understood. Particularly, subgrade soils have not got the required attention in the characterization of pavement materials although they are known as the “fou...

  11. Modelling of Mechanical Properties of Cement Concrete Incorporating Reclaimed Asphalt Pavement

    OpenAIRE

    MATHIAS, Vincent; Sedran, Thierry; De Larrard, François

    2009-01-01

    In many countries there is a trend to recycle wastes obtained during pavement maintenance or reconstruction, and to forbid the landfill of these products. Thus, in some circumstances it can be tempting to use reclaimed asphalt pavement (RAP) in new hydraulic concrete mixtures. This paper presents experimental data and modelling about the effect of RAP incorporation on cement concrete mechanical properties (compressive strength, tensile strengths and E-modulus). All these properties tend to de...

  12. Test of Microstructur Permeable Asphalt Pavement Used Domato Stone (Quarsite Dolomite As Course Agregate for Surface Layer of Road Pavement

    Directory of Open Access Journals (Sweden)

    Firdaus Chairuddin

    2014-06-01

    Full Text Available The experiment works was dividing into two phases, for phase one was developed to investigate the properties of aggregates and straight asphalt qualities. The experiment work for phase two was developed to design the porous asphalt mix. In this phase Japan’s method and Binamarga’s method was used to define optimum asphalt content. In this phase, has result cantabro loss weight 77.10 for asphalt quality 3% and loss weight 9.70 for asphalt quality 5%. asphalt flow down, air void and density values. The experiment work for phase two was developed to investigate the qualities of porous asphalt. In this phase, wheel tracking machine test was used to investigate the dynamic stability of mixes.

  13. Medway Tunnel Road Pavement Survey Using Different Frequency GPR Antenna Systems - A Case Study

    Science.gov (United States)

    Alani, Morteza Amir; Banks, Kevin

    2015-04-01

    This presentation reports on an extensive survey carried out on a section (just outside the westbound end of the tunnel portal) of the Medway Tunnel in North Kent, UK. The Medway Tunnel provides a dual carriageway road crossing under the River Medway between Chatham and Strood. It is 725 metres long from portal to portal and consists of three sections. The appearance of repeated cracking of the road surface in this particular section of the tunnel suggested either a steady movement of the ground or possible undermining due to an underground watercourse. Ironically, the design and construction of the road had been realised to prevent any form of structural movement. It was deemed necessary to perform a Ground Penetrating Radar (GPR) survey in order to confirm underground construction details of the road in this section of the tunnel. This presentation reports on the detailed survey and the challenges encountered during the operation, which utilised four different frequency GPR systems including 2GHz, 900MHz, 600MHz and 200MHz antennas. The presentation will also describe how decisions were made to carry out supplementary surveys based on results obtained on-site (via primary data processing) and observations made during the survey. A summary of results will be presented individually for each antenna system used, as well as comparisons between each antenna system. Results will then be mapped against the design drawings available for confirmation of construction configurations. In conclusion, the presentation will demonstrate that the tunnel road pavement is not constructed as per the information provided (design drawings). Results will clearly indicate that there is no second reinforced concrete layer present in this particular section of the road pavement (contrary to what was originally believed) and will present the actual road construction in comparison with the design drawings. The results will confirm that there is no underground watercourse present in this particular section of the tunnel (at 2-3 m depth). However, it will confirm the presence of an unknown feature at a depth of 1.2m below road surface. Acknowledgement The authors would like to acknowledge the support of the COST Action TU1208 project, as well as Medway City Council's immense support in terms of expert workforce and road survey equipment in materialising this work.

  14. Lead and zinc removal with storage period in porous asphalt pavement

    Scientific Electronic Library Online (English)

    Yao, Zhao; Chen, Zhao.

    2014-01-01

    Full Text Available Porous asphalt pavements have been used as an effective technique to overcome road runoff challenges, and to improve efficiency of rainwater utilisation in urban areas. Using porous asphalt pavements with reservoir storage and harvesting facilities is an important consideration for the future. This [...] study monitored changes in water quality indicators, such as pH, conductivity, and concentrations of lead and zinc, for water stored in porous asphalt pavement models with basalt-, limestone- and 'basalt+limestone'-filled reservoir structures. The research discusses findings over a 696-h storage period following artificial rainfall. Total lead and zinc concentrations were remarkably reduced throughout the initial flush, showing, on average, reductions of 90% and 80.5%, respectively. This pattern was consistent throughout the storage period, producing average reductions in lead and zinc of 99.98% and 79%, respectively, over 696 h. Conductivity and pH levels increased in all pavement models after the 696-h storage. The results obtained confirmed the potential of using porous asphalt pavements with reservoir structures to remove heavy metals from road runoff. This can be applied to future research on the removal mechanisms of porous asphalt pavements in relation to heavy metals in road runoff.

  15. 47 CFR 80.320 - Radiotelephone distress call and message transmission procedure.

    Science.gov (United States)

    2010-10-01

    ...false Radiotelephone distress call and message transmission procedure. 80.320 ...320 Radiotelephone distress call and message transmission procedure. (a) The...The distress call; (3) The distress message. (b) The DSC distress procedure...

  16. A TECHNIQUE OF ESTIMATION OF TECHNICAL CONDITION OF RIGID AIRFIELD PAVEMENTS IN THE CONTEXT OF RISK THEORY

    OpenAIRE

    A.N. Popov; I. G. Shashkov; A. V. Kozlov

    2012-01-01

    Problem statement. To provide for safe takeoff and landing of modern aviation complexes, specialattention is given to technical condition of artificial pavements of runways which can be serviceableor faulty, efficient or limiting. Available standard methods of an expeditious estimation of an operational-technical condition of airfield pavements are based on general principles of defect graduationand of definition of integrated total generalized indicator of pavement condition and often yield ...

  17. 47 CFR 2.403 - Retransmission of distress message.

    Science.gov (United States)

    2010-10-01

    ...2010-10-01 false Retransmission of distress message. 2.403 Section 2.403 Telecommunication...2.403 Retransmission of distress message. Any station which becomes aware...is in distress may transmit the distress message in the following cases: (a)...

  18. NonPAS: A Program for Nonlinear Analysis of Flexible Pavements

    Directory of Open Access Journals (Sweden)

    Ali Reza Ghanizadeh

    2015-05-01

    Full Text Available Normal 0 false false false EN-US X-NONE FA MicrosoftInternetExplorer4 The primary step in design of a pavement using Mechanistic-Empirical (M-E method is the analysis of pavement and calculation of the critical responses of pavement under various loadings. This confirms the need for developing pavement analysis software as an analytical base of the M-E method. To this end, NonPAS program has been developed for linear and nonlinear analysis of flexible pavements. Developed program allows nonlinear analysis of flexible pavements using five nonlinear models, including K-?, Uzan, Uzan-Witczak, MEPDG 2002 and Bilinear models. Nonlinear Analysis of flexible pavements by utilizing these constitutive models provides a more accurate modeling of granular material behavior. Developed program can be used to analyze a pavement system consists of maximum of 10 layers, which is subjected to a maximum of six circular loads. Developed program allows for calculating the responses at 400 different points of pavement. In order to validate the results of linear and nonlinear analysis, responses obtained from NonPAS have been compared with responses obtained using Kenlayer program. Results show very good agreement between responses, which are obtained using both linear and nonlinear analysis and approve that developed program can be used with high reliability for the purposes of pavement analysis and design. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;}

  19. Constructing a theoretical model of moral distress.

    Science.gov (United States)

    Barlem, Edison Luiz Devos; Ramos, Flávia Regina Souza

    2015-08-01

    Moral distress has been characterised as one of the main ethical problems affecting nurses in all health systems, and has been depicted as a threat to nurses' integrity and to the quality of patient care. In recent years, several studies tried to investigate moral distress, its causes and consequences for health professionals, clients and organisations. However, such studies are considered controversial and vulnerable, mainly because they lack a solid philosophical and empirical basis. The present article aimed at elaborating a theoretical model for moral distress, considering the process of moral deliberation, spaces of power and resistance and patient advocacy, and sought to carry out a reflection that culminated with the creation of a broader concept of moral distress. PMID:25366998

  20. Brain Aneurysm: Dealing with Emotional Distress

    Science.gov (United States)

    ... Loss GTranslate Patient Resources : For Caregivers Dealing with Emotional Distress It is not unusual for a family ... Contact: office @bafound.org (888) 272-4602 Website Design: Communication via Design, Ltd.

  1. CAUSES OF RESPIRATORY DISTRESS IN CHILDREN

    Directory of Open Access Journals (Sweden)

    M M Karambin

    2008-11-01

    Full Text Available "nThere is a lack of large, prospective epidemiologic studies concerning acute lung injury (ALI and acute respiratory distress syndrome (ARDS in pediatric population. To determine the different causes of respiratory distress in children, we prepared a retrospective study and included the whole 567 children with respiratory distress referred to 17-Shahrivar Hospital, Rasht, Guilan. Using their medical files, data including age, sex, and causes of respiratory distress were collected. SPSS 13.0 (statistical software applied for statistical analysis. Pneumonia, asthma, and croup were the major causes of ARDS in children with a rate of 38.4, 19.04, and 16.5 percent, respectively. It seems that infectious factors are at the top of the list of ARDS causing factors which can be helpful to approach and manage such patients. We suggest vaccinating these at risk groups against common infectious factors such as H. Influenza and RSV which can cause either pneumonia or inducing asthma.

  2. / Distress, demoralization and psychopathology: Diagnostic boundaries

    Scientific Electronic Library Online (English)

    John M. de, Figueiredo.

    2013-03-01

    Full Text Available Background and Objectives: The objectives of the manuscript are: (a) to review the understanding of demoralization and its assessment; (b) to describe its clinical progression; (c) to explain the differences between demoralization and other form of psychological distress; (d) to propose a set of cri [...] teria for future research on demoralization. Methods: A MEDLINE search using the keywords distress, subjective incompetence, depression, demoralization, helplessness, hopelessness and psychopathology was conducted. This was supplemented by a manual search of the literature. Results: Demoralization can be distinguished from passing or transient distress, non-specific distress, sub-threshold depression or anxiety, and certain mental disorders. Demoralization can be a risk factor for the manifestation of psychopathology, the prodromal phase of a mental disorder, or a trigger for exacerbation or recurrence of psychiatric distress symptoms. The domains of distress and demoralization are described and research diagnostic criteria for demoralization are presented. Conclusions: The scales discussed in this article differ in their time frames and have not yet been applied to the same population at the same time. The role of demoralization as a risk factor for mental disorders is just beginning to be understood. The domains and the diagnostic criteria for demoralization presented in this article need to be confirmed by epidemiological and empirical studies. Future research should continue to clarify its role in the pathogenesis of both mental disorders and physical illnesses and identify appropriate interventions for its arrest or prevention.

  3. [Exploring moral distress among clinical nurses].

    Science.gov (United States)

    Lovato, Sabrina; Lovato, Liliana; Cunico, Laura

    2012-01-01

    Moral distress in nursing practice is described as a suffering situation that arises when the nurse is unable to act her/his ethical choices, when institutional constraints interfere with acting in the way she/he believes to be right. The aim is to describe nursing practice situations causing moral distress resulting from the recognition of the ethical appropriate actions combined with the impossibility to pursue it; to describe how nurses manage moral distress situations and the strategies to cope with them. A focus group was conducted in three wards of a large teaching-hospital in the north of Italy. In another ward the nurses were asked to write a moral distress experience. A total of 40 nurses were involved and 50 experiences collected. The experiences' analysis has shown 5 source areas of moral distress: 1) clinical decision; 2) nursing competences; 3) nurse-physician collaboration; 4) organization of care; 5) safe care. For each area the most frequent themes were highlighted.Areas of clinical decision, nursing competences, nurse-physician collaboration involve nurse leaders in identification and implementation of strategies for managing moral distress. PMID:23121880

  4. Pulmonary distress following attempted suicidal hanging

    Directory of Open Access Journals (Sweden)

    Nair Shalini

    2009-02-01

    Full Text Available Objective : To assess the incidence of post-hanging pulmonary distress in cases of attempted suicidal hanging and predictors of outcome among these patients. Design : Five-year retrospective analysis. Setting: Tertiary care center in south India. Patients :A total of 335 patients who attempted suicidal hanging, aged above 16 years, were admitted during this period. Thirty-eight of them with pulmonary distress established clinically and with radiological evidence of pulmonary injury post hanging met the inclusion criteria. Measurements : Data from ICU records of 5 years, X-rays and laboratory investigations were reviewed. In patients identified to have post-hanging pulmonary distress, the neurological status, chest x-rays, arterial blood gas values and outcome data were collected and analyzed. Results : Eleven percent (n = 38 of the 335 patients admitted following attempted suicidal hanging were diagnosed to have post-hanging pulmonary distress. The overall mortality among post-hanging patients was 5%, which increased to 34.2% (n = 13 in the presence of pulmonary distress (P ? 0.001. Among the prognostic factors evaluated, a PaO 2 / FiO 2 (P/F ratio of < 100 at admission predicted a poor outcome (P ? 0.001. Conclusion : Post-hanging pulmonary distress is a relatively common complication of hanging and is associated with increased mortality. P/F ratio from arterial blood gas at admission was the only significant predictor of outcome in this group of patients.

  5. Cortico-limbic morphology separates tinnitus from tinnitus distress

    Directory of Open Access Journals (Sweden)

    Amber M Leaver

    2012-04-01

    Full Text Available Tinnitus is a common auditory disorder characterized by a chronic ringing or buzzing “in the ear.” Despite the auditory-perceptual nature of this disorder, a growing number of studies have reported neuroanatomical differences in tinnitus patients outside the auditory-perceptual system. Some have used this evidence to characterize chronic tinnitus as dysregulation of the auditory system, either resulting from inefficient inhibitory control or through the formation of aversive associations with tinnitus. It remains unclear, however, whether these “non-auditory” anatomical markers of tinnitus are related to the tinnitus signal itself, or merely to negative emotional reactions to tinnitus (i.e., tinnitus distress. In the current study, we used anatomical MRI to identify neural markers of tinnitus, and measured their relationship to a variety of tinnitus characteristics and other factors often linked to tinnitus, such as hearing loss, depression, anxiety, and noise sensitivity. In a new cohort of participants, we confirmed that people with chronic tinnitus exhibit reduced grey matter in ventromedial prefrontal cortex (vmPFC compared to controls matched for age and hearing loss. This effect was driven by reduced cortical surface area, and was not related to tinnitus distress, symptoms of depression or anxiety, noise sensitivity, or other factors. Instead, tinnitus distress was positively correlated with cortical thickness in the anterior insula in tinnitus patients, while symptoms of anxiety and depression were negatively correlated with cortical thickness in subcallosal anterior cingulate cortex (scACC across all groups. Tinnitus patients also exhibited increased gyrification of dorsomedial prefrontal cortex (dmPFC, which was more severe in those patients with constant (vs. intermittent tinnitus. Our data suggest that the neural systems associated with chronic tinnitus are different from those involved in aversive or distressed reactions to tinnitus.

  6. Reuse of Lathe Waste Steel Scrap in Concrete Pavements

    Directory of Open Access Journals (Sweden)

    Pooja Shrivastavaa

    2014-12-01

    Full Text Available These project works assess on the study of the workability and mechanical strength properties of the concrete reinforced with industrialized waste fibers or the recycled fibers. In each lathe industries wastes are available in form of steel scraps are yield by the lathe machines in process of finishing of different machines parts and dumping of these wastes in the barren soil contaminating the soil and ground water that builds an unhealthy environment. Now a day’s these steel scraps as a waste products used by innovative construction industry and also in transportation and highway industry. In addition to get sustainable progress and environmental remuneration, lathe scrap as worn-recycle fibers with concrete are likely to be used. When the steel scrap reinforced in concrete it acquire a term; fiber reinforced concrete and steel fibers in concrete defined as steel fiber reinforced concrete (SFRC.Different experimental studies are done to identify about fresh and hardened concrete properties of steel scrap fiber reinforced concrete (SSFRC and their mechanical properties are found to be increase due to the addition of steel scrap in concrete i.e. compressive strength, flexural strength, impact strength, fatigue strength and split tensile strength were increased but up to 0.5-2% scrap content . When compared with usual concrete to SSFRC, flexural strength increases by 40% and considerable increases in tensile and compressive strength. These steel scrap also aid to improve the shrinkage reduction, cracking resistance i.e. preventing crack propagation and modulus of elasticity. The workability of fresh SSFRC are carried out by using slump test but it restricted to less scrap contents. This work focuses on the enhancement of structural strength and improvement in fatigue life of concrete pavements by reuse of scrap steel in concrete. These concrete roads with SSFRC promises an appreciably eminent design life, offer superior serviceability and minimize crack growth and corrosion. The pioneer idea of this work is the reuse of waste lathe scrap as recycled steel fibers, which provides more cost-effective and eco-friendly sustainable SFRC PAVEMENTS.

  7. Experimental Analysis of Natural Gravel Covering as Cool Roofing and Cool Pavement

    Directory of Open Access Journals (Sweden)

    Anna Laura Pisello

    2014-07-01

    Full Text Available Passive solutions for building energy efficiency represent an interesting research focus nowadays. In particular, natural materials are widely investigated for their potential intrinsic high thermal energy and environmental performance. In this view, natural stones represent a promising solution as building envelope covering and urban pavement. This paper concerns the experimental characterization of several low-cost and local gravel coverings for roofs and urban paving, properly selected for their natural high albedo characteristics. To this aim, the in-field albedo of gravel samples is measured with varying grain size. These in-field measurements are compared to in-lab measurements of solar reflectance and thermal emissivity. The analysis shows a significant variation of the albedo with varying grain size. Both in-lab and in-field measurements agree that the stones with the finest grain size, i.e., fine sand, have the best optic-thermal performance in terms of solar reflectance (62%. This feature results in the reduction of the surface temperature when exposed to solar radiation. Moreover, a natural mixed stone is compared to the high reflectance stone, demonstrating that the chosen stone presents an intrinsic “cool” behavior. Therefore, this natural, low-cost, durable and sustainable material could be successfully considered as a natural cool roof or cool paving solution.

  8. A Simple Field Test to Evaluate the Maintenance Requirements of Permeable Interlocking Concrete Pavements

    Directory of Open Access Journals (Sweden)

    Terry Lucke

    2015-05-01

    Full Text Available Adequate infiltration through Permeable Interlocking Concrete Pavements (PICPs is critical to their hydraulic and stormwater treatment performance. Infiltration is affected by clogging caused by the trapping of fines in the PICP surface, which, over time, reduces treatment performance. Clogging can be reduced by periodic maintenance such as vacuum sweeping and/or pressure washing. Maintenance requirements can be indicated by measuring reduced infiltration rates. This paper compared infiltration results using the standard test (C1781M-14a with the results of a new stormwater infiltration field test (SWIFT developed in Australia to evaluate the maintenance requirements of PICPs. A strong correlation (Pearson’s r = ?0.714 was found between results using the two methods. This study found that the SWIFT was a reliable method for estimating the degree of clogging of PICPs while successfully overcoming some of the problems with the more technical existing test methodology such as horizontal water leakage (use of sealant, unrealistic pressure heads, speed of test, and portability. The SWIFT test is a simple, fast and inexpensive way for asset managers and local government employees to quickly assess the maintenance requirements of PICP installations in the field.

  9. Influence of mixture composition on the noise and frictional characteristics of flexible pavements

    Science.gov (United States)

    Kowalski, Karol J.

    Both traffic noise and wet pavement-tire friction are mainly affected by the tire/pavement interaction. Existing laboratory test methods allow for evaluation of polishing resistance of the aggregates only. Currently, there is no generally accepted standardized laboratory test method to address noise related issues and the overall frictional properties of pavements (including macrotexture). In this research, which included both laboratory and field components, friction and noise properties of the flexible (asphalt) pavements were investigated. As a part of this study, a laboratory device to polish asphalt specimens was developed and the procedure to evaluate mixture frictional properties was proposed. Following this procedure, forty-six different Superpave mixtures (each utilizing a different aggregate blends), one stone matrix asphalt (SMA) mixture and one porous friction course (PFC) mixture were tested. Six of the above mixes (four Superpave mixtures, SMA mixture and PFC mixture) were selected for laboratory noise testing. This testing was performed using a one-of-a-kind tester called the Tire/Pavement Test Apparatus (TPTA). In addition, the field sections constructed using Superpave, SMA and PFC mixtures were also periodically tested for friction and noise. Field measurements included testing of total of 23 different asphalt and two concrete pavements. The field friction testing was performed using both portable CTM and DFT devices and the (ASTM E 274) locked wheel friction trailer. The laboratory friction testing was performed using CTM and DFT devices only. The results of both field and laboratory friction measurements were used to develop an International Friction Index (IFI)-based frictional requirement for laboratory friction measurements. The results collected in the course of the study indicate that the IFI-based flag values could be successfully used in place of SN-based flag values to characterize frictional characteristics of pavements.

