New Radiation-Protective Binder for Special-Purpose Composites

2016 ◽  
Vol 683 ◽  
pp. 318-324 ◽  
Author(s):  
Anna Nikolaevna Grishina ◽  
Evgeniy Valerjevich Korolev
Keyword(s):  
Building Materials ◽  
Setting Time ◽  
Sol Gel ◽  
Mineral Admixtures ◽  
Normal Density ◽  
Forming Process ◽  
Composite Binder ◽  
Linear Coefficient ◽  
Setting Times ◽  
Sol Gel Process

The present work is devoted to the examination of new radiation-protective binder for special-purpose composite materials. The mixture for such advanced binder is developed. The mixture includes portland cement together with special component – barium hydrosilicates. The latter are micro-sized mineral admixtures which are synthesized by means of low-temperature sol-gel process. The parameters of early structure forming process (including normal density and setting time) are studied. Mechanical properties of the developed binders are determined. It has been shown that admixture of barium hydrosilicates leads to an increase of normal density. Both low and high setting times are reducing for composite binder with barium hydrosilicates. Values of compressive strength are significantly higher (up to 75%) if compared with traditional binder for radiation-protective building materials. It is also revealed during examination of protective properties that for X-ray photons with energy Eγ = 0.1 MeV linear coefficient of attenuation increases by 80%.

THE EFFECT OF COMPOSITION CHANGE IN SOL-GEL SYNTHESIZED PSC

2008 ◽  
Vol 20 (01) ◽  
pp. 53-59
Author(s):  
Wen-Hsi Wang ◽  
Yuan-Ling Lee ◽  
Chun-Pin Lin ◽  
Feng-Huei Lin
Keyword(s):  
Setting Time ◽  
Sol Gel ◽  
Hydration Product ◽  
Xrd Pattern ◽  
Ph Variation ◽  
Initial Strength ◽  
Filling Materials ◽  
Retrograde Filling ◽  
Significant Difference ◽  
Sol Gel Process

Modified calcium silicate cement had previously been developed as a dental retrograde filling. It had great sealing ability, good biocompatibility, and anti-bacterial properties. However, its clinical application was limited by a long setting time and poor handling property. In previous study,1, 2 the setting property of PSC was greatly improved due the sol-gel process, without the addition of transition metal element. In this study, different ratio of starting material of PSC was prepared. The composition of each group was also altered with the ratio of the starting materials according to the result of XRD pattern. There is no significant difference in pH variation profile between each group. Even though low C 3 S / C 4 AF ratio (DX631 and DX541 groups) possessed high initial strength at first 24 hours after hydration, there was no increase in strength ever since according to the result of microhardness. However, the groups with high C 3 S / C 4 AF ratio (DX811 and DX721 groups) possessed relatively low initial strength at 24 hours after hydration, but the strength increased rapidly and continuously at least for the next six days of hydration. Moreover, the peak intensity of hydration product (Portlandite) on XRD pattern in DX811 group was much higher than other three groups, and this was also in agreement with the result of microhardness. DX811 group is determined to be the optimal one for the further development in the application as root-end filling materials.

scholarly journals COMPOSITE BINDERS BASED ON CONCRETE SCRAP

2020 ◽  
pp. 8-18
Author(s):  
A. Ahmed ◽  
R. Lesovik ◽  
S. Al Mamouri ◽  
T. Gunchenko
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Setting Time ◽  
Normal Density ◽  
Composite Binder ◽  
Construction Products ◽  
Normative Documentation ◽  
Optimal Strength ◽  
Vibration Mill

