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FIBER-REINFORCED CONCRETE

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International Journal of Civil Engineering and Technology (IJCIET)
Volume 10, Issue 04, April 2019, pp. 1341-1345, Article ID: IJCIET_10_04_139
Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=10&IType=04
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication
Scopus Indexed
FIBER-REINFORCED CONCRETE:
POLYDISPERSE REINFORCEMENT
Daria D. Saidakova
Department of Soil Mechanics and Geotechnical engineering, Institute of Hydraulic
Engineering and Power Plant Construction, National Research Moscow State University of
Civil Engineering, Moscow, Russian Federation,
Aleksandr V. Strelchenko
Department of Soil Mechanics and Geotechnical engineering, Institute of Hydraulic
Engineering and Power Plant Construction, National Research Moscow State University of
Civil Engineering, Moscow, Russian Federation
Yevgenia M. Lazareva
Department of Construction of Thermal and Atomic Power Stations, Institute of Hydraulic
Engineering and Power Plant Construction, National Research Moscow State University of
Civil Engineering, Moscow, Russian Federation.
Dmitry S. Matveev
Institute of Construction and Architecture, National Research Moscow State University of
Civil Engineering, Moscow, Russian Federation
Sergey V. Trofimov
Institute of Construction and Architecture, National Research Moscow State University of
Civil Engineering, Moscow, Russian Federation
Kirill V. Vlasov
Institute of Construction and Architecture, National Research Moscow State University of
Civil Engineering, Moscow, Russian Federation.
Andrey G. Ishnazarov
Institute of Construction and Architecture, National Research Moscow State University of
Civil Engineering, Moscow, Russian Federation,
Vakhtang V. Nikolava
Institute of Construction and Architecture, National Research Moscow State University of
Civil Engineering, Moscow, Russian Federation
\http://www.iaeme.com/IJCIET/index.asp
1341
[email protected]
Daria D. Saidakova, Aleksandr V. Strelchenko, Yevgenia M. Lazareva, Dmitry S. Matveev,
Sergey V. Trofimov, Kirill V. Vlasov, Andrey G. Ishnazarov, Vakhtang V. Nikolava and
Shamil G. Yakubov
Shamil G. Yakubov
Institute of Economics, Management and Information Systems in Construction and Real
Estate, National Research Moscow State University of Civil Engineering, Moscow, Russian
Federation
ABSTRACT
Currently, there is the large development of dispersion-reinforced concrete in the
construction industry. This is due to the fact that with all the advantages of concrete
and reinforced concrete, they also have several disadvantages, the most serious of
which is considered to be low crack resistance, which causes brittle fracture of
structures under load. Such drawbacks can be eliminated by using the fiber-reinforced
concrete - a composite material, which can be described as a cement matrix with
discrete fibers of different sizes throughout the entire volume.
Keywords: concrete, fiber-reinforced concrete, fiber-reinforcement, fibre concrete,
polydispersed reinforcement, reinforcement
Cite this Article: Daria D. Saidakova, Aleksandr V. Strelchenko, Yevgenia M.
Lazareva, Dmitry S. Matveev, Sergey V. Trofimov, Kirill V. Vlasov, Andrey G.
Ishnazarov, Vakhtang V. Nikolava and Shamil G. Yakubov, Fiber-Reinforced
Concrete: Polydisperse Reinforcement. International Journal of Civil Engineering and
Technology, 10(04), 2019, pp. 1341-1345
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=04
1. INTRODUCTION
The first information about Fiber-reinforced concrete appeared at the beginning of the XX
century and is associated with the name of the Russian engineer V.P. Nekrasov [1], who worked
on increasing the resistance of concrete to loads in compressed and stretched layers of a
structure by adding thin iron wires to concrete.
At the first stage of research, such a technique was considered only as an assist to the core
reinforcement, however, the expediency of using disperse concrete reinforcement was already
obvious at the time and was also confirmed by foreign scientists. For example, Harry Porter in
1910 stated that by the applying of wire and nails, the mechanical characteristics of concrete
increase by about 8 times [2, 3]. However, gradually the idea of dispersed reinforcement was
forgotten, and only in the 60s, when the acute need to improve the physical and mechanical
properties of concrete arose, it developed rapidly again. Researchers faced the task of
increasing the tensile strength of concrete and increasing the fracture toughness due to the use
of steel wire fibers and other fibers [4].
