Author: Ayesha Shah
Publisher:
ISBN: 9780309687256
Category : Pavements
Languages : en
Pages : 0
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Book Description
Incompatibility between aggregate type and asphalt binder, presence of standing water or water under pressure in the pavement layers, and improper construction practices are some of the many factors that influence moisture susceptibility of flexible pavements. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 595: Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements documents practices used by state departments of transportation to prevent or to minimize moisture damage in hot-mix asphalt pavements.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
A technical review of moisture damage of asphalt pavements and antistripping additives has beencompleted as part of a review and testing study for the Transportation Association of Canada that has the objective of developing a Canadian manual on the assessment of moisture susceptibility and selection of antistripping additives. The review is based on practical asphalt technology experience, questionnaires to agencies and asphalt cement suppliers, and the technical literature on moisture damage of asphalt pavements. Methods of mitigating moisture damage in asphalt pavement structures, in addition to the use of antistripping additives, such as drainage, compaction, aggregates selection, mix designs and quality control, were reviewed in terms of stripping mechanisms and causes. The Strategic Highway Research Program has involved considerable research on the moisture susceptibility of asphalt concrete and appropriate laboratory procedures to assess moisture damage. Qualitative and quantitative (strength) tests for assessing the moisture susceptibility of hot-mix asphalt mixes are reviewed. There is strong technical support for the Tunnicliff-Root (ASTM D 4867), Modified Lottman (AASHTO T 283) and Ontario MTO Immersion Marshall (LS-283) tests. The use of liquid (amines generally) and hydrated lime antistripping additives is considered. There is considerable technical information on the comparative efficacy of hydrated lime as an antistripping additive. An important area of research need is appropriate quality control/quality assurance to monitor the field effectiveness of antistripping additives. For the covering abstract of this conference see IRRD number 872978.
Author: Russell G. Hicks
Publisher: Transportation Research Board
ISBN: 9780309049245
Category : Technology & Engineering
Languages : en
Pages : 104
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Book Description
This synthesis will be of interest to pavement designers, construction engineers, maintenance engineers, and others interested in avoiding or limiting moisture damage in asphalt concrete. Information is provided on physical and chemical explanations for moisture damage in asphalt concrete, along with a discussion of current practices and test methods for determining or reducing the susceptibility of various asphalt concrete components and mixtures to such damage. Moisture damage in asphalt concrete is a nationwide problem which often necessitates premature replacement of highway pavement surfaces. This report of the Transportation Research Board describes the underlying physical and chemical phenomena responsible for such damage. Current test methods used to determine the susceptibility of asphalt concretes, or their constituents, to moisture damage are described and evaluated. Additionally, current practices for minimizing the potential for moisture damage are examined.
Author: Christopher J. DeCarlo
Publisher:
ISBN:
Category : Asphalt
Languages : en
Pages : 19
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Book Description
Asphalt materials experience substantial amounts of environmental damage throughout their lives as surface layers in pavements. One of the most prominent forms of environmental damage, moisture-induced damage, is caused by the weakening of internal bonds of the material because of the presence of moisture in the voids of asphalt mixtures and is a common problem for asphalt pavements in wet climates. Moisture-induced damage is typically accounted for during asphalt mixture design by conducting performance tests to ensure the material is not susceptible to severe damage from moisture, although many of these methods have seen mixed amounts of success historically. The main objective of this study is to evaluate the ability of multiple asphalt mixture moisture susceptibility tests to identify good and poor performing mixtures with respect to moisture-induced damage to replace current mix design testing requirements. Ten plant-produced hot mix asphalt materials with established good and poor field moisture performance were subjected to various moisture susceptibility test methods. The results from these procedures are assessed to determine which procedure is most effective and practical as a moisture susceptibility test for routine usage during asphalt mixture design for transportation agencies. Results from this study suggest that performance tests with stiffness-based measurements, such as dynamic modulus paired with moisture conditioning and the saturated aging tensile stiffness procedure, show better correlation to field performance than traditional test methods such as AASHTO T-283, Standard Method of Test for Resistance of Compacted Asphalt Mixtures to Moisture-Induced Damage, and that the Hamburg wheel tracker test is the most effective and practical test method to reliably identify mixtures prone to experiencing moisture-induced damage.
Author: Edith Arambula
Publisher:
ISBN:
Category : Asphalt
Languages : en
Pages : 15
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Book Description
The presence of waIn ter in asphalt pavements deteriorates their condition and causes distresses that result in high maintenance costs to state and federal agencies. The objective of this research was to execute dynamic and relaxation tests and evaluate their effectiveness in assessing moisture susceptibility of asphalt mixture specimens with different air void structures determined using X-ray computed tomography (CT) and conditioned using the modified Lottman procedure. The dynamic test consisted of the application of a sinusoidal cyclic compressive load on the specimen while maintaining the strain within a specified range. The relaxation test, performed in both direct tension and compression, consisted of the application of a constant static strain. A statistical analysis was used to study the effectiveness of the tests in evaluating the moisture susceptibility of the asphalt mixtures. The results showed that none of the tests (dynamic or relaxation) were consistent in differentiating between the moisture conditioned and unconditioned specimens or between the responses of the different mixtures within each condition. In addition, the results of the dynamic and relaxation tests were compared after applying different methods to convert frequency-domain data to time-domain data.