The object of research is composite binders obtained from concrete scrap of destroyed buildings and structures for the production of various construction products and structures. Fractions of concrete scrap of 0,0–0,16 mm and 0,16–0,315 mm are used, since x-rayphase analysis of various fractions of concrete scrap shows that these fractions have the highest content of non-hydrated particles of alite and belite. The influence of the specific surface area on the normal density of cement dough and the setting time of binders is established. Comparative physical and mechanical indicators of hardening of binders with different specific surfaces indicate that the most stable results with a uniform increase in strength is the composition of a binder with a specific surface of 964 m2 / kg, with an increase in strength from 2 to 7 days – 27 % and from 7 to 28 days – 21 %. This binder is characterized by optimal strength at the age of 28 days – 25,5 MPa. With a specific surface of 964 m2/kg, the best conditions are created for the formation of the primary frame and its further fouling with various calcium crystalline hydrates, which ensure optimal density and strength. This composite binder has a specific surface area of 964 m2/kg and is more energyefficient. Composite binders obtained in a vibration mill from concrete scrap fractions (0,0–0,16 and 0,16–0,315 mm) meet the requirements of normative documentation on setting time and physico-mechanical parameters, which allows to recommend them for use as binders in the production of construction products and structures for various purposes.

Influence of Colloidal Silica on Final Properties of no Cement Castables

2021 ◽  
Vol 321 ◽  
pp. 125-130
Author(s):  
David Zemánek ◽  
Lenka Nevřivová
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Bulk Density ◽  
Colloidal Silica ◽  
Sol Gel ◽  
Setting Times ◽  
Sol Gel Process ◽  
Initial Setting ◽  
Basic Parameters ◽  
Silica Sols

This paper deals with sol-gel process and application in no cement castables based on andalusite. The use of calcium free binder increases the refractory parameters of material and allows its faster drying. Six colloidal sols from CWK Bad Köstritz based on SiO2 were tested, which differed not only in concentration and particle size, but also in pH. The influence of silica sols on the consistency of fresh castable, initial setting and final setting times were investigated. Furthermore, basic parameters after firing, such as bulk density, apparent porosity, flexural and compressive strength, were tested.

scholarly journals Selection of mixtures for 3D printing

2021 ◽  
Vol 13 (3) ◽  
Author(s):  
Boris Bondarev ◽  
Veniamin Bayazov ◽  
Oleg Korneev ◽  
Ilya Vostrikov ◽  
Aleksey Meshcheryakov ◽  
...  
Keyword(s):  
3D Printing ◽  
Russian Federation ◽  
Building Materials ◽  
Setting Time ◽  
Additive Technologies ◽  
High Rate ◽  
Curved Structures ◽  
Setting Times ◽  
Optimal Setting ◽  
The Russian Federation

Currently, the construction industry needs to reduce material and technical, energy, labor, and as a result, financial costs, reduce the risk of injury in the production process and improve the quality of finished products through mechanization and automation, increases interest in the possibilities of additive technologies in the construction of structures of buildings and structures. Every year, the volume of work on the construction of objects using 3D technologies is growing quite intensively and this is becoming more and more relevant. The high rate of construction, the lack of decking, the reduction of the possibility of design deviations, thanks to the accuracy of the 3D printer, the widespread use of curved structures, which allows not only to reduce stress, but also to increase the level of stylistic quality, all this creates a demand for additive technologies. This article presents the results of experiments that allow us to continue the development in the field of optimizing the composition of building mixes in experimental construction with the use of 3D printing, since in the Russian Federation, a direction in the field of research of building materials for additive technologies is emerging. This article presents the results of optimizing the composition of building mixes used for additive technologies for the Lipetsk region, since it includes blast furnace slag, which is a by-product of PJSC Novolipetsk Metallurgical Combine. As a result of tests of the concrete mixture, it was found that the density is 1940.3 kg/m3, the setting time: the beginning — 3 hours 20 minutes, the end — 4 hours, the mobility of the cone immersion, 3.40 mm, the strength (28 days): compressed — 30.4 MPa, bending — 4.7 MРа. The data indicate that the resulting mixture has the necessary rheological properties and optimal setting times and can be used for the construction of buildings and structures using 3D printing. Thus, the results of this work will allow us to continue the development in the field of optimizing the composition of building mixes in experimental construction using 3D printing, since in the Russian Federation, a direction in the field of research of building materials for additive technologies is emerging.