  10. Differential Effects Of Maternal Sensitivity To Infant Distress And Non-Distress On Social-Emotional Functioning

    OpenAIRE

    Leerkes, Esther M.; Blankson, A. Nayena; O'Brien, Marion

    2009-01-01

    Associations between maternal sensitivity to infant distress and non-distress and infant social-emotional adjustment were examined in a subset of dyads from the NICHD Study of Early Child Care (N = 376). Mothers reported on infant temperament at 1 and 6 months postpartum, and maternal sensitivity to distress and non-distress were observed at 6 months. Child behavior problems, social competence, and affect dysregulation were measured at 24 and 36 months. Maternal sensitivity to distress but no...

  11. Recycling of radioactive oil sludge waste into pavement brick

    International Nuclear Information System (INIS)

    Malaysia produces about 1450 tons of radioactive oil sludge waste per year and there is an urgent need to find a permanent solution to the storage and disposal of this radioactive waste problem. Several treatment methods such bacteria farming, ultracentrifuge, steam reforming and incineration are currently being used but the core issue of the radioactive material in the oil sludge had not been solved. The paper relates a study on utilizing the radioactive component of the oil sludge and turning them into pavement brick. Characteristic study of this radioactive component by XRD and XRF show that it mainly comprised of quartz and anorthite minerals. While the radioactivity analysis by gamma technique shows that more than 90 % of this radioactivity comes from this soil component with Ra-226 and Ra-228 as the main radionuclides. A vitrified brick was then produced from this sediment by mixing it with low radioactive local red clay. The result also shows that the formation of the vitrified layer may be due high content of K in the red clay. Tensile test on the brick shows that it has more than four times the strength of commercial clay brick. Long duration leaching test on the brick also shows that there is no dissolution of radionuclide from the brick. (author)

  12. Road roughness evaluation using in-pavement strain sensors

    Science.gov (United States)

    Zhang, Zhiming; Deng, Fodan; Huang, Ying; Bridgelall, Raj

    2015-11-01

    The international roughness index (IRI) is a characterization of road roughness or ride quality that transportation agencies most often report. The prevalent method of acquiring IRI data requires instrumented vehicles and technicians with specialized training to interpret the results. The extensive labor and high cost requirements associated with the existing approaches limit data collection to at most once per year for portions of the national highway system. Agencies characterize roughness only for some secondary roads but much less frequently, such as once every five years, resulting in outdated roughness information. This research developed a real-time roughness evaluation approach that links the output of durable in-pavement strain sensors to prevailing indices that summarize road roughness. Field experiments validated the high consistency of the approach by showing that it is within 3.3% of relative IRI estimates. After their installation and calibration during road construction, the ruggedized strain sensors will report road roughness continuously. Thus, the solution will provide agencies a real-time roughness monitoring solution over the remaining service life of road assets.

  13. GPR abilities in investigation of the pavement transversal cracks

    Science.gov (United States)

    Krysi?ski, Lech; Sudyka, Jacek

    2013-10-01

    This paper describes the results of an investigation into the capabilities of the GPR technique within the field of pavement crack diagnostics. Initially, laboratory tests were performed on prototypes simulating idealized cracks. Next, long-term visual observation and repeated GPR scanning were performed, on three roads of semi-rigid construction, several hundreds of meters long and subjected to heavy traffic. Furthermore, a road of rigid construction was tested, having a more than 70-year history of use. In several cases the cracks were probed by drillings, in order to recognize structures responsible for signal generation, or to explain reasons of signal lacking. The main result of this work is a list of GPR indications of cracks, which can be noticed on echograms. It was created through a correlation of the visually-observed cracks with the corresponding echograms, with decimeter accuracy. Several types of GPR responses were classified and linked to possible categories of crack structures, or to processes associated with the presence of cracks (as crumbling, erosion, and lithological alterations). The poor visibility of cracks was also studied, due to small crack size, or to the blurred character of the damaged area, or else to masking effects related to coarse grains in the asphalt mixture. The efficiency of the proposed method for the identification and localization of cracks is higher when a long-term GPR observation is performed.

  14. Cytokinin signaling regulates pavement cell morphogenesis in Arabidopsis.

    Science.gov (United States)

    Li, Hongjiang; Xu, Tongda; Lin, Deshu; Wen, Mingzhang; Xie, Mingtang; Duclercq, Jérôme; Bielach, Agnieszka; Kim, Jungmook; Reddy, G Venugopala; Zuo, Jianru; Benková, Eva; Friml, Jiří; Guo, Hongwei; Yang, Zhenbiao

    2013-02-01

    The puzzle piece-shaped Arabidopsis leaf pavement cells (PCs) with interdigitated lobes and indents is a good model system to investigate the mechanisms that coordinate cell polarity and shape formation within a tissue. Auxin has been shown to coordinate the interdigitation by activating ROP GTPase-dependent signaling pathways. To identify additional components or mechanisms, we screened for mutants with abnormal PC morphogenesis and found that cytokinin signaling regulates the PC interdigitation pattern. Reduction in cytokinin accumulation and defects in cytokinin signaling (such as in ARR7-over-expressing lines, the ahk3cre1 cytokinin receptor mutant, and the ahp12345 cytokinin signaling mutant) enhanced PC interdigitation, whereas over-production of cytokinin and over-activation of cytokinin signaling in an ARR20 over-expression line delayed or abolished PC interdigitation throughout the cotyledon. Genetic and biochemical analyses suggest that cytokinin signaling acts upstream of ROPs to suppress the formation of interdigitated pattern. Our results provide novel mechanistic understanding of the pathways controlling PC shape and uncover a new role for cytokinin signaling in cell morphogenesis. PMID:23090432

  15. Hydrological consequences of soil surface type and condition

    OpenAIRE

    Solé-Benet, Albert

    2010-01-01

    Extensive semi-arid areas over mica schist in SE Spain have soils with a sandy loam texture, a poorly developed structure, a relatively high infiltrability and a quite high saturated hydraulic conductivity. Under non-tillage land use, a stony pavements armours the soil surface and is responsible for high infiltration, low runoff and almost negligible erosion. However, when this stony pavement is absent, and no plant cover is present, i.e. in tilled soils, this soil is very vuln...

  16. Modelling of composite concrete block pavement systems applying a cohesive zone model

    DEFF Research Database (Denmark)

    Skar, Asmus; Poulsen, Peter Noe

    This paper presents a numerical analysis of the fracture behaviour of the cement bound base material in composite concrete block pavement systems, using a cohesive zone model. The functionality of the proposed model is tested on experimental and numerical investigations of beam bending tests. The pavement is modelled as a simple slab on grade structure and parameters influencing the response, such as analysis technique, geometry and material parameters are studied. Moreover, the analysis is extended to a real scale example, modelling the pavement as a three-layered structure. It is found that the cohesive model is suitable for simulation of crack propagation in cement bound materials subjected to monotonic loading. The methodology implemented gives a new understanding of the mechanical behaviour of cement bound materials which can be used in further refinements of mechanical models for composite block pavements. It is envisaged that the methodology implemented in this study can be extended and thereby contribute to the ongoing development of rational failure criteria that can replace the empirical formulas currently used in pavement engineering.

  17. Utilizationof Hypo Sludge by Eco-Efficient Development of Rigid Pavement in Rural Roads

    Directory of Open Access Journals (Sweden)

    Prof. Jayeshkumar Pitroda1 , Dr. L.B.Zala2 , Dr.F.S.Umrigar

    2013-09-01

    Full Text Available The paperproducing industry generates various wastes coming out from the various processes. From the preliminary waste named as hypo sludge, due to its low calcium is taken out to replace the cement in concrete. Major initiatives are needed in India to use these large volumes in construction industry especially in rigid pavement construction and other infrastructure projects. Moreover Use of Hypo Sludge in construction of rigid pavement will improve transportation functionality and ecological sustainability and results in improved traffic safety and reduced life-cycle cost. Use of Hypo Sludge in construction of rigid pavement will benefit urban growth, public health and surrounding communities by encouraging smart growth by integrating and guiding future growth. It is also needed to reduce the cost of concrete pavement for rural development in India. So our study is concerned with eco-efficient utilization of Hypo sludge as partial replacement of cement in concrete for development of low cost rigid pavement of rural road infrastructure.The Hypo sludge was replaced within the range of 10-40% by weight of cement. In the present study, 5 different mixes of Hypo Sludge are tested for parameters like: compressive strength, flexural strength and cost

  18. Reflectance of interurban-road pavements from radar-based measurements

    Science.gov (United States)

    Fernandez, Paz; Peña-García, Antonio; Poyatos-Martínez, David; Escot-Bocanegra, David; Fernández-Oliveras, Alicia

    2013-11-01

    Reflectance measurements in interurban-road typical pavements are essential for traffic security. The reflectance of interurban-road pavements presents high variability due to such variables as climatic and atmospheric conditions and the presence of foreign materials on the road (e.g. dirt, fuel or oil). For this reason, the recording of real-time measurements for these kinds of pavements is a complex task. However, its critical importance in traffic safety demands precise measurements under all the possible conditions. In this context, the use of remote-sensing systems working in the radar spectral range is of great interest. With active sensors that receive their own radar signal, the reflectance measurements made by the remote-sensing system are not influenced by the atmospheric conditions. In this work, we present a radar-based methodology to develop real-time measurements of the reflectance in typical interurban-road pavements. We are engaged in extending this new method to study the reflectance of interurban-road pavements within the visible spectrum.

  19. PAHs underfoot: Contaminated dust from coal-tar sealcoated pavement is widespread in the United States

    Science.gov (United States)

    Van Metre, P.C.; Mahler, B.J.; Wilson, J.T.

    2009-01-01

    We reported in 2005 that runoff from parking lots treated with coal-tar-based sealcoat was a major source of polycyclic aromatic hydrocarbons (PAHs) to streams in Austin, Texas. Here we present new data from nine U. S. cities that show nationwide patterns in concentrations of PAHs associated with sealcoat Dust was swept from parking lots in six cities in the central and eastern U. S., where coal-tar-based sealcoat dominates use, and three cities in the western U. S., where asphalt-based sealcoat dominates use. For six central and eastern cities, median ?? PAH concentrations in dust from sealcoated and unsealcoated pavement are 2200 and 27 mg/kg, respectively. For three western cities, median ?? PAH concentrations in dust from sealcoated and unsealcoated pavement are similar and very low (2. 1 and 0. 8 mg/kg, respectively). Lakes in the central and eastern cities where pavement was sampled have bottom sediments with higher PAH concentrations than do those in the western cities relative to degree of urbanization. Bottom-sediment PAH assemblages are similar to those of sealcoated pavement dust regionally, implicating coal-tar-based sealcoat as a PAH source to the central and eastern lakes. Concentrations of benzo[a]pyrene in dust from coal-tar sealcoated pavement and adjacent soils greatly exceed generic soil screening levels, suggesting that research on human-health risk is warranted.

  20. PAHs underfoot: contaminated dust from coal-tar sealcoated pavement is widespread in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Peter C. Van Metre; Barbara J. Mahler; Jennifer T. Wilson [U.S. Geological Survey, Austin, TX (USA)

    2009-01-15

    We reported in 2005 that runoff from parking lots treated with coal-tar-based sealcoat was a major source of polycyclic aromatic hydrocarbons (PAHs) to streams in Austin, Texas. Here we present new data from nine U.S. cities that show nationwide patterns in concentrations of {Sigma}PAHs associated with sealcoat. Dust was swept from parking lots in six cities in the central and eastern U.S., where coal-tar-based sealcoat dominates use, and three cities in the western U.S., where asphalt-based sealcoat dominates use. For six central and eastern cities, median SPAH concentrations in dust from sealcoated and unsealcoated pavement are 2200 and 27 mg/kg, respectively. For three western cities, median SPAH concentrations in dust from sealcoated and unsealcoated pavement are similar and very low (2.1 and 0.8 mg/kg, respectively). Lakes in the central and eastern cities where pavement was sampled have bottom sediments with higher PAH concentrations than do those in the western cities relative to degree of urbanization. Bottom-sediment PAH assemblages are similar to those of sealcoated pavement dust regionally, implicating coal-tar-based sealcoat as a PAH source to the central and eastern lakes. Concentrations of benzo(a)pyrene in dust from coal-tar sealcoated pavement and adjacent soils greatly exceed generic soil screening levels, suggesting that research on human-health risk is warranted. 30 refs., 4 figs., 2 tabs.

  1. Life Cycle Assessment of Pavements: A Critical Review of Existing Literature and Research

    Energy Technology Data Exchange (ETDEWEB)

    Santero, Nicholas; Masanet, Eric; Horvath, Arpad

    2010-04-20

    This report provides a critical review of existing literature and modeling tools related to life-cycle assessment (LCA) applied to pavements. The review finds that pavement LCA is an expanding but still limited research topic in the literature, and that the existing body of work exhibits methodological deficiencies and incompatibilities that serve as barriers to the widespread utilization of LCA by pavement engineers and policy makers. This review identifies five key issues in the current body of work: inconsistent functional units, improper system boundaries, imbalanced data for asphalt and cement, use of limited inventory and impact assessment categories, and poor overall utility. This review also identifies common data and modeling gaps in pavement LCAs that should be addressed in future work. These gaps include: the use phase (rolling resistance, albedo, carbonation, lighting, leachate, and tire wear and emissions), asphalt fumes, feedstock energy of bitumen, traffic delay, the maintenance phase, and the end-of-life phase. This review concludes with a comprehensive list of recommendations for future research, which shed light on where improvements in knowledge can be made that will benefit the accuracy and comprehensiveness of pavement LCAs moving forward.

  2. Distress screening using distress thermometer in head and neck cancer patients undergoing radiotherapy and evaluation of causal factors predicting occurrence of distress

    Directory of Open Access Journals (Sweden)

    Shirley Lewis

    2013-01-01

    Full Text Available Introduction: Distress is commonly seen in head and neck cancer patients undergoing radiotherapy. Causal factors of distress are multifactorial; which encompasses physical, psychological, spiritual, and existential factors with complex interrelationship among the factors. Materials and Methods: Thirty patients undergoing head and neck radiotherapy were included in the study. Patients were screened for pain scores, distress scores, physical and psychological symptoms, and spiritual and emotional distress. Results: Significant increasing trend seen for pain score, distress score, and total number of symptoms during 2 nd week, 4 th week, and on completion of radiotherapy treatment (all P′s < 0.001 compared to pretreatment. Those who had chemotherapy (CT along with radiation had significantly greater pain score (t = 5.54, P = 0.03 and distress score (t = 3.9, P = 0.05 at 2 weeks into radiotherapy compared to those who did not receive CT. There was significantly higher grade of skin toxicity in those with spiritual distress (Somers′ d = 0.36, P = 0.02 and higher grade of mucositis in those with existential distress (d = 0.34, P = 0.02 at 4 weeks into radiotherapy. Conclusion: Positive correlation between distress score and pain score and occurrence of physical symptoms. Increasing trend seen for pain score, distress score, and total number of symptoms during 2 nd week, 4 th week, and completion of radiotherapy treatment compared to pretreatment. Increase in distress score in those with existential and spiritual distress.

  3. Psychological distress among women with newly diagnosed breast cancer

    DEFF Research Database (Denmark)

    Mertz, Birgitte; Bistrup, Pernille Envold; Johansen, Christoffer; Dalton, Susanne Oksbjerg; Deltour, Isabelle; Kehlet, Henrik; Kroman, Niels

    2012-01-01

    PURPOSE: Psychological distress is common in the cancer continuum. Our objectives were to determine the prevalence of distress and to investigate the related problems and the characteristics of women with breast cancer who experienced psychological distress at the time of diagnosis. METHODS: We...... used cross-sectional data from a questionnaire study. Women with newly diagnosed breast cancer were consecutively invited to respond before breast surgery. Between October 2008 and October 2009, a total of 357 responded out of 426 (84%) invited. Among these, 343 patients completed the 'distress...... cut-off of 3 on the distress thermometer, 77% of women with breast cancer reported distress, whereas when the cut-off was 7, 43% were distressed. The mean distress score was 5.4 (SD, 3.1). The most frequently reported problems were worry (77%) and nervousness (71%). Distress was significantly...

  4. Challenges confronting road freight transport and the use of vehicle-pavement interaction analysis in addressing these challenges

    Scientific Electronic Library Online (English)

    W J vd M, Steyn; C L, Monismith; W A, Nokes; J T, Harvey; T J, Holland; N, Burmas.

    2012-04-01

    Full Text Available Traditional arguments for maintaining riding quality of pavement are expanded in this paper to examine the effects of deteriorating riding quality on vehicle operating costs, freight damage and logistics. The objectives of this paper are to analyse the effects of different levels of riding quality o [...] n a truck and its freight, and to discuss potential applications of the analysis in terms of effectiveness of the freight transport system. The paper discusses needs and drivers influencing freight transport costs, vehicle-pavement interaction concepts, and the potential physical effects and costs from roads with deteriorating riding quality. A case study is presented analysing vehicle-pavement interaction for selected roadways in California. It is concluded that investments in pavement and freight transport industry improvements can be investigated by applying vehicle-pavement interaction analysis to evaluate damage to pavement, vehicle and freight that would result from alternative levels of pavement riding quality. The paper recommends that existing concepts, tools and resources such as dedicated truck lanes and vehicle-pavement interaction analysis can help to improve the freight transport system. A framework is proposed to better understand the scale of potential impacts of riding quality from localised effects to larger-scale influences, including costs to customers and global competitiveness.

  5. Evaluating the Infiltration Performance of Eight Dutch Permeable Pavements Using a New Full-Scale Infiltration Testing Method

    Directory of Open Access Journals (Sweden)

    Floris Boogaard

    2014-07-01

    Full Text Available Permeable pavements are a type of sustainable urban drainage system (SUDS technique that are used around the world to infiltrate and treat urban stormwater runoff and to minimize runoff volumes. Urban stormwater runoff contains significant concentrations of suspended sediments that can cause clogging and reduce the infiltration capacity and effectiveness of permeable pavements. It is important for stormwater managers to be able to determine when the level of clogging has reached an unacceptable level, so that they can schedule maintenance or replacement activities as required. Newly-installed permeable pavements in the Netherlands must demonstrate a minimum infiltration capacity of 194 mm/h (540 l/s/ha. Other commonly used permeable pavement guidelines in the Netherlands recommend that maintenance is undertaken on permeable pavements when the infiltration falls below 0.50 m/d (20.8 mm/h. This study used a newly-developed, full-scale infiltration test procedure to evaluate the infiltration performance of eight permeable pavements in five municipalities that had been in service for over seven years in the Netherlands. The determined infiltration capacities vary between 29 and 342 mm/h. Two of the eight pavements show an infiltration capacity higher than 194 mm/h, and all infiltration capacities are higher than 20.8 mm/h. According to the guidelines, this suggests that none of the pavements tested in this study would require immediate maintenance.

  6. Psychological distress and in vitro fertilization outcome

    Science.gov (United States)

    Pasch, Lauri A.; Gregorich, Steven E.; Katz, Patricia K.; Millstein, Susan G.; Nachtigall, Robert D.; Bleil, Maria E.; Adler, Nancy E.

    2016-01-01

    Objective To examine whether psychological distress predicts IVF treatment outcome as well as whether IVF treatment outcome predicts subsequent psychological distress. Design Prospective cohort study over an 18-month period. Setting Five community and academic fertility practices. Patients Two hundred and two women who initiated their first IVF cycle. Interventions Women completed interviews and questionnaires at baseline and at 4, 10, and 18 months follow-up. Main Outcome Measures IVF cycle outcome and psychological distress. Results Using a binary logistic model including covariates (woman’s age, ethnicity, income, education, parity, duration of infertility, and time interval), pre-treatment depression and anxiety were not significant predictors of the outcome of the first IVF cycle. Using linear regression models including covariates (woman’s age, income, education, parity, duration of infertility, assessment point, time since last treatment cycle, and pre-IVF depression or anxiety), experiencing failed IVF was associated with higher post-IVF depression and anxiety. Conclusions IVF failure predicts subsequent psychological distress, but pre-IVF psychological distress does not predict IVF failure. Instead of focusing efforts on psychological interventions specifically aimed at improving the chance of pregnancy, these findings suggest that attention be paid to helping patients prepare for and cope with treatment and treatment failure. PMID:22698636

  7. Psychological distress among patients with epilepsy

    Directory of Open Access Journals (Sweden)

    Asma Khalid

    2011-01-01

    Full Text Available Background: Epilepsy is a disorder of the brain characterized by recurrent seizures which are physical reactions to sudden, usually brief, too much electrical discharges in a group of brain cells. Psychological distress often accompanies epilepsy. It badly affects the disease and the treatment outcome. Whereas, familial social support is a positive factor. The objective of the present study was to see the difference of Psychological distress among the patients of Epilepsy; the comparisons on the variables of the study were made between gender, age, marital status, education, socio-economic status and type of Epilepsy. Materials and Methods: Sample comprised of 50 patients with epilepsy. These participants were divided into three subgroups according to their ages that are children, adolescence and adults. Patients were taken from hospitals Islamabad and Muzaffarabad (AJK. Results: The result showed that psychological distress is higher among male patients with generalized epilepsy and among those who are un-married, un-educated, having low socioeconomic status and lower familial social support. Conclusion: It can be concluded that psychological distress is common co morbidity in patients with epilepsy. During treatment, Counseling to the patients and the family can better help in coping with distress during their illness.

