Composites Part B 88 (2016) 220e228

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Composites Part B
journal homepage: www.elsevier.com/locate/compositesb

Mechanical properties of FRCM using carbon fabrics with different

coating treatments
Jacopo Donnini a, Valeria Corinaldesi a, *, Antonio Nanni b
a
Politecnica delle Marche, Engineering Faculty, Ancona, Italy
Universita
b
University of Miami, Dept. of Civil, Arch. & Environ. Engineering, Miami, FL, USA

a r t i c l e i n f o a b s t r a c t

Article history: The use of composite materials for repair and retrofit of structures has become a common use among the
Received 1 September 2015 engineering community. Fabric Reinforced Cementitious Matrix (FRCM) is a composite material specif-
Received in revised form ically designed for masonry and concrete rehabilitation and is becoming a viable alternative to FRP,
6 November 2015
whenever the project conditions do not allow the use of organic polymer based composites. FRCM is
Accepted 18 November 2015
Available online 2 December 2015
usually constituted by one or multiple plies of dry fabrics (carbon, glass, aramid, basalt or PBO fibers)
embedded into an inorganic matrix. If a polymer is used to either cover or bond the fabric strands, such
polymer does not fully penetrate and impregnate the fibers as it would for FRP. The purpose of this
Keywords:
A. Carbon fibre
research work is to study how different types and amounts of organic coatings applied to a carbon fabric
A. Fabrics/textiles could affect the bond behavior between fabric and mortar. The effectiveness of coating treatments was
A. Fibre Reinforced Cementitious Matrix studied by means of direct tensile, pull-off and shear-bond double-lap tests. Experimentation was carried
(FRCM) out on different combinations of fabrics and mortars, by varying the levels of pre-impregnation of the
B. Adhesion fabric during its manufacturing. In addition, the use of a quartz sand layer applied to the fabric after
B. Debonding impregnation was investigated. Experimental evidence shows a promising enhancement of the bond
between fabric and matrix and, therefore, of the entire system even with the use of low percentages of
resin, depending on the type of mortar used.
© 2015 Elsevier Ltd. All rights reserved.

1. Introduction TRC is usually associated to new industrial products, FRCM is a

composite system specifically designed for the repair and rehabil-
The world of composite materials is constantly evolving and itation of concrete and masonry structures, introducing an alter-
during the last decades important progress has been made with native to the existing repair methods such as steel plate bonding,
regard to construction applications. Today the focus is on the welded steel meshes, section enlargement or external post-
development of new composites with brittle matrix (cement-based tensioning. The great advantages offered by this class of compos-
matrix, sometimes mixed with a limited amount of organic com- ites are in their lightness, low invasiveness, ease of installation, cost
pounds) reinforced with continuous fibers in form of fabric, woven effectiveness and operators' safety.
according to a weft-warp configuration. The use of dry or partially-impregnated fabrics made of carbon,
Among the category of brittleematrix composites, two types of aramid, basalt, glass or PBO fibers coupled with inorganic matrix
material can be distinguished: Textile Reinforced Concrete (TRC) allows overcoming some issues, typical of FRPs, such as limited heat
and Fiber Reinforced Cementitious Matrix (FRCM). TRC is a com- and fire resistance, lack of vapor permeability and impossibility of
posite material made of open-meshed textile structures and a fine- application on humid surfaces. Inorganic matrices may provide
grained concrete that has been successfully used for the production higher compatibility with the substrate of old masonry construc-
of lightweight structures such as thin shells, cladding panels, ven- tion (clay bricks, tuff, stone blocks), they offer better quality in
tilade façade systems and other manufactured products [1,2]. While terms of reversibility of the intervention and advantages in term of
cost and time of installation, especially on irregular surfaces [3e11].
FRCM composites have some drawbacks such as, for instance, a
* Corresponding author. lower quality adhesion between fabric and matrix and the brittle-
E-mail addresses: j.donnini@univpm.it (J. Donnini), v.corinaldesi@univpm.it ness of the matrix itself. The bond at the fabricemortar interface is
(V. Corinaldesi), nanni@umiami.edu (A. Nanni).

