Evaluating Mechanical Properties of Macro-Synthetic Fiber-Reinforced Concrete with Various Types and Contents
Concrete, as one of the most widely used construction materials, has a brittle behavior. Adding fibers with different types and contents would affect the ductility behavior and mechanical properties of concrete. Hence, an experimental study was conducted to investigate effects of type and content of...
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Інститут проблем міцності ім. Г.С. Писаренко НАН України
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irk-123456789-1737212020-12-19T01:25:49Z Evaluating Mechanical Properties of Macro-Synthetic Fiber-Reinforced Concrete with Various Types and Contents Daneshfar, M. Hassani, A. Aliha, M.R.M. Berto, F. Научно-технический раздел Concrete, as one of the most widely used construction materials, has a brittle behavior. Adding fibers with different types and contents would affect the ductility behavior and mechanical properties of concrete. Hence, an experimental study was conducted to investigate effects of type and content of polymer fibers on mechanical properties of fiber-reinforced concrete such as flexural strength, compressive strength, indirect tensile strength, and elastic modulus. In the present research, the concrete samples were made and, then, evaluated, using three different types of polymer fibers, including twisted, barchip, and fibrillated, with the contents of 0.2, 0.4, and 0.6 volume percentages, respectively. The results showed that by adding fibers to the concrete samples, the flexural and tensile strength was increased by 19.6–81.69% and 0.84–34.29%, respectively; besides, the addition of the fibers to concrete reduced the compressive strength and elasticity modulus by 4.57–26.32% and 12.48–37.08%, respectively. The concrete containing twisted and barchip fibers, despite the different types of fibers, had similar flexural performance. Бетон как один из наиболее широко используемых строительных материалов характеризуется хрупкими свойствами. Добавление в бетон волокон различного типа и содержимого влияет на податливость и механические характеристики бетона. Проведено экспериментальное исследование для оценки влияния типа и содержимого полимерных волокон на механические свойства армированного волокнами бетона (прочность при изгибе, прочность при сжатии, косвенный предел прочности при растяжении, модуль упругости). Образцы из бетона были выполнены с применением трех различных типов полимерного волокна (скрученное, щепкообразные прутки, фибриллированное) с содержанием 0.2, 0.4 и 0.6 об.% соответственно. Установлено, что, добавление волокна в образцы из бетона повышает пределы прочности на изгиб и растяжение на 19.6–81.69% и 0.84–34.29% соответственно и понижает предел прочности при сжатии и модуль упругости на 4.57–26.32% и 12.48–37.08% соответственно. Бетон, содержащий скрученные волокна и волокна в виде щепкообразных прутков, несмотря на различные типы волокон, имеет одинаковые изгибные характеристики. Бетон як один із будівельних матеріалів, що найбільш широко використовується, має крихкі властивості. Добавляння в бетон різного типу і вмісту волокон впливає на його піддатливість і механічні характеристики. Експериментально досліджено вплив типу і вмісту полімерних волокон на механічні характеристики армованого волокнами бетону (міцність при згині і при стиску, умовна границя міцності при розтязі, модуль пружності). Зразки з бетону виготовляли з добавлянням трьох типів полімерного волокна (скручене 0,2 об.