Water Sensitivity of Asphalt-aggregate Mixes PDF Download
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Author: Ronald L. Terrel Publisher: National Research Council ISBN: Category : Technology & Engineering Languages : en Pages : 204
Book Description
The research presented in this report was conducted to identify the important factors influencing the water sensitivity of asphalt paving mixtures, and to develop a test method to evaluate water sensitivity of asphalt concrete mixtures for mix design. The test method was to be performance related. A review of current procedures revealed that no single method was suitable for evaluation and related to field performance. Based on a hypothesis that air voids in the mixture may be the major source and cause of water damage, a test system was developed to evaluate the major factors that influence water sensitivity. The Environmental Conditioning System (ECS) was used to develop a test procedure that includes specimen preparation; measurement of permeability using air, water, or both; vacuum wetting; cycling at various temperatures; and continuous repeated loading while monitoring resilient modulus after each conditioning cycle.
Author: Saleh H. Al-Swailmi Publisher: ISBN: Category : Asphalt concrete Languages : en Pages : 602
Book Description
Environmental factors such as temperature, air, and water can have a profound effect on the durability of asphalt concrete mixtures. In mild climates where good quality aggregates and asphalt cement are available, the major contribution to deterioration may be due to traffic loading and the resultant distress is manifested in the form of fatigue cracking, rutting, and raveling. But, when more severe climates are coupled with poor materials and traffic, premature failure may result. The objectives of this research are twofold and includes: (1) development of a test system to evaluate the most important factors influencing the water sensitivity of asphalt concrete mixtures; and (2) development of laboratory testing procedures that will predict field performance. This research also addresses the hypothesis that much of the water damage in pavements is due to water in the asphalt concrete void system. It is proposed that most of the water problems occur when voids are in the range of about 5% to 12%. Thus, the term "pessimum" voids is used to indicate that range (opposite of optimum). In order to evaluate the hypothesis and the numerous variables, the Environmental Conditioning System (ECS) was designed and fabricated. The ECS consists of three subsystems: (1) fluid conditioning, where the specimen is subjected to predetermined levels of water, air, or vapor and permeability is measured; (2) an environmental cabinet that controls the temperature and humidity and encloses the entire load frame; and (3) the loading system that determines resilient modulus (M[subscript n]) at various times during environmental cycling and also provides continuous repeated loading as needed. The ECS has been used to evaluate four core materials and also to investigate the relative importance of mixture variables thought to be significant. Many details regarding specimen preparation and testing procedures were evaluated during a "shakedown" of the ECS. As minor variables were resolved, a procedure emerged which appears to be reasonable and suitable. An experiment design for the four core mixtures was developed, and the overall experiment design included three ranges of void (5% low; 5-12%, pessimum; 12% high). Six-hour cycles of wet-hot (60° C) and wet-freeze ( -18° C) are the principle conditioning variables, while monitoring MR at 25° C before and between cycling. A conventional testing procedure (AASHTO T-283) was also used on the core mixtures to provide a baseline for comparison. Results to date show that the ECS is capable of discerning the relative differences in "performance" such as MR. Three hot cycles and one freeze cycle appear to be sufficient to determine the projected relative performance when comparing different aggregates, asphalts, void levels, loading, etc. Based on these results, a water conditioning procedure has been recommended and also a procedure for water conditioning specimens prior to testing in fatigue, rutting, and thermal cracking.
Author: Ronald L. Terrel Publisher: National Research Council ISBN: Category : Technology & Engineering Languages : en Pages : 204
Book Description
The research presented in this report was conducted to identify the important factors influencing the water sensitivity of asphalt paving mixtures, and to develop a test method to evaluate water sensitivity of asphalt concrete mixtures for mix design. The test method was to be performance related. A review of current procedures revealed that no single method was suitable for evaluation and related to field performance. Based on a hypothesis that air voids in the mixture may be the major source and cause of water damage, a test system was developed to evaluate the major factors that influence water sensitivity. The Environmental Conditioning System (ECS) was used to develop a test procedure that includes specimen preparation; measurement of permeability using air, water, or both; vacuum wetting; cycling at various temperatures; and continuous repeated loading while monitoring resilient modulus after each conditioning cycle.
Author: Mansour Solaimanian Publisher: Transportation Research Board ISBN: 0309099064 Category : Bituminous materials Languages : en Pages : 79
Book Description
Explores whether combining the environmental conditioning system with the simple performance test would provide a superior procedure for determining the moisture susceptibility of hot-mix asphalt (HMA).
Author: Publisher: ISBN: Category : Aggregates (Building materials) Languages : en Pages : 70
Book Description
The research performed for this report was intended to recommend alternative mix design procedures and parameters for evaluation of asphalt mixture sensitivity, with more of an emphasis on volumetric relationships. Three Minnesota Department of Transportation (Mn/DOT) projects were selected to represent the following durability issues: 1) debonding of asphalt form aggregate, 2) cohesion problems, and 3) mix design problems. Materials were obtained from these construction projects and evaluated in the laboratory. Gradations were varied from the project specifications so that mixtures with more and less asphalt were evaluated along with the project mixture. Testing included the temperature susceptibility and moisture sensitivity of the mixtures, in addition to the net adsorption test on the aggregates.
Author: Chandra Manandhar Publisher: ISBN: Category : Asphalt concrete Languages : en Pages : 105
Book Description
Existing test methods to determine moisture sensitivity in Hot Mix Asphalt (HMA) are time consuming and inconsistent. This research focused on wheel tracking devices to develop a rapid test method to evaluate moisture sensitivity. The Asphalt Pavement Analyzer (APA) and the Hamburg Wheel Tracking Device (HWTD) were used for this research. Compacted cylindrical samples were fabricated using a Superpave gyratory compactor. This study selected two most commonly used mixtures, SM-12.5A with Pg 64-22 binder in overlay projects and SM-19A mixtures with PG 64-22 binder for major modification projects at the Kansas Department of Transportation. Test results show that APA tests could induce stripping in most samples without any anti-stripping agent, which could be indentified visually. However, APA results do not indicate any stripping inflection point while the HWTD results show stripping inflection points, which are important to indentify stripping potential of mixtures. The APA results show that wet tests are severe at lower temperatures whereas dry tests show high rut depths at higher temperatures. The HWTD results show improvement in the performance using anti-stripping agents at later stage. The HWTD test is more effective than the APA as a rapid test method for determining moisture sensitivity of HMA. Laboratory results from this study should be verified and correlated with field performance.
Author: Ronald L. Terrel
Author: Saleh H. Al-Swailmi
Author: Ronald L. Terrel
Author: John S. Coplantz
Author: Mansour Solaimanian
Author: 
Author: 
Author: Chandra Manandhar
Author: Byron E. Ruth
Author: William Gartner
Author: Asphalt Institute