2. METHODOLOGY
Today, the range of fibers used is very extensive, and, according to the accepted classification,
they are divided:
- By modulus of elasticity of the fiber on high modulus (steel, carbon, glass, etc.) and low
modulus (polypropylene, viscose, etc.);
- By origin on natural (asbestos, basalt, wool, etc.) and artificial (viscose, polyamide, etc.);
- By the base material on metal (most often steel) and non-metal (synthetic, mineral).
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Fiber-Reinforced Concrete: Polydisperse Reinforcement
Dispersed reinforcement is a loose material in the form of a complex of discrete fibers of
different origin, type and size, which is intended for dispersed reinforcement of concrete, as a
reinforcement and modifier of the composite structure.
By dispersed reinforcement, hardening of concrete with the help of fiber is based on the
hypothesis that the matrix of the composite transfers the applied load to evenly distributed
fibers in it due to tangential forces that act on the interface. In the case when the elastic modulus
of the fiber exceeds the elastic modulus of the concrete matrix, the bulk of the stresses are
perceived by the fibers, and the overall strength of the composite is directly proportional to
their bulk content.
For effective use, the various fibers must meet the following conditions:
• The elastic modulus of the fibers must be higher than the elastic modulus of the composite
matrix;
• Fibers should be chemically resistant and should not break down in the alkaline
environment of concrete;
• The volume of fiber production should ensure the production of products from fiberreinforced concrete;
• The cost of fibers should be minimal, considering the above requirements.
3. ANALYSIS OF FIBER-REINFORCEMENT
The main task in the development of compositions and technology of fiber concretes is the
optimization of geometrical parameters and sizes of fibers, ensuring reliable adhesion of fibers
to the concrete matrix under allowable loads, improving manufacturability, reducing labor and
energy intensity of manufacturing operations for products and structures. Fiber adhesion to
concrete and improving the processability of operations, primarily depends on the ratio of fiber
length to its diameter (l/d), which can vary widely and affect the degree of fiber anchoring in
the concrete matrix, as well as the technological properties of fiber reinforced concrete mixes.
Considering the information above, when using steel fiber, the ratio of its length to diameter
is assumed to be l/d = 80...100, which, to a certain extent, is able to satisfy the formulated
conditions, but all problems cannot be eliminated.
The main problems remain:
• Low degree of saturation of the matrix of the composite with fibers of this type, which
prevents further improvement of the physico-mechanical, deformative and operational
characteristics of dispersed reinforced concrete;
• The high cost and shortage of small-diameter steel fibers produced by cutting low-carbon
wire;
• The need to re-equip the concrete mixing plants of precast concrete enterprises, due to the
insufficient adaptability of wire fiber, which is manifested in caking and lack of flowability.
Steel fiber production is based on cutting low carbon wire, sheet steel or foil; forming melts,
milling slabs and strips and intermittent vibration cutting in the process of turning the
workpiece. Non-metallic fibers are sections of monofilaments, fibrillated membranes and
multifilament yarns, which, among other things, can be made from industrial wastes of the
relevant industries [5].
A radical way to improve the structural capabilities of steel fibers is to increase the lateral
surface of the fiber, which is the use of a fiber with a non-circular cross-section, obtained, for
example, by cutting steel tape. The cross-sectional shape, due to the manufacturing process,
provides a significant rigidity of such a fiber in the longitudinal direction, which greatly
http://www.iaeme.com/IJCIET/index.asp
1343
[email protected]
Daria D. Saidakova, Aleksandr V. Strelchenko, Yevgenia M. Lazareva, Dmitry S. Matveev,
Sergey V. Trofimov, Kirill V. Vlasov, Andrey G. Ishnazarov, Vakhtang V. Nikolava and
Shamil G. Yakubov
facilitates the process of its transportation and dosing, as well as contributes to the uniform
distribution of fibers with an increased content in the concrete mix, which leads to a serious
improvement in strength, deformation and operational fiber-reinforced concrete characteristics.
4. POLYDISPERSE REINFORCEMENT AS IMPROVING METHOD
FOR PROPERTIES AND EFFICIENCY OF FIBER-REINFORCED
CONCRETE
The goal of poly-reinforcement is to create such a material that, while preserving and
multiplying the achieved advantages, would eliminate the disadvantages of the composite that
occur in the mono-reinforcement situation. Thus, the advantages of poly-reinforcement are:
• Obtaining a composite with greater strength than mono reinforcement;
• Targeted regulation of the physicomechanical properties of the composite within wider
limits;
• The possibility of the durability and performance characteristics improving.
