<?xml version="1.0" encoding="utf-8"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>TRB Publications Index</title><link>http://pubsindex.trb.org/</link><atom:link href="http://pubsindex.trb.org/common/TRIS Suite/feeds/rss.aspx?tc=NN%3AGu" rel="self" type="application/rss+xml" /><description></description><language>en-us</language><copyright>Copyright © 2015. National Academy of Sciences. All rights reserved.</copyright><docs>http://blogs.law.harvard.edu/tech/rss</docs><managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor><webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster><image><title>TRB Publications Index</title><url>http://pubsindex.trb.org/Images/PageHeader-wTitle.png</url><link>http://pubsindex.trb.org/</link></image><item><title>Light Weight Deflectometer Configurations for Testing Thin Asphalt Pavements</title><link>http://pubsindex.trb.org/view/2475284</link><description><![CDATA[The light weight deflectometer (LWD) is used to determine fundamental soil properties such as deflection and modulus. Recently, the LWD has been investigated as a potential structural evaluation tool for thin flexible pavements to generate input data for structural performance prediction models of thin flexible pavements. The falling weight deflectometer (FWD) can be used for the evaluation of thin flexible pavements; however, the relatively high cost and logistics burden, which also may render FWD unsuitable for many local agencies, are disadvantageous for the rapid assessment of dispersed rural roadways. The LWD is a potential alternative; however, since various LWD models are available and multiple testing configurations are possible, this study focused on determining which LWD configuration(s) produce structural responses that most closely correspond to FWD. Ten different LWD combinations of base plate diameter, drop weight, and drop height were tested on two full-scale thin asphalt test sections under closely comparable temperature and moisture conditions. The LWD’s ability to indicate structural conditions was compared with that of the FWD through impulse stiffness modulus. The distribution of stress within the pavements was measured during testing. In addition, the LWD’s repeatability was assessed and found to be similar to that of the FWD. As a result, the small 5.91-in. plate diameter, 22-in. drop height, and largest available hammer weights for both LWD models obtained good repeatability and the closest correspondence to FWD when tested on thin flexible pavements.]]></description><pubDate>Mon, 16 Dec 2024 16:17:14 GMT</pubDate><guid>http://pubsindex.trb.org/view/2475284</guid></item><item><title>Investigation of Locked Wheel Skid Tester Practicability on Horizontal Curves: A Camera-Based Field Implementation</title><link>http://pubsindex.trb.org/view/2387603</link><description><![CDATA[The locked wheel skid tester (LWST) has the capability to perform efficient on-site pavement skid resistance tests without traffic control. A LWST friction test measures the longitudinal friction force and vertical load taking place at the tire–pavement interface of a standard locked wheel at a specified test speed. However, the test is specified only for straight and level pavements. Possible reasons that the LWST may fail to provide reliable friction data during vehicle cornering are biased tire speed and force measurements, missing information of vehicle side friction, and risky trailer fishtailing. Horizontal curves are widely distributed in the highway network and have a higher crash rate compared to straight segments. This paper developed a camera-based setup to monitor instant cornering behaviors of a LWST traversing on horizontal curves. Along with data from the standard LWST speed sensor and force transducer, the upgraded tester can also operate as a vehicle side friction sensor and an oversteering alert system. The dual-camera-equipped experimental vehicle was employed in field friction tests on different types of pavement horizontal curves. The captured video frames were then utilized in image processing algorithms for real-time test tire speed, sideslip angle, and articulation angle measurements with high accuracies during tests. The impact of pavement horizontal alignment design on LWST friction measurements and the result performance were assessed. The investigation extends LWST practicability on highway horizontal curves with evaluated restrictions.]]></description><pubDate>Mon, 10 Jun 2024 16:19:23 GMT</pubDate><guid>http://pubsindex.trb.org/view/2387603</guid></item><item><title>Measuring Concrete Permeability with CHIP</title><link>http://pubsindex.trb.org/view/2284531</link><description><![CDATA[This Innovations Deserving Exploratory Analysis (IDEA) project is a continuation of a previous IDEA project (NCHRP-199) that developed a prototype device to determine the permeability of hardened concrete using X-rays to measure the penetration of a tracer. In this follow-on project, the current instrument sample holder is being improved so that larger samples can be scanned. This new sample holder will also be able to find the locations of previous scans to allow the investigation of many different sample orientations, saving operator time and making the device easier to use. The software for the device will also be improved to make it easier and faster for the user. The work goes on to describe the three