%, тріскоподібні прутики 0,4 об.%, фібрильоване 0,6 об.%). Установлено, що добавляння волокна в зразки з бетону підвищує границі міцності при згині і розтязі на 19,6...81,69% та 0,84...34,29% відповідно і знижує границю міцності при стиску і модуль пружності на 4,57...26,32% і 12,48...37,08% відповідно. Назважаючи на різні типи волокон (скручене, тріскоподібні прутики), бетон має однакові характеристики при згині. 2017 Article Evaluating Mechanical Properties of Macro-Synthetic Fiber-Reinforced Concrete with Various Types and Contents / M. Daneshfar, A. Hassani, M.R.M. Aliha, F. Berto // Проблемы прочности. — 2017. — № 5. — С. 11-22. — Бібліогр.: 27 назв. — англ. 0556-171X http://dspace.nbuv.gov.ua/handle/123456789/173721 539.4 en Проблемы прочности Інститут проблем міцності ім. Г.С. Писаренко НАН України |
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Научно-технический раздел Научно-технический раздел Daneshfar, M. Hassani, A. Aliha, M.R.M. Berto, F. Evaluating Mechanical Properties of Macro-Synthetic Fiber-Reinforced Concrete with Various Types and Contents Проблемы прочности |
| description |
Concrete, as one of the most widely used construction materials, has a brittle behavior. Adding fibers with different types and contents would affect the ductility behavior and mechanical properties of concrete. Hence, an experimental study was conducted to investigate effects of type and content of polymer fibers on mechanical properties of fiber-reinforced concrete such as flexural strength, compressive strength, indirect tensile strength, and elastic modulus. In the present research, the concrete samples were made and, then, evaluated, using three different types of polymer fibers, including twisted, barchip, and fibrillated, with the contents of 0.2, 0.4, and 0.6 volume percentages, respectively. The results showed that by adding fibers to the concrete samples, the flexural and tensile strength was increased by 19.6–81.69% and 0.84–34.29%, respectively; besides, the addition of the fibers to concrete reduced the compressive strength and elasticity modulus by 4.57–26.32% and 12.48–37.08%, respectively. The concrete containing twisted and barchip fibers, despite the different types of fibers, had similar flexural performance. |
| format |
Article |
| author |
Daneshfar, M. Hassani, A. Aliha, M.R.M. Berto, F. |
| author_facet |
Daneshfar, M. Hassani, A. Aliha, M.R.M. Berto, F. |
| author_sort |
Daneshfar, M. |
| title |
Evaluating Mechanical Properties of Macro-Synthetic Fiber-Reinforced Concrete with Various Types and Contents |
| title_short |
Evaluating Mechanical Properties of Macro-Synthetic Fiber-Reinforced Concrete with Various Types and Contents |
| title_full |
Evaluating Mechanical Properties of Macro-Synthetic Fiber-Reinforced Concrete with Various Types and Contents |
| title_fullStr |
Evaluating Mechanical Properties of Macro-Synthetic Fiber-Reinforced Concrete with Various Types and Contents |
| title_full_unstemmed |
Evaluating Mechanical Properties of Macro-Synthetic Fiber-Reinforced Concrete with Various Types and Contents |
| title_sort |
evaluating mechanical properties of macro-synthetic fiber-reinforced concrete with various types and contents |
| publisher |
