scholarly journals Управление физико-механическими характеристиками бетона за счет варьирования высоты и шага технологических выступов хомутов виброцентрифугирующих устройств

2021 ◽  
Vol 46 (1) ◽  
Author(s):  
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Cross Section ◽  
Mechanical Characteristics ◽  
Experimental Studies ◽  
Strength Analysis ◽  
Technological Parameters ◽  
Axial Tensile ◽  
Concrete Mix ◽  
Physical And Mechanical Characteristics

Для регулирования вариатропной структуры центрифугированных изделий авторы данной статьи совместили процесс центрифугирования с вибрированием. Во время эксперимента вибрации формы обеспечивались за счет надетых на валы установки хомутов. Представлена авторская экспериментальная установка для создания виброцентрифугированных образцов кольцевого сечения с вариатропной структурой, а также способ их изготовления. Выделены технологические параметры вибрирования, которые оказывали наиболее значимое влияние на характеристики виброцентрифугированного бетона, конструкций и изделий из него. В опытах варьировались высота технологических выступов хомутов и шаг между ними. Исследовалось влияние этих факторов на физико-механические характеристики бетона: плотность; кубиковая прочность на сжатие; призменная прочность на сжатие; прочность на растяжение при изгибе; прочность на осевое растяжение. Приведен анализ результатов экспериментальных исследований и получены следующие физико-механические характеристики виброцентрифугированных бетонов, изготовленных с использованием хомутов: лучшие – с высотой технологических выступов 5 мм и шагом между ними 30 мм, самый низкий показатель – соответственно 2,5 мм при любом шаге. Ключевые слова: виброцентрифугированный бетон, физико-механические характеристики, прочность при сжатии, плотность, бетонная смесь, центрифугирование, прочность при изгибе To regulate the variatropic structure of centrifuged products, the authors of this article combined the process of centrifugation with vibration. During the experiment, vibrations of the mold were provided with clamps set on the shafts of the installation. The author's experimental setup for creating vibrocentrifuged samples of annular cross-section with a variatropic structure, as well as a method for their manufacture is presented. The technological parameters of vibration, which had the most significant effect on the characteristics of vibrocentrifuged concrete, structures and products made of it, were identified. In the experiments, the height of the technological protrusions of the clamps and the pitch between them were varied. The influence of these factors on the physical and mechanical characteristics of concrete was investigated: density; cube compressive strength; prismatic compressive strength; bending tensile strength; axial tensile strength. Analysis of the results of experimental studies is given and the following physical and mechanical characteristics of vibrocentrifuged concretes made using clamps have been obtained: the best ones with a height of technological protrusions of 5 mm and a step between them of 30 mm, the lowest indicator is, respectively, 2.5 mm at any step. Keywords: vibrocentrifuged concrete, physical and mechanical characteristics, compressive strength, density, concrete mix, centrifugation, flexural strength

scholarly journals Amorphous fiber based on the Fe-B-C molten system for bulk reinforcement of concrete

2018 ◽  
Vol 245 ◽  
pp. 03019 ◽  
Author(s):  
Artemiy Cherkashin ◽  
Yasmin Begich ◽  
Polina Sherstobitova ◽  
Oleg Tolochko
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Mechanical Characteristics ◽  
Test Material ◽  
Comparative Tests ◽  
Physical And Mechanical Characteristics

The article deals with the use of amorphous fiber of the Fe-B-C system, which was obtained by spinning the melt. Comparative tests of the samples made on the basis of the test material on the compressive strength and tensile strength of the traditional destructive method were made. The conductivity of the samples was also tested. Physical and mechanical characteristics of the material are obtained.

scholarly journals The Effect of Twisted Polymer Fiber on Physical and Mechanical Characteristics of Concrete C35

