scholarly journals Study on Hydration and Strengthening of High Alumina Cements

2017 ◽  
Vol 15 (12) ◽  
pp. 22-27
Author(s):  
Nicolae Angelescu ◽  
Cristina Stancu ◽  
Sofiane Amziane ◽  
Vasile Bratu ◽  
Elena Valentina Stoian
Keyword(s):  
Mechanical Properties ◽  
Binary System ◽  
High Temperatures ◽  
Refractory Concrete ◽  
Physical And Mechanical Properties ◽  
Mineralogical Composition ◽  
High Alumina ◽  
Great Success ◽  
High Refractoriness ◽  
Main Factor

Abstract Refractory concretes based on aluminous cements are used with great success in areas where high temperatures are required. The mineralogical composition of the high alumina cement is the main factor which gives the physical and mechanical properties at high temperatures of refractory monolithic materials.It is therefore desirable to use high alumina cements based on mineralogical compounds with high refractoriness, because in the end those beneficial properties can be found in the final product - refractory concrete.The aim of this paper is to design, realize and characterize different compositions of high alumina cements based on mineralogical compounds with the highest refractory from the CaO-Al2O3 binary system (i.e. CA, CA2, and CA6), and to find ways of hydraulic activation of calcium hexa aluminate, also.

Basic Physical and Mechanical Properties of Composites Based on Three Different Cements

2016 ◽  
Vol 677 ◽  
pp. 186-190 ◽  
Author(s):  
Monika Čáchová ◽  
Eva Vejmelková ◽  
Kateřina Šestáková ◽  
Pavel Reiterman ◽  
Martin Keppert ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Open Porosity ◽  
Mercury Porosimetry ◽  
Physical And Mechanical Properties ◽  
Mineralogical Composition ◽  
Physical Parameters ◽  
Vacuum Saturation ◽  
Saturation Method ◽  
Properties Of Composites

This article is focused on cement based composites. Two cements differing in mineralogical composition are utilised as main binder in composites mixtures. Results of measured physical parameters of studied materials are presented. For the sake of comparison, a reference material with Portland cement was also prepared. Basic physical properties (measured by water vacuum saturation method and by helium pycnometry), characterizations of pore system (determined by mercury porosimetry) and mechanical properties are the matter of this study. Composites show various open porosity; the results of open porosity of materials containing special cements show higher values, in comparison with composite based on Portland cement. This fact of course influences other material characteristics - mainly mechanical properties.

scholarly journals Effects of High Temperatures on the Physical and Mechanical Properties of Carbonated Ordinary Concrete

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Qifang Xie ◽  
Lipeng Zhang ◽  
Shenghua Yin ◽  
Baozhuang Zhang ◽  
Yaopeng Wu
Keyword(s):  
Mechanical Properties ◽  
Weight Loss ◽  
Elastic Modulus ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Physical And Mechanical Properties ◽  
Surface Characteristics ◽  
Time Service ◽  
Different Temperatures ◽  
Cooling Methods

Fires are always known for seriously deteriorating concrete in structures, especially for those with certain carbonation due to long-time service. In this paper, 75 prism specimens were prepared and divided into four groups (three carbonated groups and one uncarbonated group). Specimens were tested under different temperatures (20, 300, 400, 500, 600, and 700°C), exposure times (3, 4, and 6 hours), and cooling methods (water and natural cooling). Surface characteristics, weight loss rate, and residual mechanical properties (strength, initial elastic modulus, peak, and ultimate compressive strains) of carbonated concrete specimens after elevated temperatures were investigated and compared with that of the uncarbonated ones. Results show that the weight loss rates of the carbonated concrete specimens are slightly lower than that of the uncarbonated ones and that the cracks are increased with raising of temperatures. Surface colors of carbonated concrete are significantly changed, but they are not sensitive to cooling methods. Surface cracks can be evidently observed on carbonated specimens when temperature reaches 400°C. Residual compressive strength and initial elastic modulus of carbonated concrete after natural cooling are generally larger than those cooled by water. The peak and ultimate compressive strains of both carbonated and uncarbonated concrete specimens increase after heating, but the values of the latter are greater than that of the former. Finally, the constitutive equation to predict the compressive behaviors of carbonated concrete after high temperatures was established and validated by tests.

