scholarly journals Structure Formation and Properties of Concrete Based on Organic Hydraulic Binders

2020 ◽  
Vol 19 (3) ◽  
pp. 181-194 ◽  
Author(s):  
B. M. Khroustalev ◽  
U. A. Veranko ◽  
V. V. Zankavich ◽  
Yu. G. Aliakseyeu ◽  
Yue Xuejun ◽  
...  
Keyword(s):  
Structure Formation ◽  
Cement Content ◽  
Interaction Mechanism ◽  
Solid State Physics ◽  
Transition Layers ◽  
Interfacial Layers ◽  
Significant Strength ◽  
Direct Formation ◽  
Cement Binder ◽  
Complex Binder

The article addresses the issues of structure formation of road composite materials containing hydraulic (рortland cement) and organic (bitumen) binders. It has been determined that organic and hydraulic binders, being thermodynamically incompatible, are capable of interaction and complement each other. Structure formation processes are associated with interphase transition layers interaction mechanism and the direct formation of phase contacts with cement crystallohydrates. The interphase boundary is diffuse and is established through interphase transition layers. The emergence of interfacial layers is thermodynamically advantageous, since it contributes to a decrease in Gibbs free energy and does not contradict modern concepts of solid state physics. It was established that with cement content of about 30 % of complex bitumen-cement binder volume, there will appear (nucleate) phase contacts that will prevail in the binder structure when the cement content is more than 60 %. In the case phase contacts prevail, concrete will demonstrate significant strength at high temperatures, but low temperature and fatigue crack resistance, which will lead to their durability loss. The cement content of 30–40 % of the total complex binder can be considered optimal.

Influence of Fly Ash on Microstructure of Complex Binder Pastes

2015 ◽  
Vol 1088 ◽  
pp. 608-612 ◽  
Author(s):  
Xiang Li ◽  
Jian Jun Yan ◽  
Hua Quan Yang
Keyword(s):  
Fly Ash ◽  
Cement Content ◽  
Cementitious Materials ◽  
Complex Binder

The microstructure of complex binder pastes was investigated by means of XRD and SEM-EDS. The results show that adding fly ash means decline of cement content in cementitious materials, which leads to the decrease of Ca (OH)2 content in complex binder pastes. The Ca (OH)2 crystal still exists in the complex binder pastes at the age of 360 days. By replacing part of cement with fly ash, the early microstructure of complex binder pastes becomes loosened. With the extension of curing ages, a great quantity of low CaO/SiO2 ratio of C-S-H gel is generated, which makes complex binder pastes compact gradually.

scholarly journals Effects of Initial Surface Evaporation on the Performance of Fly Ash-Based Geopolymer Paste at Elevated Temperatures

2021 ◽  
Vol 12 (1) ◽  
pp. 364
Author(s):  
Thathsarani Kannangara ◽  
Maurice Guerrieri ◽  
Sam Fragomeni ◽  
Paul Joseph
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Elevated Temperatures ◽  
Cement Content ◽  
Initial Surface ◽  
Surface Evaporation ◽  
Significant Strength ◽  
Ca 50 ◽  
Alternative Type ◽  
Maximum Compressive Strength

Geopolymer concrete is a valuable and alternative type of concrete that is free of traditional cement. Generally, geopolymer concretes require a source material, which is rich in silicon and aluminum. Furthermore, fly ash-based geopolymer concretes have been proven to have superior fire resistance, primarily due to their ceramic properties, and are inherently environmentally-friendly given their zero-cement content. This paper presents the effects on initial evaporation on the performance of fly ash-based geopolymer pastes after exposure to elevated temperatures of 400 °C and 800 °C. The fly ash (FA) samples used in the present study included: Gladstone and Gladstone/Callide. The results for sealed samples placed in the oven during curing were much more consistent than the samples that were not kept covered. In addition, Gladstone fly ash-based geopolymer samples that were sealed recorded an initial maximum compressive strength reading of ca. 75 MPa, while sealed Gladstone/Callide fly ash-based geopolymer samples, of the same mix design, only recorded an initial maximum compressive strength reading of ca. 50 MPa (both subjected to oven curing at 60 °C for 24 h). However, Gladstone/Callide fly ash-based geopolymer samples exhibited a significant strength gain, ca. 90 MPa, even after being subjected to 400 °C.

Selected physical and mechanical properties of high-density wet formed fibreboards produced with different cement content

2019 ◽  
Vol 106 ◽  
pp. 77-84
Author(s):  
WERONIKA FILIPIAK ◽  
GRZEGORZ KOWALUK
Keyword(s):  
Mechanical Properties ◽  
Cement Content ◽  
Physical And Mechanical Properties ◽  
Binder Content ◽  
High Density ◽  
Reference Panel ◽  
Physical Parameters ◽  
Content Increase ◽  
Mechanical Parameters ◽  
Cement Binder

Selected physical and mechanical properties of high-density wet formed fibreboards produced with different cement content. The aim of this work was to produce, in laboratory conditions, high-density wet formed fibreboards with a different cement binder content: 0%; 0.5%; 1%; 2%; 5%; 10%. The panels were tested for their physical and mechanical properties in order to determine the effect of added cement on the properties of the boards. The results show that the mechanical parameters of the tested panels grow compare to the reference panel when the mass share of cement is 0.5%, and decreases with the cement share increase to 10%. The remaining physical parameters of the tested panels get worse with the cement content increase.

