scholarly journals Reuse of Heat Resistant Glass Cullet in Cement Composites Subjected to Thermal Load

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4434
Author(s):  
Aleksandra Powęzka ◽  
Jacek Szulej ◽  
Paweł Ogrodnik
Keyword(s):  
Compressive Strength ◽  
Chemical Properties ◽  
Cement Composite ◽  
Cement Composites ◽  
Thermal And Mechanical Properties ◽  
Glass Cullet ◽  
X Ray ◽  
Average Value ◽  
Heat Resistant ◽  
Physico Chemical

The article describes the possibility of using waste glass cullet as an alternative aggregate for the production of cement composites. Three concrete mixes based on Portland cement CEM I 42.5 R with different contents of recyclate were designed. Borosilicate glass cullet was introduced into the batch by reducing the content of natural aggregate by 0%, 2.5% and 7.5%. Apparent density, water absorption and compressive strength at elevated temperature were measured. The temperature distribution, in cubic samples, was followed by thermocouples. The elements were heated in a special furnace at the temperatures of 200 °C, 400 °C, 600 °C and 800 °C. The composite topography and phase composition were observed using X-ray energy scattering electron microscopy. The results show that the appropriate modification of the cement composite with 2.5% heat-resistant glass cullet improves both the thermal and mechanical properties. Compressive strength reaches an average value of 48.6 MPa after 28 days. The increase in temperature weakens the structure of the composite. It was found that the obtained cement composite has good physico–chemical properties. The research results are presented in the article.

scholarly journals Influence of Dispersing Method on the Quality of Nano-Admixtures Homogenization in Cement Matrix

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4865
Author(s):  
Elżbieta Horszczaruk ◽  
Paweł Łukowski ◽  
Cyprian Seul
Keyword(s):  
High Speed ◽  
Mechanical Performance ◽  
Chemical Properties ◽  
Cement Composite ◽  
Cement Matrix ◽  
Cement Composites ◽  
Nano Sio2 ◽  
Mechanical Stirring ◽  
Physico Chemical ◽  
Nano Fe3o4

In recent years, a nano-modification of the cement composites allowed to develop a number of new materials. The use of even small amount of nano-admixture makes possible not only to improve the physico-mechanical properties of the cement materials, but also to obtain the composite with high usability, optimised for the given application. The basic problem of nano-modification of the cement composites remains the effectiveness of dispersing the nanomaterials inside the cement matrix. This paper deals with the effect of the type and size of the nanoparticles on the tendency to their agglomeration in the cement matrix. The main techniques and methods of dispersing the nanomaterials are presented. It has been demonstrated, on the basis of the results of testing of three nanomodifiers of 0D type (nano-SiO2, nano-Fe3O4 and nano-Pb3O4), how the structure and properties of the nanomaterial affect the behaviour of the particles when dissolving in the mixing water and applying a superplasticiser. The nanoparticles had similar size of about 100 nm but different physico-chemical properties. The methods of dispersing covered the use of high-speed mechanical stirring and ultrasonication. The influence of the method of nano-modifier dispersing on the mechanical performance of the cement composite has been presented on the basis of the results of testing the cement mortars modified with 3% admixture of nano-SiO2.

Physico-Chemical and Morphological Changes of Sayong Kaolinite Clay Treated with Sulphuric Acid for Enzyme Immobilization

2013 ◽  
Vol 832 ◽  
pp. 589-595 ◽  
Author(s):  
N.A. Edama ◽  
A. Sulaiman ◽  
K.H. Ku Hamid ◽  
M.N. Muhd Rodhi ◽  
Mohibah Musa ◽  
...  
Keyword(s):  
Surface Area ◽  
Sulphuric Acid ◽  
Enzyme Immobilization ◽  
Morphological Changes ◽  
Chemical Properties ◽  
X Ray Diffraction ◽  
Kaolinite Clay ◽  
X Ray ◽  
Mineral Oxides ◽  
Physico Chemical

