Scientific and Technical Aerospace Reports

Scientific and Technical Aerospace Reports
Author:
Publisher:
Total Pages: 700
Release: 1995
Genre: Aeronautics
ISBN:
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Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Nondestructive Testing of Pavements and Backcalculation of Moduli

Nondestructive Testing of Pavements and Backcalculation of Moduli
Author: Shiraz D. Tayabji
Publisher: ASTM International
Total Pages: 534
Release: 2000
Genre: Materials
ISBN: 0803128584
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As with the previous two symposia, the 32 papers from the June/July, 1999, Seattle symposium present advances in the nondestructive testing of pavements using conventional falling weight deflectometer techniques and other promising techniques such as ground penetrating radar, rolling weight deflecto

Development of In-situ Detection Methods for Materials-related Distress (MRD) in Concrete Pavements

Development of In-situ Detection Methods for Materials-related Distress (MRD) in Concrete Pavements
Author: Scott Schlorholtz
Publisher:
Total Pages: 84
Release: 2003
Genre: Nondestructive testing
ISBN:
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The purpose of this research was to summarize existing nondestructive test methods that have the potential to be used to detect materials-related distress (MRD) in concrete pavements. The various nondestructive test methods were then subjected to selection criteria that helped to reduce the size of the list so that specific techniques could be investigated in more detail. The main test methods that were determined to be applicable to this study included two stress-wave propagation techniques (impact-echo and spectral analysis of surface waves techniques), infrared thermography, ground penetrating radar (GPR), and visual inspection. The GPR technique was selected for a preliminary round of "proof of concept" trials. GPR surveys were carried out over a variety of portland cement concrete pavements for this study using two different systems. One of the systems was a state-of-the-art GPR system that allowed data to be collected at highway speeds. The other system was a less sophisticated system that was commercially available. Surveys conducted with both sets of equipment have produced test results capable of identifying subsurface distress in two of the three sites that exhibited internal cracking due to MRD. Both systems failed to detect distress in a single pavement that exhibited extensive cracking. Both systems correctly indicated that the control pavement exhibited negligible evidence of distress. The initial positive results presented here indicate that a more thorough study (incorporating refinements to the system, data collection, and analysis) is needed. Improvements in the results will be dependent upon defining the optimum number and arrangement of GPR antennas to detect the most common problems in Iowa pavements. In addition, refining high frequency antenna response characteristics will be a crucial step toward providing an optimum GPR system for detecting materials related distress.

Transport Infrastructure and Systems

Transport Infrastructure and Systems
Author: Gianluca Dell'Acqua
Publisher: CRC Press
Total Pages: 1134
Release: 2017-03-16
Genre: Science
ISBN: 1315281880
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Transport Infrastructure Asset management in transport infrastructure, financial viability of transport engineering projects/ Life cycle Cost Analysis, Life-Cycle Assessment and Sustainability Assessment of transport infrastructure/ Infrastructures financing and pricing with equity appraisal, operation optimization and energy management/ Low-Volume roads: planning, maintenance, operations, environmental and social issues/ Public-Private Partnership (PPP) experience in transport infrastructure in different countries and economic conditions/ Airport Pavement Management Systems, runway design and maintenance/ Port maintenance and development issues, technology relating to cargo handling, landside access, cruise operations/ Infrastructure Building Information Modelling (I-BIM) / Pavement design and innovative bituminous materials/ Recycling and re-use in road pavements, environmentally sustainable technologies/ Stone pavements, ancient roads and historic railways/ Cementitious stabilization of materials used in the rehabilitation of transportation infrastructure. Transport Systems Sustainable transport and the environment protection including green vehicles/ Urban transport, land use development, spatial and transport planning/ Bicycling, bike, bike-sharing systems, cycling mobility/ Human factor in transport systems/ Intelligent Mobility: emerging technologies to enable the smarter movement of people and goods/Airport landside: access roads, parking facilities, terminal facilities, aircraft apron and the azdjacent taxiway/ Transportation policy, planning and design, modelling and decision making/ Transport economics, finance and pricing issues, optimization problems, equity appraisal/ Road safety impact assessments, road safety audits, the management of road network safety and safety inspections/ Tunnels and underground structures: preventing incidents-accidents mitigating their effects for both people and goods/ Traffic flow characteristics, traffic control devices, work zone traffic control, highway capacity and quality of service/ Track-vehicle interactions in railway systems, capacity analysis of railway networks/ Risk assessment and safety in air and railway transport, reliability aspects/ Maritime transport and inland waterways transport research/ Intermodal freight transport: terminals and logistics.

