M. HUANG et al.: EXPERIMENTAL AND ANALYTICAL STUDY OF A NEW KIND OF STEEL-PV A HYBRID FIBER CONCRETE ...
183–194
EXPERIMENTAL AND ANALYTICAL STUDY OF A NEW KIND
OF STEEL-PV A HYBRID FIBER CONCRETE IN THE
ANCHORAGE ZONE OF A BRIDGE EXPANSION AND
CONTRACTION INSTALLATION
EKSPERIMENTALNA IN ANALITI^NA [TUDIJA NOVE VRSTE
HIBRIDNEGA BETONA IZ JEKLA IN PV A VLAKEN ZA SIDRI[^E
IN[TALACIJE RAZTEZANJA IN KR^ENJA MOSTU
Minshui Huang
1*
, Zihao Wan
1
, Yongzhi Lei
1
, Xin Shi
2
, Guoming Shu
2
1
School of Civil Engineering and Architecture, Wuhan Institute of Technology, 693 Xiongchu Ave., Wuhan 430073, Hubei, China
2
Department of Civil Engineering, Hebei Jiaotong Vocational and Technical College, 219 Pearl River Avenue, Yuhua,
Shijiazhuang 050035, Hebei, China
Prejem rokopisa – received: 2020-04-02; sprejem za objavo – accepted for publication: 2020-11-13
doi:10.17222/mit.2020.053
In this paper, a new kind of steel-polyvinyl alcohol (PV A) hybrid fiber concrete with high early strength and better road perfor-
mance is proposed for use in the anchorage zone of a bridge expansion and contraction installation (BECI). Firstly, a compre-
hensive test design method is adopted to evaluate the mechanical properties of the concrete by adding different percentages of
fibers, and the optimal percentages of steel and PV A fiber additives are determined. The results of the compressive and flexural
strength test indicated that the concrete with added 1.5 % steel fiber and 0.12 % PV A fiber has a higher early strength. Secondly,
to evaluate the performance of the improved concrete, the finite-element method was adopted to model the anchorage zone con-
crete of the BECI, and the loading location of maximum stress was determined and some factors, such as overload and horizon-
tal force coefficient, were considered. The maximum stresses of the anchorage zone are less than the ultimate stresses of the
steel-PV A hybrid fiber concrete. It can be concluded that the improved concrete has better road performance. Finally, a case
study of the actual bridge was carried out to verify the practical value of the steel-PV A hybrid fiber concrete. Although there is
some reduction in the compressive strength, the new concrete is more suitable than the conventional concrete to meet the re-
quirements for the construction of concrete in the anchorage zone of the BECI, which can reduce the construction period and
show great practical application value.
Keywords: steel-PV A hybrid fiber concrete, bridge expansion and contraction installation, anchorage zone, finite-element
method
V ~lanku avtorji predlagajo uporabo nove vrste hibridnega betona, utrjenega z jeklenimi in polivinil alkoholnimi (PV A) vlakni,
ki ima visoko za~etno trdnost in bolj{e cestne karakteristike glede raztezanja in kr~enja mostnih konstrukcij (BECI) v sidri{~u
oziroma vpetju. Avtorji so najprej uporabili splo{no uporabljeno preizkusno metodo oblikovanja (dizajna) in dolo~ili mehanske
lastnosti betona glede na razli~no vsebnost jeklenih in PV A-vlaken. Rezultati preizkusov za~etne tla~ne in upogibne trdnosti
betona so pokazali, da sta optimalni vsebnosti dodanega jekla 1,5 mas. % in 0,12 mas. % PV A-vlaken. Sledilo je {e ovrednotenje
lastnosti izbolj{anega betona s pomo~jo modela na osnovi metode kon~nih elementov za in{talacijo raztezanja in kr~enja
betonske konstrukcije v coni vpetja. S pomo~jo modela so dolo~ili tudi maksimalne napetosti v tej coni in koeficient
horizontalne sile. Ugotovili so, da so maksimalne sile v sidri{~u manj{e kot je poru{na trdnost hibridnega betona vlakna iz
PV A-jekla. Avtorji na osnovi izbranega primera dejanske mostne konstrukcije tudi ugotavljajo, da ima ta vrsta betona bolj{e
cestne karakteristike. S tem so potrdili njegovo prakti~no vrednost oziroma uporabnost. ^eprav ima novi beton nekoliko manj{o
tla~no trdnost je primernej{i kot konvencionalni beton, za vpetje betonske konstrukcije ter njeno raztezanje in kr~enje, kar tudi
zmanj{a ~as izgradnje in potrjuje njegovo prakti~no oziroma uporabno vrednost.
Klju~ne besede: hibridni beton, oja~an z jeklom in vlakni PV A, in{talacija raztezanja in kr~enja mostne konstrukcije, cona
vpetja, sidri{~e
1 INTRODUCTION
Expansion and contraction installation, a key func-
tional part of bridges, undertakes the repeated load im-
pact of traffic and is always exposed to adverse environ-
mental conditions. These factors have major negative
effects on the lifecycle of a BECI, which means the
bridge will be easy to damage and difficult to repair.