This study analyzed the effects of sulphuric acid (H2SO4) treatment on pysico-chemical properties and morphological changes of clay obtained from Sg. Sayong, Perak. The clay was ground and sieved to <150μm and treated with different concentrations of H2SO4. The treatment was completed by refluxing the clay with different concentration of H2SO4 (1M, 5M and 10M ) at 100 °C for 4 hours and followed by calcination at 500 °C for 1 hour. The physic-chemical properties and morphological changes of the untreated and treated clay were compared using Surface Area Analyser, X-Ray Diffraction (XRD), Field Emission Scanning Electron Micrograph (FESEM), X-Ray Diffraction (XRD) and Fourier Transformed Infrared Spectroscopy (FTIR). The results showed that acid treatment of 5M increased the surface area from 25 m2/g to 75 m2/g and the pore volume increased from 0.1518 cc/g to 0.3546 cc/g. The nanopore size of the clay decreased from 24.8 nm to 19.4 nm after treated with acid. This can be explained due to the elimination of the exchangeable cations and generation of microporosity. The results of XRF showed SiO2 increased from 58.34% to 74.52% and Al2O3 reduced from 34.6% to 18.31%. The mineral oxides such as Fe2O3, MgO, CaO, K2O and TiO2 also reduced. This concluded that H2SO4 treatment has led to significant removal of octahedral Al3+, Fe3+ cations and other impurities. In conclusion, this study showed the physico-chemical properties and morphology of Sayong clay were improved once treated with H2SO4 and therefore suggests better supporting material for enzyme immobilization.

Physical Chemistry of the Interface between Attached Micro-Organisms and Their Support

1990 ◽  
Vol 22 (1-2) ◽  
pp. 1-16 ◽  
Author(s):  
P. G. Rouxhet ◽  
N. Mozes
Keyword(s):  
Photoelectron Spectroscopy ◽  
Bacterial Adhesion ◽  
Surface Composition ◽  
Chemical Properties ◽  
Dlvo Theory ◽  
Support Surface ◽  
X Ray ◽  
Polymer Molecules ◽  
Physico Chemical ◽  
Micro Organisms

The thermodynamic approach of adhesion and DLVO theory are complementary to predict initial bacterial adhesion; the interplay between short- and long-range forces, respectively, may be due to surface roughness. Due to the influence of electrical double layer interactions, adhesion can be promoted by treatments leading to modification of the cell or support surface properties. Adhesion is influenced by cell-cell interactions, by the cpresence of polymer molecules on the surface and by the composition of the medium. X-ray photoelectron spectroscopy can be applied to determine the elemental composition of the surface of microorganisms; some information on the chemical functions can also be obtained. The surface composition is related to physico-chemical properties which play a determining role in adhesion and flocculation, in particular the hydrophobicity and the zeta potential.

scholarly journals Corrosion Behavior of Pre-Rusted Rebars in Cement Mortar Exposed to Harsh Environments

2020 ◽  
Vol 10 (23) ◽  
pp. 8705
Author(s):  
Gankhuyag Burtuujin ◽  
Dasom Son ◽  
Indong Jang ◽  
Chongku Yi ◽  
Hyerin Lee
Keyword(s):  
Corrosion Rate ◽  
Cement Mortar ◽  
Cement Composite ◽  
Harsh Environments ◽  
Experimental Program ◽  
Cement Composites ◽  
X Ray Diffraction ◽  
Half Cell ◽  
Cell Potential ◽  
X Ray

Rebar embedded inside reinforced concrete structures becomes corroded due to various factors. However, few studies have focused on the corrosion of pre-rusted rebar embedded in cement composites, and the findings reported thus far are inconsistent. Therefore, in this study, an experimental program was undertaken to examine the effect of pre-rusting on the further corrosion of reinforcements in cement composites. Pre-rust was induced using two different solutions (CaCl2 and HCl). The corrosion rate in the cement composite was analyzed using the half-cell potential and polarization resistance methods. In addition, scanning electron microscopy with energy-dispersive X-ray analysis and X-ray diffraction analysis were used to examine the morphology of the rust. The results show that the corrosion rate of the rebar embedded in the cement composite can be increased by more than 3.8 times depending on the pre-rust conditions (RE: 0.0009 mm/year, HCl: 0.0035 mm/year). In addition, we found that the corrosion products in the pre-rusted layer were comparable to those of the rebar corroded in the marine atmosphere.

scholarly journals Effect of TiO2 Addition on Mortars: Characterization and Photoactivity