Modification of Silica Gel by Nanosilica

2016 ◽  
Vol 714 ◽  
pp. 35-39
Author(s):  
Adéla Peterová ◽  
Petr Kotlík
Keyword(s):  
Crack Propagation ◽  
Silica Nanoparticles ◽  
Internal Stress ◽  
Silica Gel ◽  
Time Domain ◽  
Building Materials ◽  
Sol Gel ◽  
Silica Gels ◽  
Laboratory Conditions ◽  
Sol Gel Process

Consolidants based on silica gel have been widely used for the consolidation of decaying monuments. Consolidants reinforce building materials by replacing cement that has decayed. However, silica gels are formed by polycondensation, during which process they shrink and may crack from the internal tension. Therefore, their lifetime is limited and the building materials have to be treated time and time again. In this study, we investigate whether silica nanoparticles are able to absorb the internal stress caused by gel solidification and, thereby, prevent crack propagation. We carried out a time domain study of the sol-gel process under a stable laboratory conditions.

scholarly journals Composition, Properties and Using Fields of Product of Phosphogypsum Recycling

2020 ◽  
Author(s):  
Fedor Kapustin ◽  
Nikolay Mityushov ◽  
Sergey Bednyagin
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Building Materials ◽  
Setting Time ◽  
Physical And Mechanical Properties ◽  
Mineral Admixtures ◽  
Copper Smelting ◽  
Effect Of Temperature ◽  
Mineral Additive ◽  
Composition Properties

Nowadays about 200 million tons of phosphogypsum (PG) have been stored in the dumps of the chemical industry and non–ferrous metallurgy of Russia which pollutes the environment. This waste contains up to 98 % of two–water gypsum and impurities including rare earth metals (REM) in an amount of up to 0.5 % preventing its use in the production of building materials. A complex technology of FG recycling including extraction of REM, neutralization and dehydration of the pulp for using in the production of gypsum binders and Portland cement. Results of determination of density, grain, chemical and mineral compositions and structure of the product of recycling of FG of the “Sredneuralsky copper smelting plant” are presented. After the REM extraction, the PG is a loose lumpy mass with moisture content of 28–32 % which contains about 10 % of particles larger than 40 mm and not more than 60 % of particles less than 10 mm, it has a true density of 2.26 g/cm3, pH of aqueous extract is 5.95. It has the following chemical composition, mass. %: 0.87 SiО2; 0.93 A12O3; 0.20 Fe2O3; 31.00 CaO; 0.034 MgO; 44.27 SО3; 0.10 K2О; 0.42 Nа2О; 0.45 Р2О5(general); 20.73 of mass loss of ignition. The mineral composition of the PG processing product is represented by two-water gypsum and a slight amount of quartz. The possibility of using gypsum–containing waste in the production of gypsum binders and cement is considered. The effect of temperature and duration of firing, the dispersion, the type and quantity of chemical and mineral admixtures on physical and mechanical properties of gypsum binder, the influence of the type and amount of mineral additive on pelletizing and physic–mechanical properties of the granulated and pressed PG and its effects on setting time and strength of Portland cement are represented. It is recommended to use PG to obtain low–temperature and composite gypsum binders, regulation of Portland cement setting after extraction of REM. Keywords: phosphogypsum, recycling, composition, properties, technology, gypsum binder, Portland cement

scholarly journals Synthesis of Silicon-Containing Chitosan Hydrogels in a Glycolic Acid Medium

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
A. B. Shipovskaya ◽  
O. N. Malinkina ◽  
Yu. Yu. Zhuravleva ◽  
S. M. Rogacheva
Keyword(s):  
Sol Gel ◽  
Gelation Time ◽  
Forming Process ◽  
One Pot ◽  
Polymeric Salt ◽  
Sol Gel Process ◽  
Organically Modified ◽  
Organically Modified Silica ◽  
Chitosan Hydrogels ◽  
Sol Gel Synthesis