Nowadays, heavy traffic jams and economic impacts are
becoming increasingly serious due to the maintenance of
BECI. But there are few researches on the rapid
replacement technology of BECI. Therefore, it is critical
to repair or replace the damaged BECI in a short time
and overcome the problems caused by construction.
Meanwhile, the durability and suitability of BECI should
be ensured too.
Because the concrete in the anchorage zone has great
effects on the construction period, the early mechanical
properties of the concrete were studied by numerous
scholars. In the early 20
th
century, discarded steel wire
was added into concrete and used as a good additive to
improve the properties of the concrete. J. P. Romualdi
Materiali in tehnologije / Materials and technology 55 (2021) 2, 183–194 183
UDK 625.821.5:625.843:620.1:624.21/.8 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 55(2)183(2021)
*Corresponding author's e-mail:
huangminshui@tsinghua.org.cn (Minshui Huang)

and G. B. Baston
1,2
proposed a theory of fiber spacing,
which is a milestone in the development of steel fiber
concrete; however, the theory is for an ideal situation.
The factors, such as slip between fiber and matrix con-
crete and uneven distribution of fiber, are not considered
in the theory. The ultra-high-performance fiber concrete
is introduced in 1990s to obtain the performance of high
strength and toughness, and cementing material and steel
fiber are both considered as good additives to ordinary
concrete.
3–7
Fiber concrete is a composite material,
which is constituted by mixing fiber with cement and
mortar or matrix concrete. Compared to ordinary con-
crete, it has good performances of compressive strength
and strain hardening. Fiber concrete can be classified
into two types: single fiber and hybrid fiber. For in-
stance, as a single fiber concrete, polyvinyl alcohol
(PV A) fiber concrete has good capability of shear resis-
tance. Its ultimate displacement in shear failure is twice
more than the ordinary concrete, and its ultimate tensile
strain is obviously improved.
8–14
Therefore, the single fi-
ber additive can improve the mechanical properties of
the concrete and durability by inhibiting its early plastic
cracking and the expansion of the crack.
15–17
The type, shape and size of fibers are the key factors
to improve the performance of ultra-high-performance fi-
ber concrete. Different fibers improve the performance
of concrete in various ways.
18–22
For example, steel fiber
is the main reason for strength promotion, and PV A fiber
can improve the deformation capability. The experimen-
tal research of A. W. Dhawale
23
pointed out that PV A
fiber can be used as a reinforcement additive for cement-
ing composite material. V . C. Li
24
adopted PV A-engi-
neered cementitious composites (PV A-ECC) as a rough
layer of concrete to build a composited beam. The me-
chanical test showed that the beam has a higher ultimate
strain and strength than a beam covered by plain con-
crete. J. S. Lawler
25
mixed micro PV A fiber and hook
type steel fiber with mortar to make some specimens,
and the flexural and shear tests proved that the bending,
shearing and penetration resistance are improved. Al-
though the single fiber additive can promote the perfor-
mance of concrete, the comprehensive performance can-
not satisfactorily meet the requirements of complex
practical applications.
In this study, a new type of steel-PV A hybrid fiber
concrete with better characteristics of high early
strength, high ductility is proposed. Firstly, the compre-
hensive experimental method is adopted to evaluate and
analyze the mechanical properties of the concrete speci-
mens by adding different amounts of fibers, and the opti-
mal content of steel and PV A fiber additives is deter-
mined. Furthermore the functional mechanism of the
steel-PV A fiber is discussed. Then, the finite-element
model of the anchorage zone concrete is setup based on
ANSYS, which is exploited to comparatively evaluate
the road performance of the improved concrete. Some in-
fluencing factors, such as the loading location of maxi-
mum stress, the overload and horizontal force coeffi-
cient, are considered. The maximum stresses of the an-
chorage zone are extracted to compare with the ultimate
stresses of the steel-PV A hybrid fiber concrete. More-
over, an engineering example is considered to furtherly
prove the applicability of the new concrete in the mainte-
nance of the BECI.
2 RAW MATERIALS AND EXPERIMENTAL
METHOD
2.1 Raw materials
2.1.1 Cement
As a key technical index that directly affects the
strength value of concrete, cement plays an important
role in the construction of concrete. In this study, the
42.5# general purpose Portland cement (P.O 42.5) is
adopted.
2.1.2 Aggregates
Aggregates can be categorized into two categories:
coarse aggregate and fine aggregate. These function as
the concrete framework construction and pore filling, re-
spectively. It usually accounts for about 80 % of the con-
crete volume. The aggregate used in this investigation is
determined according to the Chinese Standard JGJ 52.
