scholarly journals Mathematical modeling of mechanical properties of vibro-centrifuged fiber-reinforced concrete of variatropic structure

2021 ◽  
Vol 2131 (3) ◽  
pp. 032090
Author(s):  
E Shcherban’ ◽  
A Beskopylny ◽  
L Mailyan ◽  
S Stel’makh ◽  
D El’shaeva
Keyword(s):  
Reinforced Concrete ◽  
Technology Development ◽  
Technological Development ◽  
Experimental Studies ◽  
Angular Speed ◽  
Fiber Reinforced Concrete ◽  
Strength Characteristics ◽  
Design Parameters ◽  
Angular Rotation ◽  
Fiber Concrete

Abstract Today, one of the most relevant areas in the construction industry, linked to the requirements and provisions of the Strategy of Scientific and Technological Development, and in accordance with the priority areas of science and technology development, is the development and improvement of low-material, low-energy and low - resource-intensive technologies for the manufacture of concrete and reinforced concrete products and structures. In this regard, the technology of vibrocentrifugation, which allows to obtain concrete with an improved variatropic structure, is quite promising. In this work, the influence of the design parameters of the technological equipment and the parameters of the centrifugation modes on the integral strength characteristics of vibrocentrifugated fiber concrete was evaluated. In total, 13 samples of the annular section were manufactured and tested. Calculations of the integral strength characteristics of vibrocentrifugated fiber concrete depending on the height of the technological protrusions of the clamps and the angular rotation speed were performed by the method of orthogonal composite planning of the 2nd order using the MathCAD program. The mathematical method of planning the experiment is aimed at creating mathematical empirical models that determine the influence of the incoming variable factors on the strength characteristics. Thus, according to the results of experimental studies, the optimal height of the technological protrusions and the angular speed of rotation were determined. Thus, further regulation of technological factors in the manufacture of vibrocentrifugated products and structures will allow us to obtain the most effective ring-section structures with enhanced variatropy.

Experimental Studies of Fiber-Reinforced Concrete under Axial Tension

2021 ◽  
Vol 1038 ◽  
pp. 323-329
Author(s):  
Zlata Holovata ◽  
Daria Kirichenko ◽  
Irina Korneeva ◽  
Stepan Neutov ◽  
Marina Vyhnanets
Keyword(s):  
Reinforced Concrete ◽  
Experimental Studies ◽  
Fiber Reinforced Concrete ◽  
Load Application ◽  
Fiber Reinforced ◽  
Large Aggregate ◽  
Second Stage ◽  
Axial Tension ◽  
Deformation Properties ◽  
Fiber Concrete

The design of a stand for testing concrete and fiber-reinforced concrete specimens-"eight" in tension, which provides axial load application and minimizes the effect of stress concentration at the ends of the specimen. The design of the stand is such that the distance between the axis of load application and the central hinge is 108 cm, and between this hinge and the axis of the test specimen is 21 cm, as a result of which the load transferred to the specimen is 5.143 times greater than the applied one. At the first stage of testing, it was found that the optimal characteristics of the fiber-concrete mixture is a matrix with a large aggregate ≤ 10 mm with 1.0% fiber reinforcement. At the second stage, the ultimate strength of fiber-reinforced concrete for axial tension was determined - 1.28 MPa when reinforced with wave fiber and 1.37 MPa when reinforced with anchor fiber, which amounted to 4.1% and 4.4% of compressive strength, respectively. It was also found that concrete reinforced with anchor fiber has higher deformation properties than concrete reinforced with wave fiber.

scholarly journals Light concrete based on foam polyamidbe-tonic composition

2019 ◽  
Vol 7 (1) ◽  
pp. 70-75
Author(s):  
Левон Маилян ◽  
Levon Mailyan ◽  
Татьяна Голова ◽  
Tat'yana Golova
Keyword(s):  
Reinforced Concrete ◽  
Energy Efficient ◽  
Concrete Strength ◽  
Experimental Studies ◽  
Fiber Reinforced Concrete ◽  
Strength Characteristics ◽  
Building Structures ◽  
Optimal Composition ◽  
Foam Concrete ◽  
Layer Structures

One of the most important tasks of construction is the use of energy-efficient sin-gle-layer structures based on foam concrete and an increase in their bearing ca-pacity due to the use of fiber reinforcement, which will significantly improve the performance properties of fiber-reinforced concrete. Strength characteristics of fibro-foam concrete reinforced with polyamide granules with various types of filler and recommendations for its use in building structures were obtained. These experimental studies allow us to recommend the optimal composition of polyam-ide concrete compositions.