The present paper considers a “one-pot” green sol-gel synthesis of hybrid inorganic/organic hydrogels based on chitosan glycolate by using organically modified silica Si(OGly)4·2GlyOH as a precursor to form a network of ≡Si–O–Si≡ bonds at 4, 20, and 37°C. The gelation time of the multicomponent chitosan-containing system was estimated as a function of the composition (the polymer template and precursor concentrations, introduction of a low-molecular-weight accelerator NaCl) and gelation conditions (the pH and temperature of the sol-gel process). It has been shown that an increased polymeric salt concentration, the introduction of an accelerator, and increased pH and temperature accelerate the gel-forming process.

scholarly journals Structure formation of gypsum binder with zinc hydrosilicates

2019 ◽  
Vol 91 ◽  
pp. 02016 ◽  
Author(s):  
Anna Grishina ◽  
Evgenij Korolev
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Structure Formation ◽  
Calcium Ions ◽  
Building Materials ◽  
Setting Time ◽  
Zinc Content ◽  
Normal Density ◽  
Titrimetric Method

Due to high danger of mold fungi spores for humans, it is necessary to develop new fungicidal building materials, especially – materials that help to maintain biosafety in interior rooms. One of such materials is the fungicidal gypsum binder. The aim of the present work was to study the process of structure formation of gypsum in case of the presence of a previously developed fungicidal modifier which is based on hydrosilicate systems with zinc in different quantities. The studies were carried out in accordance with current regulations. The rheological and mechanical properties, including normal density, setting time and compressive strength were determined. The titrimetric method of analysis was used for determination of the content of calcium ions in the solution. It was revealed that the zinc content in the modifier does not affect the mobility of the mixture; however, it changes the rate of formation of the gypsum stone and also affects its strength. In particular, when the ratio ν(Zn)/ν(Si) is equal to 0.9, there was an increase of setting time. The mechanism of the formation of gypsum stone also changes: influence of both constructive and destructive factors simultaneously decreases. The latter was confirmed by the peculiarities of the binding of calcium ions in the presence of a fungicidal modifier.

scholarly journals Sol–gel synthesis of nanosilica-coated para-aramid fibers and their application in the preparation of paper-based friction materials

RSC Advances ◽  
2017 ◽  
Vol 7 (49) ◽  
pp. 30632-30639 ◽  
Author(s):  
Zhaoqing Lu ◽  
Wenjing Hu ◽  
Fan Xie ◽  
Longhai Zhuo ◽  
Bin Yang
Keyword(s):  
Surface Modification ◽  
Sol Gel ◽  
Aramid Fibers ◽  
Forming Process ◽  
Friction Materials ◽  
Sol Gel Process ◽  
Sol Gel Synthesis

A facile method of surface modification to fabricate nanosilica-coated aramid fibers via sol–gel process and their application for paper-based friction materials by wet-forming process.

The crystallization of thin-film ceramics

1992 ◽  
Vol 50 (1) ◽  
pp. 338-339
Author(s):  
J.M. Schwartz ◽  
L.F. Francis ◽  
L.D. Schmidt ◽  
P.S. Schabes-Retchkiman
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Sol Gel ◽  
Processing Route ◽  
Small Areas ◽  
Ceramic Thin Films ◽  
Complex Shapes ◽  
Sol Gel Process ◽  
Ceramic Precursors ◽  
Crystalline Ceramic

Ceramic thin films and coatings are of interest for electrical, optical, magnetic and thermal barrier applications. Critical for improved properties in thin films is the development of specific microstructures during processing. To this end, the sol-gel method is advantageous as a versatile processing route. The sol-gel process involves depositing a solution containing metalorganic or colloidal ceramic precursors onto a substrate and heating the deposited layer to form a crystalline or non-crystalline ceramic coating. This route has several advantages, including the ability to create tailored microstructures and properties, to coat large or small areas, simple or complex shapes, and to more easily prepare multicomponent ceramics. Sol-gel derived coatings are amorphous in the as-deposited state and develop their crystalline structure and microstructure during heat-treatment. We are particularly interested in studying the amorphous to crystalline transformation, because many key features of the microstructure such as grain size and grain size distribution may be linked to this transformation.

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