26
For the coarse aggregate, the continuous graded gravel
whose diameter is concentrated at the range 5–20 mm
can improve the workability and avoid segregation. And
for the fine aggregate, the medium sand whose diameter
is concentrated at the range of 5–20 mm is selected, as
shown in Figures 1a to 1b.
2.1.3 Water
Running water is adopted according to Chinese Stan-
dard JGJ 63.
27
2.1.4 Concrete admixture
The condensates of sodium naphthalene sulfonate
and formaldehyde, which can be used as a water reducer,
is of great physical and chemical capacity, such as wa-
ter-soluble, low-foaming and stability. Its percentage of
water reduction is 15 %, and the optimum mix percent-
age is 0.75 %. In this study, a powdered polycondensate
of naphthalene sulfonate formaladehyde water-reducing
agent was used, which is a brown-yellow powder in ap-
pearance. The solid content is greater than 92 %, the PH
value ranges between 7 and 9, the sodium sulfate content
is in the range 16–19 %. When keeping the slump un-
changed, the water reduction rate varied from 12 % to
2 0%( Figure 1c).
2.1.5 Fibers
Polyvinyl alcohol (PV A) fiber and wave-shaped steel
fiber, whose lengths are 6 mm and 20 mm respectively,
are adopted in this study (Figures 1d and 1e). The den-
sity, elongation at break, tensile strength and elastic
modulus of the PV A fiber are 910 kg/m
3
, 17±3.0 MPa,
M. HUANG et al.: EXPERIMENTAL AND ANALYTICAL STUDY OF A NEW KIND OF STEEL-PV A HYBRID FIBER CONCRETE ...
184 Materiali in tehnologije / Materials and technology 55 (2021) 2, 183–194

1400–1600 MPa and 35–39 GPa, respectively, and the
corresponding parameters for the steel fiber are
7800 kg/m
3
, 25 MPa, 1200 MPa and 200 GPa, respec-
tively.
2.2 Test design
2.2.1 Design of mix proportion
1) Determination of the mixing strength
The strength grade design of the concrete in this pa-
per is C50, and the mix proportion design of the concrete
is carried out on this basis. The mixing strength of the
concrete can be calculated as follows:
ff
k cu,0 cu,
≥+ 1645 .  (1)
where f
cu,0
is the mixing strength of the concrete (MPa);
f
cu,k
is the standard cubic compressive strength of the
concrete (MPa); is the standard deviation of the con-
crete strength (MPa).
The strength grade of concrete in this test is C50, so
f
cu,k
= 50 MPa. For the value of , in accordance with the
specification in China, JGJ55
28
, =6M P a ,a n df
cu,0
 59.87 MPa.
2) Water-cement ratio
The water-cement ratio can be calculated as follows:
W
B
f
ff
=
+
+++
 
ac e
ce,0 a b ce
(2)
where W/B is the water-cement ratio; a
and b
are the
regression coefficients, which are 0.53 and 0.20, respec-
tively;
28
is the 28-days compressive strength of the mor-
tar (MPa), when the measured 28 d compressive
strength of the mortar is not available, it can be deter-
mined as follows:
ff
g ce c cu,
=× =×=  116 425 493 ... (3)
Where  c
is the surplus coefficient of the cement
strength grade value, which can be determined according
to the actual statistical data, and it can be selected ac-
cording to JGJ55
28
when actual statistical data is not
available; f
ce,g
is the strength grade value of the cement
(MPa).
According to Equation (2) and Equation (3), the wa-
ter-cement ratio can be obtained as 0.40.
3) The amount of water
The amount of water m
w0
should comply with
JGJ55.
28
According to the concrete slump and the graded
gravel of this test, the amount of water m
w0
is 195 kg/m
3
.
Because the water reduction rate of the high-efficiency
water reducing agent is 15 %, the amount of water is
165.75 kg/m
3
.
4) Amount of cement and water-reducing agent
The amount of cement m
b0
should be calculated ac-
cording to Equation (4):
m
m
WB
b
w
0
0
165 75
04
414375 ===
/
.
.
. kg/m
3
(4)
The amount of cement used is 414.375 kg/m
3
and the
amount of water-reducing agent m
a0
can be calculated as
follows:
mm
a ab 00
=  (5)
M. HUANG et al.: EXPERIMENTAL AND ANALYTICAL STUDY OF A NEW KIND OF STEEL-PV A HYBRID FIBER CONCRETE ...
Materiali in tehnologije / Materials and technology 55 (2021) 2, 183–194 185
Figure 1: Raw materials: a) coarse aggregate, b) fine aggregate, c) water-reducing agent, d) PV A fiber, e) steel fiber

Where a
is the ratio of water-reducing agent (%).
5) The amount of sand and gravel
According to JGJ55,
28
the ratio of sand can be deter-
mined based on the type of gravel, the maximum nomi-
nal size and the water-cement ratio.