Deflocculant Polyplast 3MB-RC for unformed refractories

2020 ◽  
pp. 13-18
Author(s):  
A. A. Ponomarenko ◽  
I. V. Kormina
Keyword(s):  
Mechanical Properties ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Refractory Concrete ◽  
Physical And Mechanical Properties ◽  
Petrographic Analysis ◽  
Russian Company ◽  
Furnace Slag

The influence of the deflocculant of the Russian company Polyplast-UralSib LLC on the properties of the groove and selfdissolving masses for lining the working surfaces of thermal units is considered. It was found that when a deflocculant is introduced into the refractory concrete masses in an amount of 2.0 wt. % satisfactory workability of the mass and the required physical and mechanical properties of concrete after firing at 1000 and 1400 °C are ensured compared to the introduction of imported deflocculants ADW / ADS and SioxX / Siox-Quick. It is shown that the gutter concrete obtained using the Russian deflocculant has higher strength than concrete with an imported deflocculant, including 0.5 wt. % ADW1 and 0.5 wt. % ADS3. Petrographic analysis revealed equal resistance of the trench concrete to the effects of blast furnace slag when using Russian additives and imported SioxX and Siox-Quick in the amount of 2,0 and 0,5 wt. % as deflocculants respectively. Ill. 1. Ref. 26. Tab. 2.

scholarly journals Physical and mechanical properties of the rocks of the Starobinsky deposit forming the Third potash layer and its roof

2021 ◽  
Vol 65 (4) ◽  
pp. 484-494
Author(s):  
A. B. Petrovsky ◽  
V. Ya. Prushak ◽  
E. A. Lutovich
Keyword(s):  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
Geological Structure ◽  
Mining Operations ◽  
The Third ◽  
Composition And Structure ◽  
Mining Conditions ◽  
The Stability ◽  
Roof Falling ◽  
Main Factor

The geological structure and the physical-mechanical properties of rocks composing and overlapping the Third potash formation in the areas of the mine field mine No. 4 JSC Belaruskali, which are scheduled to practice, are studied. The geological sections of the Third potash layer and its roof were built, the thickness of sylvinite and halite layers was measured, the roof falling of the rocks of the layer with a height of up to 20 m was assessed, and the type of immediate roof was determined by the composition and structure of its constituent rocks. It was established that the strength under uniaxial compression of both sylvinite and halite layers for the areas under consideration differs slightly. Therefore, to solve engineering problems of ensuring the stability of mine workings and to calculate fastening parameters, strength values averaged over the groups of layers can be used that correlate well with the percentage of weak and clay interlayers. The same applies to Poisson’s ratio, the values of which for various layers of formation are slightly different and can be taken by their averaging. It is shown that the main factor that negatively affects the strength of rocks occurring in the roof of the Third potash seam is the presence of weak and clay interlayers, which increases with depth. The introduction of the obtained results allows us to improve the calculation accuracy of securing mining parameters, to reduce the costs of their maintenance, and to improve the safety of mining operations in developing the Third potash formation in complex geological and mining conditions.

scholarly journals Possibilities of using aluminate cements in high-rise construction

2018 ◽  
Vol 33 ◽  
pp. 02056
Author(s):  
Maria Kaddo
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Service Life ◽  
Portland Cement ◽  
Physical And Mechanical Properties ◽  
High Alumina ◽  
Corrosion Resistant ◽  
High Rise ◽  
Aluminate Cement

The article describes preferable ways of usage of alternative binders for high-rise construction based on aluminate cements. Possible areas of rational use of aluminate cements with the purpose of increasing the service life of materials and the adequacy of the durability of materials with the required durability of the building are analyzed. The results of the structure, shrinkage and physical and mechanical properties of concrete obtained from dry mixes on the base of aluminate cements for self-leveling floors are presented. To study the shrinkage mechanism of curing binders and to evaluate the role of evaporation of water in the development of shrinkage was undertaken experiment with simple unfilled systems: gypsum binder, portland cement and «corrosion resistant high alumina cement + gypsum». Principle possibility of binder with compensated shrinkage based on aluminate cement, gypsum and modern superplasticizers was defined, as well as cracking resistance and corrosion resistance provide durability of the composition.