  8. PERFORMANCE-BASED CONTRACTING IN CONSTRUCTION PHASE AND MAINTENANCE PHASE OF PAVEMENT

    Science.gov (United States)

    Yoshida, Takeshi

    Performance-based contracting for pavement in Japan started as performance warranties in construction phase, in 1999. Recently, road agencies have recognized the applicability of this type of contracting in outsourcing of maintenance activities. The objectives of this study are to clarify the issues of performance specifying in construction phase and maintenance phase of pavement, and to propose measures to be taken. This paper, with the recognition that the life of each pavement depends on performance standards for various attributes, reviews domestic and foreign examples of performance-based contracting. A performance standard based on the average of current practices can enhance product quality and service life with a warranty contract. Repair thresholds and response time for each deficiency should be considered as performance standards in maintenance phase.

  9. Plastic Damage Model to Evaluate the Fracture Size of Semi-Rigid Base Pavement

    Directory of Open Access Journals (Sweden)

    Cao Peng

    2013-01-01

    Full Text Available A simple supported beam model has been presented to simulate the response of semi-rigid pavement structure, which are consistent of the upper layer, middle layer, bottom layer, base and sub base course, during the cycle vehicle loading. This mechanics model coupled with plastic-damage mechanics model could simulate the limit broken of the pavement structure in condition that soil base layer losing bearing capacity gradually. In the meanwhile, numerical calculations based on preceding mechanics model, using the FEM software ABAQUS, have been used to define the broken size of beam. The results indicated that: when the size of simple supported beam expanded to 10 m, brittle damage could happen immediately, Just the standard vehicle loading (about 0.7 Mpa has been implement once. Objective of this study is to provide a physical and rather concrete explanation for the style and concept of the semi-rigid pavement brittle broken.

  10. A Method to Estimate the Dynamic Displacement and Stress of a Multi-layered Pavement with Bituminous or Concrete Materials

    Directory of Open Access Journals (Sweden)

    Zheng LU

    2014-12-01

    Full Text Available In this research work, a method to estimate the dynamic characteristics of a multilayered pavement with bituminous or concrete materials is proposed. A mechanical model is established to investigate the dynamic displacement and stress of the multi-layered pavement structure. Both the flexible and the rigid pavements, corresponding to bituminous materials and concrete materials, respectively, are studied. The theoretical solutions of the multi-layered pavement structure are deduced considering the compatibility condition at the interface of the structural layers. By introducing FFT (Fast Fourier Transform algorithm, some numerical results are presented. Comparisons of the theoretical and experimental result implied that the proposed method is reasonable in predicting the stress and displacement of a multi-layered pavement with bituminous or concrete materials. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6071

  11. Life cycle assessment of representative swiss road pavements for national roads with an accompanying life cycle cost analysis.

    Science.gov (United States)

    Gschösser, Florian; Wallbaum, Holger

    2013-08-01

    The subject of this paper is an environmental life cycle assessment (LCA) and life cycle cost analysis (LCCA) of processes needed to construct and maintain representative Swiss asphalt, concrete, and composite pavements (including subbase layers) applicable for the Swiss national road network over a period of 75 years. The environmental indicators analyzed are the global warming potential indicator, the nonrenewable cumulative energy demand, and the Swiss ecological scarcity indicator. Processes of the use phase of the road (fuel consumption, noise, etc.) have been evaluated qualitatively based on intensive research. The study shows that the global warming potential of concrete and asphalt pavements equilibrates over the analysis period and that concrete pavements compared to asphalt and composite pavements offer advantages in regards to the nonrenewable cumulative energy demand, the ecological scarcity indicator, and life cycle costs. The qualitative evaluation of the processes of the use phase shows for example the positive qualities of concrete pavements regarding fuel consumption and permanent noise properties. PMID:23865779

  12. Oxygen demand of aircraft and airfield pavement deicers and alternative freezing point depressants

    Science.gov (United States)

    Corsi, Steven; Mericas, Dean; Bowman, George

    2012-01-01

    Aircraft and pavement deicing formulations and other potential freezing point depressants were tested for biochemical oxygen demand (BOD) and chemical oxygen demand (COD). Propylene glycol-based aircraft deicers exhibited greater BOD5 than ethylene glycol-based aircraft deicers, and ethylene glycol-based products had lower degradation rates than propylene glycol-based products. Sodium formate pavement deicers had lower COD than acetate-based pavement deicers. The BOD and COD results for acetate-based pavement deicers (PDMs) were consistently lower than those for aircraft deicers, but degradation rates were greater in the acetate-based PDM than in aircraft deicers. In a 40-day testing of aircraft and pavement deicers, BOD results at 20°C (standard) were consistently greater than the results from 5°C (low) tests. The degree of difference between standard and low temperature BOD results varied among tested products. Freshwater BOD test results were not substantially different from marine water tests at 20°C, but glycols degraded slower in marine water than in fresh water for low temperature tests. Acetate-based products had greater percentage degradation than glycols at both temperatures. An additive component of the sodium formate pavement deicer exhibited toxicity to the microorganisms, so BOD testing did not work properly for this formulation. BOD testing of alternative freezing point depressants worked well for some, there was little response for some, and for others there was a lag in response while microorganisms acclimated to the freezing point depressant as a food source. Where the traditional BOD5 test performed adequately, values ranged from 251 to 1,580 g/kg. Where the modified test performed adequately, values of BOD28 ranged from 242 to 1,540 g/kg.

  13. How to transform an asphalt concrete pavement into a solar turbine

    International Nuclear Information System (INIS)

    Highlights: • We create a system for harvesting energy from asphalt concrete. • We create an artificial porosity in the asphalt concrete. • We connect a chimney to this porosity. • Differences in temperature produce an air flow. • This air flow serves also for cooling down the pavement. - Abstract: Asphalt concrete can absorb a considerable amount of the incident solar radiation. For this reason asphalt roads could be used as solar collectors. There have been different attempts to achieve this goal. All of them have been done by integrating pipes conducting liquid, through the structure of the asphalt concrete. The problem of this system is that all pipes need to be interconnected: if one is broken, the liquid will come out and damage the asphalt concrete. To overcome these limitations, in this article, an alternative concept is proposed:parallel air conduits, where air can circulate will be integrated in the pavement structure. The idea is to connect these artificial pore volumes in the pavement to an updraft or to a downdraft chimney. Differences of temperature between the pavement and the environment can be used to create an air flow, which would allow wind turbines to produce an amount of energy and that would cool the pavement down in summer or even warm it up in winter. To demonstrate that this is possible, an asphalt concrete prototype has been created and basics calculations on the parameters affecting the system have been done. It has been found that different temperatures, volumes of air inside the asphalt and the difference of temperature between the asphalt concrete and the environment are critical to maximize the air flow through the pavement. Moreover, it has been found that this system can be also used to reduce the heat island effect

  14. Field Evaluation of Nondestructive Tests in Measuring the Pavement Layers Density

    OpenAIRE

    H. Divandary; A Izadi; H. Behbahani; H. Ziari

    2010-01-01

    The aim of this study was field evaluation of nondestructive devices in measuring the density of road layers. Density may be considered as a reliable criterion for evaluating pavement quality and has a high level of importance in that it can ensure the proper performance of pavement at least prior the period of life-time. At present time, the most current and also accurate method to determine in-situ density of asphalt mixture is core sample method, however it has some disadvantages. As well ...

  15. Building Asphalt Pavement with SBS-based Compound Added Using a Dry Process in Greenland

    DEFF Research Database (Denmark)

    Lee, Hosin; Kim, Yongjoo; Geisler, Nivi; Jørgensen, Anders Stuhr; Villumsen, Arne; Cheon, S.; Pyun, J.

    -based compound seemed to affect the asphalt mix to become more flexible under the heavy loads. By adding SBS-based compound to asphalt mixtures using a “dry” process, it is expected that the pavement would become more resistant to rutting than a typical asphalt mixture used in Greenland while enduring its arctic...... PMA where it is formulated to melt and blend with asphalt quickly during a batch mixing process. The main objectives of this study are to (1) build asphalt pavement using asphalt mixtures with SBS-based compound added using a “dry” process at the batch plant and (2) evaluate its performance under...

  16. A comprehensive approach for the assessment of in-situ pavement density using GPR technique

    Science.gov (United States)

    Plati, Christina; Georgiou, Panos; Loizos, Andreas

    2013-04-01

    Proper construction of the asphalt pavement is a prerequisite to developing a long lasting roadway that does not require extensive future maintenance. This goal is achieved by verifying that design specifications are met through the use of quality assurance (QA) practices. The in-situ density is regarded as one of the most important controls used to ensure that a pavement being placed is of high quality because it is a good indicator of future performance. In-situ density is frequently assessed utilizing one or more of the following three methods: cores, nuclear density gauge measurements or non-nuclear density gauge measurements. Each of the above mentioned methods, however, have their distinct disadvantages. Cores, for example, are generally considered to be the most accurate means of measuring in-situ density, however, they are a time consuming and destructive test that introduces a defect into asphalt pavements. Because of the destructive nature associated with coring, contractors and agencies have alternatively used non-destructive nuclear and non-nuclear density gauges for quality control purposes. These instruments allow for a more rapid assessment of the in-situ density, allowing measurements to be taken even during the pavement's construction. The disadvantage of these gauges are that they provide density readings only at discrete locations of the asphalt pavement mat, while no consensus exists among pavement researchers on the proper correlation between the gauges and core density. In recent years, numerous alternative methods have been introduced for the assessment of in-situ density, both during asphalt pavement construction and afterwards. These methods include, amongst others, intelligent compaction, thermal imaging and ground penetrating radar (GPR). Among these methods, GPR has been defined as both a technically feasible and promising method for the nondestructive, rapid, and continuous evaluation of in-situ asphalt pavement density based on electromagnetic mixing (EM) theory, through the utilization of proper models. These models enable the prediction of asphalt mixture density dependent on its bulk dielectric constant as measured by the GPR, the dielectric properties of the asphalt mix materials, as well as other material information. The goal of the present study is to attempt to verify the prediction performance of various density models. To accomplish this goal GPR surveys were carried out in the field during asphalt pavement construction to evaluate the density results due to different compaction modes. The GPR data was analyzed to calculate the appropriate asphalt mix dielectric properties needed for the activation of the considered density prediction models. Predicted densities were compared with densities of the field cores extracted from the as-built asphalt pavement prior to trafficking. It was found that the predicted density values were significantly lower when compared to the ground truth data. A further investigation of the effect of temperature on GPR readings showed that GPR seems to overestimate the in-situ density. However, this approach could be used effectively to evaluate the performance of different compaction methods and set up the compaction pattern that is needed to achieve the desired asphalt pavement density.

  17. 47 CFR 80.319 - Radiotelegraph distress call and message transmission procedure.

    Science.gov (United States)

    2010-10-01

    ...false Radiotelegraph distress call and message transmission procedure. 80.319 ...319 Radiotelegraph distress call and message transmission procedure. (a...The distress call; (4) The distress message; (5) Two dashes of ten to...

  18. Development of a distress inventory for cancer: preliminary results.

    OpenAIRE

    Thomas B; Mohan V; Thomas I; Pandey M

    2002-01-01

    CONTEXT: Advances in cancer treatment have led to cure and prolongation of patients? lives; however associated psychosocial problems, including distress, can detrimentally affect patients? compliance with treatment and ultimately, their outcome. Symptom distress has been well addressed in many studies; however, psychological distress has only been quantified by using depression or anxiety scales/checklists or quality of life scales containing a distress sub scale/component or by...

  19. Interpersonal Relationships and Emotional Distress in Adolescence

    Science.gov (United States)

    Kenny, Rachel; Dooley, Barbara; Fitzgerald, Amanda

    2013-01-01

    The aim of this study was to examine positive and negative qualities in adolescents' interpersonal relationships and their relative importance in predicting emotional distress. Participants were 260 students from three schools in the Dublin area (119 girls; 141 boys), aged 12-18 years (M = 15.32, SD = 1.91). Students completed questionnaires…

  20. Happiness and Death Distress: Two Separate Factors

    Science.gov (United States)

    Abdel-Khalek, Ahmed M.

    2005-01-01

    The aim of the present study was to explore the relationship between happiness and death distress (death anxiety, death depression, and death obsession) in 275 volunteer Kuwaiti undergraduates. They responded to the Oxford Happiness Inventory, the Death Anxiety Scale, the Arabic Scale of Death Anxiety, the Death Depression Scale-Revised, and the…

  1. Disordered Eating and Psychological Distress among Adults

    Science.gov (United States)

    Patrick, Julie Hicks; Stahl, Sarah T.; Sundaram, Murali

    2011-01-01

    The majority of our knowledge about eating disorders derives from adolescent and young adult samples; knowledge regarding disordered eating in middle and later adulthood is limited. We examined the associations among known predictors of eating disorders for younger adults in an age-diverse sample and within the context of psychological distress

  2. Once Distressed, Jackson County Moves On.

    Science.gov (United States)

    Baldwin, Fred D.

    1998-01-01

    In 1981, Jackson County, North Carolina, appeared on the first list of "distressed counties" in Appalachia. Since then, the rural county has made significant improvements by investing in its physical infrastructure (which also promotes tourism); fostering economic-development partnerships among governments, small businesses, and local colleges;…

  3. Disordered Eating and Psychological Distress among Adults

    Science.gov (United States)

    Patrick, Julie Hicks; Stahl, Sarah T.; Sundaram, Murali

    2011-01-01

    The majority of our knowledge about eating disorders derives from adolescent and young adult samples; knowledge regarding disordered eating in middle and later adulthood is limited. We examined the associations among known predictors of eating disorders for younger adults in an age-diverse sample and within the context of psychological distress.…

  4. Techno- Economical Study of Rigid Pavement by Using the Used Foundry Sand

    Directory of Open Access Journals (Sweden)

    Vipul D. Prajapati1 , Nilay Joshi2 , Prof. Jayeshkumar Pitroda

    2013-05-01

    Full Text Available Indian road network of almost 3.5 million km comprising both paved and unpaved surfaces is the world’s second largest. Indian roads are presently constructed with not the right choice of material. The two major types of materials, bitumen and concrete are used in road construction in the country. A very small share of roads in the country is made of concrete. Though, it is superior on many counts as a medium for road buildings. The use of large amount of by-product materials as powder or fines not only avoids the requirement of landfills but also reduce the environmental problems. It is most essential to develop profitable building materials from used foundry sand. The innovative use of used foundry sand in concrete formulations as a fine aggregate replacement material was tested as an alternative to traditional concrete. The fine aggregate has been replaced by used foundry sand accordingly in the range of 0%, 10%, 30% & 50% by weight for M-20 grade concrete. Concrete mixtures were produced, tested and compared in terms of compressive and flexural strength with the conventional concrete. These tests were carried out to evaluate the mechanical properties for 7, 14 and 28 days. This research work is to investigate the behaviour of concrete while replacing used foundry sand in different proportion in concrete. This low cost concrete with good strength is used in rigid pavement for 3000 commercial vehicles per day (cvpd and Dry Lean Concrete (DLC 100mm thick for national highway to make it eco-friendly.

  5. Negative Emotions and Behaviors are Markers of Breakup Distress

    Science.gov (United States)

    Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeanette

    2013-01-01

    Method: University students who experienced a recent romantic breakup were given several self-report measures and were then divided into high versus low breakup distress groups. Results: The high breakup distress versus the low breakup distress groups had higher scores on negative emotions scales including depression, anxiety and anger and…

  6. Emotional Distress in College Students: Faculty Guide for Referrals.

    Science.gov (United States)

    Western Carolina Univ., Cullowhee, NC. Counseling and Psychological Services.

    This guide presents advice for university faculty and professional staff members to help them understand and respond when students are in emotional distress. It includes a reference for signs of extreme stress and advice on how to intervene. Common causes of emotional distress are listed and warning signs of distress are given. Suggestions are…

  7. Predictors of Psychological Distress among Infertility Clinic Patients.

    Science.gov (United States)

    Morrow, Kelly A.; And Others

    1995-01-01

    Investigated predictors of psychological distress among infertility clinic patients. Analyses indicated that infertile men and women reported greater psychological distress than the general population. Self-blame and avoidance coping significantly predicted psychological distress among men and women. Increased age and childlessness added to…

  8. Stomatal and pavement cell density linked to leaf internal CO2 concentration.

    Czech Academy of Sciences Publication Activity Database

    Šantr??ek, Ji?í; Vráblová, M.; Šimková, Marie; Hronková, Marie; Drtinová, M.; Kv?to?, J.; Vrábl, D.; Kubásek, J.; Macková, J.; Wiesnerová, Dana; Neuwithová, J.; Schreiber, L.

    2014-01-01

    Ro?. 114, ?. 2 (2014), s. 191-202. ISSN 0305-7364 R&D Projects: GA ?R(CZ) GAP501/12/1261 Institutional support: RVO:60077344 Keywords : Stomatal density * Stomata development * Pavement cells Subject RIV: CE - Biochemistry Impact factor: 3.654, year: 2014

  9. Technical Note: Outlays on Construction of Airport Runways with Prestressed and Dowelled Pavements

    Science.gov (United States)

    Wi?ckowski, Andrzej; Sznurawa, Alicja

    2015-09-01

    For two variants of runways with abrasive concrete pavements in the prestressed and dowelled technologies, analyses have been presented regarding labour, materials, use of machinery, and financial outlays, together with the necessary technological-organisational analyses and assessment of work execution cycles, by the example of construction of a runway at the Katowice Airport.

  10. EVALUATION OF RUTTING DEPTH IN FLEXIBLE PAVEMENTS BY USING FINITE ELEMENT ANALYSIS AND LOCAL EMPIRICAL MODEL

    Directory of Open Access Journals (Sweden)

    Alaa H. Abed

    2012-01-01

    Full Text Available The objective of this research is to predict rut depth in local flexible pavements. Predication model in pavement performance is the process that used to estimate the parameter values which related to pavement structure, environmental condition and traffic loading. The different local empirical models have been used to calculate permanent deformation which include environmental and traffic conditions. Finite element analysis through ANSYS computer software is used to analyze two dimensional linear elastic plane strain problem through (Plane 82 elements. Standard Axle Load (ESAL of 18 kip (80 kN loading on an axle with dual set of tires, the wheel spacing is 13.5 in (343 mm with tire contact pressure of 87 psi (0.6 MPa is used. The pavement system is assumed to be an elastic multi-layers system with each layer being isotropic, homogeneous with specified resilient modulus and Poisson ratio. Each layer is to extend to infinity in the horizontal direction and have a finite thickness except the bottom layer. The analysis of results show that, although, the stress level decrease 14% in the leveling course and 27% in the base course, the rut depth is increased by 12 and 28% in that layers respectively because the material properties is changed.

  11. 23 CFR 972.208 - Federal lands pavement management system (PMS).

    Science.gov (United States)

    2010-04-01

    ... “Pavement Management Guide,” AASHTO, 2001, is available for inspection as prescribed at 49 CFR part 7. It is... HIGHWAYS FISH AND WILDLIFE SERVICE MANAGEMENT SYSTEMS Fish and Wildlife Service Management Systems § 972... of project dates and types of construction, reconstruction, rehabilitation, and...

  12. Reducing greenhouse gas emissions through strategic management of highway pavement roughness

    Science.gov (United States)

    Wang, Ting; Harvey, John; Kendall, Alissa

    2014-03-01

    On-road vehicle use is responsible for about a quarter of US annual greenhouse gas (GHG) emissions. Changes in vehicles, travel behavior and fuel are likely required to meet long-term climate change mitigation goals, but may require a long time horizon to deploy. This research examines a near-term opportunity: management of pavement network roughness. Maintenance and rehabilitation treatments can make pavements smoother and reduce vehicle rolling resistance. However, these treatments require material production and equipment operation, thus requiring a life cycle perspective for benefits analysis. They must also be considered in terms of their cost-effectiveness in comparison with other alternatives for affecting climate change. This letter describes a life cycle approach to assess changes in total GHG (measured in CO2-e) emissions from strategic management of highway pavement roughness. Roughness values for triggering treatments are developed to minimize GHG considering both treatment and use phase vehicle emission. With optimal triggering for GHG minimization, annualized reductions on the California state highway network over a 10-year analysis period are calculated to be 0.82, 0.57 and 1.38 million metric tons compared with historical trigger values, recently implemented values and no strategic intervention (reactive maintenance), respectively. Abatement costs calculated using /metric-ton CO2-e are higher than those reported for other transportation sector abatement measures, however, without considering all benefits associated with pavement smoothness, such as vehicle life and maintenance, or the time needed for deployment.