http://dx.doi.org/10.1016/j.compositesb.2015.11.012
1359-8368/© 2015 Elsevier Ltd. All rights reserved.
 J. Donnini et al. / Composites Part B 88 (2016) 220e228 221

of fundamental importance to understand the complex behavior of 2. Research significance

this system when applied as reinforcement in concrete or masonry
structures. The interface behavior is responsible for the stress The primary purpose of this experimental work is to analyze the
transferred between the filaments within a yarn and between the bond behavior at the fabricematrix interface of three cement-
yarn and the matrix. The latter is a fundamental parameter among based mortars by varying the level of pre-impregnation of the
those that influence the interface characteristics and is determined carbon fabric, namely: dry fabric (Dry), light impregnation (L),
by the friction caused by the penetration of the matrix within the medium impregnation (M), and high impregnation (H). Addition-
yarns and on the capacity of the matrix itself to wet the single fil- ally, the effectiveness of a further treatment of a quartz sand layer
aments [12]. The inorganic matrix does not offer the same adhesive applied to the fabric after impregnation is evaluated. This treatment
properties of an epoxy, and so the bond between fabric and matrix was used in combination with light (LS), medium (MS) and high
is not so strong as in FRP systems. Moreover, the inorganic matrix is (HS) impregnation levels.
not able to fully penetrate between the filaments that constitute
the fabric yarns, because the cement grain dimensions are too large 3. Experimental investigation
compared to the space among the filaments. This uncontrolled
penetration leads to different inner and outer bond characteristics, FRCM mechanical properties were investigated by means of
and hence the failure mechanism after exceeding the maximum direct tensile tests. Then a series of double-shear and pull-off tests
pull-out load is a so called “telescopic failure”, a sequential break were performed on FRCM applied to a clayebrick substrate, in or-
down layer-by-layer from the sleeve to the core filaments [13]. der to analyze the adhesion of both the fabric within the mortar and
Some experimental studies have shown that epoxy impregnation of FRCM to the substrate. Moreover, the interface fabricematrix was
the fabric can lead to enhanced mechanical bond strength, fric- observed by means of Scanning Electron Microscope (SEM) in order
tional bond strength, and stiffness [14,15]. After impregnation by to better understand the results obtained by means of tensile tests.
epoxy, the textile can be seen as a rigid thin fabric and the slippage The mechanical properties of the three mortars used as FRCM
among filaments can be eliminated. When a coating is used, the matrix were characterized as they affect both FRCM and its
filaments are stressed more uniformly, resulting in more filaments compatibility with the substrate.
taking part in the load-bearing function [16,17]. Fabric coating is
described by ACI 549.4 R-13 such as a polymer used to either cover
3.1. Materials
or bond the yarns that does not fully penetrate and impregnate the
fibers as it would in FRP. For this reason the term “dry fiber” is used
Three different levels of epoxy impregnation (Light, Medium,
to characterize an FRCM mesh [18]. However, it is still unclear if
High) were obtained for the same bi-directional balanced carbon
fabrics pre-impregnated during the manufacture process may still
fabric (180 g/m2) as illustrated in Table 1 and in Fig. 1. A flexible
be considered “dry”, since the polymer impregnation doesn't take
epoxy resin was used for impregnation to retain the ability of the
place when applying the reinforcement, as it would in FRP. A more
fabric to adjust to the geometry of the substrate. The impregnation
detailed analysis is needed to understand how different levels of
was made using a brush technique for the light impregnation and a
impregnation of the fabric could affect the FRCM mechanical
plastic spatula for the medium and high impregnation. Addition-
properties.
ally, a layer of quartz sand (S) was also applied during the fabric
Another option to enhance the FRCM mechanical performance is
manufacturing with the purpose of reducing the slippage of the
by coating the fabric with sand after the epoxy impregnation, so
fabric within the mortar. The resin and the sand were weighed
that the peak value of pullout force, that is function of the improved
before the application, in order to guarantee a well defined amount
friction, can be increased [19,20].
for each level of impregnation. However, some variability was

Table 1
Carbon fabrics with different coating treatments.