Інститут проблем міцності ім. Г.С. Писаренко НАН України |
| publishDate |
2017 |
| topic_facet |
Научно-технический раздел |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/173721 |
| citation_txt |
Evaluating Mechanical Properties of Macro-Synthetic Fiber-Reinforced Concrete with Various Types and Contents / M. Daneshfar, A. Hassani, M.R.M. Aliha, F. Berto // Проблемы прочности. — 2017. — № 5. — С. 11-22. — Бібліогр.: 27 назв. — англ. |
| series |
Проблемы прочности |
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AT daneshfarm evaluatingmechanicalpropertiesofmacrosyntheticfiberreinforcedconcretewithvarioustypesandcontents AT hassania evaluatingmechanicalpropertiesofmacrosyntheticfiberreinforcedconcretewithvarioustypesandcontents AT alihamrm evaluatingmechanicalpropertiesofmacrosyntheticfiberreinforcedconcretewithvarioustypesandcontents AT bertof evaluatingmechanicalpropertiesofmacrosyntheticfiberreinforcedconcretewithvarioustypesandcontents |
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2025-07-15T10:27:50Z |
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2025-07-15T10:27:50Z |
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1837708368617144320 |
| fulltext |
UDC 539.4
Evaluating Mechanical Properties of Macro-Synthetic Fiber-Reinforced
Concrete with Various Types and Contents
M. Daneshfar,
a
A. Hassani,
a,1
M. R. M. Aliha,
b
and F. Berto
c
a School of Civil and Environmental Engineering, Tarbiat Modares University, Tehran, Iran
b Welding and Joining Research Center, School of Industrial Engineering, Iran University of Science
and Technology (IUST), Tehran, Iran
c Department of Mechanical and Industrial Engineering, Norwegian University of Science and
Technology (NTNU), Trondheim, Norway
1 hassani@modares.ac.ir
ÓÄÊ 539.4
Îöåíêà ìåõàíè÷åñêèõ ñâîéñòâ áåòîíà, àðìèðîâàííîãî ìàêðîñèíòåòè÷åñ-
êèìè âîëîêíàìè ðàçëè÷íîãî òèïà è ñîäåðæèìîãî
Ì. Äàíåøôàð
à
, À. Õàññàíè
à
, Ì. Ð. Ì. Àëèõà
á
, Ô. Áåðòî
â
à Ôàêóëüòåò ãðàæäàíñêîãî ñòðîèòåëüñòâà è èíæåíåðíîé çàùèòû îêðóæàþùåé ñðåäû, Óíèâåð-
ñèòåò Òàðáèàò Ìîäàðåñ, Òåãåðàí, Èðàí
á Èññëåäîâàòåëüñêèé öåíòð ïî ñâàðêå è ìîíòàæó, Ôàêóëüòåò ïðîìûøëåííîãî èíæèíèðèíãà,
Íàó÷íî-òåõíîëîãè÷åñêèé óíèâåðñèòåò Èðàíà, Òåãåðàí, Èðàí
â Ìåõàíèêî-ìàøèíîñòðîèòåëüíûé ôàêóëüòåò, Íîðâåæñêèé óíèâåðñèòåò åñòåñòâåííûõ è òåõíè-
÷åñêèõ íàóê, Òðîíõåéì, Íîðâåãèÿ
Áåòîí êàê îäèí èç íàèáîëåå øèðîêî èñïîëüçóåìûõ ñòðîèòåëüíûõ ìàòåðèàëîâ õàðàêòåðè-
çóåòñÿ õðóïêèìè ñâîéñòâàìè. Äîáàâëåíèå â áåòîí âîëîêîí ðàçëè÷íîãî òèïà è ñîäåðæèìîãî
âëèÿåò íà ïîäàòëèâîñòü è ìåõàíè÷åñêèå õàðàêòåðèñòèêè áåòîíà. Ïðîâåäåíî ýêñïåðèìåí-
òàëüíîå èññëåäîâàíèå äëÿ îöåíêè âëèÿíèÿ òèïà è ñîäåðæèìîãî ïîëèìåðíûõ âîëîêîí íà ìåõà-
íè÷åñêèå ñâîéñòâà àðìèðîâàííîãî âîëîêíàìè áåòîíà (ïðî÷íîñòü ïðè èçãèáå, ïðî÷íîñòü ïðè
ñæàòèè, êîñâåííûé ïðåäåë ïðî÷íîñòè ïðè ðàñòÿæåíèè, ìîäóëü óïðóãîñòè). Îáðàçöû èç
áåòîíà áûëè âûïîëíåíû ñ ïðèìåíåíèåì òðåõ ðàçëè÷íûõ òèïîâ ïîëèìåðíîãî âîëîêíà (ñêðó-
÷åííîå, ùåïêîîáðàçíûå ïðóòêè, ôèáðèëëèðîâàííîå) ñ ñîäåðæàíèåì 0.2, 0.4 è 0.6 îá.% ñîîò-
âåòñòâåííî. Óñòàíîâëåíî, ÷òî, äîáàâëåíèå âîëîêíà â îáðàçöû èç áåòîíà ïîâûøàåò ïðåäåëû
ïðî÷íîñòè íà èçãèá è ðàñòÿæåíèå íà 19.6–81.69% è 0.84–34.29% ñîîòâåòñòâåííî è ïîíè-
æàåò ïðåäåë ïðî÷íîñòè ïðè ñæàòèè è ìîäóëü óïðóãîñòè íà 4.57–26.32% è 12.48–37.08%
ñîîòâåòñòâåííî. Áåòîí, ñîäåðæàùèé ñêðó÷åííûå âîëîêíà è âîëîêíà â âèäå ùåïêîîáðàçíûõ
ïðóòêîâ, íåñìîòðÿ íà ðàçëè÷íûå òèïû âîëîêîí, èìååò îäèíàêîâûå èçãèáíûå õàðàêòåðèñ-
òèêè.