scholarly journals Stability properties of phase transition layers in the diffuse ISM revisited

2012 ◽  
Vol 10 (H16) ◽  
pp. 611-611
Author(s):  
Jennifer M. Stone ◽  
Shu-ichiro Inutsuka ◽  
Ellen G. Zweibel
Keyword(s):  
Phase Transition ◽  
Interstellar Medium ◽  
Numerical Simulations ◽  
Structure Formation ◽  
Thermal Conduction ◽  
Transport Processes ◽  
Radiative Heating ◽  
Transition Layers ◽  
Stability Properties ◽  
Scant Attention

AbstractIn a thermally bistable medium, cold, dense gas is separated from warm, rarified gas by thin phase transition layers, or fronts, in which radiative heating/cooling, thermal conduction, and convection of material are balanced. While these fronts have received only scant attention in the literature, and are not resolved by most current numerical simulations, they have been shown to have important ramifications for transport processes and structure formation in the diffuse interstellar medium. Here, we discuss calculations of their hydrodynamic and magnetohydrodynamic stability properties.

Applications of Transmission Electron Microscopy in the Characterization of Metal Machinability

1968 ◽  
Vol 26 ◽  
pp. 442-443 ◽  
Author(s):  
L.E. Murr ◽  
A.B. Draper
Keyword(s):  
Electron Microscopy ◽  
State Physics ◽  
Test Material ◽  
Milling Machine ◽  
Rotary Table ◽  
Solid State Physics ◽  
Materials Properties ◽  
Transmission Electron ◽  
Selection Of

The industrial characterization of the machinability of metals and alloys has always been a very arbitrarily defined property, subject to the selection of various reference or test materials; and the adoption of rather naive and misleading interpretations and standards. However, it seems reasonable to assume that with the present state of knowledge of materials properties, and the current theories of solid state physics, more basic guidelines for machinability characterization might be established on the basis of the residual machined microstructures. This approach was originally pursued by Draper; and our presentation here will simply reflect an exposition and extension of this research.The technique consists initially in the production of machined chips of a desired test material on a horizontal milling machine with the workpiece (specimen) mounted on a rotary table vice. A single cut of a specified depth is taken from the workpiece (0.25 in. wide) each at a new tool location.

The morphologies and electrical properties of indium contacts on (100) cadmium telluride surfaces

1992 ◽  
Vol 50 (2) ◽  
pp. 1422-1423
Author(s):  
A.M. Letsoalo ◽  
M.E. Lee ◽  
E.O. de Neijs
Keyword(s):  
Electrical Properties ◽  
Cadmium Telluride ◽  
Methanol Solution ◽  
Electrical Characteristics ◽  
Metal Contacts ◽  
Deposition Technique ◽  
Interfacial Layers ◽  
Semiconductor Contacts ◽  
Grown Single Crystal ◽  
Diamond Abrasive

Semiconductor devices require metal contacts for efficient collection of electrical charge. The physics of these metal/semiconductor contacts assumes perfect, abrupt and continuous interfaces between the layers. However, in practice these layers are neither continuous nor abrupt due to poor nucleation conditions and the formation of interfacial layers. The effects of layer thickness, deposition rate and substrate stoichiometry have been previously reported. In this work we will compare the effects of a single deposition technique and multiple depositions on the morphology of indium layers grown on (100) CdTe substrates. The electrical characteristics and specific resistivities of the indium contacts were measured, and their relationships with indium layer morphologies were established.Semi-insulating (100) CdTe samples were cut from Bridgman grown single crystal ingots. The surface of the as-cut slices were mechanically polished using 5μm, 3μm, 1μm and 0,25μm diamond abrasive respectively. This was followed by two minutes immersion in a 5% bromine-methanol solution.

Time-resolved high-resolution electron microscopy of structural stability in mgo clusters

1996 ◽  
Vol 54 ◽  
pp. 672-673
Author(s):  
T. Kizuka ◽  
N. Tanaka
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Magnesium Oxide ◽  
Structural Stability ◽  
High Resolution Electron Microscopy ◽  
Video Tape ◽  
Solid State Physics ◽  
Time Resolved ◽  
Resolution Electron ◽  
Structural And Functional Properties

Structure and stability of atomic clusters have been studied by time-resolved high-resolution electron microscopy (TRHREM). Typical examples are observations of structural fluctuation in gold (Au) clusters supported on silicon oxide films, graphtized carbon films and magnesium oxide (MgO) films. All the observations have been performed on the clusters consisted of single metal element. Structural stability of ceramics clusters, such as metal-oxide, metal-nitride and metal-carbide clusters, has not been observed by TRHREM although the clusters show anomalous structural and functional properties concerning to solid state physics and materials science.In the present study, the behavior of ceramic, magnesium oxide (MgO) clusters is for the first time observed by TRHREM at 1/60 s time resolution and at atomic resolution down to 0.2 nm.MgO and gold were subsequently deposited on sodium chloride (001) substrates. The specimens, single crystalline MgO films on which Au particles were dispersed were separated in distilled water and observed by using a 200-kV high-resolution electron microscope (JEOL, JEM2010) equipped with a high sensitive TV camera and a video tape recorder system.

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