  13. Coal-tar-based pavement sealcoat, polycyclic aromatic Hydrocarbons (PAHs), and environmental health

    Science.gov (United States)

    Mahler, B.J.; Van Metre, P.C.

    2011-01-01

    Studies by the U.S. Geological Survey (USGS) have identified coal-tar-based sealcoat-the black, viscous liquid sprayed or painted on asphalt pavement such as parking lots-as a major source of polycyclic aromatic hydrocarbon (PAH) contamination in urban areas for large parts of the Nation. Several PAHs are suspected human carcinogens and are toxic to aquatic life.

  14. Plutonium distribution in a desert pavement-desert mound soil system in area 11

    International Nuclear Information System (INIS)

    This interim report presents data on 238Pu, 239Pu, 240Pu, and 241Am distribution in a desert pavement desert-mount soil system in Area 11 of the Nevada Test Site. Total plutonium soil concentrations with depth, plutonium concentrations in the different particle size classes, and preliminary information on plutonium distribution as a function of mineral density fractions are included

  15. 78 FR 26847 - Including Specific Pavement Types in Federal-aid Highway Traffic Noise Analyses

    Science.gov (United States)

    2013-05-08

    ... (OGAC), and Portland cement concrete (PCC). Prediction of future noise levels is based on the ``average... Federal Highway Administration Including Specific Pavement Types in Federal-aid Highway Traffic Noise... types used in Federal-aid highway traffic noise analyses. Current highway traffic noise analyses rely...

  16. Estimation of doses from radioactively contaminated disaster wastes reused for pavements

    International Nuclear Information System (INIS)

    It is desirable that the disaster wastes contaminated by radioactive cesium after the severe accident at the Fukushima Nuclear Plant are reused as much as possible in order to minimize the quantity to be disposed of. Ministry of the Environment showed the policy that the wastes containing cesium of higher concentration than the clearance level (100 Bq/kg) were reusable as materials of construction such as subbase course materials of pavements under controlled condition with measures to lower exposure doses. In this study, in order to provide technical information for making a guideline on the use of contaminated concrete materials recycled from disaster wastes as pavement, doses for workers and the public were estimated, and the reusable concentration of radioactive cesium in the wastes was evaluated. It was shown that the external exposure of the public (children) residing near the completed pavement gave the minimum radiocesium concentration in order to comply with the dose criteria. The recycled concrete materials whose average concentration of cesium lower than 2,700 Bq/kg can be used as the subbase course materials of pavements. (author)

  17. Quantifying Evaporation and Evaluating Runoff Estimation Methods in a Permeable Pavement System - abstract

    Science.gov (United States)

    Studies on quantifying evaporation in permeable pavement systems are limited to few laboratory studies that used a scale to weigh evaporative losses and a field application with a tunnel-evaporation gauge. A primary objective of this research was to quantify evaporation for a la...

  18. Technical Note: Outlays on Construction of Airport Runways with Prestressed and Dowelled Pavements

    Directory of Open Access Journals (Sweden)

    Wi?ckowski Andrzej

    2015-09-01

    Full Text Available For two variants of runways with abrasive concrete pavements in the prestressed and dowelled technologies, analyses have been presented regarding labour, materials, use of machinery, and financial outlays, together with the necessary technological-organisational analyses and assessment of work execution cycles, by the example of construction of a runway at the Katowice Airport.

  19. Agency and Design: Pavement Failure in the Transmilenio Project, Bogotá, Colombia

    DEFF Research Database (Denmark)

    Pineda, Andres Felipe Valderrama

    Transmilenio is the world’s first mass rapid bus transit system designed and built for the city of Bogotá, Colombia. Its first phase was developed and built during the years 1998-2000. The concrete pavement of the cities main corridor, Avenida Caracas and Autopista Norte, was designed and re...

  20. Response of pavement to freeze-thaw cycles: Lebanon, New Hampshire, regional airport

    Science.gov (United States)

    Allen, Wendy L.; Quinn, William F.; Keller, Donald; Eaton, Robert A.

    1989-01-01

    In 1978 reconstruction was begun on the runway of the Lebanon Regional Airport, Lebanon, New Hampshire. The runway had experienced severe differential frost heaving and cracking during the previous three winters, which had resulted in closure of the facility during periods of extreme roughness. Temperature sensors were placed within the newly constructed pavement sections, and during the winters of 1979, 1980, and 1982 temperature data were recorded, and level surveys and repeated plate bearing tests were performed in order to provide data for the investigation. The three pavement sections were constructed to investigate the effect of section thickness on the level of frost protection provided. The sections consisted of 4 in. of asphalt concrete, 6 in. of crushed gravel and 22,30 dn 38 in. of well-graded sand subbase material. The 48-in section provided the highest level of frost protection to the subgrade. However, all three pavement sections maintained resilient stiffness values during the spring thaw period on the order of two to three times that of the pavement before reconstruction. Also, frost heave in all sections was reduced to levels that would not cause difficulty for aircraft using the facility.

  1. Effects of diurnal temperature dynamics on curing of cold-emulsion reclaimed asphalt pavements

    Directory of Open Access Journals (Sweden)

    Kiplagat Chelelgo

    2010-11-01

    Full Text Available Strength development in Cold-Emulsion Reclaimed Asphalt Pavements is gradual and largely dependent on the rate at which curing proceeds. Its early life strength is therefore low and presents a major challenge in material specification for mechanistic pavement design. The solution has been to subject a sample of the mixture to be used in the pavement to accelerated laboratory curing to the attainment of Equilibrium Moisture Content (EMC condition. Fatigue and Stiffness parameters of the mix along with the chemical properties of the binder can be determined from the cured samples and results incorporated into the pavement design process. The emphasis is in the choice of a laboratory curing protocol that adequately simulates expected curing trends in the field. Protocols in popular use employ steady state curing temperatures to predict long term behaviour of Reclaimed Asphalt Pavements. This project set out to investigate the likely effects of seasonal variations and diurnal cycles in ambient temperatures on the engineering properties of Reclaimed Asphalt and the incorporated binders. To simulate the above phenomena, a predictive model was adopted in computation of high and low temperature peaks that can be expected in two pavements, one in the tropics and the other in a temperate region. The resulting sets of temperatures were used to cyclically cure Reclaimed Asphalt Pavement cores that were manufactured by artificially aging Dense Bitumen Macadam (DBM in the laboratory and mixing it with a cationic bitumen emulsion. Another set of cores were subjected to steady temperatures as is the current practice. This acted as a control for the two cyclic temperatures under study. Use was made of a suite of tests available in the Nottingham Asphalt Tester (NAT to determine stiffness and fatigue properties of the mix under the three treatments. Bitumen binders recovered at the end of curing was tested for penetration, softening point temperatures and percentage of Asphaltenes. The findings pointed at a likelihood of severe treatment of asphalt samples by the existing laboratory curing protocols. Curing at a steady temperature led to a lower fatigue life, over estimation of early life strength and underestimation of long term strength of the cold asphalt. Low penetration values, high softening point temperatures and high percentages of Asphaltenes in bitumen from the cured samples attest to severe aging of the samples.

  2. Late Financial Distress Process Stages and Financial Ratios

    DEFF Research Database (Denmark)

    Sormunen, Nina; Laitinen, Teija

    usefulness of single financial ratios in short-term financial distress prediction when the effect of each different financial distress process stage is considered; (2) the effects of recognition of the financial distress process stage on the financial distress prediction model. The time horizon for...... according to the date of application for reorganization: the first group of businesses applied for reorganization between 1 and 182 days after the closing of accounts, and the second group between 183 and 365 days after that point. The study findings provide evidence that the financial distress process...

  3. Road Edge of Pavement, Road Edge of Pavement in Iredell County, NC from 2005 Orthophotography, Published in 2005, 1:2400 (1in=200ft) scale, Iredell County GIS.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Road Edge of Pavement dataset, published at 1:2400 (1in=200ft) scale, was produced all or in part from Orthoimagery information as of 2005. It is described as...

  4. Associations between faith, distress and mental adjustment

    DEFF Research Database (Denmark)

    Johannessen-Henry, Christine Tind

    2013-01-01

    spiritual well-being, the faith dimension of spiritual well-being and aspects of performed faith are associated with distress and mental adjustment among cancer patients. Methods. In a cross-sectional design, 1043 survivors of various cancers filled in a questionnaire on spiritual well-being (FACIT-Sp-12......), specific aspects of faith ('belief in a god', 'belief in a god with whom I can talk' and 'experiences of god or a higher power'), religious community and church attendance (DUREL), distress (POMS-SF), adjustment to cancer (Mini-MAC) and sociodemographic factors. Linear regression models were used to...... adjustment. The results illustrate the complexity of associations between spiritual well-being and specific aspects of faith with psychological function among cancer survivors...

  5. Negotiating with Labor under Financial Distress

    OpenAIRE

    Benmelech, Efraim; Bergman, Nittai; Enriquez, Ricardo J.

    2012-01-01

    We analyze how firms renegotiate labor contracts to extract concessions from labor. While anecdotal evidence suggests that firms tend to renegotiate wages downward in times of financial distress, there is no empirical evidence that documents such renegotiation, its determinants, and its magnitude. This article attempts to fill this gap. Using a unique data set of airlines, which includes detailed information on wages and pension plans, we document an empirical link between airline financial d...

  6. Mental distress: Strategies of sense-making

    OpenAIRE

    Cardano, Mario

    2010-01-01

    The irruption of severe mental distress into the life of an individual determines a deep biographical disruption. To cope with this crisis, individuals are involved in a laborious sense-making activity, through the composition of narratives intended to create a new link between past, present and future. This essay analyses the sense-making strategies that follow this dramatic experience through the comparison of four illness narratives composed by Italian participants. The narr...

  7. Road Edge of Pavement, MCAMLIS Topo, Published in 2010, 1:1200 (1in=100ft) scale, Milwaukee County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Road Edge of Pavement dataset, published at 1:1200 (1in=100ft) scale, was produced all or in part from Orthoimagery information as of 2010. It is described as...

  8. Road Edge of Pavement, Published in Not Provided, 1:12000 (1in=1000ft) scale, Geospatial Viz.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Road Edge of Pavement dataset, published at 1:12000 (1in=1000ft) scale, was produced all or in part from Road Centerline Files information as of Not Provided....

  9. A TECHNIQUE OF ESTIMATION OF TECHNICAL CONDITION OF RIGID AIRFIELD PAVEMENTS IN THE CONTEXT OF RISK THEORY

    Directory of Open Access Journals (Sweden)

    A. N. Popov

    2012-02-01

    Full Text Available Problem statement. To provide for safe takeoff and landing of modern aviation complexes, specialattention is given to technical condition of artificial pavements of runways which can be serviceableor faulty, efficient or limiting. Available standard methods of an expeditious estimation of an operational-technical condition of airfield pavements are based on general principles of defect graduationand of definition of integrated total generalized indicator of pavement condition and often yield theresults contradicting each other, which complicate making decision in relation to operation.Results and conclusions. The classification of linear constructions of airfields by responsibilitylevel is proposed. Theoretical basics and practical recommendations on estimation of a technicalcondition of rigid airfield pavements by permissible level of are formulated with respect to level ofrisk with the use of principals of reliability theory and of risk theory. The recommendations proposedrest on new principles of technical regulation established by Federal Law N 184-FZ “Ontechnical regulation”.

  10. The career distress scale: Using Rasch measurement theory to evaluate a brief measure of career distress

    DEFF Research Database (Denmark)

    Creed, Peter; Hood, Michelle

    2015-01-01

    Career distress is a common and painful outcome of many negative career experiences, such as career indecision, career compromise, and discovering career barriers. However, there are very few scales devised to assess career distress, and the two existing scales identified have psychometric weaknesses. The absence of a practical, validated scale to assess this construct restricts research related to career distress and limits practitioners who need to assess and treat it. Using a sample of 226 young adults (mean age 20.5 years), we employed item response theory to assess 12 existing career distress items for model fit, item bias, location dependency, dimensionality, reliability, suitability of response options, and construct validity. Three of the 12 items examined were removed from consideration as they did not fit the Rasch model or were not invariant across groups. The remaining 9 items, which we combined into a scale labelled the Career Distress Scale, demonstrated excellent psychometric properties, meaning that both researchers and practitioners can use it with confidence, although continued validation is required, including testing its relationship to other nomological net variables, testing predictive validity, and assessing test-retest reliability.

  11. Effects of reclaimed asphalt pavement on indirect tensile strength test of foamed asphalt mix tested in dry condition

    International Nuclear Information System (INIS)

    Indirect tensile strength (ITS) test was conducted to analyse strength of the foamed asphalt mixes incorporating reclaimed asphalt pavement. Samples were tested for ITS after cured in the oven at 40°C for 72 hours. This testing condition known as dry condition or unconditioned. Laboratory results show that reclaimed asphalt pavement (RAP) contents insignificantly affect the ITS results. ITS results significantly affected by foamed bitumen contents.

  12. Riding Quality Model for Asphalt Pavement Monitoring Using Phase Array Type L-band Synthetic Aperture Radar (PALSAR)

    OpenAIRE

    Kamiya Yoshikazu; Weerakaset Suanpaga

    2010-01-01

    There are difficulties associated with near-real time or frequent pavement monitoring, because it is time consuming and costly. This study aimed to develop a binary logit model for the evaluation of highway riding quality, which could be used to monitor pavement conditions. The model was applied to investigate the influence of backscattering values of Phase Array type L-band Synthetic Aperture Radar (PALSAR). Training data obtained during 3–7 May 2007 was used in the development process, toge...

  13. A novel finite element method for designing floor slabs on grade and pavements with loads at edges

    OpenAIRE

    Hugo Ernesto Camero Sanabria

    2015-01-01

    In the present paper a methodology to design slabs on grade for industrial floors and pavements using bi-dimensional finite elements and integrating the subgrade in the design is presented. The suggested method to design slabs on grade for industrial floors and pavements has been called the Camero Finite Element Method.  An example of an industrial floor designed to be capable of sustaining an infinite number of load applications (or a 50 years lifespan period) is here presented in order to b...

  14. Performance-based and condition-based NDT for predicting maintenance needs of concrete highways and airport pavements

    Science.gov (United States)

    Hertlein, Bernhard H.; Davis, Allen G.

    1996-11-01

    The state-of-the-art for nondestructive testing (NDT) of highway and airport pavements was evaluated in the late 1980's as part of the Strategic Highway Rehabilitation Program (SHRP). This program included many research projects in pavement construction, testing, maintenance, and rehabilitation. The limitations, as well was the capabilities of the various NDT methods then extant were examined by joint teams of federal, state, academic, and private sector engineers and researchers. The SHRP program, and the allied long-term pavement performance program clearly demonstrated that certain NDT methods performed well on asphalt pavement but performed unsatisfactorily on concrete pavements, and vice-versa. Despite this, some methods are still being used inappropriately, while other promising techniques are virtually being ignored. This paper examines some of the reasons for this, and summarizes the research and current state-of-the-art for NDT of concrete airport and highway pavements. Promising avenues for further development of test equipment, applications, data analysis, and interpretation are also discussed.

  15. 3-D cohesive finite element model for application in structural analysis of heavy duty composite pavements

    DEFF Research Database (Denmark)

    Skar, Asmus; Poulsen, Peter Noe

    2015-01-01

    can be shown that adequately good prediction of the structural response of composite pavements is obtained for monotonic loading without significant computational cost, making the model applicable for engineering design purpose. It is envisaged that the methodology implemented in this study can be......The problem of stiffness degradation in composite pavement systems from localised fracture damage in the quasibrittle cement bound granular mixture are today taken into account only by empirical formulas. These formulas deals with a limited number of materials in a restricted range of design...... options and would yield unrealistic results in ultimate loading conditions. Cohesive modelling is one of the primary methods to handle localised damage in quasi-brittle materials, e.g., concrete, describing the potential crack in a discrete manner. To increase the versatility of existing methods this...

  16. Dynamic response of concrete pavement structure with asphalt isolating layer under moving loads

    Directory of Open Access Journals (Sweden)

    Jianmin Wu

    2014-12-01

    Full Text Available A three-dimensional finite element model (3D FEM is built using ABAQUS to analyze the dynamic response of a concrete pavement structure with an asphalt isolating layer under moving loads. The 3D model is prepared and validated in the state of no asphalt isolating layer. Stress and deflection at the critical load position are calculated by changing thickness, modulus of isolating layer and the combination between the isolating layer and concrete slab. Analysis result shows that the stress and deflection of the concrete slab increase with the increase of thickness. The stress and deflection of the concrete slab decrease with the increase of combination between the isolating layer and concrete slab. The influence of changing the isolating layer modulus to the stress and deflection of the concrete slab is not significant. From the results, asphalt isolating layer design is suggested in concrete pavement.

  17. The Effect of Joint Width on Structural Performance of Asphalt Block Pavements

    Directory of Open Access Journals (Sweden)

    Ahmed Abdelgalil

    2014-02-01

    Full Text Available Asphalt blocks have been occasionally used around the world as a road pavement, but there have been very limited studies being done to evaluate the effect of joint width (spacing between the blocks on the structural performance of asphalt paving blocks. This study explains the experimental study to assess the performance and properties of asphalt paving blocks laid with different joint widths between the blocks i.e., 0, 2 and 3 mm, respectively. A total of 250 asphalt paving blocks was manufactured and tested in the laboratory to ascertain the density, air voids, the compressive strength and the rut depth and displacement occurred in asphalt paving block. The design compressive load of single asphalt paving block is 166 kN. The test results showed that the joint width plays a vital role on the performance of asphalt block pavement. Asphalt paving blocks were laid as closely in contact as possible (0 mm yields the best structural performance.

  18. The road well travelled : implications of a changing climate on pavement infrastructure in southern Canada

    International Nuclear Information System (INIS)

    The implications of a changing climate on pavement infrastructure in southern Canada were examined. The session consisted of a presentation of a research project whose purpose was to understand how climate change may affect the frequency, severity and duration of conditions that lead to three forms of pavement deterioration and deformation including permanent deformation associated with heat-related rutting; thermal cracking associated with low temperatures; and frost heave and associated seasonal deformation stress. Interactions among climatic conditions, traffic volume/mix, and construction (e.g., design standards, materials) and maintenance variables were studied. The presentation consisted of a summary of the results from a literature review component of the project and findings from a preliminary analysis of historic climate data and future scenarios of climate change. tabs., figs

  19. Assessment of Distress Associated to Psychopathology in Children and Adolescents

    Directory of Open Access Journals (Sweden)

    Wendy Reich

    2009-04-01

    Full Text Available The aim of this paper was to study the distress associated to psychopathology in children and adolescents. The sample included 330 children aged 8 to 17 years attending outpatient mental health services of the public network in Barcelona(Spain assessed using a structured diagnostic interview. A substantial part of children brought to treatment suffered distress associated to internalizing and externalizing psychological symptoms. Psychological distress was most frequent among girls and among adolescents, and was more frequently reported by children and adolescents than by their parents. It was also a marker of perception of need of psychological help, and it was significantly related to diagnosis, subthreshold conditions and functional impairment. Individual symptoms of depression, dysthymia, generalized anxiety disorder and oppositional defiant disorder were most associated with psychological distress. Given the potential importance of subjective distress as well as impairment for the identification and definition of psychopathology and planning of treatment, diagnostic assessment should include questions related to distress.

  20. Psychological and physical distress of cancer patients during radiotherapy

    CERN Document Server

    König, A

    2001-01-01

    Purpose: patients undergoing radiotherapy have physical and psychological symptoms related to the underlying disease and the treatment. In order to give the best possible support to the patients, more knowledge about the amount and the changing of distress in the course of radiotherapy is of essentially importance. Methods: The distress was measured in a consecutive sample of cancer patients (n=82) undergoing radiotherapy. Each patient was given the EORTC-QLQ-C30, the HADS and a special questionnaire which ascertain radiotherapy-specific items before starting the radiotherapy, at the onset of radiotherapy, in the third week of radiotherapy and 3 weeks after the end of radiotherapy. Results: within the first week of treatment the psychological distress of the patients is increasing; 98.8 % of the patients are 'moderate distressed', 46 % 'severe distressed'. General physical symptoms seem not to be affected by the radiotherapy, there is no changing. The distress caused by the organization of the radiotherapy is...

