scholarly journals Influence of calcium sulphoaluminoferrite on the cement stone structure

2020 ◽  
Vol 164 ◽  
pp. 14002
Author(s):  
Svetlana Samchenko ◽  
Dmitriy Zorin
Keyword(s):  
Solid Solution ◽  
Hydration Product ◽  
Cement Stone ◽  
Structure And Properties ◽  
Partial Dissolution

Usually to obtain expansive cements sulphoaluminate clinker or mix aluminate clinker with calcium sulphates (gypsum, hemihydrate, anhydrate) are used. This paper deals with the composition and properties of solid solution of calcium sulphoaluminoferrite. It was studied an influence of calcium sulphoaluminoferrite on structure and properties cement phases. For these cements ettringite is an important hydration product. The investigation of hydration and properties of sulphomineral cements shows that ettringite are formed thus providing expansion of cement stone. Study of the hydration processes of the calcium sulfoaluminoferrite mineral in gypsum solution showed that the hydration of fine mineral fractions (less than 28 μm) occurs during partial dissolution with crystallization of small ettringite crystals from solution. Sulphoaluminoferrite mineral is characterized by the growth of large prismatic ettringite crystals with their subsequent cleavage in fractions of 45–63 μm. Research showed that for expanding additives based on calcium sulfoaluminoferrite, a polyfraction composition combining only small fractions is preferable.

Effect of Isovalent Substitution on the Structure and Properties of the Zintl Phase Solid Solution Eu7Cd4Sb8–xAsx (2 ≤ x ≤ 5)

2015 ◽  
Vol 54 (24) ◽  
pp. 11767-11775 ◽  
Author(s):  
Joya Cooley ◽  
Nasrin Kazem ◽  
Julia V. Zaikina ◽  
James C. Fettinger ◽  
Susan M. Kauzlarich
Keyword(s):  
Solid Solution ◽  
Structure And Properties ◽  
Zintl Phase ◽  
Isovalent Substitution

scholarly journals Strengthening the pavement bases through the use of stabilizing additives

2018 ◽  
Vol 5 (4) ◽  
Author(s):  
Dmitry Stroev ◽  
Sergey Sizonets ◽  
Vanik Kazaryan
Keyword(s):  
Road Construction ◽  
Mineralogical Composition ◽  
High Water ◽  
Base Layer ◽  
Cement Stone ◽  
Structure And Properties ◽  
Residual Deformations ◽  
Positive Properties ◽  
Mineral Binder ◽  
Structural Base

The experience of recent years of road operation shows that one of the ways to reduce the accumulation of residual deformations in the layers of road construction, expressed in rutting, the appearance of a grid of cracks and other types of transverse and longitudinal irregularities, is used in the base layers of pavements reinforced with mineral binders of crushed-stone-gravel-sandy mixtures (HGPS). The strength and deformability of hardened HGPS is determined mainly by the structure and properties of the cement stone, which holds the aggregate grains in place. The structure and properties of reinforced HGHPs depend on: the mineralogical composition, the water-cement ratio, the fineness of the cement, the age, the preparation and hardening conditions, or the addition of additives. With the introduction of additives, you can significantly change the strength and deformability of reinforced HGPS. Currently, stabilizing additives are widely used, the introduction of which allows to provide high water resistance, crack resistance and durability of the structural base layer. At the same time, a reinforced mixture with the use of additives has not only all the positive properties of HGPS on portland cement, but also eliminates its negative sides: low values of compressive strength, tensile strength in bending, and large shrinkage deformations. Based on the above, the introduction of stabilizing additives in fortified HGPS seems to be fruitful. As an additive, the stabilizer «ARMADOR» was used. The additive is a dry bulk mixture based on polymers, salts of alkali and alkaline earth metals. With the introduction of the stabilizer «ARMADOR», the physico-mechanical parameters increase in the composition of the reinforced material. This stabilizer creates strong crystallization and coagulation bonds, the use of which is recommended in conjunction with a mineral binder.

scholarly journals FABRICATION AND PROPERTIES OF Co DOPED Bi0.5K0.5TiO3 – BiFeO3 SOLID SOLUTION

2018 ◽  
Vol 56 (1A) ◽  
pp. 197
Author(s):  
Nguyen Hoang Tuan
Keyword(s):  
Solid Solution ◽  
Raman Spectroscopy ◽  
Magnetic Properties ◽  
Crystal Structures ◽  
Solid Solutions ◽  
Sol Gel ◽  
Structure And Properties ◽  
Antiferromagnetic Ordering ◽  
Co Doped ◽  
Good Agreement

In this study, we present some results on the structure and properties of the solid solution of Bi0.5K0.5TiO3– BiFeCoO3 (BKT – BFCO) by Sol-gel method. Crystal structures of BKT – BFCO solid solutions were studies by XRD and Raman spectroscopy. The results were in good agreement with the previous reports of Bi0.5K0.5TiO3– BiFeO3 (BKT – BFO) and Bi0.5K0.5TiO3 – BiCoO3 (BKT – BCO) solid solutions. The magnetic properties were investigated via unsaturated M-H loop, which showed the competition of paramagnetic and antiferromagnetic ordering in BKT – BFCO. However, differing from the BKT – BFO and BKT – BCO solid solutions, the unclear values of saturated magnetism in BKT – BFCO raised the unexplained question, which needed further studies.

