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    Effect of polypropylene fibers and cement on the strength improvement of subgrade lying on expansive soil

    , Article Iranian Journal of Science and Technology - Transactions of Civil Engineering ; 2021 ; 22286160 (ISSN) Khan, S. Z ; Rehman, Z ; Khan, A. H ; Qamar, S ; Haider, F ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    Abstract
    The current study revealed the effectiveness of polypropylene (PP) fibers and cement to enhance the strength of black cotton soil. PP fibers and cement with different concentrations were mixed with black cotton soil. The strength of PP fiber and cement-based soil samples was measured in terms of unconfined compressive strength (UCS) and California Bearing ratio (CBR). Specimens for UCS and CBR tests were prepared at 2%, 4%, 6% and 8% of cement (by dry weight of soil) and seven percentages of polypropylene fibers i.e. 0.0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5% and 0.6% (by dry weight of soil). Fourier transform infrared (FTIR) analysis confirmed the presence of polypropylene and cement contents in... 

    Effect of polypropylene fibers and cement on the strength improvement of subgrade lying on expansive soil

    , Article Iranian Journal of Science and Technology - Transactions of Civil Engineering ; Volume 46, Issue 1 , 2022 , Pages 343-352 ; 22286160 (ISSN) Khan, S. Z ; Rehman, Z ; Khan, A. H ; Qamar, S ; Haider, F ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2022
    Abstract
    The current study revealed the effectiveness of polypropylene (PP) fibers and cement to enhance the strength of black cotton soil. PP fibers and cement with different concentrations were mixed with black cotton soil. The strength of PP fiber and cement-based soil samples was measured in terms of unconfined compressive strength (UCS) and California Bearing ratio (CBR). Specimens for UCS and CBR tests were prepared at 2%, 4%, 6% and 8% of cement (by dry weight of soil) and seven percentages of polypropylene fibers i.e. 0.0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5% and 0.6% (by dry weight of soil). Fourier transform infrared (FTIR) analysis confirmed the presence of polypropylene and cement contents in... 

    Saturated hydraulic conductivity of problematic soils measured by a newly developed low-compliance triaxial permeameter

    , Article Engineering Geology ; Volume 278 , 2020 Sadeghi, H ; AliPanahi, P ; Sharif University of Technology
    Elsevier B.V  2020
    Abstract
    Research on the reliable characterization of saturated permeability has received great yet necessary attention globally. However, most studies were carried out on soils with a volumetric tendency being almost insensitive to water saturation or at least with this hidden assumption. This is clearly not the case when dealing with the two broad categories of problematic soils, including collapsible and expansive soils. As confirmed by previous research, at least one-fifth of the planet comprises of these soils with a relatively fair distribution. Therefore, the main objective of this study is to introduce a low-compliance double cell/burette permeameter to track all volumetric changes during the... 

    Hysteresis of soil water retention and shrinkage behaviour for various salt concentrations

    , Article Geotechnique Letters ; Volume 11, Issue 1 , 2021 , Pages 21-29 ; 20452543 (ISSN) Sadeghi, H ; Nasiri, H ; Sharif University of Technology
    ICE Publishing  2021
    Abstract
    Laboratory investigation on the influence of solute concentration on the soil water-retention curve (SWRC) and volumetric behaviour of expansive soils has received much attention in recent years due to increasing environmental pollution. However, most studies only considered applying wetting or drying path with almost no attention to hydraulic hysteresis. Furthermore, these studies have focused on examining expansive soils and only marginal effort has been devoted to collapsible soils. Therefore, the main objective of this study is to systematically explore the SWRC and shrinkage characteristics of an artificially made collapsible soil at various molar concentrations. The tests were... 

    An improved Kalman filtering approach for the estimation of unsaturated flow parameters by assimilating photographic imaging data

    , Article Journal of Hydrology ; Volume 590 , 2020 Rajabi, M. M ; Belfort, B ; Lehmann, F ; Weill, S ; Ataie Ashtiani, B ; Fahs, M ; Sharif University of Technology
    Elsevier B.V  2020
    Abstract
    As a non-invasive method, photographic imaging techniques offer some interesting potentials for characterization of soil moisture content in unsaturated porous media, enabling mapping at very fine resolutions in both space and time. Although less explored, the wealth of soil moisture data provided by photographic imaging is also appealing for the estimation of unsaturated soil hydraulic parameters through inverse modeling. However, imaging data have some unique characteristics, including high susceptibility to noise, which can negatively affect the parameter estimation process. In this study a sequential data assimilation approach is developed to simultaneously update soil moisture content...