Sustainable Nanopozzolan Modified Cement: Characterizations and Morphology of Calcium Silicate Hydrate during Hydration

There are environmental and sustainable benefits of partially replacing cement with industrial by-products or synthetic materials in cement based products. Since microstructural behaviours of cement based products are the crucial parameters that govern their sustainability and durability, this study investigates the microstructural comparison between two different types of cement replacements as nanopozzolan modified cement (NPMC) in cement based product by focusing on the evidence of pozzolanic reactivity in corroboration with physical and mechanical properties. Characterization and morphology techniques using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) were carried out to assess the pozzolanic reactivity of cement paste modified with the combination of nano- and micro silica as NPMC in comparison to unmodified cement paste (UCP) of 0.5 water to cement ratio (w/c). Results were then substantiated with compressive strength (CS) results as mechanical property. Results of this study showed clear evidence of pozzolanicity for all samples with varying reactivity with NPMC being the most reactive

Sustainable Nanopozzolan Modified Cement: Characterizations and Morphology of Calcium Silicate Hydrate during Hydration

There are environmental and sustainable benefits of partially replacing cement with industrial by-products or synthetic materials in cement based products. Since microstructural behaviours of cement based products are the crucial parameters that govern their sustainability and durability, this study investigates the microstructural comparison between two different types of cement replacements as nanopozzolan modified cement (NPMC) in cement based product by focusing on the evidence of pozzolanic reactivity in corroboration with physical and mechanical properties. Characterization and morphology techniques using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) were carried out to assess the pozzolanic reactivity of cement paste modified with the combination of nano- and micro silica as NPMC in comparison to unmodified cement paste (UCP) of 0.5 water to cement ratio (w/c). Results were then substantiated with compressive strength (CS) results as mechanical property. Results of this study showed clear evidence of pozzolanicity for all samples with varying reactivity with NPMC being the most reactive

Synthesis and elastic properties of ternary ZnO-PbO-TeO2 glasses

Tellurite glass systems in the form [ZnO]x [(TeO2)0.7-PbO)0.3]1-x (x=0, 0.15, 0.17, 0.20, 0.22 and 0.25 mol%) have been prepared by the conventional melt quenching technique. The amorphous and glassy characteristic of samples were confirmed by XRD technique. Both longitudinal and shear ultrasonic velocities were measured by using the pulse-echo method at 5 MHz resonating frequency at room temperature. Elastic moduli (longitudinal modulus, shear modulus, Young’s modulus and Bulk modulus), Poisson’s ratio have been calculated, and the correlation between elastic moduli with those of glass composition is discussed. All elastic constants of the glass system were estimated as well as the microhardness, acoustic impedance, thermal expansion coefficient, softening temperature, and Debye temperature has been determined using the experimental data. The experimental data of the elastic moduli for investigating glasses were compared with those of theoretically calculated values using Makishima-Mackenzie theory, bond compression model and Rocherulle model

A facile synthesis of amorphous silica nanoparticles by simple thermal treatment route

A facile thermal treatment route was for the first time used to successfully synthesize amorphous silica nanoparticles. Various techniques were employed to study the structural, phase and elemental composition of the material at different calcination temperature between 500-750oC. The XRD analysis confirms the formation silica to be in an amorphous state and further revealed that the material remained in amorphous state even when calcined at 750oC. The FT-IR spectra shows that the calcination process has enable the removal of organic source from PVP and formation of amorphous silica nanoparticles. The average particle size of the material estimated from the TEM images shows that the particle were <10nm. The optical absorbance exhibited in the UV region reveals amorphous silica nanoparticles possess a wide band gap ranging from 3.803-4.126eV calcined between 500 to 750oC. The EDX analysis has confirmed the presence of Si and O as the only elements in the material formed, which implies thermal treatment method is effective for the synthesis of amorphous silica nanoparticles

Effect of reaction time on structural and optical properties of porous SiO2 nanoparticles

The effect of different reaction time on the structural and optical properties of porous SiO2 nanoparticles by simple precipitation method was comprehensively studied in this work. In this study, an aqueous sodium silicate was reacted with ethanol in deionized water and stirred between 30 to 180 min as for mixture to react. The filtered product was subjected to drying and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared reflection (FTIR), surface area analyzer, Raman and UV-Vis spectroscopy. The produced SiO2 nanoparticles powder was in amorphous form with the average particle size less than 100 nm. The sample with reaction time 90 min shows fine porous characteristic with the highest specific surface area and average pore volume. This different characteristic also gives a significant change in optical properties of the final product

Influence of heavy metal oxides to the mechanical and radiation shielding properties of borate and silica glass system

