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Crack healing performance of hot mix asphalt containing steel slag by microwaves heating
Phan, Tam Minh,Park, Dae-Wook,Le, Tri Ho Minh Elsevier 2018 Construction and Building Materials Vol.180 No.-
<P><B>Abstract</B></P> <P>This study aims to analyze the applicability of steel slag in the asphalt mixtures for the self-healing purpose using microwave heating technique. Hot mix asphalt (HMA) mixtures were developed from four different levels of steel wool fibers (SWF) as a conductive additive and two types of aggregate were used: steel slag aggregate and conventional aggregate. Then, the thermal distribution, as well as the optimum healing time of test samples, were recorded by the infrared camera. 10 damage-healing cycles were applied in all mixtures to evaluate their healing performance under microwave heat. Test results suggested that adding two percent SWF by weight of asphalt mixture provides the best healing level for both types of aggregate mixtures. At this SWF level, the substitution of 30% normal coarse aggregate by steel slag is very promising due to its presence not only provides better healing results but also helps the whole mixture improve the load-displacement relationship with higher ductile behavior. Overall, the application of steel slag in HMA is a prominent solution which contributes toward the sustainable development.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Steel slag shows better microwave absorption compared to the conventional aggregate. </LI> <LI> Under microwave heating, adding lower than 2% SWF is optimum for healing of HMA. </LI> <LI> Mixtures show ductile behavior at early cycles and brittle characteristics at late times. </LI> <LI> Slag mixture obtain better healing performance compared to the original aggregate. </LI> <LI> The crack formation affects the healing effectiveness. </LI> </UL> </P>
Phan Minh Tam,Park Dae-Wook,Kim Hal-Su 한국도로학회 2020 한국도로학회논문집 Vol.22 No.6
PURPOSES : This study aims to determine the type (e.g., melting point, freezing point, latent heat fusion) and optimal content of phase change material (PCM) based on the numerical and experimental analyses evaluating the effects of heat transfer in PCM-modified asphalt pavement systems. METHODS : The effect of PCM on the thermophysical properties of PCM-modified asphalt concrete can be taken as an effective volumetric heat capacity. The volumetric fraction of PCM was calculated using an iterative method. The numerical model was established and computed using the MATLAB 2020 software. The optimum PCM design tool was developed to select the type and contents of the PCM. The PCM was chosen based on the following criteria: black-ice-formation delay time, minimize temperature increase, and increase temperature area. To validate the numerical model, asphalt mixtures were modified with varying PCM contents, and the temperature response of the PCMmodified asphalt samples was examined via temperature test. RESULTS : The numerical results showed that incorporating PCM into the asphalt mixture can slow the cooling rate of the pavement system. The predicted results from the optimum PCM design tool were highly consistent with the measured values from the laboratory temperature test. CONCLUSIONS : The temperature of PCM-modified asphalt pavement can be predicted via numerical method. The effect of PCM on the thermophysical properties can be considered as effective volumetric heat capacity; while the volume fraction of PCM can be calculated via an iterative method. The accuracy of the numerical model was confirmed by a high agreement between the measured and predicted values.
Effect of Steel Slag on Self-healing Performance of Asphalt Concrete Using Microwave Technique
Tam Minh Phan,Dae-Wook Park,Tri Ho Minh Le,Namyu Kim,Allistair Bliss Tam 한국도로학회 2018 한국도로학회 학술대회 발표논문 초록집 Vol.2018 No.05
This paper evaluates the affection of steel slag in the asphalt mixtures for the self-healing purpose through microwave heating technique. Four different contents of steel wool fibers (SWF) were developed in hot mix asphalt and two types of aggregate were used: steel slag aggregate and normal aggregate. By using the infrared camera, the thermal distribution, as well as the optimum healing time of test samples, were recorded. All mixtures were evaluated their healing performance throughout 8 cycles. The substitution of about 30% normal coarse aggregate by steel slag is prominent due to its effect not only produces better healing performance but also enhances the whole mixture improve load-displacement trend with higher ductile behavior. The application of steel slag in HMA is a promising method which contributes toward the sustainable roadway development.
New Technique for the Synthesis of Carbon Nanotubes
Phan Ngoc Minh,Phan Hong Khoi,Nguyen Van Chuc,Phan Ngoc Hong,Ngo Thi Thanh Tam 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5
Carbon nanotubes (CNTs) are considered as a promising material for various applications. However, due to their limited availability and high purchasing costs, at the present time, only a few of these applications have been realized. The realization of CNT-based devices and CNT-based materials depends on success in material synthesis and on the possibility of controlling the nanotube's chirality, diameter and purity. This paper describes new simple techniques for (i) synthesis of vertically-aligned carbon nanotubes (VA-CNTs), (ii) mass and low-cost production of multiwall carbon nanotubes (MWCNTs) and (iii) growth of individual CNTs on tungsten tips.