case studies that use the developed technology. The first case study focuses on the effectiveness of wet curing and how different curing lengths impact the Diffusion coefficient (Dic) of the concrete. Next, the performance of silane sealers is measured in field cores. Finally, the long-term change in the Dic is measured with mixtures that contain different amounts and types of fly ash. The work goes on to improve the reliability of the test by increasing the number of angles to evaluate the sample and the width of the analysis area. Finally, work was done to decrease the length of the testing time from 28 days to roughly 6 h. The test is accelerated by using a current to drive the tracer through the concrete. More research is needed to use this with a wide range of materials to investigate the effectiveness, but the results look promising. An overview of the test method is provided with the suggested wording that is useful for developing a testing standard.]]></description><pubDate>Wed, 01 Nov 2023 15:00:37 GMT</pubDate><guid>http://pubsindex.trb.org/view/2284531</guid></item><item><title>Development of an Automated and Rapid Conditioning and Testing Device for Cracking and Rutting</title><link>http://pubsindex.trb.org/view/2227520</link><description><![CDATA[The Innovations Deserving Exploratory Analysis (IDEA) product described herein is an asphalt mixture automated testing system with zero intervention (AMAZE). The system includes five components: (a) a rapid cooling subsystem, (b) an air void measurement subsystem, (c) a temperature conditioning subsystem, (d) a material testing subsystem, and (e) a robot arm. During this research project, automation was achieved with a robot arm for air void measurement, temperature conditioning, and cracking and rutting testing. Currently, neither cracking nor rutting tests are used at plants to evaluate asphalt mix cracking or rutting resistance during mix production, or to identify and eliminate cracking- or rutting-prone mixes from being paved on the road. This is because the current state-of-practice tests require at least a day to cool, condition, and test hot cylindrical specimens immediately out of a Superpave gyratory compactor mold, which is not practical for controlling mix performance quality during its production. The innovative AMAZE product makes it possible for state departments of transportation (DOTs) and asphalt industry professionals to evaluate asphalt mix cracking and rutting resistances as part of the daily quality control/quality acceptance (QC/QA) testing during mix production. This testing ensures the consistency and performance quality of the mix by identifying and eliminating cracking- or rutting-prone mixes from being placed on roads. Every year, around 360 million tons of asphalt mixes, with an associated cost of around $20 billion, are placed on roads in the United States. It is expected that this new system can increase the life of asphalt mixes by a minimum of 15 percent. The estimated savings is $3.0 billion annually. The system will also reduce maintenance costs, traffic delays, and travel time for every road user.]]></description><pubDate>Sat, 12 Aug 2023 14:21:46 GMT</pubDate><guid>http://pubsindex.trb.org/view/2227520</guid></item><item><title>Development of In Situ Cyclic Borehole Shear Soil Test Device</title><link>http://pubsindex.trb.org/view/2144215</link><description><![CDATA[Static soil shear strength parameters in the form of friction angle and cohesion are required inputs for the safe design of foundations and earth retaining structures for virtually all transportation infrastructure including bridges, buildings, railways, wharves, piers, ports, tunnels, and pavements. Additionally, measuring the dynamic and cyclic behavior of soil in terms of stress-strain hysteresis loops as well as the associated evolution of pore water pressure is important for obtaining modulus and damping parameters for seismic design, determining post-cyclic strength, and liquefaction susceptibility analysis. These soil parameters are typically obtained by retrieving soil samples and testing them in the laboratory, which is time-consuming, expensive, and the results are sensitive to sample disturbance. Alternatively, the shear strength parameters may be estimated using empirical correlations to in situ penetration tests such as the Standard Penetration Test (SPT) or Cone Penetration Test (CPT). However, neither of these tests directly measure the shear strength of soil and instead rely upon empirical correlations that can be imprecise due to large statistical variability. Furthermore, the SPT and CPT do not subject the soil to repeated continuous cyclic loading conditions like those imposed by earthquakes or vibration sources. The goal of this project was to develop a new in situ testing device that could measure static and dynamic soil properties in the soil’s natural setting, with less sample disturbance and requiring less time than laboratory tests. In this Innovations Deserving Exploratory Analysis (IDEA) project, a Cyclic Borehole Shear Test (CBST) device was developed to enable the rapid in situ measurement of cyclic behavior and monotonic shear strength properties of soil. Based on the results of several field testing trials, numerous refinements and modifications were made to the system including the physical testing apparatus inserted into the borehole, the electronic and pneumatic measurement and control system, and the software control program. Comparisons of field test results to those of conventional laboratory tests demonstrated that the device can measure meaningful cyclic behavior of soil in situ. Further research will be pursued to more rigorously relate the measured displacements from the device to shear strains in the soil surrounding the borehole, and to study applications of the device to in situ measurement of the liquefaction behavior of soils. With further research, the device thus has the potential to fundamentally transform the presently empirical techniques used in practice for assessment of soil liquefaction resistance into a more mechanistic physics-based framework.]]