The amount of sand and gravel can be obtained as
follows:
 a
m
mm
mmmm
=
+
×
+++=
⎧ ⎨ ⎪ ⎩ ⎪ s
sg
bgsw
0
00
0000
100
2400
%
(6)
where s
is the ratio of sand (%), which is 34 % in the
paper; m
s0
is the amount of sand (kg/m
3
); m
g0
is the
amount of gravel (kg/m
3
).
The grading of the steel-PV A hybrid fiber concrete is
designed according to standard specifications in China,
JGJ 55
28
and CECS 207.
29
The target grade is C50, of
which the actual values of cement, gravel, sand, water
and water-reducing agent in the mix are (414.38, 618.79,
1201.08, 165.75 and 3.108) kg/m
3
, respectively.
2.2.2 Design and curing of the specimens
To obtain the mechanical behavior of the steel-PV A
hybrid fiber concrete, some concrete samples were made
in the laboratory. The production process of the test
specimens, such as the order of feeding, the stirring
method, and stirring time, can have direct or indirect ef-
fects on the overall performance of the concrete. To
avoid the uneven distribution of the fibers in the tests, a
dry-blending method is used to prepare the hybrid fiber
concrete. The dimensions of the samples are
(100×100×100) mm for compressive strength test, and
(100×100×400) mm for flexural strength test. And the
curing periods are 1 d and 3 d, respectively. Six sets of
test specimens with a total content of 2 % and nine sets
with a maximum content of 1.5 % are shown in Table 1.
2.3 Mechanical test
The mechanical property tests are designed according
to Chinese standard, GB/T 50081,
30
whose main proce-
dures of compressive strength test can be summarized as
follows:
1) the test specimens at a specified age are adopted,
their surfaces cleaned and the integrity checked;
2) the selected specimens are placed on the middle of
the pressure plate, meanwhile, the surface which is per-
pendicular to the pouring surface is determined as the
pressure-bearing surface (Figure 2a);
3) turn on the machine, when the upper-pressure
plate of the machine is imminent to touch the specimen,
the pressure plate stops falling and the oil return valve is
closed;
4) the oil delivery valve is opened, the loading rate is
limited to a constant that ranges from 0.5 MPa/s to
0.8 MPa/s;
5) when the failure of the specimen is observed and it
starts to deform dramatically, adjusting the throttle of the
machine is stopped until the specimen is totally broken,
and the value of the failure load is recorded.
The compressive strength of concrete can be calcu-
lated as follows:
f
F
A
k cu,
C
C
=
max
(7)
where f
cu,k
is the compressive strength of the test speci-
men (MPa); F
Cmax
is the ultimate loading in the com-
pressive test (N); and A
C
is the load area of test speci-
men (mm
2
).
The determination of the compressive strength should
be completed with the following provisions. First, the
arithmetic mean value of the measured values of the
three specimens is the strength value of this group of
specimens. Second, if the maximum or minimum value
of the three measured values exceeds 15 % of the median
value. The maximum value and the minimum value
should be discarded, and the median value should be
taken as the compressive strength value of this group of
specimens. Third, if the maximum and the minimum val-
ues both exceed the median value by more than 15 % of
the median value, the test results of this group of speci-
mens are invalid.
When the concrete strength grade is less than C60,
the strength value measured with non-standard speci-
mens should be multiplied by the size conversion factor,
M. HUANG et al.: EXPERIMENTAL AND ANALYTICAL STUDY OF A NEW KIND OF STEEL-PV A HYBRID FIBER CONCRETE ...
186 Materiali in tehnologije / Materials and technology 55 (2021) 2, 183–194
Table 1: Hybrid fiber content (maximum steel content is 1.5 % and total fiber content is 2 %)
Category
Maximum steel fiber content is 1.5 % Total fiber content is 2 %
Specimen No. Steel fiber PV A Specimen No. Steel fiber PV A
No fiber S0P0 0 0 S0P0 0 0
Steel fiber only
S4P0 1 0 S2P0 2 0
S5P0 1.5 0 / / /
PV A fiber only
S0P4 0 0.08 S0P2 0 2
S0P5 0 0.12 / / /
Hybrid fiber
S4P4 1 0.08 S1P1 1 1
S4P5 1 0.12 S3P1 1.5 0.5
S5P4 1.5 0.08 S1P3 0.5 1.5
S5P5 1.5 0.12 / / /

which is 1.05 for (200×200×200) mm specimen and 0.95
for (100×100×100) mm specimen.
Moreover, when the flexural strength test is per-
formed, the tested specimens are first placed in the cen-
ter of the bending anti-bending device, as shown in Fig-
ure 2b, and the smooth surface is used as the bearing
surface. The testing machine is started, which should be
run at a continuous and equable speed of 0.8–1.0 MPa/s,
until the specimen is nearly broken. Record the breaking
load and the fracture position of the lower edge of the
specimen.