Establishment of Reliable Methodologies to Determine In-situ Moisture Content of Base and Subgrade Soils

Establishment of Reliable Methodologies to Determine In-situ Moisture Content of Base and Subgrade Soils
Author: Richard Liu
Publisher:
Total Pages: 74
Release: 1999
Genre: Roads
ISBN:
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Pavement life span is often affected by the amount of voids in the base and subgrade soils, and especially by the soil moisture content. Time Domain Reflectometry (TDR) and Ground Penetrating Radar (GPR) are two desirable techniques to indirectly measure the in-situ soil moisture content through electrical properties of soils. The pre-purchased Tektronix 1502B TDR Cable Tester equipped with Campbell Scientific SDM1502 Communications Interface and PS 1502B Power Control Module system was successfully modified, installed, and integrated into the existing weather station in conjunction with the Texas Mobile Load Simulator (TxMLS) research project. The test sections were located on US281 near Jacksboro, Texas. The TDR results from US281 test sites indicated that the TDR sensors responded to the rainfall events favorably. The two-year field test results indicated that the TDR readings interpreted by Topp's (1980) and Ledieu's (1986) equations agreed well with the real measured value for the subgrade; none of the existing models for the base layers was found to be suitable for the soil moisture content conversion used in this research study. An empirical equation was established to determine the weight-based moisture content of the compacted base materials. Although the TDR system provides valuable information, it requires considerable time and effort to process data. In addition, the TDR system consumed too much power and caused malfunctions of the weather station. In that regard, a new Moisture Sensor (MS) system was developed in this study and verified at the Materials and Tests (MAT) section of Texas Department of Transportation. The results from MAT section indicated that the MS system provides a more reliable solution than that of the TDR system. In addition, it is much easier to process the MS data. Furthermore, the MS system consumes almost no battery power and is an ideal solution for a long-term monitoring of pavement moisture content. GPR was also employed at the same test sites. The Inversion Method was applied for converting moisture content of soils. Laboratory tests were satisfactory; yet the field application of this study needs further experiments to improve the results.

Report

Report
Author:
Publisher:
Total Pages: 460
Release: 1964
Genre: Highway research
ISBN:
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Ground Penetrating Radar Applications on Roads and Highways

Ground Penetrating Radar Applications on Roads and Highways
Author: Timo Saarenketo
Publisher:
Total Pages: 56
Release: 1994
Genre: Ground penetrating radar
ISBN:
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This report will describe the various kinds of information that can be obtained from roads and highways with Ground Penetrating Radar. In the last 5 years, attention has focused on measuring the thickness of the asphalt surfacing layer on flexible pavements with air-launched horn antennas. Other antennas are available with substantially different depths of penetration, and for use in a wide range of other pavement applications. The purpose of this report is to describe the range of applications of GPR in pavement evaluation. Cases include subgrade investigations, bedrock evaluations, locating sinkholes, detecting frost damage, and identifying defects such as stripping or voids and monitoring crack growth within the pavement structure. The large variety of cases, conducted in Texas and Finland, illustrates the unique ability of GPR to rapidly evaluate subsurface conditions. The sinkhole detection study represents our initial effort to use low frequency deep penetrating radar on Texas pavements. A unique feature of this paper is the proposed classification of the frost susceptibility of subgrade soils by their measured dielectric constant and electrical conductivity.