According to Golantsev V.A. [6], the principle of polydisperse reinforcement is based on
the fact that the fiber of various geometric parameters used for this ensures the formation of
spatial cells at different levels of the concrete structure. Larger cells are superimposed on
smaller ones, while the sizes of the structural cells of each level depend on the reinforcement
options. Thus, the fibers of small diameters will be in the cramped conditions of larger cells,
and the larger fiber fibers are placed in the matrix of the composite, which has microreinforcement. In this case, microfibers impede the development of microdefects at the
cracking stage, being in the contact zone of larger diameter fibers, and reduce the stress
concentration, thereby contributing to their redistribution to a larger amount of concrete. In this
embodiment, there is an increase in the adhesion strength of fibers of a larger diameter with
the matrix, which ultimately allows increasing the strength of the composite.
However, over the time, after many experimental and theoretical studies, this approach to
the structure formation of fibrous concrete became irrelevant, as it is purely theoretical in nature
and therefore gives a very idealized idea of the structure of fibrous concrete, which is based on
the classical laws of composite materials, but does not take into account the important structureforming role and originality of the concrete matrix, and also practically does not affect the role
of the contact zone at the interface of the "fiber-matrix" phase, the state of which largely
determines the most important characteristics of dispersed reinforced concrete.
Y.V. Pukharenko formulated a new concept [7], which consists the fact that at each
structural level of fiber-reinforced concrete two phases can be distinguished, which interact
with each other across the interface through the contact zone at all stages of structure formation
and subsequent work of the material:
• Dispersed phase, representing a set of segments of fibers of a given size;
• Dispersion medium - a matrix in which significant changes occur in the process of
formation of the structure and properties of the composite.
Thermodynamically, the structure of dispersed reinforced concrete is formed due to the
tendency of the phases to equilibrium by reducing their internal surface energy. At the same
time, as shown by comparative tests of the kinetics of the increasing ductile strength of concrete
with and without fibers, the formation of structural aggregates, a system consisting of a fiber
surrounded by a dense and durable layer of cement neoplasms, is leading. The high energy of
interconnection of particles inside the system allows such aggregates to be considered as
independent elements of the structure that come into contact with the dispersion medium
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Fiber-Reinforced Concrete: Polydisperse Reinforcement
through the interface. At the same time, the interdependent arrangement of these elements can
be maintained only up to a certain critical concentration of reinforcing fibers. By an increase
in the percentage of reinforcement or a geometrical factor, they approach each other with the
final formation of a fiber-cement framework with monolithing at the points of contact and
filling the resulting cells with a matrix material of lower density and strength. The options of
dispersed reinforced concrete are determined by the degree of anisotropy of the fiber-cement
frame, the volume concentration of the phases and the interaction energy, as well as the length
of the internal interfaces, which in turn depends on the type and dispersion of the initial
components, the composition of the dispersion-reinforced concrete and the technology of
manufacturing products.
5. CONCLUSION
Fiber concretes are the most prominent representatives in a series of building composites,
which brings together the best qualities of the original components - reinforcing fibers and
concrete.
Dispersed-reinforcement by the fibers of various nature and sizes helps to improve the
strength, deformative and energy characteristics of concrete. At the same time, reinforcement
of several types of fibers simultaneously is particularly effective, which allows to control the
complex of necessary characteristics in a single composite.
REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
[7]
V. P. Nekrasov, Method of indirect arming of concrete. Moscow: Transpechat, 1925, 255.
H.F. Porter, Preparation of Concrete from selection of materials to final disposition.
Proceedings of the National Association of Cement Users, ACJ, Vol 6, 1910.
I. A. Felts, Fibrous Concrete – background. Regulatory framework, problems and solutions,
ALITinform: Cement. Concrete. Dry mix. 2009, №2, 44-53.
S.P. Shah and V.K. Rangan, Fiber Reinforced Concrete Properties, ACJ, №2. 1971.
U. H. Magdeev, Yu. V. Pukharenko, V. I. Morozov, D. A. Panteleev, M. I. Zhavoronkov,
Study of properties of steel fiber based on amorphous metal fiber, Vestnik VolgGASU, Vol
31(50), 2013, 132-135.
V.A. Golantsev, Properties and features of poly-reinforced fiber-reinforced concrete, Ph.D
diss., Leningrad Institute of Civil Engineering, Leningrad, 1990, 214.
Yu.V. Pukharenko, Scientific and practical bases for the formation of the structure and
properties of fiber-reinforced concrete, doctoral diss., Saint Petersburg State University of
Architecture and Civil Engineering, Saint Petersburg, 2005, 315.
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