2018 ◽  
Vol 14 (1) ◽  
pp. 126-135
Author(s):  
Reza Mirzaei ◽  
Naser Zarifmoghaddam
Keyword(s):  
Tensile Strength ◽  
Reinforced Concrete ◽  
Modulus Of Elasticity ◽  
Mechanical Characteristics ◽  
Fiber Reinforced Concrete ◽  
Polymer Fiber ◽  
New Materials ◽  
Concrete Mix ◽  
Physical And Mechanical Characteristics

 Concrete as the most used material, is known as an integral part of construction. So far, many studies have been done in the field of improving the quality of concrete that most of them have examined change in concrete mix which is called concrete mix plan. However, the use of additives and also replacing commonly used materials in concrete with new materials always has been noteworthy. In this study, description of tests that have been done on fiber reinforced concrete will be discussed. Also, the condition of concrete mix plan will be discussed. Comparison between results of the tests showed that Forta reinforced concretes have more compressive, flexural and tensile strength and modulus of elasticity than normal and ordinary concretes.Journal of the Institute of Engineering, 2018, 14(1): 126-135 

scholarly journals Adherence between steel bars and lightweight concrete with EPS beads

2017 ◽  
Vol 10 (1) ◽  
pp. 122-140
Author(s):  
A. L. SARTORI ◽  
L. M. PINHEIRO ◽  
R. M. DA SILVA ◽  
S. B. FREITAS ◽  
T. G. CESAR
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Mechanical Characteristics ◽  
Lightweight Concrete ◽  
Monotonic Loading ◽  
Adherence Behavior ◽  
Ordinary Concrete ◽  
Cylinder Test ◽  
Pull Out ◽  
Steel Bars

Abstract This paper describes the adherence behavior of a structural lightweight concrete with EPS beads (SLCEB) in a monotonic loading, based in a bibliographic review and in pull-out tests. The results of these SLCEB tests were compared with those of an ordinary concrete (OC) and with the values based in indications of the Brazilian code ABNT NBR 6118:2014 - Design of concrete structures. The pull-out tests of two batches of SLCEB and one of OC were analyzed, in a total of 60 tests. Mechanical characteristics were determined too, such as: compressive strength and tensile strength in split cylinder test. The calculated results according to the above mentioned standard were very different from those obtained in the tests, indicating that the theoretical values are more conservative than the experimental ones. It was also verified that it is possible to use SLCEB in structures with respect to the adequate adherence of reinforcement in the concrete.

Influence of Palm Oil Fibers Length Variation on Mechanical Properties of Reinforced Crude Bricks

2022 ◽  
Author(s):  
Mazhar Hussain ◽  
Daniel Levacher ◽  
Nathalie Leblanc ◽  
Hafida Zmamou ◽  
Irini Djeran Maigre ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Thermal Properties ◽  
Composite Materials ◽  
Physical Properties ◽  
Palm Oil ◽  
Mechanical Characteristics ◽  
Natural Fibers ◽  
Indirect Tensile

Crude bricks are composite materials manufactured with sediments and natural fibers. Natural fibers are waste materials and used in construction materials for reinforcement. Their reuse in manufacturing reinforced crude bricks is eco-friendly and improves mechanical and thermal characteristics of crude bricks. Factors such as type of fibers, percentage of fibers, length of fibers and distribution of fibers inside the bricks have significant effect on mechanical, physical and thermal properties of biobased composite materials. It can be observed by tests such as indirect tensile strength, compressive strength for mechanical characteristics, density, shrinkage, color for physical properties, thermal conductivity and resistivity for thermal properties, and inundation test for durability of crude bricks. In this study, mechanical and physical characteristics of crude bricks reinforced with palm oil fibers are investigated and effect of change in percentage and length of fibers is observed. Crude bricks of size 4*4*16 cm3 are manufactured with dredged sediments from Usumacinta River, Mexico and reinforced with palm oil fibers at laboratory scale. For this purpose, sediments and palm oil fibers characteristics were studied. Length of fibers used is 2cm and 3cm. Bricks manufacturing steps such as sediments fibers mixing, moulding, compaction and drying are elaborated. Dynamic compaction is opted for compaction of crude bricks due to energy control. Indirect tensile strength and compressive strength tests are conducted to identify the mechanical characteristics of crude bricks. Physical properties of bricks are studied through density and shrinkage. Durability of crude bricks is observed with inundation test. Thermal properties are studied with thermal conductivity and resistivity test. Distribution and orientation of fibers and fibers counting are done to observe the homogeneity of fibers inside the crude bricks. Finally, comparison between the mechanical characteristics of crude bricks manufactured with 2cm and 3cm length with control specimen was made.