The flexural strength can be obtained as follows:
f
Fl
bh
f
=
2
(8)
Where f
f
is the flexural strength of the specimen
(MPa); F is the ultimate loading in the flexural test (N);
l is the span between the supports (mm); h and b are the
height and width, respectively. The compressive and
flexural strength results need to be multiplied by 0.95
and 0.85, respectively, which are the conversion factors
for the non-standard sizes.
The method for determining the flexural strength
value is the same as that for determining the compressive
strength value. Moreover, if one of the three specimens
has a fracture surface beyond the position of the concen-
trated loads, the flexural strength of the concrete is cal-
culated based on the test results of the other two speci-
mens. If the difference of the two measured values is no
more than 15 % of the smaller measured values, the flex-
ural strength is the average of the two measured values.
Otherwise, the test is invalid. If the fracture position of
the lower edge of two specimens locates outside the
loading line, the test is also invalid.
When the concrete strength grade is less than C60,
the strength value of the non-standard specimen should
be multiplied by the size conversion factor, which is 0.85
for (100×100×400) mm specimens.
3 ANALYSIS AND DISCUSSION
3.1 Compressive strength test
After a standard curing for 1 d and 3 d, the concrete
specimens with different fibers were tested to obtain
their compressive strengths, which are shown in Fig-
ure 3.
It can be seen from Figure 3 that with a total fiber
content of 2 %, the compressive strength of the concrete
is the minimum when the contents of the steel fiber and
PV A fiber are 0.5 % and 1.5 %, respectively, and the
compressive strength is the maximum when the content
of steel fiber is 2 % (S2P0). In the condition of the maxi-
mum steel content is no more than 1.5 %, when the con-
tents of steel fiber and PV A fiber are 1.5 % and 0.12 %
(S5P5), the compressive strengths of concrete after a
standard curing of 1 d and 3 d are the maximum, with
values of 10.23 MPa and 31.52 MPa, respectively.
As shown in Figure 3, it is obvious that the fibers
have some improvement on the failure forms of the con-
crete specimens. For the ordinary concrete specimen,
during the process of the compressive strength test, one
or two micro-cracks occurred firstly on the surface, the
initial micro-cracks will expand to other cracks around
them. As the load continuously increases, the width of
cracks will be expanded gradually, and their number will
rapidly increase. This phenomenon remains normal until
the cracks distribute in the specimen from top to bottom
and the specimen will break into pieces in the end. The
failure form of the ordinary concrete specimen is brittle,
which means that a brittle failure has occurred. However,
the crack expansion processes of the steel fiber and
PV A-steel concrete specimens are slow. Although their
ultimate strength cannot be improved, the decline rate
will be slowed down after the fibers areadded. Mean-
while, when the failures of the specimens occur, the fi-
bers try to glue the pieces in a whole cube, which indi-
cates that the specimens have good ductility.
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Materiali in tehnologije / Materials and technology 55 (2021) 2, 183–194 187
Figure 2: Mechanical test: a) compressive strength test, b) flexural strength test

3.2 Flexural strength test
After a standard curing of 1 day and 3 days, the con-
crete specimens with different fiber contents are tested to
obtain their flexural strengths, which are shown in Fig-
ure 4. The appropriate content of PV A and steel fibers
will obviously improve the early flexural strength. When
the contents of the steel fiber and the PV A fiber are
1.5 % and 0.12 % (S5P5), the flexural strength is the
maximum, with the values of 2.08 MPa and 4.48 MPa,
respectively.
As shown in Figure 4, the ordinary concrete speci-
men broken directly into two parts in the flexural
strength test, which is a brittle failure. However, the
specimen with hybrid fibers shows incomplete fracture
form due to gluing the fibers in the fracture surface. The
results indicate that the fibers can promote the ductility
of the concrete specimens.
3.3 Functional mechanism analysis
The results of Section 3.2 indicate that steel fiber,
PV A fiber, and steel-PV A hybrid fibers have some posi-
tive effects on the early compressive and flexural
strengths of the concrete. However, due to the difference
of their additive contents, the performances of only sev-
eral specimens such as S5P0, S4P4, S5P4 and S5P5 for
compressive strength test and S2P0, S5P0, S0P4, S0P5,
S4P4, S5P4 and S5P5 for flexural strength test are im-
proved, and the improvement degree of flexural strength
is 81.3 %, better than that of that of the compressive
strength, which is 30.9 %.
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188 Materiali in tehnologije / Materials and technology 55 (2021) 2, 183–194
Figure 3: Results of compressive test: a) total fiber content is 2 %, b) maximum steel content is no more than 1.5 %, c) failure forms of ordinary
concrete, d) failure forms of steel fiber concrete, e) failure forms of PV A fiber concrete, f) failure forms of steel-PV A hybrid fiber concrete

The main reason for the enhancement mechanism of
hybrid fiber concrete is that the PV A fiber has good com-
patibility with cement, which can form cohesion between
the PV A fiber and the cement. At the same time, the PV A
fiber can absorb the cracking energy, which means it can
inhibit the micro cracks inside the specimen and slow
down the expansion of the initial cracks. This mecha-
nism delays the failure and promotes the overall ductility
of the concrete specimen.