  1. Distress among Indigenous North Americans: Generalized and Culturally Relevant Stressors.

    Science.gov (United States)

    Walls, Melissa L; Whitbeck, Les B

    2011-07-01

    Stress process and life-course models of mental distress emphasize socio-cultural and historical processes that influence stress exposure and the impact of stress on mental health outcomes. Drawing from these theoretical orientations as well as concepts from the historical trauma literature, we examine the effects of culturally relevant and more generalized sources of stress on distress among North American Indigenous adults, and tests for the potential cumulative and interactive effects of stress on distress across the life-course via self-reported early childhood and adult/contemporary stressors. Results of OLS regression analyses reveal positive, significant associations between general stressors and distress as well as culturally-meaningful stressors and distress. In addition, we found evidence of the accumulating and interactive impact of stress on psychological distress. PMID:22368789

  2. A demedicalized view of maternal distress: conceptualization and instrument development.

    Science.gov (United States)

    Arditti, Joyce A; Grzywacz, Jospeh G; Gallimore, Sara Wang

    2013-11-01

    The goal of this article was to describe instrument development of a demedicalized, multidomain view of maternal distress, with psychological, relational, and situational manifestations. We developed a pilot instrument derived from our previous grounded theory conceptualization of maternal distress and administered it to a purposive sample of 100 low-income single mothers. Analyses testing the relationship between maternal distress and depressive symptoms, guilt, child rearing stress, and community needs variables suggested that the maternal distress inventory had convergent, discriminant, and concurrent validity. Not only was maternal distress distinct from depressive symptomology and generalized child rearing stress, it appeared to be more meaningfully associated with "real world" outcomes of interest to psychological service providers than purely psychological measures of the distress. PMID:22984879

  3. New Technology and Experimental Study on Snow-Melting Heated Pavement System in Tunnel Portal

    OpenAIRE

    Jinxing Lai; Junling Qiu; Jianxun Chen; Haobo Fan; Ke Wang

    2015-01-01

    In recent years, with the rapid growth of economy and sharp rise of motor vehicles in China, the pavement skid resistance in tunnel portals has become increasingly important in cold region. However, the deicing salt, snow removal with machine, and other antiskid measures adopted by highway maintenance division have many limitations. To improve the treatment effect, we proposed a new snow-melting approach employing electric heat tracing, in which heating cables are installed in the structural ...

  4. Wear particles generated from studded tires and pavement induces inflammatory reactions in mouse macrophage cells.

    Science.gov (United States)

    Lindbom, John; Gustafsson, Mats; Blomqvist, Göran; Dahl, Andreas; Gudmundsson, Anders; Swietlicki, Erik; Ljungman, Anders G

    2007-06-01

    Health risks associated with exposure to airborne particulate matter (PM) have been shown epidemiologically as well as experimentally, pointing to both respiratory and cardiovascular effects. These health risks are of increasing concern in society, and to protect public health, a clarification of the toxic properties of particles from different sources is of importance. Lately, wear particles generated from traffic have been recognized as a major contributing source to the overall particle load, especially in the Nordic countries where studded tires are used. The aim of this study was to further investigate and compare the ability to induce inflammatory mediators of different traffic-related wear particles collected from an urban street, a subway station, and studded tire-pavement wear. Inflammatory effects were measured as induction of nitric oxide (NO), IL-6, TNF-alpha, arachidonic acid (AA), and lipid peroxidation after exposure of the murine macrophage like cell line RAW 264.7. In addition, the redox potential of the particles was measured in a cell-free system. The results show that all particles tested induce IL-6, TNF-alpha, and NO, and those from the urban street were the most potent ones. In contrast, particles collected from a subway station were most potent to induce lipid peroxidation, AA release, and formation of ROS. Particles from studded tire-pavement wear, generated using a road simulator, were able to induce inflammatory cytokines, NO, lipid peroxidation, and ROS formation. Interestingly, particles generated from pavement containing granite as the main stone material were more potent than those generated from pavement containing quartzite as the main stone material. PMID:17516662

  5. Laboratory Study on Grout Injection for Improving Subgrade of Airfield Pavements

    OpenAIRE

    Teck Shang Goh; Osamu Takashi

    2014-01-01

    This paper shares the authors’ experience of using low pressure grouting to improve the subgrade performance. The first part of the paper introduced a case history where low pressure grouting was applied in weakened subgrade of the active airport pavements in Kuala Lumpur International Airport (KLIA). The treated areas seemed to have been improved and only one of all eight treated areas had reoccurrence of depression. However, the performance of the treated area was difficult to be eval...

  6. Moss cushions facilitate water and nutrient supply for plant species on bare limestone pavements

    DEFF Research Database (Denmark)

    Jensen, Kaj Sand; Hammer, Kathrine

    2012-01-01

    Dense moss cushions of different size are distributed across the bare limestone pavements on Øland, SE Sweden. Increasing cushion size is predicted to physically protect and improve performance and colonization by vascular plants. Therefore, we tested water balance, phosphorus supply, and species richness, and evaluated duration of plant activity during desiccation as a function of ground area, for a large collection of moss cushions. We found that lower evaporation and higher water storage cont...

  7. Leaching of polycyclic aromatic hydrocarbons from new and reclaimed asphalt pavements

    OpenAIRE

    LEGRET, M; ODIE, L; DEMARE, D; MONERON, P; Jullien, A.

    2005-01-01

    This work presented herein displays the results of a study addressing environmental concerns related to the possible leaching of pollutants from new and reclaimed asphalt pavement. Samples from an experimental site were tested in both static batch tests and columns leaching tests. Selected polycyclic aromatic hydrocarbons (PAHs) were analysed in leachates. The results have allowed us to consider the leaching of pollutants to be rather weak. Concentrations in solutions from batch leaching test...

  8. Leaching of heavy metals and polycyclic aromatic hydrocarbons from reclaimed asphalt pavement

    OpenAIRE

    LEGRET, M; ODIE, L; DEMARE, D; Jullien, A.

    2005-01-01

    The work presented herein displays the results of a study addressing environmental concerns related to the possible leaching of pollutants from reclaimed asphalt pavement. Samples from an experimental site were tested in both static batch tests and column leaching tests. Selected heavy metals and polycyclic aromatic hydrocarbons (PAHs) were analysed in leachates. The results have allowed us to consider the leaching of pollutants to be rather weak for most of the parameters studied. Concentrat...

  9. Asphalt rubber interlayer benefits on reflective crack retardation of flexible pavement overlays

    OpenAIRE

    Shakir, Shatnawi; Pais, Jorge; Minhoto, Manuel

    2011-01-01

    This paper provides an overview of the asphalt rubber interlayer benefits on reflective crack retardation in flexible pavement preservation and rehabilitation strategies. These interlayers are known in California as asphalt rubber absorbing membrane interlayers (SAMI-R) or as asphalt rubber aggregate membrane interlayers (ARAM-I) chip seals. These interlayers have been used successfully as part of cape seals and as part of an overlay system. The paper focuses on the performance in terms of fi...

  10. The Efficiency Analysis of Low Impact Development Applied in Taiwan: A Case Study of Porous Pavement

    Science.gov (United States)

    Huang, Y. H.; Liu, H. J.; Hsu, N. S.; Chang, F. M.

    2014-12-01

    Low Impact Development (LID) has been developed since the end of 1990s. Lots of successful experience based on this new technology have been made. Taiwan Executive Yuan is conducting a six-year (2014~2019) program "Integrated River Basin Management Plan" applying LID to build sponge cities. Construction and Planning Agency, Ministry of the Interior is editing the manual of LID technology for Taiwan. However, since the hydrological environments, physiographic conditions, climates, the strength and frequency of disasters in Taiwan are different from that in America, this study takes the first laboratory experiment and model simulation to evaluate the efficiency of application of LID in Taiwan.LID Facilities includes porous pavement, rain garden, green roof, tree box filter facilities and so on, and in this study, porous pavement is taken as an example for discussion. In the part of laboratory experiments, the sand box experiments is designed to operate with the specified rainfall return period calculated by Horton formula and rainfall characteristics of Taipei. Then the outflow hydrograph in each designed rainfall of specified return period can be evaluated. As for model simulation, this study constructs LID simulation elements by SWMM model and tests the suitability for simulation of the outflow hydrograph obtained from experiments, and definitely quantifies the efficiency of water retention and flood reduction of porous pavement. The results fits well with the experimental observation data with less than 10% error of pick flow. It suggests that, with LID simulation elements constructed in this study, the efficiency of LID in actual on-site application can be evaluated.The results shows that porous pavement is able to delay arrival time of pick about 5% ~10% and reduce the pick flow about 5%~20%, and hold the ability of near 3~5% water retention. It proves that application of LID can retain water and reduce flood in Taiwan.

  11. Hypolithic Microbial Community of Quartz Pavement in the High-Altitude Tundra of Central Tibet

    OpenAIRE

    Wong, Fiona K. Y.; Lacap, Donnabella C; Lau, Maggie C. Y.; Aitchison, J. C.; Cowan, Donald A.; Pointing, Stephen B.

    2010-01-01

    The hypolithic microbial community associated with quartz pavement at a high-altitude tundra location in central Tibet is described. A small-scale ecological survey indicated that 36% of quartz rocks were colonized. Community profiling using terminal restriction fragment length polymorphism revealed no significant difference in community structure among a number of colonized rocks. Real-time quantitative PCR and phylogenetic analysis of environmental phylotypes obtained from clone libraries w...

  12. Recycled asphalt mixtures with foamed bitumen: an alternative to build ecofriendly road pavements

    OpenAIRE

    Palha, Daniela; Fonseca, Paulo; Silva, Hugo Manuel Ribeiro Dias da; Oliveira, Joel; Abreu, Liliana

    2015-01-01

    Nowadays, recycling has become a very important objective for the society in the scope of a closed loop product life cycle. In recent years, new recycling techniques have been developed in the area of road pavements that allow the incorporation of high percentages of reclaimed asphalt (RA) materials in recycled asphalt mixtures. The use of foamed bitumen for production of recycled asphalt mixtures is one of those techniques, which also allows the reduction of the mixing temperatures (warm mix...

  13. Effect of crumb rubber gradation on a rubberized cold recycled mixture for road pavements

    DEFF Research Database (Denmark)

    Pettinari, Matteo; Simone, Andrea

    2015-01-01

    Cold recycling technique represents the most environmental friendly solution for pavement rehabilitation nowadays. In fact, this technique allows the use of the highest percentage of reclaimed asphalt avoiding the energy consumption related to aggregates heating required by the traditional hot mix asphalt design. The mix design represents a key phase of the cold mix production. The study of workability and compactability properties combined with a deep laboratory investigation is required. The i...

  14. The effect of Cryogenic Crumb Rubber in cold recycled mixes for road pavements

    DEFF Research Database (Denmark)

    Pettinari, Matteo; Dondi, Giulio; Sangiorgi, Cesare; Hededal, Ole

    2014-01-01

    Over recent years, the necessity of reducing the environmental mpact of building new infrastructures has increasingly directed research toward developing innovative manufacturing methods and materials that can satisfy these objectives. Cold recycling, widely used in renovating road pavements in Italy, is also moving in this direction, lowering the manufacturing temperatures of bituminous mixes and reducing or ultimately eliminating the use of virgin raw materials. Currently, a wide range of mate...

  15. Towards a global, environmental evaluation of pavement materials and techniques in France

    OpenAIRE

    Jullien, A.; DE LARRARD, F

    2003-01-01

    This work takes places in the context of the creation of a new research team at LCPC, performing studies in the field of sustainable development applied to roads. The present on-going projects - a recycling road works using hot-mix reclaimed asphalt pavement and a data base on material recycling in roads - are leading to the collection of significant environmental data. These projects also include the application of LCA methodology to roads, and display a territorial approach. Finally the res...

  16. Uniform auxin triggers the Rho GTPase-dependent formation of interdigitation patterns in pavement cells

    OpenAIRE

    Xu, Tongda; Nagawa, Shingo; Yang, Zhenbiao

    2011-01-01

    The investigation of Rho-family GTPases has uncovered mechanisms for spatiotemporal control of cellular processes such as cell polarization, movement, morphogenesis and cell division. Now Rho GTPase plays another leading role in the discovery of a new signaling mechanism for auxin, a multifunctional hormone that regulates pattern formation in plants. Arabidopsis leaf epidermal pavement cells (PCs) develop the puzzle-piece cell shape with interlocking lobes and indentations via interdigitated ...

  17. Disentangling Depression and Distress Networks in the Tinnitus Brain

    OpenAIRE

    Joos, Kathleen; Vanneste, Sven; Ridder, Dirk

    2012-01-01

    Tinnitus is the continuous perception of an internal auditory stimulus. This permanent sound often affects a person's emotional state inducing distress and depressive feelings changes in 6–25% of the affected population. Distress and depression are two distinct emotional states. Whereas distress describes a transient aversive state, interfering with a person's ability to adequately adapt to stressors, depressive feelings should rather be considered as a more constant emotional state. Based on...

  18. Distress, anxiety, and depression in cancer patients undergoing chemotherapy

    OpenAIRE

    Thomas Bejoy C; Devi Nandkumar; Sarita Gangadharan P; Pandey Manoj; Hussain Badridien M; Krishnan Rita

    2006-01-01

    Abstract Background Chemotherapy for cancer is an intense and cyclic treatment associated with number of side-effects. The present study evaluated the effect of chemotherapy on distress, anxiety and depression. Patients and methods A total of 117 patients were evaluated by using distress inventory for cancer (DIC2) and hospital anxiety and depression scale (HADS). Majority of the patients were taking chemotherapy for solid tumors (52; 44.4%). Results The mean distress score was 24, 18 (15.38%...

  19. Financial Distress Prediction in Emerging Market: Empirical Evidences from Iran

    OpenAIRE

    Mahdi Salehi; Bizhan Abedini

    2009-01-01

    In this article the ability of financial ratios for prediction of financial distress of the listed companies in Tehran Stock Exchange (TES) was investigated. For this reason, the multiple regression models were used and a model was presented for prediction of financial distress in listed companies in TES. The assessment of the model was done by utilizing the data of two groups. The first group contained 30 companies which don't have any financial distress, and the second group, similarly, con...

  20. Epidemiologia do distress psicológico: estudo transversal de base populacional

    OpenAIRE

    Sparrenberger Felipe; Santos Iná dos; Lima Rosângela da Costa

    2003-01-01

    OBJETIVO: Determinar a prevalência e a distribuição de distress na esfera psicológica na população urbana adulta. MÉTODOS: Foram estudadas 3.942 pessoas maiores de 20 anos, do município de Pelotas, RS. Distress foi definido por meio de um indicador de bem-estar, a Escala de Faces, e através da autopercepção de nervosismo. O teste do qui-quadrado foi usado para testar associação com características sociodemográficas. RESULTADOS: A prevalência de distress psicológico foi de 14% quando se utiliz...

  1. Partner relationship satisfaction and maternal emotional distress in early pregnancy

    OpenAIRE

    Eberhard-Gran Malin; Slinning Kari; Røsand Gun-Mette B; Røysamb Espen; Tambs Kristian

    2011-01-01

    Abstract Background Recognition of maternal emotional distress during pregnancy and the identification of risk factors for this distress are of considerable clinical- and public health importance. The mental health of the mother is important both for herself, and for the physical and psychological health of her children and the welfare of the family. The first aim of the present study was to identify risk factors for maternal emotional distress during pregnancy with special focus on partner r...

  2. Framing the Issues: Moral Distress in Health Care

    OpenAIRE

    Pauly, Bernadette M.; Varcoe, Colleen; Storch, Jan

    2012-01-01

    Moral distress in health care has been identified as a growing concern and a focus of research in nursing and health care for almost three decades. Researchers and theorists have argued that moral distress has both short and long-term consequences. Moral distress has implications for satisfaction, recruitment and retention of health care providers and implications for the delivery of safe and competent quality patient care. In over a decade of research on ethical practice, registered nurses a...

  3. Joy, Distress, Hope, and Fear in Reinforcement Learning (Extended Abstract):

    OpenAIRE

    Jacobs, E.J.; Broekens, J.; Jonker, C.M.

    2014-01-01

    In this paper we present a mapping between joy, distress, hope and fear, and Reinforcement Learning primitives. Joy / distress is a signal that is derived from the RL update signal, while hope/fear is derived from the utility of the current state. Agent-based simulation experiments replicate psychological and behavioral dynamics of emotion including: joy and distress reactions that develop prior to hope and fear; fear extinction; habituation of joy; and, task randomness that increases the int...

  4. Psychological distress in morbid obesity in relation to weight history

    OpenAIRE

    PETRONI, MARIA LETIZIA; VILLANOVA, NICOLA; AVAGNINA, SEBASTIANO; FUSCO, MARIA ANTONIA; FATATI, GIUSEPPE; Compare, Angelo; MARCHESINI, GIULIO

    2007-01-01

    Background: Very few data are available on psychological distress in morbidly obese subjects in relation to the history of their weight. In subjects with childhood obesity, psychological distress might be better than in adult-onset obesity, because of progressive adaptation to the social stigma. Methods: Psychological distress was tested in relation to BMI at age 20 years (BMI-20), weight history and somatic co-morbidities in 632 treatment-seeking, morbidly obese participants from the QUOV...

  5. The Upper Eocene crustose coralline algal pavement in the Colli Berici, north-eastern Italy

    Directory of Open Access Journals (Sweden)

    Davide Bassi

    2005-10-01

    Full Text Available A crustose coralline algal pavement, identified in Upper Eocene (Priabonian shallow water, middleramp carbonates in north-eastern Italy (Colli Berici, Southern Alps, represents a rare example of this facies.The crustose pavement consists of a coralline crust bindstone with a wackestone-packstone matrix, and is characterised by the dominance of crustose coralline thalli composed primarily of melobesioids (Lithothamnion and Mesophyllum and mastophoroids (Spongites, Lithoporella, Neogoniolithon. In places the coralline bindstone can be seen to develop from isolated encrusting-to-foliose thalli which bifurcate and join to form an open framework interbedded with matrix debris from crusts. Various forms of rhodoliths occur commonly within this facies. The largest discoidal rhodoliths (up to 12 cm of large diameter show an inner arrangement consisting of loosely packed laminar (encrusting-to-foliose coralline thalli with a high percentage of constructional voids (50-63%. Accessory components are represented by larger hyaline perforated foraminifera such as nummulitids and orthophragminids. This facies formed in a ramp palaeoenvironment characterised by relatively low hydrodynamic energy and low rates of sedimentation. Channelised structures present within the facies were formed by return currents which swept the middle ramp creating such distal structures. Further toward the distal middle-ramp the return currents decreased in energy and discharged nutrients allowing the mesotrophic crustose coralline algal pavement to develop.

  6. Temporal evolution modeling of hydraulic and water quality performance of permeable pavements

    Science.gov (United States)

    Huang, Jian; He, Jianxun; Valeo, Caterina; Chu, Angus

    2016-02-01

    A mathematical model for predicting hydraulic and water quality performance in both the short- and long-term is proposed based on field measurements for three types of permeable pavements: porous asphalt (PA), porous concrete (PC), and permeable inter-locking concrete pavers (PICP). The model was applied to three field-scale test sites in Calgary, Alberta, Canada. The model performance was assessed in terms of hydraulic parameters including time to peak, peak flow and water balance and a water quality variable (the removal rate of total suspended solids). A total of 20 simulated storm events were used for model calibration and verification processes. The proposed model can simulate the outflow hydrographs with a coefficient of determination (R2) ranging from 0.762 to 0.907, and normalized root-mean-square deviation (NRMSD) ranging from 13.78% to 17.83%. Comparison of the time to peak flow, peak flow, runoff volume and TSS removal rates between the measured and modeled values in model verification phase had a maximum difference of 11%. The results demonstrate that the proposed model is capable of capturing the temporal dynamics of the pavement performance. Therefore, the model has great potential as a practical modeling tool for permeable pavement design and performance assessment.

  7. Numerical Investigation of Design Strategies to Achieve Long-Life Pavements

    CERN Document Server

    Ghauch, Ziad G

    2011-01-01

    Increasing the HMA base thickness and modifying the HMA mixture properties to improve the resistance to fatigue cracking are among the most popular methods for achieving long-lasting pavements. Such methods are based on the idea of reducing the tensile strain at the bottom of the HMA layer below the Fatigue Endurance Limit (FEL), a level of strain below which no cumulative damage occurs to the HMA mixture. This study investigates the effectiveness of several design strategies involved in long-life, perpetual pavement design. A 3D Finite Element model of the pavement involving a linear viscoelastic constitutive model for HMA materials and non-uniform tire contact stresses is developed using ABAQUS 6.11. The effects of asphalt base course thickness and mixture type, rich binder layer, and aggregate subbase layer are examined. Four asphalt base course mixture types, namely dense graded, polymer modified, high modulus, and standard binder, are studied as a function of the asphalt base course thickness. The result...

