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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 5
Flexural strengthening of reinforced concrete beams with carbon fibers reinforced polymer (CFRP) sheet
bonded to a transition layer of high performance cement-based composite
matrix used, mortar and microconcrete. The steel fiber specified
here as “A”, with trade name FS8-Wirand, was provided by the
company Maccaferri – Latin America, has length of 25 mm with
hooks at the ends and a diameter of 0.75 mm. As for the fiber “C”,
provided by the same manufacturer has a length of only 13 mm,
hooks at the ends and a diameter of 0.75 mm.
2.3. Results of flexural tests on three points
2.3.1 Loads and resistances
In order to determine the flexional toughness of the composites, it
was followed the recommendations prescribed by the work group
(RILEM [7]). In the Table 2 are presented the values of loads and
resistance calculated based on these recommendations.
For mortar composites, the addition of fibers constantly increased
the value of resistance (f
fct,L
) thus, for these composites the matrix
contribution in terms of resistance was increased with the incorpo-
ration of steel fibers. The hybrid composites with addition of steel
microfibers of type C to the fibers type A, were those with higher
values of resistance (f
fct,L
) among all the composite cement-based
of mortar analyzed.
Regarding the composite cement-based of microconcrete, the re-
sistance value (f
fct,L
) for the composite CPM1A decreased in rela-
tion to the composite CPM. This showed that the isolated presence
of fiber A does not improve the contribution of the micro concrete
matrix regarding the resistance. However, with the incorporation
of steel microfibers into fibers type A, it was verified an increase in
the resistance value f
fct,L
. This tendency was verified for the com-
posites CPM1A1C and CPM1A2C, in which, the resistance was
respectively, 28% and 37% higher than the CPM.
The values of resistances f
eq,2
and f
eq,3
, characterize the compos-
ites behavior in relation to the fibers performance. In addition, it
is highlighted among the composite cement-based of mortar, the
performance of the composites CPA1.5A, CPA2A, CPA1.5A0.5C,
CPA1.5A1.5C and CPA1.5A2.5C and, among the microconcrete
composite cement-based, only the composite CPM1A2C. In these
composites, the action of steel fibers has increased the level of the
2.1 Test setup
In order to evaluate the behavior to bending tensile of cement-
based composite it was performed bending tests on three points
in prismatic specimens with central notch as recommended by
(RILEM [7]). In the Figure 3 it is possible to observe the general
aspect of the test setup. The tests were conducted by controlling
the crack mouth opening displacement (CMOD), by using for this
purpose a clip gauge.
2.2. Composites analyzed
It was analyzed a set of thirteen distinct composites formed from
the variation in volume and type of steel fibers. They were divided
into groups formed by three prisms (150 mm x 150 mm x 500 mm)
molded with the same characteristics.
In the Table 1 are presented the different composites analyzed.
These were divided into two steps according to the type of cement
Figure � � �� �ea�s �it� tensi�e �one �a�age� �� effect of corrosion (Ferrari [5])
Figure � � �ener�� setup o� the ��e�ur�� test
on three points
P
P
clip gauge
transductor
yoke
notch
150mm
150mm
450mm