scholarly journals Numerical Simulation of Rock Failure Process with a 3D Grain-Based Rock Model

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Zengwei Zhang ◽  
Fan Chen ◽  
Chao Zhang ◽  
Chao Wang ◽  
Tuo Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Mechanical Characteristics ◽  
Failure Process ◽  
Wellbore Stability ◽  
Rock Excavation ◽  
Rock Failure Process ◽  
Rock Model ◽  
Walled Cylinder

A grain-based rock model was developed and applied to study mechanical characteristics and failure micromechanics in thick-walled cylinder and wellbore stability tests. The rock is represented as an assembly of tetrahedral blocks with bonded contacts. Material heterogeneity is modeled by varying the tensile strength at the block contacts. This grain-based rock model differs from previous disk/sphere particle-based rock models in its ability to represent a zero (or very low) initial porosity condition, as well as highly interlocked irregular block shapes that provide resistance to movement even after contact breakage. As a result, this model can reach higher uniaxial compressive strength to tensile strength ratios and larger friction coefficients than the disk/sphere particle-based rock model. The model captured the rock fragmentation process near the wellbore due to buckling and spalling. Thin fragments of rock similar to onion skins were produced, as observed in laboratory breakout experiments. The results suggest that this approach may be well suited to study the rock disaggregation process and other geomechanical problems in the rock excavation.

Development of Cement Compositions with a Finely Dispersed Additive for Consolidation of Soil by the Injection

2019 ◽  
Vol 974 ◽  
pp. 149-155
Author(s):  
Irina V. Kozlova ◽  
Alexey E. Bespalov ◽  
Alexandra V. Bespalova
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Mechanical Characteristics ◽  
Cement Stone ◽  
Soil Consolidation ◽  
Injection Solution ◽  
Concentrated Load ◽  
Reduced Viscosity ◽  
Injection Technology ◽  
Physical And Mechanical Characteristics

Cement compositions prepared by mixing cement with a stabilized finely dispersed slag suspension, which allow improving the structural, physical and mechanical characteristics of the cement stone are considered. On the first day of hardening, the strength of modified specimens increased by 54%, at the grade age - by 43%, and the porosity decreased by 13.8 and 17.3%, respectively. The possibility of obtaining an injection solution for soil consolidation on the basis of Portland cement and a stabilized slag suspension with the concentration of a finely dispersed slag of 50 g/l is considered. Studies have shown that the injection solution under study has reduced viscosity and sedimentation, increased compressive strength. After 28 days of hardening, the strength was 14.2 MPa, which is higher than the recommended values ​​for consolidation of soil under the foundations (4-6 MPa), and at a concentrated load, for the base under the foundations of the columns (9-10 MPa). The data obtained allows considering an injection solution based on Portland cement and slag suspension for the use in the injection technology of soil consolidation.

scholarly journals Thermal and mechanical properties of PCM-incorporated normal and lightweight concretes containing silica fume

2019 ◽  
Vol 46 (7) ◽  
pp. 643-656 ◽  
Author(s):  
Amin Moshtaghi Jafarabad ◽  
Morteza Madhkhan ◽  
Naser P. Sharifi
Keyword(s):  
Compressive Strength ◽  
Silica Fume ◽  
Thermal Performance ◽  
Phase Change Materials ◽  
Mechanical Characteristics ◽  
Lightweight Aggregate ◽  
Salt Hydrate ◽  
Promising Strategy ◽  
Compressive Strength Of Concrete ◽  
Physical And Mechanical Characteristics