  8. Three-dimensional finite element model for flexible pavement analyses based field modulus measurements

    International Nuclear Information System (INIS)

    In accordance with the present development of empirical-mechanistic tools, this paper presents an alternative to traditional analysis methods for flexible pavements using a three-dimensional finite element formulation based on a liner-elastic perfectly-plastic Drucker-Pager model for granular soil layers and a linear-elastic stress-strain law for the asphalt layer. From the sensitivity analysis performed, it was found that variations of +-4 degree in the internal friction angle of granular soil layers did not significantly affect the analyzed pavement response. On the other hand, a null dilation angle is conservatively proposed for design purposes. The use of a Light Falling Weight Deflectometer is also proposed as an effective and practical tool for on-site elastic modulus determination of granular soil layers. However, the stiffness value obtained from the tested layer should be corrected when the measured peak deflection and the peak force do not occur at the same time. In addition, some practical observations are given to achieve successful field measurements. The importance of using a 3D FE analysis to predict the maximum tensile strain at the bottom of the asphalt layer (related to pavement fatigue) and the maximum vertical comprehensive strain transmitted to the top of the granular soil layers (related to rutting) is also shown. (author)

  9. Performance polymeric concrete with synthetic fiber reinforcement against reflective cracking in rigid pavement overlay

    International Nuclear Information System (INIS)

    Cement concrete pavements are used for heavy traffic loads throughout the world owing to its better and economical performance. Placing of a concrete overlay on the existing pavement is the most prevalent rehabilitating method for such pavements, however, the problem associated with the newly placed overlay is the occurrence of reflective cracking. This paper presents an assessment of the performance of polymeric concrete with synthetic fiber reinforcement against reflective cracking in an overlay system. The performance of polymeric concrete with synthetic fibers as an overlay material is measured in terms of the load-deflection, strain-deflection and load-strain behavior of beams of the polymeric concrete. For this purpose, five types of beams having different number of fiber wires and position are tested for flexure strength. Deflection/strains for each increment of load are recorded. In addition, cubes of plain concrete and of concrete with synthetic fiber needles were tested after 7 and 28 days for compressive strengths. Finite element models in ANSYS software for the beams have also been developed. Beams with greater number of longitudinal fiber wires displayed relatively better performance against deflection whilst beams with synthetic fiber needles showed better performance against strains. Thus, polymeric concrete overlay with fiber reinforcement will serve relatively better against occurrence of reflective cracking. (author)

  10. Reduction in mental distress among substance users receiving inpatient treatment

    Directory of Open Access Journals (Sweden)

    Friborg Oddgeir

    2010-12-01

    Full Text Available Abstract Background Substance users being admitted to inpatient treatment experience a high level of mental distress. In this study we explored changes in mental distress during treatment. Methods Mental distress, as measured by the HSCL-10, was registered at admission and at discharge among 164 substance users in inpatient treatment in Northern Norway. Predictors of reduction in mental distress were examined utilizing hierarchical regression analysis. Results We found a significant reduction in mental distress in the sample, but the number of patients scoring above cut-off on the HSCL-10 at discharge was still much higher than in the general population. A more severe use of substances as measured by the AUDIT and the DUDIT, and being female, predicted a higher level of mental distress at admission to treatment as well as greater reduction in mental distress during treatment. Holding no education beyond 10 year compulsory school only predicted a reduction in mental distress. Conclusions The toxic and withdrawal effects of substances, level of education as well as gender, contributed to the differences in change in mental distress during treatment. Regression to the mean may in part explain some of the findings.

  11. Development of a distress inventory for cancer: preliminary results.

    Directory of Open Access Journals (Sweden)

    Thomas B

    2002-01-01

    Full Text Available CONTEXT: Advances in cancer treatment have led to cure and prolongation of patients? lives; however associated psychosocial problems, including distress, can detrimentally affect patients? compliance with treatment and ultimately, their outcome. Symptom distress has been well addressed in many studies; however, psychological distress has only been quantified by using depression or anxiety scales/checklists or quality of life scales containing a distress sub scale/component or by the use of scales that are not psychological distress-specific. AIMS: The present study is an attempt to construct a psychological distress inventory for specific use with cancer patients. SETTINGS AND DESIGN: The standardisation sample consisted of 63 randomly selected patients with head and neck cancer who had undergone/ were undergoing curative treatment at the Regional Cancer Centre, Trivandrum. PATIENTS AND METHODS: The Distress Inventory for Cancer contained 57 positively and negatively toned items. An item analysis was conducted, followed by a factor analysis, thereby identifying the domains influencing distress. RESULTS: The final questionnaire contained 26 items subdivided into four domains viz. the personal, spiritual, physical, and the family domains, with each domain providing a sub score. The reliability coefficient (Cronbach?s alpha of the scale was found to be 0.85. CONCLUSIONS: These are the preliminary results of an ongoing study on global distress and tool development process. Reported here is the first step towards development of such tool.

  12. Accuracy of the Danish version of the 'distress thermometer'

    DEFF Research Database (Denmark)

    Bidstrup, Pernille Envold; Mertz, Birgitte Goldschmidt

    2012-01-01

    Objective: Short screening instruments have been suggested to improve the detection of psychological symptoms. We examined the accuracy of the Danish version of the 'Distress Thermometer'. Methods: Between October 2008 and October 2009, 426 women with newly diagnosed primary breast cancer who were operated at the Breast Surgery Clinic of the Rigshospitalet, Copenhagen, were eligible for this study. Of these, 357 participated (84%) and 333 completed a questionnaire. The distress thermometer was evaluated against the 'hospital anxiety and depression scale' (HADS). We also examined the women's wish for referral for psychological support. Results: A cut-off score of 6 vs 7 (low:?6, high:?7) on the distress thermometer was optimal for confirming distress, with a sensitivity of 42%, a specificity of 93%, a positive predictive value (PPV) of 78% and a negative predictive value (NPV) of 73%. A cut-off score of 2 vs 3 was optimal for screening, with a sensitivity of 99%, a specificity of 36%, a PPV of 47% and a NPV of99%. Of those who were distressed using the cut-off score of 2 vs 3 on the distress thermometer, 17% (n = 41) wished to be referred for psychological support and 57% (n = 140) potentially wanted a later referral. Conclusion: The distress thermometer performed satisfactorily relative to the HADS in detecting distress in our study. A screening procedure in which application of the distress thermometer is a first step could be useful for identifying persons in need of support. Copyright © 2011 John Wiley & Sons, Ltd.

  13. Distress tolerance in social versus solitary college student drinkers.

    Science.gov (United States)

    Williams, Catherine L; Vik, Peter W; Wong, Maria M

    2015-11-01

    Low distress tolerance has been an inconsistent predictor of alcohol-related consequences in college students, but its relationships to depression and coping motives for alcohol have received stronger support. Research on college students who drink heavily in isolation suggests that this population is more likely to have a greater number and severity of alcohol-related problems, depression, and coping motives. Solitary heavy drinkers were therefore hypothesized to have lower distress tolerance than other drinkers. This study examined differences in self-reported and behavioral distress tolerance across two groups of university students: those who endorsed heavy solitary drinking (20.1%) versus those who endorsed other types of drinking. Students completed a self-report measure (Distress Intolerance Self-Report, or DISR) and behavioral measure of distress tolerance (Paced Auditory Serial Addition Test, or PASAT). Students who reported drinking heavily in isolation differed from other students on the DISR, F(1, 132) = 4.645, p = .033, η(2) = .034, but not on the PASAT, F(1, 132) = 0.056, p = .813. These students also endorsed more coping motives for alcohol. Distress tolerance did not predict drinking consequences directly, yet a mediation model linking distress tolerance to consequences through coping motives supports previous findings of distress tolerance as a distal, indirect predictor of drinking problems. The unique characteristics of solitary binge drinkers and the significance of distress tolerance as an indirect predictor of alcohol-related consequences are discussed. PMID:26114980

  14. A Statistical Analysis to Predict Financial Distress

    OpenAIRE

    Nicolas Emanuel Monti; Roberto Mariano Garcia

    2010-01-01

    The aim of this study is to apply the statistical inference to identify if a firm is likely to become financially distressed in the short term. To do this, we decided to collect data from the firms’ financial statements. The analyses performed were based on a group of 45 financial ratios observed from a sample of 86 firms operating in Argentina. First, we used the principal component analysis to turn the information in the 45 original ratios into two new global variables named as ?Risk and ?R...

  15. Associations between faith, distress and mental adjustment

    DEFF Research Database (Denmark)

    Johannessen-Henry, Christine Tind

    2013-01-01

    Objective. Several studies have suggested that religion and spirituality are important for overcoming psychological distress and adjusting mentally to cancer, but these studies did not differentiate between spiritual well-being and specific aspects of faith. We examined the extent to which...... = ?0.79, CI ?0.92; ?0.66) and increased adjustment to cancer (fighting spirit, anxious preoccupation, helplessness-hopelessness). Specific aspects of faith were associated with high confusion-bewilderment and tension-anxiety, but also lower score on vigor-activity, and with higher anxious...

  16. The Undervaluation of Distressed Company's Equity

    OpenAIRE

    Schmidt, Frederik

    2009-01-01

    In a simple firm value model we consider the impact of the insolvency probability on the valuation of equity and debt, which are assumed to be not publicly traded. For the case of a distressed company, which usually has high debt and low equity, we can show that the impact becomes increasingly important. Disregarding this yields an overvaluation of debt and an undervaluation of equity. We calculate the sensitivity of equity with regard to debt, which is isomorphic to the sensitivity of a c...

  17. Acute respiratory distress caused by Neosartorya udagawae

    Directory of Open Access Journals (Sweden)

    John J. Farrell

    2014-10-01

    Full Text Available We describe the first reported case of acute respiratory distress syndrome (ARDS attributed to Neosartorya udagawae infection. This mold grew rapidly in cultures of multiple respiratory specimens from a previously healthy 43-year-old woman. Neosartorya spp. are a recently recognized cause of invasive disease in immunocompromised patients that can be mistaken for their sexual teleomorph, Aspergillus fumigatus. Because the cultures were sterile, phenotypic identification was not possible. DNA sequencing of ITS, calmodulin and ?-tubulin genes supported identification of Neosartorya udagawae. Our case is the first report of ARDS associated with Neosartorya sp. infection and defines a new clinical entity.

  18. Making the Grade but Feeling Distressed: Gender Differences in Academic Performance and Internal Distress.

    Science.gov (United States)

    Pomerantz, Eva M.; Altermatt, Ellen Rydell; Saxon, Jill L.

    2002-01-01

    There is disagreement over whether girls or boys are at risk in the context of school. Girls outperform boys in school, particularly in stereotypically feminine subjects. However, girls are also more vulnerable to internal distress than boys are. The aim of this research was to understand this pattern of gender differences. (Author)

  19. Assessment of work intensification by managers and psychological distressed and non-distressed employees : a multilevel comparison

    DEFF Research Database (Denmark)

    Bamberger, Simon Grandjean; Larsen, Anelia

    2015-01-01

    Work intensification is a popular management strategy to increase productivity, but at the possible expense of employee mental stress. This study examines associations between ratings of work intensification and psychological distress, and the level of agreement between compared employee-rated and manager-rated work intensification. Multi-source survey data were collected from 3,064 employees and 573 company managers from the private sector in 2010. Multilevel regression models were used to compare different work intensification ratings across psychological distress strata. Distressed employees rated higher degree of total work intensification compared to non-distressed employees, and on three out of five sub ratings there were an increased prevalence of work intensification in the case group. In general, there was poor agreement between employee and company work intensification rating. Neither manager-rated work intensification nor employee/manager discrepancy in work intensification ratings was associated with psychological distress. Distressed employees had a higher total score of employee/manager agreed work intensification, and a higher prevalence of increased demands of labour productivity. This study demonstrates higher ratings of employee/manager agreed work intensification in distressed employees compared to non-distressed employees, challenging previous findings of reporting bias in distressed employees' assessment of work environment.

  20. Hospitals in distress. Problems and solutions.

    Science.gov (United States)

    Sachs, P R

    1993-04-01

    In the past five years the number of hospitals in financial distress has increased alarmingly. And though hospital administrators are feeling more optimistic now that their institutions will survive, they recognize the need to remain vigilant. It is important to recognize the warning signs of financial distress. Hospitals normally proceed through four stages of financial disintegration if no measures are taken to intercede: weak performance/condition, default, bankruptcy and dissolution. As the stages progress, fewer options for redress can be taken and loss of personnel and assets becomes inevitable. Materiel managers who regularly monitor key statistics, such as non-salary expenses per adjusted occupied bed, days in accounts payable, inventory dollars per adjusted occupied bed and so forth, can recognize the warning signs and take appropriate measures. Corrective actions can include reducing inventory levels, renegotiating contracts and leases, rebidding key contracts and supply items and extending purchase payment terms. A case study shows how a medical center experiencing weak performance implemented expense reductions in utilization, contracts, purchase costs/rebidding and inventory for substantial savings. PMID:10124964

  1. Biofeedback Treatment of Paradoxical Vocal Fold Motion and Respiratory Distress in an Adolescent Girl

    OpenAIRE

    Warnes, Emily; Allen, Keith D.

    2005-01-01

    In this investigation, we evaluated the effectiveness of surface electromyography (EMG) biofeedback to treat paradoxical vocal fold motion in a 16-year-old girl. EMG biofeedback training occurred once per week over the course of 10?weeks. In a changing criterion design, muscle tension showed systematic changes that corresponded with changes in the criterion. Overall, baseline muscle tension levels were reduced over 60%, with corresponding reductions in episodes of respiratory distress and che...

  2. Diseño, construcción y funcionamiento de un prototipo para medir cargas vehiculares en un pavimento flexible / Design, construction and operation of a prototype to measure load in a flexible pavement structure

    Scientific Electronic Library Online (English)

    Hugo, Rondón; Eduardo, Delgadillo; Wilson, Vargas.

    Full Text Available El artículo presenta el diseño y la construcción de un prototipo con el cual es posible medir cargas vehiculares en un pavimento flexible, a partir de las vibraciones que dichos vehículos generan cuando se movilizan sobre esta estructura vial. El principio físico es simple: cuando un vehículo circul [...] a sobre la superficie de un pavimento, éste genera vibraciones que pueden ser percatadas en zonas adyacentes a la vía en estudio, y las amplitudes de dichas deformaciones pueden dar información sobre la magnitud de la carga rodante. Adicionalmente, se reportan los resultados de un estudio de campo ejecutado con el fin de calibrar una ecuación matemática que simula las señales de vibración obtenidas con el prototipo. De manera general se concluye que el prototipo es capaz de predecir la carga que circula sobre el pavimento a partir de las vibraciones que éstos inducen cuando transitan sobre la capa de rodadura. Abstract in english This paper presents the design and construction of a prototype able to measure weigh-in-motion on a flexible pavement structure, through the vibrations generated when vehicles move on these road structures. The physical principle is simple: when a vehicle is moving across the pavement road surface, [...] it creates vibrations that can be noticed in areas adjacent to the analyzed highway and the amplitudes of these vibrations can provide information on the magnitude of the vehicle load. Additionally, the paper reports the results of a field study performed in order to calibrate a mathematical equation which simulates the vibration signals obtained by the prototype when vehicles move across the road surface. As a general conclusion, the prototype is able to predict the load that is moving on the pavement, through the vibrations that they induce when transiting on its surface.

  3. 47 CFR 80.321 - Acknowledgement of receipt of distress message.

    Science.gov (United States)

    2010-10-01

    ...Acknowledgement of receipt of distress message. 80.321 Section 80.321 ...Acknowledgement of receipt of distress message. (a) Stations of the maritime mobile service which receive a distress message from a mobile station...

  4. Rutting mechanisms and advanced laboratory testing of asphalt mixtures resistance against permanent deformation

    OpenAIRE

    Miljkovi? Miomir; Radenberg Martin

    2011-01-01

    Permanent deformation in asphalt layers which manifestation on pavement surface is named rutting represents one of the most significant distresses of asphalt pavements. Depending on the level, it can be a huge inconvenience for traffic safety, driving comfort, and overall pavement life-cycle. Rutting may be classified into three basic types: one-dimensional or vertical compaction, lateral flow or plastic movement, and mechanical deformation. As an addition to Superpave® mixture volumetr...

  5. Child Rearing and Children's Prosocial Initiations toward Victims of Distress.

    Science.gov (United States)

    Zahn-Waxler, Carolyn; And Others

    1979-01-01

    Investigates the relation between maternal rearing behavior and the ways children aged 1 1/2 to 2 1/2 years cope with emotions of distress in others. Specifically examined children's reparation for transgression when they were the cause of distress and their altruism when they were bystanders. (JMB)

  6. Psychopathic Traits, Victim Distress and Aggression in Children

    Science.gov (United States)

    van Baardewijk, Yoast; Stegge, Hedy; Bushman, Brad J.; Vermeiren, Robert

    2009-01-01

    Background: The relationship between psychopathic traits and aggression in children may be explained by their reduced sensitivity to signs of distress in others. Emotional cues such as fear and sadness function to make the perpetrator aware of the victim's distress and supposedly inhibit aggression. As children high in psychopathic traits show a…

  7. Psychological distress and mortality in systolic heart failure

    DEFF Research Database (Denmark)

    Pelle, Aline J; Pedersen, Susanne S.; Schiffer, Angélique A; Szabó, Balázs; Widdershoven, Jos W; Denollet, Johan

    2010-01-01

    Depression, anxiety, and type D ("distressed") personality (tendency to experience negative emotions paired with social inhibition) have been associated with poor prognosis in coronary heart disease, but little is known about their role in chronic heart failure. Therefore, we investigated whether...... these indicators of psychological distress are associated with mortality in chronic heart failure....

  8. Development of a Brief Diabetes Distress Screening Instrument

    OpenAIRE

    Fisher, Lawrence; Glasgow, Russell E; Mullan, Joseph T.; Skaff, Marilyn M.; Polonsky, William H

    2008-01-01

    PURPOSE Previous research has documented that diabetes distress, defined as patient concerns about disease management, support, emotional burden, and access to care, is an important condition distinct from depression. We wanted to develop a brief diabetes distress screen instrument for use in clinical settings.

  9. Intrusive Thoughts: A Primary Variable in Breakup Distress

    Science.gov (United States)

    Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeannette

    2013-01-01

    University students who were high versus low on breakup distress scores were given self-report measures to assess their intrusive thoughts about the romantic breakup and their somatic symptoms that followed the breakup as well as their extracurricular activities and social support that might alleviate their breakup distress. In a regression…

  10. Men's Multiple Roles and Their Relationship to Men's Psychological Distress.

    Science.gov (United States)

    Barnett, Rosalind C.; And Others

    1992-01-01

    Examined men's subjective experiences in work and family roles and psychological distress in 300 employed, married men in 2-earner couples. After controlling for job quality, both marital-role and parental-role quality were significant predictors of men's psychological distress. Parental status was not. Both marital-role and parental-role quality…

  11. The Political Economy of Distress in East Asian Financial Institutions

    OpenAIRE

    Bongini, Paola; Constantijn A. Claessens; Ferri, Giovanni

    2000-01-01

    Politics and regulatory capture can play an important role in financial institutions distress. East Asia's financial crisis featured many distressed and closed financial intermediaries in an environment with many links between government, politicians, supervisors, and financial institutions. This makes the East Asian financial crisis a good event for studying how such connections affect the ...

  12. Assessing Racial Microaggression Distress in a Diverse Sample.

    Science.gov (United States)

    Torres-Harding, Susan; Turner, Tasha

    2015-12-01

    Racial microaggressions are everyday subtle or ambiguous racially related insults, slights, mistreatment, or invalidations. Racial microaggressions are a type of perceived racism that may negatively impact the health and well-being of people of color in the United States. This study examined the reliability and validity of the Racial Microaggression Scale distress subscales, which measure the perceived stressfulness of six types of microaggression experiences in a racially and ethnically diverse sample. These subscales exhibited acceptable to good internal consistency. The distress subscales also evidenced good convergent validity; the distress subscales were positively correlated with additional measures of stressfulness due to experiencing microaggressions or everyday discrimination. When controlling for the frequency of one's exposure to microaggression incidents, some racial/ethnic group differences were found. Asian Americans reported comparatively lower distress and Latinos reporting comparatively higher distress in response to Foreigner, Low-Achieving, Invisibility, and Environmental microaggressions. African Americans reported higher distress than the other groups in response to Environmental microaggressions. Results suggest that the Racial Microaggressions Scale distress subscales may aid health professionals in assessing the distress elicited by different types of microaggressions. In turn, this may facilitate diagnosis and treatment planning in order to provide multiculturally competent care for African American, Latino, and Asian American clients. PMID:25237154

  13. What Ensues from Emotional Distress? Implications for Competence Estimation.

    Science.gov (United States)

    Pomerantz, Eva M.; Rudolph, Karen D.

