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Experimental Investigation on FACA and FACACRETE – An Innovative Building Material
Ajmal Muhammed,Palanisamy Thangaraju 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.11
Recently, many studies are put forward by researchers to utilize waste materials like fly ash, GGBS, etc. in the construction industry due to the problems arise in the disposal of these materials. A novel study on incorporating the FACA (fly ash artificial coarse aggregate) in concrete is illustrated in this paper by comparing fly ash artificial coarse aggregate concrete (FACACRETE) with normal concrete. Different mixtures of geo-polymers were prepared using different molarities of NaOH solution and varying alkaline solution to fly ash ratio. These mixtures were cast to form a hard mass and cured. It is then pulverized in to fly ash artificial coarse aggregates (FACA). The properties of FACA were determined and are compared with conventional coarse aggregates. From the experiment, it is found that the FACA is a lightweight aggregate. It can be used for wearing as well as non–wearing surfaces as per IS: 383 – 2016. It is found that 8MA1 (8 Molar NaOH solution and 0.4 is the alkaline solution to fly ash ratio) is economical and can be used for further research as NaOH needed is less. This mix (8MA1) of FACA is used to prepare fly ash artificial coarse aggregate concrete (FACACRETE). The mechanical properties of both normal concrete and FACACRETE are compared and the results suggest that the compressive, splitting tensile, flexural strengths and the stress–strain relationship of FACACRETE is comparable with conventional concrete of same grade as per IS 456. The compressive toughness and compressive index of the FACACRETE is found to be more than the conventional concrete. The failure pattern of FACACRETE is associated with multiple cracking and that of normal concrete is localized failure. On considering the experimental investigations conducted here, it is found that the FACA can be used to replace conventional coarse aggregate in concrete.
Ajmal, C Muhammed,Menamparambath, Mini Mol,Choi, Hyouk Ryeol,Baik, Seunghyun IOP 2016 Nanotechnology Vol.27 No.22
<P>Highly conductive flexible adhesive (CFA) film was developed using micro-sized silver flakes (primary fillers), hybrids of silver nanoparticle–nanowires (secondary fillers) and nitrile butadiene rubber. The hybrids of silver nanoparticle–nanowires were synthesized by decorating silver nanowires with silver nanoparticle clusters using bifunctional cysteamine as a linker. The dispersion in ethanol was excellent for several months. Silver nanowires constructed electrical networks between the micro-scale silver flakes. The low-temperature surface sintering of silver nanoparticles enabled effective joining of silver nanowires to silver flakes. The hybrids of silver nanoparticle–nanowires provided a greater maximum conductivity (54 390 S cm<SUP>−1</SUP>) than pure silver nanowires, pure multiwalled carbon nanotubes, and multiwalled carbon nanotubes decorated with silver nanoparticles in nitrile butadiene rubber matrix. The resistance change was smallest upon bending when the hybrids of silver nanoparticle–nanowires were employed. The adhesion of the film on polyethylene terephthalate substrate was excellent. Light emitting diodes were successfully wired to the CFA circuit patterned by the screen printing method for application demonstration.</P>
Silver nanoflowers for single-particle SERS with 10 pM sensitivity
Roy, Shrawan,Muhammed Ajmal, C,Baik, Seunghyun,Kim, Jeongyong IOP Pub 2017 Nanotechnology Vol.28 No.46
<P>Surface-enhanced Raman scattering (SERS) has received considerable attention as a noninvasive optical sensing technique with ultrahigh sensitivity. While numerous types of metallic particles have been actively investigated as SERS substrates, the development of new SERS agents with high sensitivity and their reliable characterization are still required. Here we report the preparation and characterization of flower-shaped silver (Ag) nanoparticles that exhibit high-sensitivity single-particle SERS performance. Ag nanoflowers (NFs) with bud sizes in the range 220–620 nm were synthesized by the wet synthesis method. The densely packed nanoscale petals with thicknesses in the range 9–22 nm exhibit a large number of hot spots that significantly enhance their plasmonic activity. A single Ag NF particle (530–620 nm) can detect as little as 10<SUP>−11</SUP> M 4-mercaptobenzoic acid, and thus provides a sensitivity three orders of SERS magnitude greater than that of a spherical Ag nanoparticle. The analytical enhancement factors for single Ag NF particles were found to be as high as 8.0?×?10<SUP>9</SUP>, providing unprecedented high SERS detectivity at the single particle level. Here we present an unambiguous and systematic assessment of the SERS performances of the Ag NFs and demonstrate that they provide highly sensitive sensing platforms by single SERS particle.</P>