Carbon fabric bidirectional balanced, 180 g/m2

Coating Dry (no coating) (dry) Light impregnation (L) Medium impregnation (M) High impregnation (H)
2
Weight after impregn. (g/m ) 180 245 328 550

Coating Light impregnation þ Sand (LS) Medium impregnation þ Sand (MS) High impregnation þ Sand (HS)

Weight after impregnation (g/m2) 883 1000 1800

222 J. Donnini et al. / Composites Part B 88 (2016) 220e228

3.2. Preparation of specimens

Mortar mixing and specimen preparation was made per man-

ufacturer's instructions. Six cubes (50  50  50 mm) and six cyl-
inders (Ø50  100 mm) were prepared for each mortar mixture,
cast and wet cured at 20  C up to 28 days.
FRCM tensile coupon dimensions were 410  60  10 mm in
order to have three carbon yarns inside each coupon section. The
panels were manufactured using a manual impregnation technique
by first applying a thin layer (5 mm) of cementitious matrix fol-
lowed by a layer of the fabric, pre-cut to panel size, which was
purposely and evenly wetted with the fresh matrix. The top layer of
matrix was then applied as flat as possible with a finishing trowel.
The panels were cured for 28 days at laboratory conditions of 20  C
and 70% relative humidity before cutting and conditioning was
performed. Individual coupons were cut using a diamond-tipped
wet saw with a rigid fixture to ensure consistent specimen
widths (see Fig. 2).
Double shear specimens were prepared using the same tech-
nique, locating the fabric at a distance of 20 mm from the upper
surface of the brick, and a bond length of 150 mm. The thickness
and the width of the FRCM were the same as those of the specimens
prepared for the tensile test (10  60 mm) (see Fig. 3).
Finally, pull-off specimens were prepared by drilling a shallow
core perpendicular to the surface of the brick and applying a steel
disk with a diameter of 50 mm to the external surface using an
epoxy adhesive (see Fig. 4).

3.3. Tensile tests

FRCM mechanical properties were analyzed by means of tensile

tests, using a clevis grip system, as described in the Annex A of
AC434 [21]. In this case the load is transferred to the fabric only
through the matrix. The specimen has multiple degrees of freedom
providing pinned-end supports. This configuration reduces
bending and most importantly allows for slippage of the fabric at
the grips so that the performance of different yarn coating treat-
ments and their bond within the matrix can be investigated. The
clevis type grip system is illustrated in Fig. 2. Axial deformation was
measured using a clip-on extensometer with a 100 mm gauge
length directly anchored to the metal tabs surface. The load was
applied under displacement control at 0.3 mm/min.
A total of 70 uniaxial tensile tests, five for each configuration,
were conducted using a screw driven Universal Test Frame with a
Fig. 1. Schematic representation of the fabric sections depending on the impregnation maximum capacity of 130 kN.
treatment.
The idealized tensile stressestrain curve of an FRCM coupon is
initially linear until cracking of the cementitious matrix occurs,
expected, because the coating was manually applied: the process
then, it changes slope and the second linear segment continues
should be industrialized to obtain more consistent results.
until the ultimate capacity (su, 3 2) is reached. The transition point
As cement-based matrix, three different kinds of commercial
(st1, 31) corresponds to the intersection of these two segments. The
mortars were considered, with different mechanical characteristics.
FRCM uncracked linear elastic behavior is characterized by the
Their strength class was 15, 30 and 45 MPa (‘Mortar-15’, ‘Mortar-30’
uncracked tensile modulus of elasticity, E1. The second segment is
and ‘Mortar-45’), respectively, as reported in Table 2.
characterized by the cracked tensile modulus of elasticity, E2 [22].

Table 2
Mechanical properties of the mortars used as FRCM matrices.