Êëþ÷åâûå ñëîâà: àðìèðîâàííûé âîëîêíàìè áåòîí, ïðî÷íîñòü ïðè ñæàòèè, ìîäóëü
óïðóãîñòè, ïðî÷íîñòü ïðè èçãèáå.
Introduction. Fiber-reinforced concrete is a type of concrete that is mixed with fibers.
Various types of fibers are used to produce fiber-reinforced concrete, which include glass,
polymer, carbon, and steel [1].
In the present research, macro-synthetic polymer fibers were used. Some of the
consequences of applying macro-synthetic fibers in concrete include reduced shrinkage of
fresh and hardened concrete, increased ductility, vulnerability and hardness of concrete,
© M. DANESHFAR, A. HASSANI, M. R. M. ALIHA, F. BERTO, 2017
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 5 11
increased strength against fatigue stresses, increased durability and lifetime of concrete,
improved concrete mechanical properties (tensile strength, flexural strength, etc.), control
of secondary/thermal cracks of concrete, preventing the in-depth propagation of cracks,
post-cracking chargeability and reduced permeability against chloride and sulfate ions [2].
To date, numerous studies have been conducted on fiber-reinforced concrete, most of which
have been focused on the evaluation of fiber-reinforced concrete using steel and plastic
fibers or their combination. Banthia and Yoo [3] conducted a study on the mechanical
properties of high-performance fiber-reinforced concrete and reported that the use of
various types of steel fibers could improve concrete’s mechanical properties. Further,
adding macro-steel fibers to the conventional concrete improved the tensile strength, strain
capacity and flexural strength compared to the micro-steel fibers. Alberti et al. [4] studied
self-compacting fiber-reinforced concrete by combining polyolefin and steel fibers, and
reported that the combination of polyolefin and steel fibers had higher performance in
terms of rupture toughness and flexure than use of a single type of fiber. Vibhuti et al. [5]
performed an experimental study on the mechanical properties of fiber-reinforced concrete
for pavement and evaluated the effect of adding single and hybrid fibers to concrete.
Accordingly, they reported that the hybrid fibers led to improved compressive strength, as
compared to single fibers, while hybrid fibers also significantly improved the flexural
strength. Eswari [6] conducted an experiment on the flexural performance of the hybrid
fiber-reinforced concrete and evaluated the effect of different contents of polymer and steel
fibers on the flexural strength and performance of the fiber-reinforced concrete specimens.