></description><pubDate>Sun, 02 Apr 2023 17:11:01 GMT</pubDate><guid>http://pubsindex.trb.org/view/2144215</guid></item><item><title>Multi-Criteria Assessment of Bridge Sites for Conducting PSTD/ISTD: Case Histories</title><link>http://pubsindex.trb.org/view/2001663</link><description><![CDATA[The Federal Highway Administration (FHWA) has recently developed the Portable Scour Testing Device (PSTD) to improve scour analysis around bridge piers in cohesive soils as part of the NextScour project. The PSTD is a compact field erosion testing device that, apart from a drill rig and larger water pump, has a lot of similarity with the In-situ Scour Testing Device (ISTD) in mechanism and data acquisition. The purpose of this paper is to provide recommendations on the suitability of using PSTD and ISTD at sites that have cohesive subsurface soils. An overview of the capabilities and limitations of the PSTD/ISTD in relation to hydraulic considerations, soil types, depth coverages, and erodibility potential is given. A multi-criteria assessment methodology to evaluate site suitability for conducting PSTD/ISTD is presented. The assessment methodology was utilized to detect suitable sites among 30 Illinois bridge sites using soil layer information, boring locations, groundwater level readings, in-situ testing results, geospatial analysis, site accessibility, and aerial photos.]]></description><pubDate>Mon, 01 Aug 2022 15:45:39 GMT</pubDate><guid>http://pubsindex.trb.org/view/2001663</guid></item><item><title>Evaluation of the Asphalt Binder Quality Tester</title><link>http://pubsindex.trb.org/view/1979311</link><description><![CDATA[This report presents an evaluation of a cooperative research and development effort that supported the development of the Asphalt Binder Quality Tester. The report will be of interest to those responsible for materials testing and quality assurance protocols for asphalt mixes. The report also addresses the broader topics of technology transfer, diffusion of innovation, and methods to quantify the value of research.]]></description><pubDate>Sun, 12 Jun 2022 15:24:52 GMT</pubDate><guid>http://pubsindex.trb.org/view/1979311</guid></item><item><title>Investigation of IDEAL-CT Device Equivalence: Are All Devices Equal?</title><link>http://pubsindex.trb.org/view/1953303</link><description><![CDATA[The IDEAL-CT (InDirect tEnsile AsphaLt Cracking Test) has rapidly become a popular cracking test for asphalt mixture acceptance. There have been several studies conducted to ensure this test is sufficient and acceptable for mixture acceptance purposes with respect to testing variability and the test’s ability to detect mixture quality improvements. A potential source of testing variability yet to be comprehensively studied is the variability introduced between testing devices. This paper provides a case study for the potential CTIndex variability, which can be attributed to the test device and the impact this has on determining whether devices are equivalent. The two one-sided tests (TOST) equivalence test, applied to this study, is a more appropriate statistical test to determine device equivalence when compared with typical hypothesis tests like analysis of variance. The TOST requires the user to have an understanding of an acceptable limit of deviation between two devices to determine both the statistical and practical equivalence between devices. This paper details the equivalence testing of 100 unique device-to-device comparisons and provides an example of the importance of using an appropriate number of samples to set achievable limits for accepting device equivalency. A relatively simple approach to assessing equivalence is recommended to IDEAL-CT users in situations in which device-to-device comparisons have real-world consequences. Finally, guidance is provided for selecting a minimum number of samples required to adequately test for device-to-device equivalence.]]