    2003-01-01

    This 3-wave longitudinal study spanning 12 months examined the process by which emotional distress contributes to competence estimation in 9- to 13-year-olds. Findings indicated that emotional distress predicted negative beliefs about the self and the world over time; these beliefs in turn predicted decrements in competence estimation over time.…

  14. Partnership Transitions and Mental Distress: Investigating Temporal Order

    Science.gov (United States)

    Blekesaune, Morten

    2008-01-01

    The study uses 15 waves of the British Household Panel Survey and the General Health Questionnaire to investigate changes in mental distress over several years surrounding transitions both into and out of marital partnerships (marriages and cohabitations) using fixed effects models. Entering marital partnerships is associated with reduced distress…

  15. Frustrated Fertility: Infertility and Psychological Distress among Women.

    Science.gov (United States)

    McQuillan, Julia; Greil, Arthur L.; White, Lynn; Jacob, Mary Casey

    2003-01-01

    Tests the hypothesis that women who have experienced infertility report higher psychological distress. Examines whether roles or resources condition the effects of infertility or whether its effects are limited to childless women. Infertility combined with involuntary childlessness is associated with significantly greater distress. For women in…

  16. Coal-tar-based pavement sealcoat and PAHs: implications for the environment, human health, and stormwater management

    Science.gov (United States)

    Mahler, Barbara J.; Van Metre, Peter C.; Crane, Judy L.; Watts, Alison W.; Scoggins, Mateo; Williams, E. Spencer

    2012-01-01

    Coal-tar-based sealcoat products, widely used in the central and eastern U.S. on parking lots, driveways, and even playgrounds, are typically 20-35% coal-tar pitch, a known human carcinogen that contains about 200 polycyclic aromatic hydrocarbon (PAH) compounds. Research continues to identify environmental compartments—including stormwater runoff, lake sediment, soil, house dust, and most recently, air—contaminated by PAHs from coal-tar-based sealcoat and to demonstrate potential risks to biological communities and human health. In many cases, the levels of contamination associated with sealed pavement are striking relative to levels near unsealed pavement: PAH concentrations in air over pavement with freshly applied coal-tar-based sealcoat, for example, were hundreds to thousands of times higher than those in air over unsealed pavement. Even a small amount of sealcoated pavement can be the dominant source of PAHs to sediment in stormwater-retention ponds; proper disposal of such PAH-contaminated sediment can be extremely costly. Several local governments, the District of Columbia, and the State of Washington have banned use of these products, and several national and regional hardware and home-improvement retailers have voluntarily ceased selling them.

  17. Integration of a prototype wireless communication system with micro-electromechanical temperature and humidity sensor for concrete pavement health monitoring

    Directory of Open Access Journals (Sweden)

    Shuo Yang

    2015-12-01

    Full Text Available In recent years, structural health monitoring and management (SHMM has become a popular approach and is considered essential for achieving well-performing, long-lasting, sustainable transportation infrastructure systems. Key requirements in ideal SHMM of road infrastructure include long-term, continuous, and real-time monitoring of pavement response and performance under various pavement geometry-materials-loading configurations and environmental conditions. With advancements in wireless technologies, integration of wireless communications into sensing device is considered an alternate and superior solution to existing time- and labor-intensive wired sensing systems in meeting the requirements of an ideal SHMM. This study explored the development and integration of a wireless communications sub-system into a commercial off-the-shelf micro-electromechanical sensor-based concrete pavement monitoring system. A success-rate test was performed after the wireless transmission system was buried in the concrete slab, and the test results indicated that the system was able to provide reliable communications at a distance of more than 46 m (150 feet. This will be a useful feature for highway engineers performing routine pavement scans from the pavement shoulder without the need for traffic control or road closure.

  18. Characterization of cementitiously stabilized subgrades for mechanistic-empirical pavement design

    Science.gov (United States)

    Solanki, Pranshoo

    Pavements are vulnerable to subgrade layer performance because it acts as a foundation. Due to increase in the truck traffic, pavement engineers are challenged to build more strong and long-lasting pavements. To increase the load-bearing capacity of pavements, subgrade layer is often stabilized with cementitious additives. Thus, an overall characterization of stabilized subgrade layer is important for enhanced short- and long-term pavement performance. In this study, the effect of type and amount of additive on the short-term performance in terms of material properties recommended by the new Mechanistic-Empirical Pavement Design Guide (MEPDG) is examined. A total of four soils commonly encountered as subgrades in Oklahoma are utilized. Results show that the changes in the Mr, ME and UCS values stabilized specimens depend on the soil type and properties of additives. The long-term performance (or durability) of stabilized soil specimens is investigated by conducting freeze-thaw (F-T) cycling, vacuum saturation and tube suction tests on 7-day cured P-, K- and C-soil specimens stabilized with 6% lime, 10% CFA and 10% CKD. This study is motivated by the fact that during the service life of pavement stabilized layers are subjected to F-T cycles and moisture variations. It is found that that UCS value of all the stabilized specimens decreased with increase in the number of F-T cycles. A strong correlation was observed between UCS values retained after vacuum saturation and F-T cycles indicating that vacuum saturation could be used as a time-efficient and inexpensive method for evaluating durability of stabilized soils. In this study, short- and long-term observations from stabilization of sulfate bearing soil with locally available low (CFA), moderate (CKD) and high (lime) calcium-based stabilizers are determined to evaluate and compare the effect of additive type on the phenomenon of sulfate-induced heave. The impact of different factors on the development of the ettringite, responsible for sulfate-induced heaving, is also discussed. For Level 2 design of pavements, a total of four stress-based statistical models and two feed-forward-type artificial neural network (ANN) models, are evaluated for predicting resilient modulus of 28-day cured stabilized specimens. Specifically, one semi-log stress-based, three log-log stress-based, one Multi-Layer Perceptrons Network (MLPN), and one Radial Basis Function Network (RBFN) are developed. Overall, semi-log stress-based and MLPN neural network are found to show best acceptable performance for the present evaluation and validation datasets. Further, correlations are presented for stress-based models to correlate Mr with compacted specimen characteristics and soil/additive properties. Additionally, the effect of type of additive on indirect tensile and fatigue characteristics of selected stabilized P- and V-soil is evaluated. This study is based on the fact that stabilized layer is subjected to tensile stresses under wheel loading. Thus, the resilient modulus in tension (M rt), fatigue life and strength in tension (sigmat) or flexure (represented by modulus of rupture, MOR) becomes another important design parameter within the mechanistic framework. Cylindrical specimens are prepared, cured for 28 days and subjected to different stress sequences in indirect tension to study the Mrt. On the other hand, stabilized beam specimens are compacted using a Linear Kneading Compactor and subjected to repeated cycles of reloading-unloading after 28 days of curing in a four-point beam fatigue apparatus for evaluating fatigue life and flexural stiffness. It is found that all three additives improved the Mrt, sigmat and MOR values; however, degree of improvement varied with the type of additive and soil. This study encompasses the differences in the design of semi-rigid pavements developed using AASHTO 1993 and AASHTO 2002 MEPDG methodologies. Further, the design curves for fatigue performance prediction of stabilized layers are developed for different stabilized pavement sections. Knowledge gained f

  19. Diseño de losas de hormigón con geometría optimizada Design of concrete pavement with optimized slab geometry

    Directory of Open Access Journals (Sweden)

    Juan Pablo Covarrubias V.

    2012-12-01

    Full Text Available Se ha desarrollado una nueva metodología para diseñar pavimentos de hormigón, la cual reduce el espesor de losas optimizando el tamaño de estas, dada la geometría de los ejes de los camiones. El diseño considera el apoyo sobre una base granular, tratada con cemento o asfáltica. Considera que no existe adherencia entre la base, o pavimento antiguo y la losa de hormigón. El principio fundamental del método de diseño consiste en diseñar el tamaño de la losa para que no más de un set de ruedas se encuentre en una determinada losa, minimizando así la tensión de tracción crítica en la superficie. Se han construido tramos de prueba a gran escala y probado bajo cargas aceleradas con espesores de hormigón de 8, 15 y 20 cm. todas con base granular y sobre capas asfálticas sin adherir. Las pruebas demostraron que una disminución en las dimensiones de la losa permite que siendo de bajo espesor, soporte una cantidad considerable de ejes equivalentes antes de comenzar a agrietarse. Las losas de hormigón sobre bases granulares con un espesor de 20 cm. no mostraron agrietamiento a pesar de haber sido ensayados a mas de 50 millones de EE. Losas de espesor de 15 cm mostraron grietas a los 12 millones de ejes equivalentes en promedio, mientras que las losas de 8 cm de espesor, resistió 75.000 ejes equivalentes antes de las primeras grietas. Además las pruebas realizadas demostraron que las losas de hormigón con fibra pueden soportar hasta 20 veces más tráfico antes de comenzar a agrietarse, así como proporcionar una vida útil más larga una vez agrietadas A partir de esto se ha desarrollado un software de diseño mecánico-empírico llamado OptiPave, que optimiza el diseño geométrico y el espesor de las losas de hormigón considerando las condiciones particulares de cada proyecto; ya sea clima, tráfico, capa, y materiales. Las tensiones críticas han sido calculadas utilizando el análisis de elementos finitos, para diferentes condiciones de cargas mecánicas y térmicas en diferentes posiciones. El agrietamiento de las losas se determina calculando la fatiga del hormigón y los modelos utilizados por la guía de diseño AASHTO del año 2007 y mediante calibración en secciones de prueba a gran escala. La nueva metodología diseña losas de hormigón que en promedio son 7 cm más delgadas para vías de alto tráfico en relación con el diseño tradicional de pavimentos AASHTO (1993. El método de diseño también es capaz de diseñar de manera eficiente pavimentos de hormigón para vías de menor volumen de tráfico que no son cubiertos con los actuales métodos de diseño de pavimento dando una alternativa a soluciones en asfalto.A new technology has been developed to design concrete pavements, which reduces slabs' thickness and optimizes their sizes, because of trucks axles' geometry. The design is supported by a gravel base treated with concrete or asphalt. It assumes there is no adherence between the base (existing pavement and the concrete slab. The core principle of this design method consists of designing a slab size, so that no more than one wheel set stays on a given slab, thus minimizing the critical tensile stress on the surface. Test segments have been built on a large scale and they have been tested under accelerated loads, with concrete thickness of 8, 15 and 20 cm, all of them having a gravel base and non-adhered asphaltic layers. Tests demonstrated that a reduced-size slab, of low thickness, might bear a considerable amount of equivalent axles before cracking takes place. Concrete slabs on gravel bases with 20 cm thickness did not suffer from cracking, in spite of being tested under more than 50 millions of equivalent axles. Slabs of 15 cm thickness suffered from cracking when tested under an average of 12 millions equivalent axles, while slabs of 8 cm thickness endured 75,000 equivalent axles before the first cracking took place. Besides the executed tests demonstrated that fiber concrete slabs may endure until 20 times more traffic before cracking and they are able to pro

  20. Avaliação do ruído através do SPBI (Statistical Pass-By Index) em diferentes pavimentos / Noise evaluation using the SPBI (Statistical Pass-By Index) for different pavements

    Scientific Electronic Library Online (English)

    Luciano Pivoto, Specht; Sérgio C., Callai; Oleg A., Khatchatourian; Raquel, Kohler.

    2009-12-01

    Full Text Available O transporte rodoviário causa grande impacto no meio ambiente, tanto pelo grande consumo de energia quanto pela infra-estrutura física necessária a sua operação. A emissão de gases e os ruídos causados pelo tráfego causam danos irreversíveis ao meio ambiente e têm sido alvo de inúmeros estudos e pes [...] quisas. Sabe-se que o atrito pneu/pavimento e as propriedades acústicas dos revestimentos influenciam de sobremaneira a geração e a propagação do ruído. Essa pesquisa tem como objetivo avaliar o ruído causado pelo tráfego de veículos em quatro diferentes pavimentos implantados em diferentes rodovias através do SPBI (Statistical Pass-By Index). A metodologia adotada seguiu as prescrições da norma ISO 11819-1, a qual determina que um decibelímetro seja instalado na lateral da via para medir o ruído máximo causado pela passagem de um veículo. O revestimento em CBUQ foi o pavimento cujas maiores medidas foram observadas (86,84dBA) seguido do CCP (83,28dBA), do TSD (83,26dBA) do MICRO (81,14dBA) e da CPA (81,03dBA). Os resultados indicam que a escolha adequada do revestimento pode atenuar de maneira expressiva o ruído causado pelo tráfego rodoviário. Abstract in english Highway transportation causes immense environmental impacts, as much by the enormous use of energy as for the physical infrastructure necessary for its operation. The gas emission and traffic noise cause irreversible damages to the environment and this has been the objective of a lot of studies and [...] researches. It is known that the contact between tire and pavement surface and the acoustic properties of the coverings influence the noise’s generation and propagation. This research aims to evaluate the noise caused by the traffic of vehicles in four different pavements through SPBI (Statistical Pass-By Index). The methodology followed the prescriptions of the norm ISO 11819-1; the decibelimeter is installed in the road side and it records the maximum noise caused by each vehicle. HMA presents higher noise measurement (86,84dBA) followed by PCC (83,28dBA), ST (83,26dBA) MICRO (81,14dBA) and PC (81,03dBA). The results indicate that correct pavement selection can reduce, in an expressive way, the noise caused by road traffic.

  1. Avaliação do ruído através do SPBI (Statistical Pass-By Index em diferentes pavimentos Noise evaluation using the SPBI (Statistical Pass-By Index for different pavements

    Directory of Open Access Journals (Sweden)

    Luciano Pivoto Specht

    2009-12-01

    Full Text Available O transporte rodoviário causa grande impacto no meio ambiente, tanto pelo grande consumo de energia quanto pela infra-estrutura física necessária a sua operação. A emissão de gases e os ruídos causados pelo tráfego causam danos irreversíveis ao meio ambiente e têm sido alvo de inúmeros estudos e pesquisas. Sabe-se que o atrito pneu/pavimento e as propriedades acústicas dos revestimentos influenciam de sobremaneira a geração e a propagação do ruído. Essa pesquisa tem como objetivo avaliar o ruído causado pelo tráfego de veículos em quatro diferentes pavimentos implantados em diferentes rodovias através do SPBI (Statistical Pass-By Index. A metodologia adotada seguiu as prescrições da norma ISO 11819-1, a qual determina que um decibelímetro seja instalado na lateral da via para medir o ruído máximo causado pela passagem de um veículo. O revestimento em CBUQ foi o pavimento cujas maiores medidas foram observadas (86,84dBA seguido do CCP (83,28dBA, do TSD (83,26dBA do MICRO (81,14dBA e da CPA (81,03dBA. Os resultados indicam que a escolha adequada do revestimento pode atenuar de maneira expressiva o ruído causado pelo tráfego rodoviário.Highway transportation causes immense environmental impacts, as much by the enormous use of energy as for the physical infrastructure necessary for its operation. The gas emission and traffic noise cause irreversible damages to the environment and this has been the objective of a lot of studies and researches. It is known that the contact between tire and pavement surface and the acoustic properties of the coverings influence the noise’s generation and propagation. This research aims to evaluate the noise caused by the traffic of vehicles in four different pavements through SPBI (Statistical Pass-By Index. The methodology followed the prescriptions of the norm ISO 11819-1; the decibelimeter is installed in the road side and it records the maximum noise caused by each vehicle. HMA presents higher noise measurement (86,84dBA followed by PCC (83,28dBA, ST (83,26dBA MICRO (81,14dBA and PC (81,03dBA. The results indicate that correct pavement selection can reduce, in an expressive way, the noise caused by road traffic.

  2. Sharing, liking, commenting, and distressed? The pathway between Facebook interaction and psychological distress.

    Science.gov (United States)

    Chen, Wenhong; Lee, Kye-Hyoung

    2013-10-01

    Studies on the mental health implications of social media have generated mixed results. Drawing on a survey of college students (N=513), this research uses structural equation modeling to assess the relationship between Facebook interaction and psychological distress and two underlying mechanisms: communication overload and self-esteem. It is the first study, to our knowledge, that examines how communication overload mediates the mental health implications of social media. Frequent Facebook interaction is associated with greater distress directly and indirectly via a two-step pathway that increases communication overload and reduces self-esteem. The research sheds light on new directions for understanding psychological well-being in an increasingly mediated social world as users share, like, and comment more and more. PMID:23745614

  3. Politics, economic distress mark Rmoga sessions

    International Nuclear Information System (INIS)

    This paper reports that election year energy politics clashed with economic distress at Rocky Mountain Oil and Gas Association's annual meeting in Denver early this month. Energy Sec. James D Watkins used the occasion to hail omnibus energy legislation passed by a House-Senate conference committee just hours before he spoke. But not all producers and refiners in the audience shared his enthusiasm for the energy bill, a hard-won Bush administration goal that many Rmoga members doubt will help this industry much. Several of them privately expressed dismay over Watkins' praise, delivered to a beleaguered oil and gas group, of Department of Energy research programs boosting clean coal technology and battery powered vehicles

  4. ACUTE RESPIRATORY DISTRESS SYNDROME IN PREGNANCY

    Directory of Open Access Journals (Sweden)

    Madhumala

    2015-04-01

    Full Text Available Acute respiratory distress syndrome (ARDS is a clinical syndrome of severe dyspnea of rapid onset, hypoxemia, and diffuse pulmonary infiltrates leading to respiratory failure. ARDS occurs in pregnancy and may have unique causes. Overall mortality for both the mother and the fetus is high and significant morbidity can persist even after initial recovery. ARDS is associated with obstetric causes such as amniotic fluid embolism, preeclampsia, septic abortion, and retained products of conception or non - obstetr ic causes that include sepsis, aspiration pneumonitis, influenza pneumonia, blood transfusions, and trauma. Here is a 24 years old female admitted with 7months of amenorrhea, who presented with respiratory failure, she was intubated and ventilated for 47da ys. She recovered, and a live baby was delivered. She was discharged after 73days.

  5. Acute respiratory distress syndrome: evaluation and management.

    Science.gov (United States)

    Cortés, I; Peñuelas, O; Esteban, A

    2012-03-01

    Acute respiratory distress syndrome (ARDS) is a life-threatening condition that affects patients admitted in the Intensive Care Units (ICUs) under mechanical ventilation. ARDS is a process of non-hydrostatic pulmonary edema and hypoxemia associated with a variety of conditions, resulting in a direct (e.g., pneumonia) or indirect (e.g., sepsis) lung injury and is associated with a significant morbidity and mortality. A large body of clinical and basic research has focused in ventilatory strategies and novel pharmacological therapies but, nowadays, treatment is mainly supportive. Mechanical ventilation is the hallmark of the management of these patients. In the last decades, the recognition that mechanical ventilation can contribute to harming the lung has changed the goals of this therapy and has driven research to focus in ventilatory strategies that mitigate lung injury. This review emphasizes clinical aspects in the evaluation and management of ARDS in the ICUs and updates the latest advances in these therapies. PMID:22357372

  6. Neuroleptic-induced acute respiratory distress syndrome

    Scientific Electronic Library Online (English)

    Francisco Garcia, Soriano; Elcio dos Santos Oliveira, Vianna; Irineu Tadeu, Velasco.

    Full Text Available CONTEXTO: Apresentamos um caso de síndrome neuroléptica maligna e de síndrome do desconforto respiratório do adulto relacionada ao uso do neuroléptico. Discutimos a possível relação clínica e as alterações de creatinino-quinase, relaxamento muscular e função respiratória. RELATO DE CASO: Paciente de [...] 41 anos, homem, branco. Internado por otalgia e paralisia facial periférica à direita. A tomografia computadorizada de crânio mostrou uma área hiperdensa de 2 cm de diâmetro na região da artéria intercomunicante anterior. Os exames pré-operatórios revelaram: pH 7.4, PaCO2 40 torr, PaO2 80 torr (em ar ambiente), Hb 13.8 g/dl, nitrogênio uréico no plasma 3.2 mmol/l, e creatinina 90 mmol/l. A radiografia de tórax era normal. O paciente fez jejum de 12 horas previamente à cirurgia. Foram usados na anestesia: halotano, fentanil 0.5 mg e droperidol 25 mg (intravenosa). Após seis horas o paciente apresentava PaO2 65 torr (PCO2 normal) sob FiO2 de 50% (relação PaO2/FiO2 130) e permaneceu neste nível até o final da cirurgia. O achado intraoperatório foi de um aneurisma trombosado, que foi ressecado; o vaso foi clipado. Não havia vasoespasmo. Este caso ilustra que drogas neurolépticas podem causar síndrome maligna por neuroléptico e síndrome do desconforto respiratório do adulto em associação. Contudo, há possibilidade de que o neuroléptico ou o solvente da droga possam produzir síndrome do desconforto respiratório do adulto sem apresentar as manifestações de síndrome maligna por neuroléptico. Esta possibilidade é importante pois, nos pacientes com síndrome do desconforto respiratório do adulto que estejam recebendo neurolépticos, será necessário que se pense em sua substituição, especialmente se o paciente não apresentar outros fatores que possam explicar a síndrome do desconforto respiratório do adulto. Abstract in english CONTEXT: A case of neuroleptic malignant syndrome and acute respiratory distress syndrome is presented and discussed with emphasis on the role of muscle relaxation, creatine kinase, and respiratory function tests. CASE REPORT: A 41-year-old man presented right otalgia and peripheral facial paralysis [...] . A computed tomography scan of the skull showed a hyperdense area, 2 cm in diameter, in the pathway of the anterior intercommunicating cerebral artery. Preoperative examination revealed: pH 7.4, PaCO2 40 torr, PaO2 80 torr (room air), Hb 13.8 g/dl, blood urea nitrogen 3.2 mmol/l, and creatinine 90 mmol/l. The chest x-ray was normal. The patient had not eaten during the 12-hour period prior to anesthesia induction. Intravenous halothane, fentanyl 0.5 mg and droperidol 25 mg were used for anesthesia. After the first six hours, the PaO2 was 65 torr (normal PaCO2) with FiO2 50% (PaO2/FiO2 130), and remained at this level until the end of the operation 4 hours later, maintaining PaCO2 at 35 torr. A thrombosed aneurysm was detected and resected, and the ends of the artery were closed with clips. No vasospasm was present. This case illustrates that neuroleptic drugs can cause neuroleptic malignant syndrome associated with acute respiratory distress syndrome. Neuroleptic malignant syndrome is a disease that is difficult to diagnose. Acute respiratory distress syndrome is another manifestation of neuroleptic malignant syndrome that has not been recognized in previous reports: it may be produced by neuroleptic drugs independent of the manifestation of neuroleptic malignant syndrome. Some considerations regarding the cause and effect relationship between acute respiratory distress syndrome and neuroleptic drugs are discussed. Intensive care unit physicians should consider the possibility that patients receiving neuroleptic drugs could develop respiratory failure in the absence of other factors that might explain the syndrome.