Improving the thermal performance of concrete, as an important construction and pavement material, by incorporating phase change materials (PCMs) has been the topic of much research. Also, various carrier agents such as lightweight aggregate (LWA) have been introduced to incorporate PCMs into concrete. However, incorporation of PCM-impregnated LWA reduces the compressive strength of concrete. In this study, the application of silica fume to improve the compressive strength of PCM-incorporated concrete is investigated. Two types of PCMs, salt hydrate PCM and polyethylene glycol PCM, were incorporated into concrete via scoria LWA, and different physical and mechanical characteristics of the concrete were studied when silica fume was incorporated into the mix. The results show that incorporation of silica fume increases the compressive strength of PCM-incorporated concrete, and at the same time does not diminish the thermal performance of the incorporated PCM. Therefore, incorporation of silica fume was found to be a promising strategy to improve the compressive strength of PCM-incorporated concrete.

Physical and mechanical characteristics of cement mortars and concretes with addition of clinoptilolite from Beli Plast deposit (Bulgaria), silica fume and fly ash

Clay Minerals ◽  
2011 ◽  
Vol 46 (2) ◽  
pp. 213-223 ◽  
Author(s):  
V. Lilkov ◽  
I. Rostovsky ◽  
O. Petrov
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Mechanical Characteristics ◽  
Physical And Mechanical Properties ◽  
Specific Pore Volume ◽  
Cement Mortars ◽  
Physical And Mechanical Characteristics

AbstractCement mortars and concretes incorporating clinoptilolite, silica fume and fly ash were investigated for changes in their physical and mechanical properties. It was found that additions of 10% clinoptilolite and 10% Pozzolite (1:1 mixture of silica fume and fly ash) were optimal for improvement of the quality of the hardened products, giving 8% and 13% increases in flexural and compressive strength respectively. The specific pore volume of the mortars incorporating zeolite decreased between the 28th and 180th day to levels below the values for the control composition due to the fact that clinoptilolite exhibits its pozzolanic activity later in the hydration. In these later stages, pores with radii below 500 nm increased at the expense of larger pores. The change in the pore-size distribution between the first and sixth months of hydration occurs mostly in the mortars with added zeolite.

scholarly journals Design, Simulation and Optimization of an Additive Laser-Based Manufacturing Process for Gearbox Housing with Reduced Weight Made from AlSi10Mg Alloy

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 67
Author(s):  
Liubov Magerramova ◽  
Vladimir Isakov ◽  
Liana Shcherbinina ◽  
Suren Gukasyan ◽  
Mikhail Petrov ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Strength Properties ◽  
Body Parts ◽  
The Finite Element Method ◽  
Technological Parameters ◽  
Simulation And Optimization ◽  
Precision Casting ◽  
Production Techniques ◽  
Material Forming ◽  
Physical And Mechanical Characteristics

The gas turbine engine's (GTE) development aims for the increasing the efficiency, strength, reliability and safety of its components. To create competitive engines, housing parts and components with high functionality and reduced weight are needed. Especially difficult in the design and production are the gearboxes for aviation GTE. Traditional technologies based on precision casting or material forming operations have significant limitations due to the complexity of fulfilling multiple different requirements. Nowadays, one of the progressive production techniques is additive manufacturing. The article presents the results of computational and experimental studies that substantiate the applicability of laser additive technology to reduce the mass of body parts by up to 15% while ensuring their strength properties. The physical and mechanical characteristics of aluminum alloys acceptable for the manufacturing of housing parts were analyzed. The necessary characteristics of the powder alloy of the Al-Si system and the technological parameters of the L-PBF of the modified housing of the gear reducer are established. Using the finite element method (FEM) the L-PBF process was numerically simulated and the technological modes for synthesis of the AlSi10Mg alloy powder were optimized. With the help of a serial 3D printer ProX320DMP, the prototype of a gear housing was manufactured.

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