Furthermore, the PV A fiber has good performance of
water absorbing, which can prevent the evaporation of
water. This characteristic, as a key factor, is important in
the period of concrete curing. And the hydration process
of the cement will generate many hydrated products at-
tached to the surface of the PV A fiber, which is com-
bined with the characteristic to further reduce the water
loss. Additionally, steel fiber, as a high-strength material,
is added in the concrete, which can prevent the brittle
failure in the situation of micro and macro cracks, it can
be utilized to promote the overall strength.
4 FINITE-ELEMENT ANALYSIS AND CASE
STUDY
4.1 Finite-element analysis of the concrete in the an-
chorage zone
4.1.1 Load
According to the Chinese standard specification CJJ
11-2011,
31
the maximum axle load of Highway Load-I is
applied to the finite-element model, where G = 140×10
3
N.
And its application areas are four rectangles of 0.2 m ×
0.6 m. The pressure can be obtained as follows:
p
G
A
==
×
××
=
140 10
06 02 2
058
3
..
. MPa (9)
where G and A are the axle load and application area,
respectively.
There are four different loading locations, which are
along the longitudinal direction and considered to study
the strength performance of the anchorage zone concrete
(Figure 5):
1) Location 1: The front edges of the first two wheel
tracks are next to the interface between bridge deck
pavement and anchorage zone concrete;
2) Location 2: The center lines of the first two wheel
tracks coincide with the interface between bridge deck
pavement and anchorage zone concrete;
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Materiali in tehnologije / Materials and technology 55 (2021) 2, 183–194 189
Figure 4: Results of flexural strength test: a) total fiber content is 2 %, b) maximum steel content is no more than 1.5 %. c) failure form of ordi-
nary concrete, d) failure form of steel-PV A hybrid fiber concrete

(3) Location 3: The back edges of the first two wheel
tracks are next to the interface between bridge deck
pavement and anchorage zone concrete;
4) Location 4: The center lines of the first two wheel
tracks coincide with the center lines of anchorage zone.
Moreover, the situations of overweight and emer-
gency braking have been considered as another two im-
portant factors that influence the stress in the area. For
overweight, its range of variations is 21.7 % and 37.9 %
based on the max axle load of Highway Loading Grade I.
Meanwhile, the emergency braking is converted to a hor-
izontal braking force, which is 0 for a motionless vehi-
cle, 0.10 for the motion in a constant speed, 0.25 for the
slow braking and 0.50 for emergency acceleration or
braking.
32
4.1.2 Model parameters
The local finite-element model and its parameters are
shown in Figure 6 and Table 2, where the elastic modu-
lus of the C50 concrete for3di scalculated according to
Equation (10).
33
The Cartesian coordinate is adopted in
the finite-element model, where X-direction is the vehi-
cle driving direction (longitudinal direction), Y-direction
is the depth direction of the pavement and the Z-direction
is the transverse direction of the pavement (transverse di-
rection). And the boundary condition is that the displace-
ment constraints of three directions are applied on the
bottom of the bridge deck.
Et
t
abt
E
a
()
..
=
+⋅
⋅
=+
ee
e
28
12992 8273313
06752 0 00738
0 3611
28
28
⋅
=+
⎧ ⎨ ⎪ ⎪ ⎩ ⎪ ⎪ −
e
bE
E .
..
e
(10)
where E(t) is the elastic modulus of the concrete at t
days (GPa), t is the time (days), E
28
is the elastic modu-
lus of the concrete at 28 d, which is 3.45 GPa according
to the Chinese standard specification GB 50010-2010
34
and a
e
and b
e
are the statistical parameters, respectively.
Table 2: Material parameters of finite-element model
Item Material
Elastic modulus
/MPa
Poisson’s
ratio
Bridge deck
pavement
Asphalt con-
crete
3000 0.35
Bridge slab
Cement con-
crete
30000 0.25
Anchorage
zone concrete
C50 concrete
(3d)
23470 0.20
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190 Materiali in tehnologije / Materials and technology 55 (2021) 2, 183–194
Figure 5: Loading location: a) location 1, b) location 2, c) location 3, d) location 4

In order to simplify the complexity of the model,
some basic assumptions are proposed in
35
:
1) The effects of gravity, the negative bending mo-
ment of the bridge deck and bridge vibration are all ig-
nored;
2) all materials satisfactorily meet relevant standards
and requirements;
3) the interface between the bridge deck pavement
and anchorage zone is simulated by contact element in-
stead of the mechanical connection, and the other com-
ponents are fixed with each other.
Moreover, the anchorage zone, bridge deck, and
bridge deck pavement are all simulated by Solid45, the
interface between the bridge deck pavement and anchor-
age zone is simulated by Conta173 and Targe170. The
meshed finite-element model is shown in Figure 7.
