Feasibility of using copper slag as replacement for quartz sand in the production of Ultra High Strength Concrete (UHSC) is investigated in this research work. Strength and durability performance of ...Copper Slag incorporated Ultra High Strength Concrete (CS-UHSC) was evaluated. Two type of mix proportions were used to assess the performance, one with untreated copper slag obtained as it is from industry and another with copper slag subjected to mechanical treatment. Mechanical treatment involves the grinding of copper slag to have finer size than the standard size available. Test results indicated that it is possible to produce UHSC of compressive strength more than 150 MPa with 100% untreated copper slag and 200 MPa with 100% treated copper slag as replacement for quartz sand. For complete replacement of quartz sand, reduction in compressive strength was observed with untreated copper slag, whereas an increase in strength behaviour was observed for specimens with treated copper slag. A similar trend was noticed with flexural strength and splitting tensile strength. Superior durability performance was observed in CS-UHSC compared to control UHSC with quartz sand. Thus, it is viable and advantageous to produce UHSC with copper slag as a replacement material for quartz sand.
•Attempt is made to develop Ultra High Strength Concrete (UHSC) with copper slag as aggregate substitute.•Influence of untreated and treated copper slag on strength and durability of UHSC is reported.•Copper slag can be successfully used as aggregate with enhanced mechanical and durability performance.
Red emitting ZnO at the excitation of blue light has been prepared from zinc acetate-urea precursor by sol-gel combustion method. X-ray diffraction studies confirm that the obtained material is in ...hexagonal wurtzite structure. The photo-luminescent studies reveal that the ZnO is excitable at a wide range of wave length from near UV and blue light. However, at blue light excitation, it shows a strong broad band emission than the near UV excitation, and it starts from 475 nm to 650 nm with an emission maximum of 540 nm. The diffused reflectance spectra show a strong absorption of light from 240 nm to 500 nm. At blue LED excitation (465 nm), it emits a bright broad band red emission with an emission maximum of 625 nm with a CIE chromaticity value of (x = 0.65, y = 0.37). The di band phosphor blend containing red emitting ZnO and yellow emitting YAG:Ce3+ shows warm white light emission at the excitation of blue LED (465 nm) with CIE chromaticity (x = 0.51, y = 0.31) as well as CRI of 96 and CCT of 1986K. All the results indicate that the synthesized ZnO is a promising phosphor material for the applications of WLEDs.
•Red emitting ZnO was synthesized by a sol-gel combustion method.•Excitation at blue light shows a strong red emission.•Red emitting ZnO blended with YAG:Ce3+ emits warm white light at the excitation of blue LED.
In this work, cellulose nanofibers were extracted from banana fibers via a steam explosion technique. The chemical composition, morphology and thermal properties of the nanofibers were characterized ...to investigate their suitability for use in bio-based composite material applications. Chemical characterization of the banana fibers confirmed that the cellulose content was increased from 64% to 95% due to the application of alkali and acid treatments. Assessment of fiber chemical composition before and after chemical treatment showed evidence for the removal of non-cellulosic constituents such as hemicelluloses and lignin that occurred during steam explosion, bleaching and acid treatments. Surface morphological studies using SEM and AFM revealed that there was a reduction in fiber diameter during steam explosion followed by acid treatments. Percentage yield and aspect ratio of the nanofiber obtained by this technique is found to be very high in comparison with other conventional methods. TGA and DSC results showed that the developed nanofibers exhibit enhanced thermal properties over the untreated fibers.
•Ordinary Portland cement was replaced with 5–20% by weight of sugarcane bagasse ash.•Compressive strength, chloride penetration resistance and sorptivity tests were carried out.•15% substitution of ...treated sugarcane bagasse ash (TBA) exhibited a better durability property.•Treated sugarcane bagasse ash could be used in making the ultrahigh strength concrete (UHSC).
This paper discusses the feasibility of utilizing sugarcane bagasse ash as a pozzolanic material in the production of Ultra High Strength Concrete (UHSC). Ordinary Portland Cement was replaced with Treated Bagasse Ash (TBA) in this investigation. The replacement dosage varied from 5% to 20% by weight of cement. The effect of bagasse ash on workability, compressive strength, chloride penetration resistance and sorptivity was examined. In addition to this, the effect of different curing regimens on hardened properties of UHSC was carried out. The results proved that it is possible to produce UHSC with cylinder compressive strength more than 160 MPa by incorporating bagasse ash. Optimum replacement ratio of 15% yielded better performance in all the tests, without having any adverse effects on hardened concrete. Convincingly, 20% substitution of sugarcane bagasse ash is good enough for producing UHSC.
The exfoliation of graphene from pristine graphite in a liquid phase was achieved successfully via sonication followed by centrifugation method. Ultraviolet–visible (UV–vis) spectra of the obtained ...graphene dispersions at different exfoliation time indicated that the concentration of graphene dispersion increased markedly with increasing exfoliation time. The sheet-like morphology of the exfoliated graphene was revealed by Scanning Electron Microscopy (SEM) image. Further, the morphological change in different exfoliation time was investigated by Atomic Force Microscopy (AFM). A complete structural and defect characterization was probed using micro-Raman spectroscopic technique. The shape and position of the 2D band of Raman spectra revealed the formation of bilayer to few layer graphene. Also, Raman mapping confirmed the presence of uniformly distributed bilayer graphene sheets on the substrate.
