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    Evaluation of the effect of para-aramid and micro-polyolefin fibers on permanent displacement in stone mastic asphalt
    (Kare Publishing, 2024) Saedi, Sepehr
    This study examines the role of fibers formed from para-aramid and micropolyethylene in enhancing the performance of stone mastic asphalt (SMA) mixtures against permanent deformation. The use of SMA mixtures has the potential to mitigate permanent deformation and plasticity. Marshall tests, static creep tests, fatigue tests, and wheel track tests were conducted on samples prepared using the modified Marshall design method to achieve the research objectives. According to the test results, Samples containing 1.5% of the fiber mixture's total weight exhibited greater strength than other samples. Additionally, these samples demonstrated the most minor displacement against rutting among all prepared samples. Based on these findings, incorporating fibers containing Para-aramid and Micro-polyolefin in SMA mixtures can enhance the performance of this type of mixture against permanent deformations. © 2024, Kare Publishing. All rights reserved.
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    Laboratory investigation of the effect of de-icing solutions on moisture susceptibility of hot mix asphalt with biomass fibers
    (Springer, 2024) Saedi, Sepehr
    The probability of freezing in roads exposed to snow and rain requires ice removal operations to reduce the potential dangers. Lack of maintenance and ice removal can lead to swelling, formation of transverse cracking and stripping pavements phenomenon. Due to the numerous disadvantages of using solid calcium chloride for de-icing, researchers worldwide are still seeking alternative methods to minimize its impact on infrastructure and the environment.In line with the mentioned research, this study was conducted to reduce the effect of deicing solutions on moisture damage, which is one of the most important reasons for reducing the lifespan of hot mix asphalt pavements. Liquid anti-icing and de-icing materials that can be used include calcium chloride, magnesium chloride, and sodium chloride. In using de-icing solutions, beside considering the environmental and economic aspects, it is also important to evaluate the potential damage of such material on asphalt surfaces. To begin the research phase, asphalt mixtures were prepared using the Marshall design method, combining basalt aggregates with bitumen PG 58 - 16, and limestone aggregates with the same bitumen specification. Following this, 0.3% hemp fiber was added to the mixtures, and 78 Marshall samples were prepared for testing. To initiate the research stages, asphalt samples were first prepared using two types of aggregates, basalt and limestone, containing 0.3% hemp fibers. Then, the prepared samples were subjected to sodium chloride, calcium chloride, and magnesium chloride solutions after undergoing 5 freeze-thaw cycles. They were subsequently tested under various moisture sensitivity tests. The results indicated that, in addition to the significant environmental damage caused by sodium chloride, it has a severe impact on reducing the resistance of both types of asphalt mixtures against moisture-related distress. Among the tested solutions, Cacl2 has the lowest impact on reducing the resistance of mixtures against moisture-related distress. Considering its lower environmental impact and relatively cost-effectiveness, it can be considered as a suitable option for de-icing operations in cold and snowy regions, which can also help reducing the maintenance costs of asphalt pavements.