Thus, he reported that adding fibers could improve them in the evaluated parameters
compared to the conventional concrete. Singh et al. [7] studied the flexural strength and
toughness of fiber-reinforced concrete with different percentages of polypropylene, steel
fibers and total percentage of 1%, and reported that combining 75% of the steel fibers and
25% of polypropylene fibers yielded better results in terms of compressive strength,
flexural strength and flexural toughness. Vairagade and Deshpande [8] carried out a
research on the tensile and compressive behaviors of the fibrillated polypropylene fiber-
reinforced concrete specimens, the results of which indicated the increased 7- and 28-day
compressive and tensile strengths. Dawood and Ramli [9] studied the effect of fibers on
properties of high-strength concrete and showed that adding the steel fiber with content of
1% could improve the compressive strength by 10%. Rizzuti and Bencardino [10]
investigated effect of the fiber content on compressive and flexural strength and reported
that addition of the fibers had no explicit effect on the compressive strength. Lee et al. [11]
carried out a research on the compressive behavior of the steel fiber-reinforced concrete
and showed that addition of the fibers had no significant effect on the compressive strength
and elastic modulus. Sukumar and John [12] studied the effect of adding the steel, glass,
and polypropylene fibers on concrete strength. They reported that the flexural,
compressive, and indirect tensile strength was increased by adding the fibers. Patil and
Kulkarni [13] investigated and compared the effects of the steel and glass fibers on flexural
and compressive strength. They reported that in a certain range of fiber content, the
compressive and flexural strength would be increased. Pawade et al. [14] investigated the
steel fiber performance on the elastic modulus and compressive strength and reported that
increasing the fiber content would lead to an increase in the compressive strength and
elastic modulus by 17 and 8%, respectively. Richardson [15] studied the effect of adding
the polypropylene fibers on compressive strength and reported that addition of the fibers
would result in the reduced compressive strength. Mohite and Shinde [16] experimentally
assessed the effect of steel fibers and showed that addition of the fibers would lead to a
slight increase (15%) in the compressive strength. Gowri and AngelineMary [17]
investigated the effect of the glass fibers on mechanical properties of concrete and showed
that the compressive and tensile strength would be slightly increased. Alsadey and Salem
[18] conducted a study on the effect of the polypropylene fibers on concrete strength and
M. Daneshfar, A. Hassani, M. R. M. Aliha, and F. Berto
12 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 5
reported that addition of the fibers would increase the concrete’s compressive strength by
12%. Prathap and Siva Reddy [19] conducted an experiment on the elastic modulus by
changing the steel fiber content in fiber-reinforced concrete and reported that by increasing
the fiber content, the elastic modulus would be increased. Widodo et al. [20] investigated
the effect of adding the compound (polypropylene and steel) fibers on mechanical
properties of concrete and reported that adding the compound fibers would lead to the
increase in compressive strength, elastic modulus, tensile strength, and modulus of rupture
by 22, 24, 222, and 187%, respectively.
Regarding the studies on this field and the difference in the obtained results, in the
present study, the researchers evaluated the effect of content and type of the macro-
synthetic fiber on mechanical properties of the fiber-reinforced concrete, including flexural
and compressive strength, indirect tensile strength, and elastic modulus, in order to
investigate the effect of adding fibers on the compressive strength and elastic modulus. The
given parameters in the present study, including flexural strength (ASTM C78),
compressive strength (BS 1881-116), elastic modulus (ASTM C 469), and indirect tensile
strength (ASTM C496-71), were measured. The fibers were added to the concrete mixture
in three twisted, barchip, and fibrillated forms with the volume fractions of 0.2, 0.4, and
0.6%, respectively. For each of the given parameters, three specimens were constructed and
the averaging results were inserted in the relevant tables.
1. Laboratory Program.
1.1. Test Variables. To evaluate flexural strength, compressive strength, indirect
tensile strength, and elastic modulus, the concrete mixture was designed based on ACI
211.1 standard [21]. In order to investigate effect of the fibers, all the concrete specimens
were made with the same mix design in three different types, including twisted, barchip,
and fibrillated, and with three volume fractions of 0.2, 0.4, and 0.6%. Different types of
fibers are shown in Fig. 1, and also the concrete mix design is represented in Table 1.
Table 2 represents the geometrical and physical properties of the fiber used in the research
[22]. Table 3 shows the geometrical properties of the concrete beam specimens.
Evaluating Mechanical Properties of Macro-Synthetic Fiber-Reinforced Concrete ...
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 5 13
a b
c
Fig. 1. Twisted (a), fibrillated (b), and barchip (c) fibers.
1.2. Specimen Structure. Using fiber-reinforced concrete, the beam and cubic
specimens were constructed to evaluate the flexural and compressive strengths, respectively.