2019 ◽  
Vol 9 (13) ◽  
pp. 2598 ◽  
Author(s):  
M. J. Hernández-Rodríguez ◽  
R. Santana Rodríguez ◽  
R. Darias ◽  
O. González Díaz ◽  
J. M. Pérez Luzardo ◽  
...  
Keyword(s):  
Mercury Porosimetry ◽  
Setting Time ◽  
Chemical Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Physico Chemical ◽  
Setting Process ◽  
Flow Table ◽  
Negative Effect ◽  
Important Activity

In this study, mortar specimens were prepared with a cement:sand:water ratio of 1:3:0.5, in accordance with standard EN196-1. Portland CEM I 52.5 R grey (G) and white (W) cements were used, together with normalised sand and distilled water. Different amounts of TiO2 photocatalyst were incorporated in the preparation of the mortar samples. The effect of the addition of TiO2 was studied on mechanical properties of the mortar and cement including compressive and flexural strength, consistency (the flow table test), setting time and carbonation. Characterization techniques, including thermogravimetry, mercury porosimetry and X-ray diffraction spectroscopy (XRD), were applied to study the physico-chemical properties of the mortars. It was shown that adding the photocatalyst to the mortar had no negative effect on its properties and could be used to accelerate the setting process. Specimen photoactivity with the incorporated photocatalyst was tested for NOx oxidation in different conditions of humidity (0% RH and 65% RH) and illumination (Vis or Vis/UV), with the results showing an important activity even under Vis radiation.

The Electrochemical Synthesis of Neutral Zinc(II) Complexes of Schiff Base Ligands: The Crystal Structure of Bis[N-(4-methylphenyl)salicylaldiminato]zinc(II)

1988 ◽  
Vol 43 (5) ◽  
pp. 611-615 ◽  
Author(s):  
T. Sogo ◽  
J. Romero ◽  
A. Sousa ◽  
A. de Blas ◽  
M. L. Durán ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Schiff Base ◽  
Schiff Bases ◽  
Electrochemical Synthesis ◽  
Chemical Properties ◽  
Zinc Atom ◽  
Schiff Base Ligands ◽  
Space Group ◽  
X Ray ◽  
Physico Chemical

Abstract The electrochemical synthesis and physico-chemical properties of neutral zinc(II) complexes of bidentate Schiff bases derived from salicylaldehydes are presented together with the X-ray structure of bis[N-(4-methylphenyl)salicylaldiminato]zinc(II). The crystal is monoclinic, a = 21.877(3), b = 8.801(2), c = 12.027(5) Å, β = 96.55(3)°, space group C2/c. The complex is a monomer, and the zinc atom is tetrahedrally coordinated.

scholarly journals Ni(II) Butylmethyldithiocarbamate: Physico-Chemical Properties, X-Ray Crystallography, DFT and Anti-Corrosion Screening in Different Acids

2021 ◽  
Vol 16 ◽  
pp. 1-11
Author(s):  
Nor Farah Hida Othman ◽  
Noor Syafiqah Habdul Latif ◽  
Sheikh Ahmad Izzadin Sheikh Mohd Ghazali ◽  
Erna Normaya Abdullah ◽  
Nur Nadia Dzulkifli
Keyword(s):  
Fourier Transform ◽  
Chemical Properties ◽  
Attenuated Total Reflection ◽  
X Ray ◽  
Loss Analysis ◽  
X Ray Crystallography ◽  
Industrial Sectors ◽  
Physico Chemical ◽  
Vis Spectroscopy ◽  
Acid Environment

In industrial sectors, pickling and acid cleaning are mutual processes where acid solutions, such as hydrochloric acid (HCl) and sulfuric acid (H2SO4), are used to eliminate the corrosion products yielded on metal surfaces; thus, improving the performance of the machineries. However, the usage of the acid could lead to another metal deterioration. Dithiocarbamate inhibitor is defined as an organic compound that has good corrosion inhibition properties that can work as an inhibitor in an acid environment. Dithiocarbamate (DTC) assists by reducing acid reactiveness which prohibits metal dissolution in the acid. In this study, the Ni(II) N-butylmethyldithiocarbamate (Ni[BuMedtc]2) complex was synthesised by using an in-situ method and characterised by elemental analyser, attenuated total reflection Fourier transform infrared (ATR-FTIR), ultraviolet-visible (UV-Vis) spectroscopy and X-ray crystallographic study, and the chemical properties of the Ni[BuMedtc]2 complex was successfully calculated by the Discrete Fourier Transform (DFT) approach. The experimental results which were obtained through the weight-loss analysis method in two different acids – 1 M HCl and 1 M H2SO4 – indicated that the inhibition efficiency increased as the inhibitor concentration increased. The outcome showed that the Ni[BuMedtc]2 performed better as an inhibitor in 1 M HCl as compared to in1 M H2SO4 to protect the metal exterior because H2SO4 is more corrosive due to the excessive presence of H+.