4.1.3 Discussion of finite-element analysis
To determine the loading location of maximum
stress, the stress data of interface between bridge deck
pavement and anchorage zone concrete have been ex-
tracted along the longitudinal direction of the bridge
deck. The maximum shear and compressive stresses are
listed in Table 3.
Table 3: Maximum of shear and compressive stress at four loading lo-
cations
Loading
location
 X
/MPa  Y
/MPa  Z
/MPa XY
/MPa XZ
/MPa YZ
/MPa
1 0.212 0.376 0.159 0.121 0.067 0.069
2 0.203 0.680 0.252 0.072 0.071 0.123
3 0.119 0.376 0.168 0.093 0.030 0.057
4 0.010 0.154 0.062 0.068 0.053 0.018
As listed in Table 3, compared to the others, there is
an obvious change for X
and YZ
in loading location 2, so
loading location 2 and its stress distribution (Y-direction
and YZ-direction) can be determined to study the road
performance of the steel-PV A hybrid fiber concrete.
Therefore, the stress distributions of the interface along
the transverse direction (Z) are shown in Figure 8.
Figure 8 indicates that the normal stress Y
is in the
applying load area of the wheel tracks, and the maximum
normal stress occurs at a depth of 4 mm from the bridge
deck. For the depth in the range of 0–4 cm, the normal
stress of the wheel outside is tensile. Meanwhile, there is
an increasing trend for the normal stress in applying the
load area. But normal stress of the wheel outside is com-
pressive in the depth of 4–10 cm, while the trend for the
normal stress in the applying load area is declined.
Moreover, for the shear stress YZ
, one can conclude that
the shear stress around the wheel is greater than other lo-
cations, its maximum can be obtained at the outside of
the wheels. When the depth is in a range of 0–4 cm and
M. HUANG et al.: EXPERIMENTAL AND ANALYTICAL STUDY OF A NEW KIND OF STEEL-PV A HYBRID FIBER CONCRETE ...
Materiali in tehnologije / Materials and technology 55 (2021) 2, 183–194 191
Figure 6: Finite-element model of the BECI of Jihe Bridge
Figure 7: Meshed finite-element model
Figure 8: Interface stresses along the transverse direction (Z):
a) normal stress, b) shears tress YZ

4–10 cm, the shear stress at the outside of the wheels are
increasing and decreasing, respectively, which are
mainly affected by the vehicle weight and reaction force
of bridge slab.
In the following, as an important factor, the over-
weight, is also considered in this study. The overload co-
efficients can be determined as 21.7 % and 37.9 %, and
their calculated loads are 0.706 MPa and 0.800 MPa. The
maximum stresses under different overload levels are
listed in Table 4.
Table 4: Maximum stresses under different overload levels
Loading value
/MPa
Compressive stress
/MPa
Shear stress
/MPa
0.580 0.680 0.123
0. 706 0.827 0.150
0.800 0.938 0.170
From Table 4, there is a positive relationship be-
tween the maximum normal and shear stress under dif-
ferent overload levels. Meanwhile, under the overload
level of 37.9 %, the maximum normal stress and shear
stress are far less than the ultimate stresses of the con-
crete after 3-day standard curing, which means the vehi-
cle load cannot cause an overload damage to the anchor-
age zone concrete. Hence, the mechanical properties of
the steel-PV A hybrid fiber concrete are better than that of
the ordinary C50 concrete, which means the former is
more difficult to destroy under the same loading condi-
tions. Although the elastic modulus of the hybrid fiber
concrete cannot be quantified accurately, the mechanical
analysis of the C50 concrete provides a powerful and
creditable proof to ensure the better road performance in
anchorage zone concrete.
In addition, the braking of vehicles can cause damage
and separation of the interface between bridge deck
pavement and concrete in the anchorage zone; therefore,
based on the applied standard values of 0.58 MPa, the
vehicle braking is converted to a horizontal force to ob-
tain the maximum stresses, which are listed in Table 5.
Table 5: Maximum stresses under different horizontal force coeffi-
cients
Horizontal force
coefficient
Compressive stress
/MPa
Shear stress
/MPa
0 0.680 0.123
0.10 1.396 0.368
0.25 2.730 0.948
0.50 5.170 1.947
It can be seen from Table 5 that the maximum com-
pressive and shear stresses increase with the horizontal
force coefficients. It is implied that there is a great influ-
ence of the horizontal force coefficient on the interface
stress. When the horizontal force coefficient changes
from 0 to 0.10, the compressive and shear stress will in-
crease by 105.3 % and 199.2 %, respectively. As the co-
efficient reaches 0.25, the stress increases rapidly and the
change of the shear stress is more obvious. And for the
maximum coefficient of 0.50, the maximum shear stress
is 1.947 MPa, which is still less than the flexural strength
of the steel-PV A hybrid fiber concrete. In the final analy-
sis, there is a good capability of the improved concrete to
resist the shear stress generated by the emergency brak-
ing of vehicles, which can satisfactorily meet the require-
ments of early high strength for the anchorage zone con-
crete.