Moreover, the indirect tensile strength and elastic modulus were evaluated by a cylindrical
specimen. The fibers used in this study were of three types, namely: in fibrillated, twisted,
and barchip, with 0.2, 0.4, and 0.6 vol.%. Firstly, cement was mixed with sand and fibers
and, then, the water mixed with super plasticizer was added to the mixture, in order for the
14 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 5
T a b l e 1
Research Mix Design
Materials Coarse
aggregate
Fine
aggregate
Cement Water Super
plasticizer
Fiber
Weight per
unit volume
(kg/m3)
880 789 442 199 2.2 1.8 3.6 5.4
T a b l e 2
Geometrical and Physical Properties of Fibers
Material Shape Resistance
to acidic
and alkaline
environments
Water
absorption
Melting
point
(�C)
Flash
point
(�C)
Polyolefin Macro/single strand
of fine string sticking
together
Excellent – 120 590
Elastic
modulus
(GPa)
Tensile
strength
(MPa)
Diameter
(mm)
Length
(mm)
Density
(g/cm3)
Color
4.2 570–660 0.3 38 0.91–0.96 gray
T a b l e 3
Nominating Specimens
Name of specimens Shape of fiber Fiber volume fraction (vol.%)
B2 Barchip 0.2
B4 Barchip 0.4
B6 Barchip 0.6
F2 Fibrillate 0.2
F4 Fibrillate 0.4
F6 Fibrillate 0.6
T2 Twisted 0.2
T4 Twisted 0.4
T6 Twisted 0.6
N – 0
M. Daneshfar, A. Hassani, M. R. M. Aliha, and F. Berto
fibers to be uniformly distributed within the mixture. Afterwards, the fiber-reinforced
concrete mixture was poured into the prepared molds.
1.3. Laboratory Settings and Measurements.
1.3.1. Flexural Strength. In accordance with ASTM C78 Standard [23], the four-point
loading and beam dimensions were selected as 350 100 100� � mm. The distance between
the two upper and the two lower supports was set as 100 and 300 mm, respectively. The
vertical load was applied at the loading rate of 0.5 mm/min.
1.3.2. Compressive Strength. Compressive strength is an important parameter to
determine the material’s performance during its service life. According to BS 1881-116
Standard [24], compressive loading and cubic specimens with the dimensions of
100 100 100� � mm were selected.
1.3.3. Elastic Modulus. Elastic modulus of the concrete specimens is obtained
according to ASTM C 469 Standard [25]. The test specimens were cylindrical with the
dimensions of 150 300� mm. Figure 2 shows the specimen and device used to measure the
elastic modulus.
1.3.4. Indirect Tensile Strength. Indirect tensile (bisection or Brazilian) test was
performed in accordance with ASTM C496-71 Standard [26] using cylindrical specimens
with the dimensions of 150 300� mm. The compressive load was applied at the rate of
0.011 to 0.023 MPa and the maximum rupture force was measured. Figure 3 depicts the
device setting for measuring the specimen indirect tensile strength.
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 5 15
Fig. 2. Setting the device and measuring elastic modulus.
Fig. 3. Setting of the device and measuring the indirect tensile strength.
Evaluating Mechanical Properties of Macro-Synthetic Fiber-Reinforced Concrete ...
2. Experimental Results and Discussion.
2.1. Flexural Strength. In order to obtain the flexural strength of the fiber-reinforced
concrete specimens, the specimens were made in accordance with the ASTM C78 Standard
and underwent the four-point flexural loading. The load–displacement curve of the span
was derived and the maximum flexural strength was assessed via the maximum flexural
force through Eq. (1),
R
PL
bd
�
2
. (1)
Table 4 and Fig. 4 present the flexural strength results for various fiber-reinforced
concrete specimens.
2.2. Compressive Strength. The compressive strength tests were performed in
accordance with the BS 1881-116 Standard, and their results are shown in Table 5 and Fig. 5.
16 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 5
T a b l e 4
Results for Flexural Strength of Concrete Specimens
Specimen P, N R, MPa Percent
increase (%)
N 13,399.76 4.02 0
B2 16,026.67 4.81 19.60
B4 18,377.48 5.51 37.15
B6 18,797.02 5.64 40.28
T2 16,610.00 4.98 23.88
T4 17,906.13 5.37 33.58
T6 20,401.70 6.12 52.23
F2 20,325.36 6.10 51.68
F4 21,974.15 6.59 63.99
F6 24,345.86 7.30 81.69
Fig. 4. Flexural strength versus fiber content.