scholarly journals PHYSICO-CHEMICAL PROPERTIES OF A COMPOSITE MATERIAL BASED ON CALCIUM HYDROPHOSPHATE AND A SUBSTRATE FROM ASPEN BARK

2020 ◽  
pp. 357-364
Author(s):  
Mikhail Yur'yevich Belash ◽  
Irina Vladimirovna Korol'kova ◽  
Yevgeniya Vladimirovna Veprikova ◽  
Galina Nikolayevna Bondarenko ◽  
Irina Vladimirovna Korol'kova ◽  
...  
Keyword(s):  
Composite Material ◽  
Water Resistance ◽  
Catalytic Effect ◽  
Substrate Surface ◽  
Chemical Properties ◽  
Analysis Data ◽  
X Ray ◽  
Physico Chemical ◽  
Mineral Components ◽  
Initial Content

The physicochemical properties of the composite material obtained by sequentially impregnating the substrate from aspen bark with water solutions of KH2PO4 and CaCl2 under certain conditions were studied. Using the method of X-ray phase analysis, it was found that the main products of the interaction of KH2PO4 and CaCl2, which flows from the aspen bark on the substrate surface, are CaHPO4 and KCl. In this case, calcium chloride is present in the obtained composite material in the form of a complex compound CaCl2·Ca(OH)2·H2O. Using IR-spectral analysis, it was revealed that there is no interaction between the functional groups of the aspen bark substrate and mineral compounds during the preparation of the composite material. Based on thermal analysis data, the catalytic effect of the mineral components that make up the developed composite material on the decomposition of hemicellulose, cellulose and lignin that make up the substrate from aspen bark is revealed. It was found that the composite material modified with CaHPO4 is characterized by increased water resistance and after treatment with water at room temperature for 24 hours, 9.85% of phosphates are removed from it (from their initial content). This allows one to use the resulting composite material based on aspen bark as a delayed-action fertilizer.

scholarly journals An Investigation of the Mechanical and Physical Characteristics of Cement Paste Incorporating Different Air Entraining Agents using X-ray Micro-Computed Tomography

Crystals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 23 ◽  
Author(s):  
Mohamed Abd Elrahman ◽  
Mohamed E. El Madawy ◽  
Sang-Yeop Chung ◽  
Stanisław Majer ◽  
Osama Youssf ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Compressive Strength ◽  
Thermal Insulation ◽  
Cement Paste ◽  
Aluminum Powder ◽  
Hollow Microspheres ◽  
Cement Composites ◽  
Micro Computed Tomography ◽  
Cement Pastes ◽  
X Ray

Improving the thermal insulation properties of cement-based materials is the key to reducing energy loss and consumption in buildings. Lightweight cement-based composites can be used efficiently for this purpose, as a structural material with load bearing ability or as a non-structural one for thermal insulation. In this research, lightweight cement pastes containing fly ash and cement were prepared and tested. In these mixes, three different techniques for producing air voids inside the cement paste were used through the incorporation of aluminum powder (AL), air entraining agent (AA), and hollow microspheres (AS). Several experiments were carried out in order to examine the structural and physical characteristics of the cement composites, including dry density, compressive strength, porosity and absorption. A Hot Disk device was used to evaluate the thermal conductivity of different cement composites. In addition, X-ray micro-computed tomography (micro-CT) was adopted to investigate the microstructure of the air-entrained cement pastes and the spatial distribution of the voids inside pastes without destroying the specimens. The experimental results obtained showed that AS specimens with admixture of hollow microspheres can improve the compressive strength of cement composites compared to other air entraining admixtures at the same density level. It was also confirmed that the incorporation of aluminum powder creates large voids, which have a negative effect on specimens’ strength and absorption.

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