Conference Papers

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Author: search.filters.author.George, G.

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    PFWD, CBR and DCP evaluation of lateritic subgrades of Dakshina Kannada, India
    (2008) Nageshwar Rao, Ch.; George, G.; Shivashankar, R.
    The performance of pavements depends to a large extent on the strength and stiffness of the subgrades. Among the various methods of evaluating the subgrade strength, the use of portable falling weight deflectometers (PFWD) is gaining popularity in the recent years. This is due to its simplicity in design, portability, and the added advantages of providing quick and reliable estimates of the Young's modulus of elasticity of pavement subgrades. Hence it was felt that there is a need to study the correlation between results obtained using the PFWD and those obtained using the traditional approaches such as the California bearing ratio (CBR) test, the dynamic cone penetrometer (DCP) test. The work described herein focuses on exploring the correlations between the results obtained using the PFWD, and the results obtained using the CBR method and DCP for lateritic soils at various locations of Dakshina Kannada district of the State of Karnataka, India. Regression models were developed as part of this study to enable the prediction of CBR values based on the average of observed values of the Young's modulus obtained using the PFWD (Epfwd), and prediction of Epfwd from the average penetration-rates of DCPs performed for field density, and field-moisture content.
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    Dispersion analysis of nanofillers and its relationship to the properties of the nanocomposites
    (Elsevier Ltd, 2021) George, G.; Dev, A.P.; Asok, N.N.; Anoop, M.S.; Anandhan, S.
    The dispersion and distribution characteristics of the reinforcements are the key reasons that influence the mechanical properties of the nanocomposites. In this paper, the dispersion and distribution analysis of nanofillers in a representative polymer is performed and the results are correlated to the crystalline and mechanical properties of the nanocomposite. The nanocomposite used in the present study is Elvaloy®4924 (EVACO)/halloysite nanotubes (HNTs) composite. The dispersion of halloysite nanotubes in the EVACO matrix is recorded as aluminum elemental maps obtained from energy dispersive spectroscopy (EDS). The dispersion and distribution of fillers in the composite are quantified using an image processing technique and it is correlated to the crystalline and tensile properties of the composites. The better dispersion and distribution of HNTs at 1wt.% filler loading resulted in a remarkable improvement in the crystallinity of the composite, which is measured by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The tensile strength was highest for composites loaded with 1 wt.% filler, and the strength decayed as the loading was further increased. Agglomeration of halloysite nanotubes and polymer-filler debonding was the major reason behind the reduction in tensile strength with filler loading, as observed in the scanning electron micrographs of the fractured surfaces. © 2021 Elsevier Ltd. All rights reserved.
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    Effect of nanofillers on the crystalline and mechanical properties of EVACO polymer nanocomposites
    (Elsevier Ltd, 2021) George, G.; Hareendran, H.; Kumar, T.M.A.; Joshy, S.; Sanju, A.C.; Anandhan, S.
    In this work, the effect of different fillers on the crystalline and mechanical properties of the poly(ethylene-co-vinyl acetate-co-carbon monoxide) (EVACO) terpolymer composite is studied systematically. Alumina trihydrate nanoparticles (nano-ATH), halloysite nanotubes (HNTs), and the multiwalled carbon nanotubes (MWCNTs) are the representative fillers used in the present study. The surface of MWCNTs are decorated using carbonyl, however, nano-ATH and HNTs are used without any surface treatment. The mechanical properties of the composites are evaluated using a tensile test and the improvement in the mechanical properties can be correlated to the improvement in the crystallinity in the composite. The presence of nanofillers in the EVACO matrix significantly influenced the crystallinity, which was determined by X-ray diffraction. The fractography studies reveal the presence of agglomerates at high filler loading results in the subsequent reduction in the tensile properties. Interestingly, the MWCNTs at very low filler loading significantly enhances the tensile properties of EVACO. © 2021 Elsevier Ltd. All rights reserved.