M. Daneshfar, A. Hassani, M. R. M. Aliha, and F. Berto
2.3. Elastic Modulus. Elastic modulus can be obtained directly from the initial slope
of the stress–strain curve. To obtain the curve, the load is gradually applied at the rate of
2–3 MPa per second as long as the P-value reaches the value of maximum force. Then, the
load is reduced at the same rate, at which it had been increased. This loading and unloading
process is repeated for three times. After completion of the three loading cycles, the fourth
cycle is applied at the above loading rate up to P0 (approximately corresponding to the
stress value of 5 MPa). The load is maintained for thirty seconds; meanwhile, the
displacement of �b from displacement sensors is measured. Then, the load is increased to
P-value, which is approximately 0.4 of the maximum value, and kept for thirty seconds.
Similarly, �a is read from the displacement sensors and, after calculating the read mean
difference (� �a b� ), the results are recorded as �4. Afterwards, the loading is reduced to
P0 and, then, the 5th loading cycle is applied similar to the initial load. The fifth loading
cycle is also performed through the above method. The corresponding displacement is
recorded, as well as the mean value (�5) obtained via the displacement variations obtained
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 5 17
T a b l e 5
Results on the Compressive Strength of Cubic Concrete Specimens
Specimen Compressive strength
(MPa)
Percent change
(%)
N 67.52 0
B2 62.50 �7.43
B4 64.43 �4.57
B6 63.10 �6.55
T2 63.40 �6.10
T4 64.40 �4.62
T6 63.20 �6.40
F2 53.70 �20.47
F4 56.85 �15.80
F6 49.75 �26.32
Fig. 5. Diagram of compressive strength of cubic specimens versus fiber content.
Evaluating Mechanical Properties of Macro-Synthetic Fiber-Reinforced Concrete ...
from the sensor. The specimen loading is shown in Fig. 6. The elastic modulus is calculated
using Eq. (2):
E
P P
A
l
n
�
� 0
�
. (2)
Table 6 and Fig. 7 illustrate the elastic moduli of concrete specimens versus the fiber
content variation.
18 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 5
T a b l e 6
Elastic Moduli of Different Concrete Specimens
Specimen Elastic modulus (MPa) Percent change (%)
N 32,798 0
B2 27,341 �16.64
B4 28,504 �13.09
B6 26,784 �18.34
T2 27,941 �14.81
T4 28,704 �12.48
T6 26,635 �18.79
F2 22,411 �31.67
F4 24,704 �24.68
F6 20,635 �37.08
Fig. 6. The loading scheme for measuring the elastic modulus [25].
Fig. 7. Elastic modulus versus fiber content variation.
M. Daneshfar, A. Hassani, M. R. M. Aliha, and F. Berto
2.4. Indirect Tensile Strength. According to procedure described in the ASTM
C496-71 Standard [26] or [27], after recording the maximum rupture force, the indirect
tensile strength is obtained from Eq. (3):
T
P
ld
�
2
�
, (3)
where T , P, l, and d are defined, respectively, as tensile strength (MPa), maximum
applied load indicated by the testing machine (N), length (mm), and diameter (mm).
The obtained strength estimation results are presented in Table 7 and Fig. 8.
Conclusions. In this study, the flexural strength, compressive strength, elastic modulus,
and indirect tensile strength were measured for fiber-reinforced concrete specimens with
the same mix design, three types and three different contents of fibers, and also effect of the
fibers on these parameters was investigated.
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T a b l e 7
Indirect Tensile Strength Assessment Results
Specimen P, N Tensile strength (MPa) Increase (%)
B2 235,825.9 3.34 0.84
B4 245,348.1 3.47 4.92
B6 308,107.6 4.36 31.75
F2 248,021.3 3.51 6.06
F4 273,748.1 3.87 17.06
F6 314,042.4 4.45 34.29
T2 238,074.6 3.37 1.81
T4 243,263.5 3.44 4.02
T6 303,595.0 4.30 29.82
N 233,919.5 3.31 0.03
Fig. 8. Tensile strength versus with fiber content.