></description><pubDate>Wed, 18 May 2022 10:52:28 GMT</pubDate><guid>http://pubsindex.trb.org/view/1953303</guid></item><item><title>Quantifying In Situ Tack Coat Performance Using the TackBond Tester for Quality Control</title><link>http://pubsindex.trb.org/view/1895178</link><description><![CDATA[In light of the various quality assurance (QA) issues pertaining to tack coats that occur during construction, there is a need for a means of verifying interlayer bond quality in situ. Despite the immense use of tack coat as a constituent in paving, there are no construction specifications with provisions for the quantification of tack coat bond quality in laboratory or field settings. In this study, a construction QA process for tack coat bond performance was proposed. A novel field tack coat bond strength test device, TackBond, was developed and used for this purpose. The performance of engineered (new tack coat technologies that are tracking less) and conventional tack coats was also evaluated in the laboratory and the field using the developed TackBond test system. The TackBond device was improved in this study by adding features that render it more practical, portable, accurate, and better suited for a variety of pavement surface conditions. Engineered tack coat performance was compared with that of tack coats used conventionally on both milled and overlay surface types. The suitability of the TackBond Test device for capturing the true response of each tack coat was first evaluated by comparing results from TackBond laboratory tests with monotonic direct shear tests (DST) on laboratory-produced samples. Strong correlations between the two test types were achieved. Results of field and laboratory TackBond tests showed that the in situ QA control process developed in this study could be effectively used to improve the in situ tack coat bond performance.]]></description><pubDate>Sun, 05 Dec 2021 18:49:26 GMT</pubDate><guid>http://pubsindex.trb.org/view/1895178</guid></item><item><title>Development of a New Erosion Test by the Hydrodynamic Pressure Generator for Evaluating the Moisture Damage of Semi-Rigid Base Materials</title><link>http://pubsindex.trb.org/view/1572539</link><description><![CDATA[The present study developed a new erosion test device, termed hydrodynamic pressure generator, for evaluating the moisture susceptibility of semi-rigid base materials. The hydrodynamic pressure generator was used to generate hydrodynamic loads at variable frequencies and pressures to erode the semi-rigid base materials, and a triaxial apparatus was used to provide confining and axial pressures to the specimens during erosion. After the erosion test, the uniaxial compression strength test was performed on the specimens. The results show that the direct cause of moisture damage to the semi-rigid base materials of the pavement is the erosion effect of high hydrodynamic pressure. The greater the hydrodynamic pressure value, the stronger the erosion effect of the specimen, and the damage of the semi-rigid base materials is also more obvious. The results also reveal that under the same erosion conditions, the longer the specimen curing age, the stronger the ability to resist moisture damage. The value of the hydrodynamic pressure largely depends on the confining pressure and the axial pressure conditions of the specimens, the higher the confining pressure and axial pressure, the greater the hydrodynamic pressure. In addition, the effect of hydrodynamic pressure on the erosion and destruction of semi-rigid base materials is time-dependent, and as the erosion time increases, the damage rate of the specimen will reduce slowly.]]></description><pubDate>Sat, 02 Mar 2019 15:41:14 GMT</pubDate><guid>http://pubsindex.trb.org/view/1572539</guid></item><item><title>DART Field Validation and Prototype Refinement</title><link>http://pubsindex.trb.org/view/1516265</link><description><![CDATA[This report summarizes findings from a National Cooperative Highway Research Program (NCHRP) Innovations Deserving Exploratory Analysis (IDEA) Type 2 study to validate a field-ready prototype of the Duomorph Asphalt Rheology Tester (DART) as a low-cost and easy-to-use asphalt binder testing device. The DART is a piezoelectric sensor-based portable testing system that addresses the need of the paving industry to cost effectively monitor the uniformity or specification compliance of asphalt binder samples at various points along its supply chain. In this study, the research team performed validation tests to determine the effectiveness of the DART in production environments such as a paving job site, a field laboratory, and a binder production facility.  These tests validated that the DART technology has great potential for use in quality assurance, especially for verification testing at a higher sampling rate than the current practice.]]></description><pubDate>Tue, 19 Jun 2018 10:08:16 GMT</pubDate><guid>http://pubsindex.trb.org/view/1516265</guid></item><item><title>Walking Friction Tester for Low-Speed Skid Resistance Testing of Pavement</title><link>http://pubsindex.trb.org/view/1494462</link><description><![CDATA[The British Pendulum Number (BPN) measured by the British Pendulum Tester (BPT) is commonly used as a surrogate for pavement microtexture. However, there are known operational limitations with the use of BPT. The Walking Friction Tester (WFT) developed at the Chang’an University offers a practical alternative to measure low-speed pavement friction. This paper first describes an experimental program conducted to compare the BPT and WFT tests in the following three aspects: (i) Correlation relationship between BPN and WFT friction coefficients; (ii) Variability of the measured BPN and WFT friction coefficient respectively; and (iii) Speed comparison of field tests using BPN and WFT. Next, tests were performed to examine the variability of WFT test results with respect to walking speed and water film thickness respectively. The study showed that BPN and WFT friction coefficients were positively correlated with a high correlation coefficient of 0.78. WFT measured data were found to have smaller variability than BPN data. The results also showed that WFT tests were independent of changes in walking speeds of operators and variations of water applied from the spray jet. Since WFT with a test tire offers a more realistic testing mode than BPT using a sliding pad, produces less variability in the measured values, and generates continuous friction data in much shorter time than measuring discrete point data by BPT, it can serve as a useful practical alternative to BPT in measuring the low-speed friction properties of pavement materials in the laboratory or in the field.]]