Experimental Studies of Reinforced Concrete and Fiber-Reinforced Concrete Beams with Short-Term and Long-Term Loads

2019 ◽  
Vol 968 ◽  
pp. 227-233 ◽  
Author(s):  
Stepan Neutov ◽  
Maryna Sydorchuk ◽  
Mykola Surianinov
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Concrete Beams ◽  
Experimental Studies ◽  
Fiber Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Short Term ◽  
Ordinary Concrete ◽  
Fiber Concrete ◽  
Steel Fiber Concrete

Experimental studies of the stress-strain state of reinforced concrete and fiber-reinforced concrete beams under short-term and long-term loads were carried out. The tests were carried out on three series of beams of different types - from ordinary concrete, steel fiber concrete and combined section, when the lower zone of the beam with a height of0.5his made of steel fiber concrete, and the upper one is made of ordinary concrete. During short-term loading, the load was applied in steps with a 10-minute exposure at each step to failure or to a predetermined level of a continuously acting load. In the interval between the steps, the process of cracking was tracked. After reaching a given level of loading, the load was fixed and maintained unchanged with a spring cassette for 300 days. Deformations were measured using strain gauges and dial gauges. Deflections and relative deformations of the extreme upper and extreme lower fibers for three types of beams are determined. It has been established that stabilization of deflections in beams from steel fiber concrete occurs much earlier (100 days) than in beams made of ordinary concrete (175 days). Studies have shown that the beams of ordinary concrete in the process of long-acting load lowered the carrying capacity by 5.5%. The bearing capacity of steel concrete beams, in contrast, increased by 7.6%.

EXPERIMENTAL STUDIES OF REINFORCED CONCRETE STRUCTURES WITH CROSS-SHAPED SPATIAL CRACK UNDER TORSION WITH BENDING

2020 ◽  
Vol 92 (6) ◽  
pp. 13-25
Author(s):  
Vl.I. KOLCHUNOV ◽  
◽  
A.I. DEMYANOV ◽  
M.M. MIHAILOV ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Experimental Determination ◽  
Calculation Method ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Design Parameters ◽  
Reinforced Concrete Structures ◽  
Experimental Scheme

The article offers a method and program for experimental studies of reinforced concrete structures with cross-shaped spatial crack under torsion with bending, the main purpose of which is to check the design assumptions and experimental determination of the design parameters of the proposed calculation method. The conducted experimental studies provide an opportunity to test the proposed calculation apparatus and clarify the regularities for determining deflections, angles of rotation of extreme sections, and stresses in the compressed zone of concrete. For analysis, the article presents a typical experimental scheme for the formation and development of cracks in the form of a sweep, as well as characteristic graphs of the dependence of the angles of rotation of end sections.

scholarly journals EXPERIMENTAL STUDIES OF REINFORCED CONCRETE BEAMS STRENGTHENED WITH STEEL FIBER JACKET

2020 ◽  
pp. 34-45
Author(s):  
O. Radaikin ◽  
L. Sharafutdinov
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Concrete Beams ◽  
Experimental Studies ◽  
Breaking Load ◽  
Fiber Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Steel Fiber Reinforced Concrete ◽  
Joint Work ◽  
Loaded Crack

The purpose of the study is to experimentally study the joint work of steel fiber reinforced concrete (SFB) reinforcement jacket and reinforced concrete beams at all stages of loading to further develop a methodology for calculating this method of reinforcing bending elements. The main results of the study consist in assessing the strength, stiffness, fracture toughness, as well as the nature of fracture with a picture of the development of cracks for the examined 4 samples (two with a jacket of reinforcement, two - control - without reinforcement). It has been established that the use of SFB jacket with a thickness of 45 mm and with a fiber content percentage of 2,5% (at a flow rate of 196 kg/m3) increases the breaking load by 20 %, stiffness from 3,4 to 11 times as it is loaded, crack resistance 2,4-2,8 times. The results are compared with computer modeling in ANSYS PC: the discrepancy in the load of crack formation, fracture and deflection values for full-scale samples and a computer model are within 6,3 %, which indicates the reliability of the numerical results and the possibility of using the proposed computer models in further studies on topic of the article.