scholarly journals Modeling of structuring processes at hardening of expanding cements and concretes on their basis

2018 ◽  
Vol 196 ◽  
pp. 04035 ◽  
Author(s):  
Igor Kharchenko ◽  
Alexander Panchenko ◽  
Alexey Kharchenko ◽  
Vyacheslav Alekseev
Keyword(s):  
Theoretical Analysis ◽  
Rheological Model ◽  
Experimental Studies ◽  
High Strength ◽  
Cementitious Materials ◽  
Cement Stone ◽  
Formation Processes ◽  
Structure And Properties ◽  
Potential Index ◽  
Kinetics Of

This paper reports the results of experimental research of the effect of strain-restriction conditions on the structure and properties of sulfoaluminate expanding cementitious materials. Theoretical analysis of the development of pattern formation processes is performed by applying the developed rheological model, illustrating features of the kinetics of structure-forming processes according to the ratio of the potential index of extension with linear, flat and volumetric limitation of deformations of the extension. The results show that rheological model adequately correlates with the results of experimental studies and can be described mathematically. Found that with the volume limitation of deformations arising when mixing crystallographic phases with high density and strength, the pore structure of the cement stone contains mainly gel pores. This is the main prerequisite for obtaining a dense, high-strength and durable structure of cement stone and concrete on its basis.

The Role of Sodium Hydroxide in the System C3A-CaSO4-H2O at 30°C

1986 ◽  
Vol 85 ◽  
Author(s):  
Hanaa Youssef Ghorab ◽  
Safaa Hussein Abou El Fetouh
Keyword(s):  
Solid Solution ◽  
Sodium Hydroxide ◽  
Calcium Hydroxide ◽  
Hydration Product ◽  
Ion Concentration ◽  
Molar Ratio ◽  
Alkaline Solutions ◽  
Hydration Reaction ◽  
X Ray Diffraction

ABSTRACTThe hydration reaction of C3A with gypsum (molar ratio = 1:1.5) has been studied in water and in sodium hydroxide solutions at 30°C. The hydration product were analyzed microscopically and by means of X-ray diffraction. The concentration of sulfate and aluminum in solution was determined spectrophotometrically. In the absence of alkali, the amount of ettringite formed passes through a maximum and is accompanied by almost complete consumption of sulphate ion in solution. Alkali depresses the formation of ettringite and accelerates that of calcium hydroxide. The monosulfate hydrate appears immediately in alkaline solutions and water then reappears after a day as a solid solution with the tetracalcium aluminate hydrate. The formation of the monophase solid solution is accompanied by the consumption of C3A, ettringite, and calcium hydroxide and by an increase in the amount of the dissolved aluminum. The presence of alkali markedly increases the initial sulfate ion concentration from solution.

Structure and properties of (1 − x)Pb(Mg1/2W1/2)O3 − xPb(Zr0.5Ti0.5)O3 solid solution ceramics

2008 ◽  
Vol 43 (15) ◽  
pp. 5258-5264 ◽  
Author(s):  
D. White ◽  
X. Zhao ◽  
M. F. Besser ◽  
X. Tan
Keyword(s):  
Solid Solution ◽  
Structure And Properties

ChemInform Abstract: Effect of Isovalent Substitution on the Structure and Properties of the Zintl Phase Solid Solution Eu7Cd4Sb8-xAsx(2 ≤ x ≤ 5).

ChemInform ◽  
2016 ◽  
Vol 47 (8) ◽  
pp. no-no
Author(s):  
Joya Cooley ◽  
Nasrin Kazem ◽  
Julia V. Zaikina ◽  
James C. Fettinger ◽  
Susan M. Kauzlarich
Keyword(s):  
Solid Solution ◽  
Structure And Properties ◽  
Zintl Phase ◽  
Isovalent Substitution

scholarly journals About the influence of hardening conditions on the structure and properties of expansive concretes

2018 ◽  
Vol 193 ◽  
pp. 03025 ◽  
Author(s):  
Vyacheslav Alekseev ◽  
Igor Harchenko ◽  
Aleksey Harchenko ◽  
Sofia Bazhenova
Keyword(s):  
Research Methodology ◽  
Concrete Structures ◽  
Operating Conditions ◽  
Cement Stone ◽  
Structure And Properties ◽  
Technical Parameters ◽  
Material Change ◽  
Volumetric Deformation ◽  
Durability Of Concrete

The paper describes the effect of hardening conditions on the hydration of cement stone and methods of controlling the concrete formation on the basis of the above research methodology. It has been proved that when the humidity of the medium in which hardening takes place is regulated, the strength and the deformation of the material change. By adding an expand-ing component to concrete, it is possible to adjust the technical parameters of concrete and simulate the durability of concrete structures. Thus, the study of the mechanisms of volumetric deformation during hardening of cement stone with a different ratio of the expanding additive allows designing con-crete compositions for different operating conditions.

Sign in / Sign up

Export Citation Format

Share Document