></description><pubDate>Sun, 21 Jan 2018 17:53:28 GMT</pubDate><guid>http://pubsindex.trb.org/view/1494462</guid></item><item><title>Development of Duplicate Shear Test for Asphalt Mixtures</title><link>http://pubsindex.trb.org/view/1438088</link><description><![CDATA[Permanent shear deformation is the main cause for rutting in asphalt concrete layers. The paper presents the development of a new test device to replicate similar loading conditions and constraints of the Superpave Shear Tester (SST). The Duplicate Shear Tester (DST) determines the mechanical average of the shear properties and responses of two specimens loaded simultaneously. The DST device is simple and inexpensive and can be used with any universal testing machine that can provide repeated dynamic and static axial loads in a temperature-controlled environment. The two most used SST tests, the Frequency Sweep Test at Constant Height (FSCH) and the Repeated Shear Test at Constant Height (RSCH) were performed with the DST device mounted inside of a UTM-25 test system.To evaluate the effectiveness of the DST, four asphalt surface mixtures were subjected to FSCH tests at 30°C and RSCH tests at 50°C. For each mixture, three pairs of specimens were tested. The data analysis indicated that the DST test is highly repetitive and reliable in measuring the shear dynamic modulus and phase angle at load frequencies between 0.5 Hz to 10 Hz, for which a variability of less than 10 percent was observed. A variability higher than 10 percent was recorded for the FSCH tests done at frequencies lower than 0.5 Hz. A variability slightly higher than 10 percent was observed in the RSCH test for the permanent shear deformation for two of the four asphalt mixtures.]]></description><pubDate>Thu, 26 Jan 2017 14:32:25 GMT</pubDate><guid>http://pubsindex.trb.org/view/1438088</guid></item><item><title>Development and Implementation of the Asphalt Embrittlement Analyzer</title><link>http://pubsindex.trb.org/view/1405345</link><description><![CDATA[This project involved the development of an acoustic emission-based Asphalt Embrittlement Analyzer (AEA) device as an advanced diagnostic tool to assess the degree of aging, crack resistance, and resiliency of near-surface properties in asphalt pavements. A sophisticated computer code was developed to analyze acoustic emission (AE) signals, to identify microcrack presence and location, and to produce a diagnostic schematic illustrating embrittlement temperature versus location (depth from surface of pavement). The AEA test offers: simplicity and portability; the ability to characterize the continuous and rapid change in surface properties as a function of depth from the surface; suitability for characterization of both binders and mixtures; relative insensitivity to sample size and fracture size effect; relative insensitivity to sample geometry; and suitability for determining the optimum timing and method(s) for preventive maintenance and rehabilitation. In addition, as a design tool, the AEA can be used to assess the effectiveness and proper use of rejuvenators in achieving the goal of restoring the pavement surface to a crack-resistant state.]]></description><pubDate>Fri, 29 Apr 2016 14:14:54 GMT</pubDate><guid>http://pubsindex.trb.org/view/1405345</guid></item><item><title>Hamburg Wheel-Track Test Equipment Requirements and Improvements to AASHTO T 324</title><link>http://pubsindex.trb.org/view/1403029</link><description><![CDATA[In this study, a comprehensive experimental program was conducted to evaluate the capability of five commercially available Hamburg Wheel Tracking (HWT) equipment as well as their ability to accurately measure, control, and maintain the desired test conditions as specified in AASHTO T 324. Based on the results of this study, researchers were tasked to provide proposed revisions with commentary to AASHTO T 324 to enable the use of a performance type specification for Hamburg test equipment.  Modifications are proposed to address equipment capabilities, components, or design feature in order  to ensure proper testing and accurate, reproducible results.  Proposed modifications are discussed in this  report  to  ensure  repeatable  measurements  and that  the  results  from  different manufacturers  are  comparable.    These  modifications  include  change  to  temperature measurement and range, impression measurement system, data collection, and data analysis and  reporting.    In  addition  to  the  proposed  modifications  to  the  AASHTO  T  324 specifications, the vendors may need to modify their equipment to meet the new  specification requirements.]]></description><pubDate>Mon, 18 Apr 2016 15:35:19 GMT</pubDate><guid>http://pubsindex.trb.org/view/1403029</guid></item></channel></rss>