4.2 Application example
In order to evaluate the road performance of the hy-
brid fiber concrete, the concrete is used for the anchor-
age zone of the Jihe Bridge, which is located in the city
of Fuyang, Anhui province, China. The experimental
compressive strengths are shown in Table 6.
Table 6: Experimental compressive strengths of steel-PV A hybrid fi-
ber concrete under different curing stages
Concrete 1 d /MPa 3 d /MPa 28 d /MPa
Steel-PV A hybrid fiber
concrete
18.7 36.9 50.9
Steel fiber concrete (C50) 10.9 42.1 53.7
The results of Table 6 indicate that the site experi-
mental compressive strengths of the hybrid fiber con-
crete after 1 d and 3 d curing are both higher than the re-
sults in the lab. And comparing to the C50 concrete, the
M. HUANG et al.: EXPERIMENTAL AND ANALYTICAL STUDY OF A NEW KIND OF STEEL-PV A HYBRID FIBER CONCRETE ...
192 Materiali in tehnologije / Materials and technology 55 (2021) 2, 183–194
Figure 9: BECI of the Jihe Bridge using the steel-PV A hybrid fiber
concrete

strength of steel-PV A hybrid fiber concrete is better in
the condition of 1-day curing than for a steam curing of
48 h, but slightly lower in the condition of 3 d and 28 d.
The measured results imply that although the compres-
sive strength of the improved concrete has slightly lower,
its early strength is very suitable for the quick construc-
tion of the anchorage zone concrete, which can reduce
the period of closed traffic and improve the durability of
anchorage zone concrete.
As shown in Figure 9, the steel-PV A hybrid fiber
concrete was utilized in the expansion and contraction
installations’ anchorage zone of the bridge for about 1
year, which is verified by the regular traffic flow. The
new concrete without any damage has good road perfor-
mance, the improvement of concrete is useful and suc-
cessful.
5 CONCLUSIONS
In this paper, an improved steel-PV A hybrid fiber
concrete with high early strength is proposed and con-
structed by adding steel and PV A fiber in the ordinary
concrete. The comprehensive test design method is
adopted to evaluate and analyze the mechanical proper-
ties of concrete by adding a single steel fiber, single PV A
fiber, and hybrid fiber. After1da n d3do fstandard cur-
ing, the mechanical performances, such as compressive
strength and flexural strength, are obtained by compres-
sive and flexural tests in the laboratory. Additionally, the
function mechanism of the steel-PV A fiber is discussed.
Further, the finite-element model of the anchorage zone
concrete is established to compare the road performance
of the ordinary concrete and the improved concrete, and
the maximum stress loading location is determined to
evaluate the effects to anchorage zone concrete. Mean-
while, some factors such as the overload and horizontal
coefficient are also considered. The maximum shear and
compressive stress are extracted, which are compared
with the ultimate stress of steel-PV A hybrid fiber con-
crete. Eventually, an application example is introduced to
verify the practical road performance of the improved
concrete. The conclusions can be summarized as fol-
lows:
1) PV A fiber and steel fiber additives have a negative
effect on the early compressive strength of ordinary con-
crete. However, PV A fiber is more sensitive to the
strength reduction. And for the flexural strength, PV A,
steel and steel-PV A hybrid fiber both have some en-
hancement to ordinary concrete. The optimum added
percentages of the fiber additives are 1.5 % for steel and
0.12 % for PV A.
2) The ordinary concrete has significant brittleness.
However, due to the fiber glued in the fracture surface,
the improved concrete has good ductility and can slow
down the destruction process of the concrete specimen.
3) From the results of the finite-element analysis, it is
shown that the maximum stresses in the condition of
37.9 % overload and 0.5 horizontal coefficients are less
than the ultimate test stress of 3 days curing of ordinary
concrete C50. As the early mechanical performances of
the steel-PV A hybrid fiber concrete are better than that of
ordinary concrete C50. The improved concrete shows
good performances of high early strength and ductility,
which satisfactorily meet the principle of quick traf-
fic-opening and shorten the repair period of expansion
and contraction installations.
4) Through the case study, it is found that the early
compressive strength of the steel-PV A hybrid fiber con-
crete is improved, but the strength after 28 d of standard
curing decreased. The proposed steel-PV A hybrid fiber
concrete has good ductility and its basic mechanical per-
formance can be ensured. Compared to the ordinary con-
crete, although there is some reduction in the compres-
sive strength, the improved concrete is very suitable for
the quick repair requirements of the anchorage zone,
which can reduce the period of closed traffic and show
good practical application performance.
Acknowledgement
The authors gratefully acknowledge that this study
was supported by the Science and Technology Progress
Project in Transportation (2017), Anhui Province, China
(Study on Rapid Replacement of Highway Bridge Ex-
pansion Joint Device).
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