scholarly journals Study on Damage Characteristics of Fiber Concrete under Acid Rain Erosion

2020 ◽  
Vol 198 ◽  
pp. 01010
Author(s):  
Duo Wu
Keyword(s):  
Reinforced Concrete ◽  
Acid Rain ◽  
Great Influence ◽  
Basalt Fiber ◽  
Corrosion Damage ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Damage Characteristics ◽  
Fiber Concrete ◽  
Rain Erosion

Concrete structure will be corroded under acid rain scouring and soaking for a long time, which has a great influence on its durability life. In order to further study the damage characteristics of fiber reinforced concrete under acid rain erosion, the formation mechanism of acid rain and its influence on the corrosion and deterioration of concrete and fiber materials were analyzed in this paper. Taking basalt fiber concrete as an example, the characteristics such as porosity, compressive strength and mechanical indexes were studied and analyzed. Moreover, the reasons for the optimal fiber content was briefly analyzed. The results show that the inner structure of basalt concrete mixed with 0.1% fiber was the most stable and the corrosion resistance was the most satisfying.This conclusion has certain reference significance for the corrosion damage research of fiber reinforced concrete.

scholarly journals Normal Sections Calculation of Bending Reinforced Concrete and Fiber Concrete Elements

2018 ◽  
Vol 7 (3.2) ◽  
pp. 176
Author(s):  
Dmytro Kochkarev ◽  
Tatyana Galinska ◽  
Oleksandr Tkachuk
Keyword(s):  
Reinforced Concrete ◽  
Rectangular Cross Section ◽  
Nonlinear Function ◽  
Fiber Reinforced Concrete ◽  
Deformation Model ◽  
Fiber Reinforced ◽  
Deformation Diagram ◽  
First Case ◽  
Fiber Concrete ◽  
Concrete Elements

The basic principles of the normal sections calculation of reinforced concrete and fiber reinforced concrete bending elements are considered. In the article the power and deformation methods of calculation of reinforced concrete and fiber concrete elements of rectangular cross-section are presented. The deformation model of the calculation of reinforced concrete and fiber concrete elements is presented in the framework of the method of calculation resistance of the section. This method makes possible from the common methodological positions to perform calculations of reinforced concrete and fiber concrete elements. Namely, to select reinforcement and to determine the carring capacity. The proposed deformation model for calculating fiber concrete elements is based on generally accepted preconditions. A hypothesis of plane cross sections is accepted as fair. The deformation diagram of compressed concrete is described by a nonlinear function with established parametric points. Distribution of stresses in stretched concrete is taken rectangular with corresponding coefficients which are taken depending on the type of deformation diagram. Determination of the carring capacity of fiber concrete elements occurs under extreme deformation criteria. Two cases of destruction of the investigated elements are considered. The first case is the destruction due to the achievement of limiting deformations in the concrete of the compressed zone with the simultaneous achievement of the fluidity limit in the working reinforcement. The second case is the destruction due to the achievement of limiting deformations in the concrete of the compressed zone without reaching the fluidity limit in the working reinforcement. Both cases of calculation are reduced to one functional dependence. This avoids the delimitation of different calculation cases. The main no dimensional modifier is the mechanical coefficient of reinforcement. According to the developed method, examples of calculations of reinforced concrete, fiber reinforced concrete elements and fiber concrete elements with longitudinal reinforcement are executed. The possibility of a spread variant design of reinforced concrete and fiber concrete elements is shown. 

Mechanical Properties of Polypropylene Fiber Concrete after High Temperature

2014 ◽  
Vol 662 ◽  
pp. 24-28 ◽  
Author(s):  
Xi Du ◽  
You Liang Chen ◽  
Yu Chen Li ◽  
Da Xiang Nie ◽  
Ji Huang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Polypropylene Fiber ◽  
Plain Concrete ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Fiber Concrete ◽  
Compressive Strength Of Concrete ◽  
Polypropylene Fiber Reinforced Concrete

With cooling tests on polypropylene fiber reinforced concrete and plain concrete that were initially subjected to different heating temperatures, the change of mechanical properties including mass loss, uniaxial compressive strength and microstructure were analyzed. The results show that the compressive strength of concrete tend to decrease with an increase in temperature. After experiencing high temperatures, the internal fibers of the polypropylene fiber reinforced concrete melted and left a large number of voids in it, thereby deteriorating the mechanical properties of concrete.

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