Author: Maria Lorena Garcia Cucalon
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Economic, environmental and engineering benefits promote the rapid implementation of WMA technologies. However, concerns remain based on changes in the production process that may lead to moisture susceptibility in the early life as compared to HMA. To evaluate WMA moisture susceptibility during this critical period, standard laboratory tests were used for three field projects each with an HMA control mixtures and multiple WMA mixtures. Different specimen types were also evaluated to capture differences in mix design, quality control/quality assurance, and field performance. Specimens were evaluated for moisture susceptibility by Indirect Tensile (IDT) Strength, Resilient Modulus (MR) and Hamburg Wheel-Track Testing (HWTT). Specimens for IDT and MR were tested dry and then tested wet after conditioning as described in AASHTO T283 with one freeze-thaw cycle. HWTT was used to assess both moisture susceptibility and rutting potential under repeated loads in the presence of water at elevated temperatures (i.e., 122°F [50°C]), and the output parameters used for evaluation were the calculated Stripping Inflection Point (SIP) and the rut depth at 5000 load cycles. Based on the results of the laboratory tests performed on PMFC cores acquired at construction and with time, WMA during its early life exhibited inferior moisture resistance when compared to HMA. However, with time, specifically after one summer, the dry and wet properties of WMA became equivalent to those of HMA. For WMA constructed in the fall, the results from this study suggest that the inclusion of recycled asphalt pavement (RAP) or an anti-stripping agent may alleviate possible moisture susceptibility issues in the early life during wet, winter weather conditions. While some laboratory test results demonstrated that WMA is more moisture susceptible than HMA, field performance reported to date from the three projects used in this study shows no evidence of moisture damage. Therefore the search for a laboratory test to screen mixtures for moisture susceptibility continues. An alternative approach, applying Griffith crack growth theory and utilizing IDT, MR and air voids% the adhesive bond energy of asphalt mixtures was calculated for Texas field project. This value holds promise for characterizing performance of asphalt mixtures by considering basic properties and grouping into one representative value. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149392
Author: Amy Epps Martin
Publisher:
ISBN: 9780309375061
Category : Pavements, Asphalt concrete
Languages : en
Pages : 33
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Book Description
TRB's National Cooperative Highway Research Program (NCHRP) Report 817: Validation of Guidelines for Evaluating the Moisture Susceptibility of WMA Technologies presents validated guidelines proposed for identifying potential moisture susceptibility in warm mix asphalt (WMA) during mix design. The report further corroborates the moisture susceptibility thresholds described in NCHRP Report 763: Evaluation of the Moisture Susceptibility of WMA Technologies.
Author: R. Christopher Williams
Publisher:
ISBN:
Category : Pavements, Asphalt
Languages : en
Pages : 138
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Book Description
Pavements are subjected to different stresses during their design lives. A properly designed pavement will perform adequately during its design life, and the distresses will not exceed the allowable limits; however, there are several factors that can lead to premature pavement failure. One such factor is moisture sensitivity. AASHTO T 283 is the standard test used in the moisture susceptibility evaluation of asphalt mixtures, but the results of the test are not very representative of the expected behavior of asphalt mixtures. The dynamic modulus test measures a fundamental property of the mixture. The results of the dynamic modulus test can be used directly in the Mechanistic-Empirical Pavement Design Guide (MEPDG) and are considered a very good representation of the expected field performance of the mixture. Further research is still needed to study how the dynamic modulus results are affected by moisture. The flow number test was studied in previous research as a candidate test for moisture-susceptibility evaluation, but the results of that research were not favorable. This research has four main objectives. The first objective of this research is to evaluate the usefulness of the dynamic modulus and flow number tests in moisture-susceptibility evaluation. The second objective is to compare the results to those achieved using the AASHTO T 283 test. The third objective is to study the effect of different methods of sample conditioning and testing conditions. The fourth objective of the research is to study the variability in the test results.
Author: Sunghwan Kim
Publisher:
ISBN:
Category : Pavements, Asphalt
Languages : en
Pages : 70
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Book Description
Even though moisture sensitivity of Hot Mix Asphalt (HMA) mixtures has been recognized as a major form of distress in asphalt concrete pavements since the advent of asphalt paving technology, the mechanism of this problem has not been clearly identified until now. However, it has been agreed that it can be characterized by the loss of adhesive bond between the asphalt binder and the aggregate or by a softening of the cohesive bonds within the asphalt binder, both of which are due to the action of loading under traffic in the presence of moisture. The evaluation of Hot Mix Asphalt moisture sensitivity has been divided into two categories: visual inspection test and mechanical test. However, most of them have been developed in pre-Superpave mix design. This research was conducted to develop a new test protocol which can overcome the problems of the current procedures and to evaluate the possibility of using the Nottingham Asphalt Tester (NAT) in the resulting procedure.
Author: Jaejun Lee
Publisher:
ISBN:
Category : Moisture conditioning
Languages : en
Pages : 9
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Book Description
A pothole is one of the distresses in asphalt pavement caused by the presence of water in the asphalt pavement and the presence of traffic passing over the affected area. Recently, lots of potholes were observed due to heavy rain in Korea. Thus, the indirect tensile strength ratio (TSR) is commonly used based on the AASHTO T 283 procedure to evaluate the moisture susceptibility of an asphalt mixture; however, TSR cannot be used as a representative index for the mechanical behavior of the moisture-conditioned asphalt mixture. In this study, the dynamic modulus |E*| laboratory test is applied as a replacement test for the TSR in order to assess the moisture susceptibility of four different asphalt mixtures. The dynamic modulus test is used to determine the % of retained stiffness, a term that was referred to as the dynamic modulus ratio (DMR). The results of both TSR and DMR conducted on the same mixtures are compared and statistically analyzed. The logistic regression model was used to evaluate the correlation between TSR and DMR. The correlation between TSR and DMR at 20°C is significant. However, there was no relation between TSR and DMR at other temperature ranges (5°C, 40°C, 54.4°C) because there was different viscoelastic behavior at different temperature.