Alkali treatment coupled with high pressure defibrillation and acid treatment have been tried on banana fibers obtained from the pseudo stem of the banana plant Musa sapientum. The structure and ...morphology of the fibers have been found to be affected on the basis of the concentration of the alkali and acid and also on the pressure applied. Steam explosion in alkaline medium followed by acidic medium is found to be effective in the depolymerization and defibrillation of the fiber to produce banana nanowhiskers. The chemical constituents of raw and steam exploded fibers were analyzed according to the ASTM standards. Structural analysis of steam exploded fibers was carried out by FTIR and XRD. The fiber diameter and percentage crystallinity of the modified fibers were investigated using X-ray diffraction studies. Characterization of the fibers by SFM and TEM supports the evidence for the development of nanofibrils of banana fibers.
Steam explosion process is employed for the successful extraction of cellulose nanofibrils from pineapple leaf fibres for the first time. Steam coupled acid treatment on the pineapple leaf fibres is ...found to be effective in the depolymerization and defibrillation of the fibre to produce nanofibrils of these fibres. The chemical constituents of the different stages of pineapple fibres undergoing treatment were analyzed according to the ASTM standards. The crystallinity of the fibres is examined from the XRD analysis. Characterization of the fibres by SEM, AFM and TEM supports the evidence for the successful isolation of nanofibrils from pineapple leaf. The developed nanocellulose promises to be a very versatile material having the wide range of biomedical applications and biotechnological applications, such as tissue engineering, drug delivery, wound dressings and medical implants.
Cost-effective white-light emitting highly-defective ZnO is synthesized by a sol–gel combustion method using urea and zinc salt at a low temperature. The obtained ZnO can be excited in a wide range ...of wavelength from 270 to 480nm. The excitation of ZnO by blue light emits a bright white-light which covers from blue to red wavelength region. The stable white-light emission is found to have originated from the defective structure of ZnO by the synthesis method. This could be highly useful for producing cost-effective white-light emitting diodes. The structural, morphological and optical properties of ZnO particle are analyzed by XRD, SEM, PL Spectra and DRS.
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•Highly-defective ZnO was synthesized.•The obtained ZnO shows a strong absorption in the blue light region.•Excitation at blue light shows a bright white light emission.
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Rust-induced photocatalytic and antibacterial activities of ZnO nanoparticles derived from Prosopis juliflora leaf extracts by biosynthesis using the hydrothermal method at 170 °C are ...reported in this study. The characterization has been accomplished by various methods such as XRD, DRS, FT-IR, SEM, TEM, EDAX, and PL spectra. XRD exhibits that ZnO has a hexagonal wurtzite structure with a preferred orientation of 101 planes. The functional groups, which are present in the leaf extracts, are responsible for corresponding peaks in FT-IR spectra. The FESEM images of the synthesized nanoparticles show the morphology sphere like structure. ZnO particle size of 65 nm has been observed from HR-TEM analysis. The elemental composition has a good agreement with the biosynthesized ZnO nanoparticles. The antibacterial activities have been carried out in vitro assays against four different pathogens viz Escherichia coli (E. coli), Rhodococcus rhodochrous (R. rhodochrous), Bacillus subtilis (B. subtilis) and Vibrio cholera (V. Cholera) against a standard (streptomycin sulfate). Furthermore, the Photocatalytic ability of the titled nanoparticles has been experimented from the rust solution with methylene blue and degradation under UV radiation of 99%. The proposed mechanism is based on scavenger studies and it is investigated during the photo degradation of Methylene blue. The catalytic amount and recovery of photocatalyst have also been studied in detail.
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► Well interconnected web like nanofibrils extracted from pineapple leaf fibers by steam coupled acid treatment. ► Nanofibres prepared by this technique observed to have very high ...percentage yield and aspect ratio in comparison with other conventional methods. ► High strength nanocellulose reinforced polyurethane composites developed for medical application. ► Assessment of medical applicability of the developed nanocomposites for use as tissue implants such as heart valves and vascular grafts.
Nanocellulose is the crystalline domains obtained from renewable cellulosic sources, used to increase mechanical properties and biodegrability in polymer composites. This work has been to study how high pressure defibrillation and chemical purification affect the PALF fibre morphology from micro to nanoscale. Microscopy techniques and X-ray diffraction were used to study the structure and properties of the prepared nanofibers and composites. Microscopy studies showed that the used individualization processes lead to a unique morphology of interconnected web-like structure of PALF fibers. The produced nanofibers were bundles of cellulose fibers of widths ranging between 5 and 15nm and estimated lengths of several micrometers. Percentage yield and aspect ratio of the nanofiber obtained by this technique is found to be very high in comparison with other conventional methods. The nanocomposites were prepared by means of compression moulding, by stacking the nanocellulose fibre mats between polyurethane films. The results showed that the nanofibrils reinforced the polyurethane efficiently. The addition of 5wt% of cellulose nanofibrils to PU increased the strength nearly 300% and the stiffness by 2600%. The developed composites were utilized to fabricate various versatile medical implants.
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