Projekt BVFF - publicerade   BVFF nummer:  2013-072 Projekttitel  Monitoring and measurement of healing in asphalt mixtures Projektledare/Kontaktperson  Björn Birgisson/Denis Jelagin Telefon  8 790 8698 Utförarorganisation  KTH Medutförare  Denis Jelagin, KTH New doctoral student, KTH Bakgrund  Healing potential of asphalt mixtures is one of the major factors controlling mixtures fatigue life. It is thus very important to be able to characterize mixtures healing properties and to predict the effect of healing on materials performance in the field. In state of practice pavement design methods the effect of healing on pavement performance is accounted for through the empirical calibration parameters. This precludes quantitative estimates of the effects of the material choice, traffic and environmental factors on healing of asphalt materials in the field. In order to overcome that shortcoming, an explicit healing model is introduced in a new Calibrated Mechanistic pavement design procedure being developed at Highway and Railway Engineering Division, KTH. The current healing model is however still based on empirical observations and does not allow to link fundamental material properties with healing. It is therefore proposed in the present project to develop a new test method to characterize healing in asphalt mixtures and establish a new healing model based on fundamental material properties. Sammanfattning  The planning, design and material selection and construction of sustainable, long life asphalt pavements is today limited by our inability to measure and predict the rate of damage recovery in asphalt roads (commonly referred to as healing rate), as well as our inability to select bitumen with superior healing capacity over others with less healing capacity. This project develops the testing methods/specification framework for the measuring of healing rate of asphalt mixtures as well as the healing capacity of bitumens from different geologic sources. The project also will result in a new performance-based healing material model that will be implemented into the new Swedish calibrated mechanics-based pavement design procedure. This will result in more robust and reliable pavements and more pavements for the money through e.g. improved selection of materials, improved designs and ability to predict pavement residual life as well as associated improved LCC/LCA models. Förväntat resultat  Hur ser resultatet ut Recommended test methods for the testing of asphalt mixture healing rates, bitumen healing capacity, and a new healing performance material model for use in the new Swedish Mechanics-Based pavement design procedure. Two main practical outputs of the project will be: - A new nondestructive testing framework to characterize asphalt healing capabilities based on its fundamental properties. The first test method is focused on high quality monitoring of the healing rates/histories of asphalt mixtures. The testing method use for this purpose will be the slow dynamics test method, which combines long term very low strain level (~10-9) monitoring of dynamic stiffness with conventional large strain (~10-5) testing of the specimen at regular time intervals. This method was introduced in Sweden through a doctoral project by Anders Gudmarsson at KTH, under the supervision of Nils Ryden and Bjorn Birgisson. The method is sensitive to very small changes in the material, and is thus ideally suited for the monitoring of healing. The new nondestructive geophysics testing framework for characterizing the rheological properties of asphalt mixtures developed at KTH by Anders Gudmarsson will also be used as a starting point in this study. The initial testing will focus on unaged mixtures, followed by the testing of aged mixtures. - It is well known that healing capacity of bitumen varies based on its geologic origin and blending sources. It is therefore necessary to characterize the healing capacity as a function of temperature of bitumens from different geologic sources. Hence, the second test method used will be focused on testing the healing capacity of bitumen from different sources. This will be accomplished through measuring the energy dissipation characteristics of healing bitumen from different geologic origins and sources. For this purpose, the project will use the measurement of complex permittivity to obtain the dissipative energy characteristics of bitumen. - Finally, the results of the nondestructive testing will be used to develop an improved predictive healing model for the new Swedish Calibrated-Mechanics based thickness design procedure for asphalt roads to describe healing processes in asphalt. Koppling till andra projekt/delprojekt/foljdprojekt - The testing methods to be evaluated are a direct extension of the work done in the SBUF doctoral project performed by Anders Gudmarsson under the supervision of Bjorn Birgisson and Nils Ryden, as well as the associated financing from PEAB. This project also links to the current doctoral project on the nondestructive characterization of the effects of construction variability on pavement design, funded by the Transport Administration and SBUF. This project also links to the current doctoral project on the nondestructive characterization of the effects of construction variability on pavement design, funded by the Transport Administration and SBUF. Similarly, it is anticipated that the results from a study under the Swedish Research Council (Vetenskapsrådet) project on studying the mobility of asphalt molecules in bitumen and its relation to healing capacity (PI: Nichole Kringos) will be of use for this project. Resultatets användingsområde: With the ability to monitor the healing rate/histories of given asphalt mixtures and measure the healing capacity of bitumen from different geologic sources, it will be possible to select materials that have improved healing rates after damage, as well as materials that continue to heal in real pavements for longer periods of time than is possible today. In addition, the improved healing materials model in the new calibrated mechanics-based design procedure will result in improved predictions of pavement residual life and improved LCC/LCA modeling. Plan för resultatspridning och implementering  The results of this project will be documented in two new nondestructive test specifications for the evalution of the healing rate of asphalt mixtures and well as the measurement of the healing capacity of bitumens of different geological origins and sources, respectively. In addition, the performance-based healing model developed will be implemented into the new Calibrated-Mechanics Based pavement design procedure for Sweden. The new predictive healing model will thus serve to improve the determination of residual pavement life as well as for improved LCC and LCA predictions. The results of this project will be presented at workshops for industry and agency personnel, conferences such as the Metoddagen, TRB, etc, as well as in high quality refereed international journals. Beskriv projektets tillskott till dagens State-of-the-art/-practice: New test methods for monitoring healing rate of asphalt mixtures and measurement of the healing capacity of bitumen. A new healing material model for use in calibrated mechanics-based design methods. Beskriv vilka åtgärder som tas inom projektet för implementering och på vilket annat sätt reultatet ska hanteras för att uppnå maximal nytta med projektet: Documentation, workshops and presentation for the key groups affected by the results of this project. Tidsramar  2013-04-01 2017-04-01