The Effect of Andreasen ́s Packing Distribution Modulus on the Physical and Mechanical Properties of a Low Cement Refractory Castable

2019 ◽  
Vol 1156 ◽  
pp. 97-104
Author(s):  
Vitoria Gabrieli Malimpensa ◽  
José Antonio Alves Júnior ◽  
João Baptista Baldo
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Refractory Concrete ◽  
Physical And Mechanical Properties ◽  
Dynamic Elastic Modulus ◽  
Conventional Concrete ◽  
Key Indicator ◽  
Temperature Ranges ◽  
S Model ◽  
First Time

Among modern refractory concretes (MRC), those with low cement content (LCC) where CAC = 4-6wt%, are widely commercialized, considering that their properties approximate those of burned bricks of the same class. In this work, the effect of the modulus q of Andreasen ́s particle size distribution, on the physical (porosity, bulk density) and mechanical (flexural strength and dynamic elastic modulus) properties, of either pre-fired or simply dried specimens of a ≥85% Al2O3 LCC ́s, was investigated. The different LCC ́s samples were formulated according to the Andreasen ́s model, using several distribution modulus (q = 0.22, 0.26, 0.30, 0.33 and 0.42). Measurements of the Dynamic Elastic Modulus (DEM) as a function of temperature (25 to 1500°C), using the Impulse Excitation Technique (IET), were taken as a key indicator of the microstructure dynamic behavior. For the sake of just a punctual comparative term, the physical and mechanical properties of a conventional type refractory concrete (CRC) with a higher CAC percentage (15%) formulated with q = 0.26 was also evaluated. The results indicated that distribution modulus values of; q =0.22, 0,26, 0.30 and 0.33 lead to higher DEM values. While q=0.42 lead to the smallest value in the LCC series. Also, higher DEM values ​​were obtained for LCC ́s (CAC = 5%) than for conventional concrete with CAC = 15% under the same value of q for pre-fired samples. In addition, by observing the occurrence of damping effects in specific temperature ranges, the loss of crystallization water from the calcium aluminate hydrates, as well as the development of pyroplastic behavior could be inferred. The gathered information is relevant to predict the behavior of LCC ́s and CRC ́s when put into service for the first time.

Investigations Of Physical And Mechanical Properties And Fracturing Of The Kyzyl-Alma Deposit

2021 ◽  
Vol 03 (04) ◽  
pp. 25-30
Author(s):  
Kazakov Aziz Nigmanovich ◽  
◽  
Khakberdiyev Muzaffar Rustamovich ◽  
Keyword(s):  
Mechanical Properties ◽  
Rock Pressure ◽  
Physical And Mechanical Properties ◽  
Main Factors ◽  
Main Factor

The article examines the main factors that affect the nature of the manifestation of mountain pressure. The physical and mechanical properties of rocks are the main factor determining the nature of the manifestation of rock pressure, their stability and their tendency to self-collapse.

scholarly journals Influence of the absorbed dose of radiation radiation on the destruction of polypropylene, depending on the location of the sample to the electron radiator

2020 ◽  
Vol 64 (11) ◽  
pp. 135-142
Author(s):  
Elvina R. Rakhmatullina ◽  
◽  
Rezeda Yu. Galimzyanova ◽  
Maria S. Lisanevich ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Ionizing Radiation ◽  
High Temperatures ◽  
Medical Devices ◽  
Absorbed Dose ◽  
Physical And Mechanical Properties ◽  
Special Place ◽  
The World ◽  
Object Of Study ◽  
Surgical Gowns

Currently, polypropylene is one of the most common polymers in the world. Due to its resistance to high temperatures, strength and density, it has found very wide application in the field of medicine. Polypropylene produces medical devices, pharmaceutical packaging, containers, suture threads. But a special place is occupied by non-woven materials based on polypropylene: surgical underwear, surgical gowns. As you know, to sterilize these products using ionizing radiation, which is the most effective of all methods. However, it leads to the destruction of polypropylene, as a result of which its physical and mechanical properties deteriorate. It is also known that the dose of radiation can vary depending on the location of the product in the box. Thus, materials can be degraded to varying degrees depending on the location in the box from the electronic emitter. As the object of study was selected: PP 1562R polypropylene produced by OAO Nizhnekamskneftekhim. It has been established that the location of polypropylene samples upon irradiation has little effect on the degree of their destruction.

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