  7. EXPRESSING DISTRESS IN PATIENTS WITH ADVANCED CANCER

    Directory of Open Access Journals (Sweden)

    Maura Gabriela FELEA

    2014-11-01

    Full Text Available Negative emotions (distress are recognized as part of the psychological profile of patients diagnosed with advanced stage cancer. However, most patients are not accustomed to verbalize feelings towards their physician, and generally towards family and medical care personnel. The purpose of this paper is to analyze the expression of emotions by patients in advanced stages of cancer, respectively the means by which they get to express emotions. To this respect, we identified the most common types of emotions expressed, or metaphors used by patients to describe their emotions and topics that trigger emotions. Words and phrases most commonly used are in relation to: fear, anxiety, depression, guilt, negligence, concern. They are uttered in order to depict the network created between disclosed emotions and topics on health status, symptoms, adverse effects and therapeutic choice, patient privacy, and social and family issues.

  8. Assessment of work intensification by managers and psychological distressed and non-distressed employees

    DEFF Research Database (Denmark)

    Bamberger, Simon Grandjean; Larsen, Anelia; Vinding, Anker Lund; Nielsen, Peter; Fonager, Kirsten; Nielsen, René Nesgaard; Ryom, Pia Køhler; Omland, Øyvind

    2015-01-01

    Work intensification is a popular management strategy to increase productivity, but at the possible expense of employee mental stress. This study examines associations between ratings of work intensification and psychological distress, and the level of agreement between compared employee-rated and manager-rated work intensification. Multi-source survey data were collected from 3,064 employees and 573 company managers from the private sector in 2010. Multilevel regression models were used to comp...

  9. Technical note on measuring run-off dynamics from pavements using a new device: the weighable tipping bucket

    Science.gov (United States)

    Nehls, T.; Rim, Y. Nam; Wessolek, G.

    2011-05-01

    Due to climate change, cities need to adapt to changing rainfall and rainwater run-off dynamics. In order to develop an corresponding process based run-off model for pavements, we had to improve the measurement technique to detect run-off dynamics in an appropriate high resolution. Traditional tipping buckets (TB) have a comparable low volume resolution, capable to quantify the highest intensities in a range of expected flows. This results in varying temporal resolutions for varying flow intensities, especially in low resolutions for small flow events. Therefore, their applicability for run-off measurements and other hydrological process studies is limited, especially when the dynamics of both small and big flow events shall be measured. We improved a TB by coupling it to a balance and called it weighable tipping bucket (WTB). This paper introduces the device set up and the according data processing concept. The improved volume and temporal resolution of the WTB are demonstrated. A systematic uncertainty of TB measurements compared to WTB measurements is calculated. The impact of that increased resolution on our understanding of run-off dynamics from paved urban soils are discussed, exemplary for the run-off and the surface storage of a paved urban soil. The study was conducted on a permeably paved lysimeter situated in Berlin, Germany. Referring to the paved surface, the TB has a resolution of 0.1 mm, while the WTB has a resolution of 0.001 mm. The temporal resolution of the WTB is 3 s, the TB detects individual tippings with 0.4 s between them. Therefore, the data processing concept combines both the benefits of the balance to measure small intensities with that of the TB to measure high flow intensities. During a five months period (July to November 2009) 154 rain events were detected. Accordingly, the TB and WTB detected 47 and 121 run-off events. The total run-off was 79.6 mm measured by the WTB which was 11 % higher than detected by the TB. 95 % of that difference can be appointed to water, which evaporated from the TB. To derive a surface storage estimation, we analyzed the WTB and TB data for rain events without run-off. According to WTB data, the surface storage of the permeable pavement is 1.7 mm, while using TB data leads to an overestimation of 47 % due to low volume resolution of the TB. Combining traditional TB with modern, fast, high resolution digital balances offers the opportunity to upgrade existing TB systems in order to improve their volume detection limit and their temporal resolution, which is of great advantage for the synchronization of water balance component measurements and the investigation of hydrological processes. Furthermore, we are able to quantify the uncertainty of flow measurements gained with traditional tipping buckets.

  10. Technical note on measuring run-off dynamics from pavements using a new device: the weighable tipping bucket

    Directory of Open Access Journals (Sweden)

    T. Nehls

    2010-12-01

    Full Text Available Due to climate change, cities need to adapt to changing rainfall and rainwater run-off dynamics. In order to develop an corresponding process based run-off model for pavements, we had to improve the measurement technique to detect run-off dynamics in an appropriate high resolution.

    Traditional tipping buckets (TB have a comparable low volume resolution, capable to quantify the highest intensities in a range of expected flows. This results in varying temporal resolutions for varying flow intensities, especially in low resolutions for small flow events. Therefore, their applicability for run-off measurements and other hydrological process studies is limited, especially when the dynamics of both small and big flow events shall be described.

    We improved a TB by coupling it to a balance and called it weighable tipping bucket (WTB. This paper introduces the device set up and the according data processing concept. The improved volume and temporal resolution of the WTB are demonstrated. A systematic uncertainty of TB measurements compared to WTB measurements is calculated. The impact of that increased resolution on our understanding of run-off dynamics from paved urban soils are discussed, exemplary for the run-off and the surface storage of a paved urban soil.

    The study was conducted on a permeably paved lysimeter situated in Berlin, Germany. Referring to the paved surface, the TB has a resolution of 0.1 mm, while the WTB has a resolution of 0.001 mm. The temporal resolution of the WTB is 3 s, the TB detects individual tippings with 0.4 s between them. Therefore, the data processing concept combines both the benefits of the balance to measure small intensities with that of the TB to measure high flow intensities.

    During a five months period (July to November 2009 154 rain events were detected. Accordingly, the TB and WTB detected 47 and 121 run-off events. The total run-off was 79.6 mm measured by the WTB which was 11% higher than detected by the TB. 95% of that difference can be appointed to water, which evaporated from the TB. To derive a surface storage estimation, we analyzed the WTB and TB data for rain events without run-off. According to WTB data, the surface storage of the permeable pavement is 1.7 mm, while using TB data leads to an overestimation of 47% due to low volume resolution of the TB.

    Combining traditional TB with modern, fast, high resolution digital balances offers the opportunity to upgrade existing TB systems in order to improve their volume detection limit and their temporal resolution, which is of great advantage for the synchronization of water balance component measurements and the investigation of hydrological processes.

  11. Technical note on measuring run-off dynamics from pavements using a new device: the weighable tipping bucket

    Directory of Open Access Journals (Sweden)

    T. Nehls

    2011-05-01

    Full Text Available Due to climate change, cities need to adapt to changing rainfall and rainwater run-off dynamics. In order to develop an corresponding process based run-off model for pavements, we had to improve the measurement technique to detect run-off dynamics in an appropriate high resolution.

    Traditional tipping buckets (TB have a comparable low volume resolution, capable to quantify the highest intensities in a range of expected flows. This results in varying temporal resolutions for varying flow intensities, especially in low resolutions for small flow events. Therefore, their applicability for run-off measurements and other hydrological process studies is limited, especially when the dynamics of both small and big flow events shall be measured.

    We improved a TB by coupling it to a balance and called it weighable tipping bucket (WTB. This paper introduces the device set up and the according data processing concept. The improved volume and temporal resolution of the WTB are demonstrated. A systematic uncertainty of TB measurements compared to WTB measurements is calculated. The impact of that increased resolution on our understanding of run-off dynamics from paved urban soils are discussed, exemplary for the run-off and the surface storage of a paved urban soil.

    The study was conducted on a permeably paved lysimeter situated in Berlin, Germany. Referring to the paved surface, the TB has a resolution of 0.1 mm, while the WTB has a resolution of 0.001 mm. The temporal resolution of the WTB is 3 s, the TB detects individual tippings with 0.4 s between them. Therefore, the data processing concept combines both the benefits of the balance to measure small intensities with that of the TB to measure high flow intensities.

    During a five months period (July to November 2009 154 rain events were detected. Accordingly, the TB and WTB detected 47 and 121 run-off events. The total run-off was 79.6 mm measured by the WTB which was 11 % higher than detected by the TB. 95 % of that difference can be appointed to water, which evaporated from the TB. To derive a surface storage estimation, we analyzed the WTB and TB data for rain events without run-off. According to WTB data, the surface storage of the permeable pavement is 1.7 mm, while using TB data leads to an overestimation of 47 % due to low volume resolution of the TB.

    Combining traditional TB with modern, fast, high resolution digital balances offers the opportunity to upgrade existing TB systems in order to improve their volume detection limit and their temporal resolution, which is of great advantage for the synchronization of water balance component measurements and the investigation of hydrological processes. Furthermore, we are able to quantify the uncertainty of flow measurements gained with traditional tipping buckets.

  12. "Comparison of some Structural Analyses Methods used for the Test Pavement in the Danish Road Testing Machine

    DEFF Research Database (Denmark)

    Baltzer, S.; Zhang, W.; Macdonald, R.; Ullidtz, Per

    A flexible test pavement, instrumented to measure stresses and strains in the three primary axes with the upper 400 mm of the subgrade, has been constructed and load tested in the Danish Road Testing Machine (RTM). One objective of this research, which is part of the International Pavement Subgrade...... Performance Study, is to develop an improved mechanistic subgrade failure criterion.Simulated traffic loads were applied between June and December 1997 by a dual tyre loading cart within a climate chamber maintained at a constant temperature. Three load levels (40 kN, 50 kN and 60 kN) were applied. In all...... three test series, 50000 load repetitions were applied at each load level, and the test chamber temperature was maintained at approximately 25 degree C.Instruments installed in the test pavement included: Strain measuring sensors (LVDT Soil Strain Deformation Transducers and Asphalt Strain Gauges), Soil...

  13. Surfactant alteration and replacement in acute respiratory distress syndrome

    Directory of Open Access Journals (Sweden)

    Walmrath Dieter

    2001-10-01

    Full Text Available Abstract The acute respiratory distress syndrome (ARDS is a frequent, life-threatening disease in which a marked increase in alveolar surface tension has been repeatedly observed. It is caused by factors including a lack of surface-active compounds, changes in the phospholipid, fatty acid, neutral lipid, and surfactant apoprotein composition, imbalance of the extracellular surfactant subtype distribution, inhibition of surfactant function by plasma protein leakage, incorporation of surfactant phospholipids and apoproteins into polymerizing fibrin, and damage/inhibition of surfactant compounds by inflammatory mediators. There is now good evidence that these surfactant abnormalities promote alveolar instability and collapse and, consequently, loss of compliance and the profound gas exchange abnormalities seen in ARDS. An acute improvement of gas exchange properties together with a far-reaching restoration of surfactant properties was encountered in recently performed pilot studies. Here we summarize what is known about the kind and severity of surfactant changes occuring in ARDS, the contribution of these changes to lung failure, and the role of surfactant administration for therapy of ARDS.

  14. Properties and toxicological effects of particles from the interaction between tyres, road pavement and winter traction material

    International Nuclear Information System (INIS)

    In regions where studded tyres and traction material are used during winter, e.g. the Nordic countries, northern part of USA, Canada, and Japan, mechanically generated particles from traffic are the main reason for high particle mass concentrations in busy street and road environments. In many Nordic municipalities the European environmental quality standard for inhalable particles (PM10) is exceeded due to these particles. In this study, particles from the wear of studded and studless friction tyres on two pavements and traction sanding were generated using a road simulator. The particles were characterized using particle sizers, Particle Induced X-Ray Emission Analysis and electron microscopy. Cell studies were conducted on particles sampled from the tests with studded tyres and compared with street environment, diesel exhaust and subway PM10, respectively. The results show that in the road simulator, where resuspension is minimized, studded tyres produce tens of times more particles than friction tyres. Chemical analysis of the sampled particles shows that the generated wear particles consist almost entirely of minerals from the pavement stone material, but also that Sulfur is enriched for the submicron particles and that Zink is enriched for friction tyres for all particles sizes. The chemical data can be used for source identification and apportionment in urban aerosol studies. A mode of ultra-fine particles was also present and is hypothesised to originate in the tyres. Further, traction material properties affect PM10 emission. The inflammatory potential of the particles from wear of pavements seems to depend on type of pavement and can be at least as potent as diesel exhaust particles. The results imply that there is a need and a good potential to reduce particle emission from pavement wear and winter time road and street operation by adjusting both studded tyre use as well as pavement and traction material properties

  15. Moss cushions facilitate water and nutrient supply for plant species on bare limestone pavements

    DEFF Research Database (Denmark)

    Jensen, Kaj Sand; Hammer, Kathrine

    2012-01-01

    Dense moss cushions of different size are distributed across the bare limestone pavements on Øland, SE Sweden. Increasing cushion size is predicted to physically protect and improve performance and colonization by vascular plants. Therefore, we tested water balance, phosphorus supply, and species...... oasis of improved water and nutrient supply to colonization and growth of plants....... richness, and evaluated duration of plant activity during desiccation as a function of ground area, for a large collection of moss cushions. We found that lower evaporation and higher water storage contributed equally to extending the desiccation period with increasing cushion size. Evaporation rates...

  16. Identification of pavement layers using a thermal probe / Identificação das camadas de pavimento utilizando sonda térmica

    Scientific Electronic Library Online (English)

    Radael de Souza, Parolin; Pedro Augusto Pereira, Borges; Luciano Pivoto, Specht.

    2015-03-01

    Full Text Available Para se obterem informações sobre a estrutura de pavimentos, atualmente, são realizadas prospecções significativamente destrutivas e intervenientes no tráfego. O objetivo desse trabalho é desenvolver uma técnica de identificação das espessuras das camadas de pavimentos, que consiste na instalação de [...] uma sonda térmica no pavimento, com sensores de temperatura e fontes de calor, para a obtenção da distribuição de temperatura em função do tempo e do espaço, em diferentes profundidades; na resolução do problema de transferência de calor em duas dimensões; e na estimação das espessuras e propriedades térmicas dos materiais de cada camada através do Problema Inverso. O Problema Direto foi modelado pela equação de condução do calor e resolvido com Diferenças Finitas Centrais, usando o método explícito de avanços temporais. Os Algoritmos Genético e Memético foram eficientes na estimação das espessuras das camadas e apresentaram pouca diferença entre os valores estimados a cada aplicação. A técnica proposta mostrou-se eficiente na estimação das espessuras nos testes realizados com pavimentos experimentais e traz uma nova perspectiva em avaliação estrutural, com reduzida intervenção no pavimento e interferência no tráfego. Abstract in english To obtain information about pavement structure, nowadays, destructive prospecting is carried out, interfering significantly with traffic. Proposed here in is a less destructive and invasive technique, whereby a thermal probe with temperature sensors is installed in the pavement. This process identif [...] ies the sources of heat to obtain the temperature distribution as a function of time and space at different depths; to solve the heat transfer problem in two dimensions and to estimate the thickness and thermal materials properties of each layer through the Inverse Problem. The Direct Problem has been modeled by a heat conduction equation and solved by Central Finite Differences, using the explicit method of time advancements. The Genetic and Memetic Algorithms have been efficient in estimating the thickness of the layers and they have presented little difference between the estimated values at each application. The proposed technique has been efficient in estimating the thickness in the tests with experimental pavements and it brings a new perspective for structural evaluation, with reduced pavement intervention and traffic interference.

  17. Effect of crumb rubber gradation on a rubberized cold recycled mixture for road pavements

    DEFF Research Database (Denmark)

    Pettinari, Matteo; Simone, Andrea

    2015-01-01

    valorization of recycled materials together with the goal of achieving high performance. In the present research project, two different gradations of crumb rubber, processed with the traditional grading method, have been adopted for the production of a cold recycled mixture stabilized with bitumen emulsion and......Cold recycling technique represents the most environmental friendly solution for pavement rehabilitation nowadays. In fact, this technique allows the use of the highest percentage of reclaimed asphalt avoiding the energy consumption related to aggregates heating required by the traditional hot mix...... properties of the cold recycled mixture....

  18. Metal distributions in soil receiving urban pavement runoff and snowmelt.

    Science.gov (United States)

    Sansalone, John J; Glenn, Donald W

    2007-07-01

    Wet and dry deposition of anthropogenic metals and particulates generated from urban and traffic activities can result in contamination of urban-land-use soils. These particulate residuals encompass a wide size gradation, from 1 to greater than 10 000 microm. This study hypothesized that such contamination of surficial soils can be analyzed and explained as a function of the soil/residual granulometry. This study analyzed the gradation-based physical characteristics for 10 urban transportation land-use sites with soil/residual complexes (SRCs) located throughout metropolitan Cincinnati, Ohio, and an urban residential reference site. Particle density (rho(s)) of SRCs ranged from 2.8 to 2.1 g/cm3, with the lower particle density associated with particles less than 100 microm. For each site, specific surface area generally increased with decreasing particle size, while the predominance of total surface area was associated with the coarser size fractions, except for the clayey glacial till reference site not influenced by traffic. Cumulative analysis for lead, copper, cadmium, and zinc associated with SRCs indicated that more than 50% of the metal mass was associated with particles greater than 250 microm, with more than 80% associated with particles greater than 106 microm. Study results are similar to rainfall-runoff and snowmelt distributions. Results provide guidance when considering potential fate and control of metals transported by urban drainage and are distributed across the SRC size gradation. PMID:17710918

  19. Disentangling depression and distress networks in the tinnitus brain.

    Science.gov (United States)

    Joos, Kathleen; Vanneste, Sven; De Ridder, Dirk

    2012-01-01

    Tinnitus is the continuous perception of an internal auditory stimulus. This permanent sound often affects a person's emotional state inducing distress and depressive feelings changes in 6-25% of the affected population. Distress and depression are two distinct emotional states. Whereas distress describes a transient aversive state, interfering with a person's ability to adequately adapt to stressors, depressive feelings should rather be considered as a more constant emotional state. Based on previous observations in chronic pain, posttraumatic stress disorder and depression, we assume that both states are related to separate neural circuits. We used the Dutch version of the Tinnitus Questionnaire to assess the global index of distress together with the Beck Depression Inventory to evaluate the depressive symptoms accompanying tinnitus. Furthermore sLORETA analysis was performed to correlate current density distribution with distress and depression scores, revealing a lateralization effect of depression versus distress. Distress is mainly correlated with alpha 2, beta 1 and beta 2 activity of the right frontopolar cortex and orbitofrontal cortex in combination with beta 2 activation of the anterior cingulate cortex. In contrast, the more permanent depressive alterations induced by tinnitus are associated with activity of alpha 2 activity in the left frontopolar and orbitofrontal cortex. These specific neural circuits are embedded in a greater neural network, with the parahippocampal region functioning as a crucial linkage between both tinnitus related pathways. PMID:22808188

  20. Partner relationship satisfaction and maternal emotional distress in early pregnancy

    Directory of Open Access Journals (Sweden)

    Eberhard-Gran Malin

    2011-03-01

    Full Text Available Abstract Background Recognition of maternal emotional distress during pregnancy and the identification of risk factors for this distress are of considerable clinical- and public health importance. The mental health of the mother is important both for herself, and for the physical and psychological health of her children and the welfare of the family. The first aim of the present study was to identify risk factors for maternal emotional distress during pregnancy with special focus on partner relationship satisfaction. The second aim was to assess interaction effects between relationship satisfaction and the main predictors. Methods Pregnant women enrolled in the Norwegian Mother and Child Cohort Study (n = 51,558 completed a questionnaire with questions about maternal emotional distress, relationship satisfaction, and other risk factors. Associations between 37 predictor variables and emotional distress were estimated by multiple linear regression analysis. Results Relationship dissatisfaction was the strongest predictor of maternal emotional distress (? = 0.25. Other predictors were dissatisfaction at work (? = 0.11, somatic disease (? = 0.11, work related stress (? = 0.10 and maternal alcohol problems in the preceding year (? = 0.09. Relationship satisfaction appeared to buffer the effects of frequent moving, somatic disease, maternal smoking, family income, irregular working hours, dissatisfaction at work, work stress, and mother's sick leave (P Conclusions Dissatisfaction with the partner relationship is a significant predictor of maternal emotional distress in pregnancy. A good partner relationship can have a protective effect against some stressors.