Evaluating Mechanical Properties of Macro-Synthetic Fiber-Reinforced Concrete ...
The main results of this study are as follows:
1. The addition of fibers with the volume fraction of 0.2–0.6% to the concrete
mixture:
(i) increased flexural strength of the specimens containing barchip, twisted, and
fibrillated fibers by 19.6–40.28%, 23.88–52.23%, and 51.68–81.69%, respectively;
(ii) reduced the compressive strength of the specimens containing fibrillated, barchip,
and twisted fibers by 15–26%, 4–7%, and 4–6%, respectively;
(iii) reduced the elastic modulus of the specimens containing barchip, twisted, and
fibrillated fibers by 13.09–18.34%, 12.48–18.79%, and 24.68–37.08%, respectively;
(iv) increased the indirect tensile strength of the specimens containing barchip,
twisted, and fibrillated fibers by 0.84–31.75%, 1.81–29.82%, and 6.06–34.29%, respectively.
2. Despite the difference between the barchip and twisted fibers, results of the
parameters obtained for these fibers were close.
3. Since the increased fiber content makes the specimen mixing quite problematic, it is
recommended to use the fiber content in the range of 0.2–0.6 volume percentages.
4. With regard to the obtained results, the use of fibers for structures such as concrete
pavement, in which flex and tension are significantly important, is shown to improve the
flexural and tensile strength, leading to the increased durability, loading capacity, and
structure lifetime. Nevertheless, the addition of fibers would reduce the compressive
strength and elastic modulus, which should be taken into consideration in the structural
design.
Ð å ç þ ì å
Áåòîí ÿê îäèí ³ç áóä³âåëüíèõ ìàòåð³àë³â, ùî íàéá³ëüø øèðîêî âèêîðèñòîâóºòüñÿ, ìàº
êðèõê³ âëàñòèâîñò³. Äîáàâëÿííÿ â áåòîí ð³çíîãî òèïó ³ âì³ñòó âîëîêîí âïëèâຠíà
éîãî ï³ääàòëèâ³ñòü ³ ìåõàí³÷í³ õàðàêòåðèñòèêè. Åêñïåðèìåíòàëüíî äîñë³äæåíî âïëèâ
òèïó ³ âì³ñòó ïîë³ìåðíèõ âîëîêîí íà ìåõàí³÷í³ õàðàêòåðèñòèêè àðìîâàíîãî âîëîê-
íàìè áåòîíó (ì³öí³ñòü ïðè çãèí³ ³ ïðè ñòèñêó, óìîâíà ãðàíèöÿ ì³öíîñò³ ïðè ðîçòÿç³,
ìîäóëü ïðóæíîñò³). Çðàçêè ç áåòîíó âèãîòîâëÿëè ç äîáàâëÿííÿì òðüîõ òèï³â ïîë³-
ìåðíîãî âîëîêíà (ñêðó÷åíå 0,2 îá.%, òð³ñêîïîä³áí³ ïðóòèêè 0,4 îá.%, ô³áðèëüîâàíå
0,6 îá.%). Óñòàíîâëåíî, ùî äîáàâëÿííÿ âîëîêíà â çðàçêè ç áåòîíó ï³äâèùóº ãðàíèö³
ì³öíîñò³ ïðè çãèí³ ³ ðîçòÿç³ íà 19,6...81,69% òà 0,84...34,29% â³äïîâ³äíî ³ çíèæóº
ãðàíèöþ ì³öíîñò³ ïðè ñòèñêó ³ ìîäóëü ïðóæíîñò³ íà 4,57...26,32% ³ 12,48...37,08%
â³äïîâ³äíî. Íàçâàæàþ÷è íà ð³çí³ òèïè âîëîêîí (ñêðó÷åíå, òð³ñêîïîä³áí³ ïðóòèêè),
áåòîí ìຠîäíàêîâ³ õàðàêòåðèñòèêè ïðè çãèí³.
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Received 12. 06. 2017
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