Six borate and silica glasses with varying compositions were investigated for their mechanical and radiation shielding viability. Makishima-Mackenzie elastic model was utilized to study the elastic properties of the investigated glasses. The obtained results illustrated that PbO and Bi2O3 oxides reduced the glass samples' mechanical properties. For instance, the bulks' model decreased between 68.15 and 44.10 GPa, the shear model also followed the same trend and decreased from 31.95 to 23.33 GPa, reducing the PbO and Bi2O3 ratios in the studied glass samples. Monte Carlo N-Particle Transport Code (MCNP-5) was utilized to evaluate the investigated glasses' shielding capacity. The obtained results depict that the highest linear attenuation coefficient (LAC) occurred at 0.356 MeV; it takes values 0.618, 1.024, 1.161, 1.271, 1.963, and 2.071 cm-1 for G1, G2, G3, G4, G5, and G6. Based on the simulated values of LAC, other shielding properties such as transmission rate (TR), radiation protection efficiency (RPE), half-value layer (HVL) were evaluated. The calculated results illustrated that the shielding properties enhanced with Bi2O3 and PbO insertion ratios. © 2021 The Author(s)

Synthesis and theoretical characterization of ternary Cux(Ge30Se70)100−x glasses

The Cux(Ge30Se70)100−x (0 ≤ x ≤ 12 at.%) chalcogenide alloys have been synthesized by the conventional melt quenching technique. The physical properties such as the mean coordination number, density, molar volume, compactness, overall bond energy, and cohesive energy were estimated for the Cu doped Ge-Se glassy alloys. The chemical bond approach (CBA) was used to predict the type and proportion of the formed bonds in the studied glasses. Subsequently, several structural and physical properties have been estimated. The results show that the studied glasses are rigidly connected, having an average coordination number increase from 2.6 to 2.77. The density and glass compactness show an increase with the Cu content, whereas the main atomic volume decreases. The cohesive energy and the heat of atomization show a similar behavior trend with the enhancement of Cu % in the Ge-Se binary glasses. The optical band gap was estimated theoretically compared with the previously published experimental values for the Cux(Ge30Se70)100−x (0 ≤ x ≤ 12 at.%) thin films. The covalency parameter &gt;91% for the studied glasses so that the compositions may be used as a stable glass former. Furthermore, the mechanical properties as the elastic bulk modulus, Poisson's ratio, Young's modulus, micro-hardness, and Debye temperature were investigated as a function of the Cu content. © 2021The authors extend their appreciation to the Deanship of Scientific Research at King Khalid University , Saudi Arabia, for funding this work through the General Research Project Under Grant Number ( GRP/146/42 )

Role of carbon addition on the microstructure and mechanical properties of cemented tungsten carbide and steel bilayer

The development of several novel multifunctional components to perform specific unique functions is directed towards meeting the demands for advanced components in industries. In this study, the role played by carbon (Cgr) variation on the steel part composition of cemented tungsten carbide and steel bilayer processed via powder metallurgy was investigated. Microstructural examination through field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS) revealed the presence of detrimental eta carbide phase (M6C) distributed across the interface of sintered bilayer compacts. A significant reduction of M6C was observed with 0.8 wt.% Cgr when interlayer diffusion was accelerated resulting in better morphology and higher hardness values of 735.70 and 150.97 kgf mm⁻² in WC and Fe layers, respectively. Tensile strength property was evaluated to examine the sintering compatibility and the interfacial bond strength of bilayer specimens. Excellent bond strength was achieved in all sintered bilayer with increasing Cgr level and enhanced densification which consequently improved tensile strength by 19%

Ultrasonic Relaxation of TeWB Glasses at Low Temperatures

The ultrasonic relaxation of tellurite glasses xB2O3 – 70 TeO2 – (30 – x) WO3, 0 ≤ x ≤ 30 mol% was investigated by measuring the ultrasonic attenuation (αL) in these glasses in the thermal range 140–300 K (T) at various frequencies (f). Some characteristics can be obtained from the relation of αL–T, such as the average activation energy (Ep) and the attempt frequency (f0). The variables Ep and f0 are a function of frequency and B2O3 content. Moreover, the relation αL–T accounts well for the oscillations of the oxygen atoms in a relaxation process. Such a physical process is originated from transmitting ultrasonic energy to the oscillating oxygen atoms in a dual-well potential. The relaxation process is inspected by a model named central force one. The subtracted different physical variables from such a model are a function of B2O3 content. © 2021 The Author(s).The authors express their gratitude to the Deanship of Scientific Research, Majmaah University, Saudi Arabia, for funding this research work under Grant (R-2021-125)

A systematical characterization of teo2–v2o5 glass system using boron (Iii) oxide and neodymium (iii) oxide substitution: Resistance behaviors against ionizing radiation

This study aimed to performan extensive characterization of a 74.75TeO2–0.25V2O5–(25 - x)B2O3-xNd2O3 glass system with (x = 0, 0.5, 1.0, and 1.5 mol%) for radiation shielding properties. Linear and mass attenuation coefficients were determined using Phy-X PSD software and compared with the simulation using Monte Carlo software MCNPX (version 2.7.0). Half value layer, mean free path, tenth value layer, effective atomic number, exposure buildup factor, and energy absorption buildup factors of VTBNd0.0, VTBNd0.5, VTBNd1.0, and VTBNd1.5 glasses were determined, respectively. The results showed that boron (III) oxide and neodymium (III) oxide substitution has an obvious impact on the gamma ray attenuation properties of the studied glasses. It can be concluded that the VTBNd1.5 sample with the highest content of neodymium (III) oxide (1.5 mol%) is the superior sample for shielding of gamma radiation in the investigated energy range. © 2021 by the authors