Material Description Compressive strength Elastic modulus Splitting tensile Unit weight
(MPa) (GPa) strength (MPa) (kg/m3)

Mortar- Polymer-modified, lightweight, fiber reinforced, pozzolanic Average 17 12.5 3.6 1650
15 hydraulic binder CoV (%) 6.2 7.5 8.2

Mortar- Polymer-modified, cement-based repair mortar Average 32 27.5 7.1 2194

30 CoV (%) 5.3 10.4 6.4

Mortar- Sprayable, fiber-reinforced, structural repair mortar Average 50 34.5 6.2 2275
45 CoV (%) 5.1 8.3 5.4
 J. Donnini et al. / Composites Part B 88 (2016) 220e228 223

Fig. 2. Tensile test set-up.

Tensile stress at any time was calculated using the following application, the resistant area to be used for calculations remained
equation: the same, equal to the reference fabric based on dry fibers (Af).
The uncracked tensile modulus of elasticity was calculated for
the first linear segment by:
. 
s¼N Af ws (1) E1 ¼ Ds=D3 (2)

where N is the applied load, Af is the fabric area per unit width where Ds is the difference in tensile stress between two selected
(mm2/mm) and ws is the nominal width of the specimen, (mm). points (MPa) and D3 is the corresponding difference in tensile strain
Even if the section area of the yarns was increased by the coating (mm/mm).

Fig. 3. Double-shear test set-up and different failure modes (fibers breakage and slippage).
224 J. Donnini et al. / Composites Part B 88 (2016) 220e228

Fig. 4. Possible failure modes of pull-off test.

Table 3
Results of tensile tests [according to AC434, Annex A].

Mortar Fabric E1 (GPa) E2 (GPa) st1 (MPa) su (MPa) 31 (‰) 32 ( ‰) Failure mode

Mortar-15 Dry Average 1379 e 622 447 0.006 0.083 S

CoV (%) 64 e 17 7 16 44
L Average 1552 50 878 1160 0.006 0.233 S
CoV (%) 19 16 8 8 10 6
M Average 735 43 540 1354 0.007 0.359 S
CoV (%) 18 17 8 7 17 23
H Average 1230 38 621 1048 0.006 0.359 S
CoV (%) 16 8 11 17 43 24
LS Average 1446 59 678 844 0.005 0.217 S
CoV (%) 39 11 19 3 33 18
MS Average 2317 43 649 988 0.002 0.192 S
CoV (%) 35 18 15 6 38 14
HS Average 965 96 531 1210 0.005 0.221 S
CoV (%) 32 26 20 3 40 17

Mortar-30 Dry Average 3753 61 1241 747 0.004 0.073 S

CoV (%) 40 16 17 12 37 31
LS Average 4530 e 1603 656 0.004 0.057 S
CoV (%) 27 e 4 6 35 29
MS Average 3614 64 1447 1137 0.004 0.110 S
CoV (%) 32 18 15 14 41 34

Mortar-45 Dry Average 5189 e 986 575 0.002 0.103 S

CoV (%) 38 e 9 14 25 30
LS Average 4945 30 1088 713 0.002 0.137 S
CoV (%) 61 21 10 14 55 37
MS Average 4375 42 875 1358 0.002 0.226 F/S
CoV (%) 67 5 19 7 46 14
HS Average 3128 49 782 1366 0.002 0.260 F/S
CoV (%) 54 25 15 18 38 22

S) Slippage of the fabric within the matrix; F) Fabric failure.

Fig. 5. FRCM tensile test: fibers slippage within the matrix.

 J. Donnini et al. / Composites Part B 88 (2016) 220e228 225

Fig. 6. FRCM tensile test: fibers rupture.

The cracked tensile modulus of elasticity was calculated for the with the seven carbon fabrics at different level of impregnation. The
second segment, considering two points at stress levels of 0.90su visualization of the possible failure modes is reported in Fig. 4.
and 0.60su and their corresponding strains.
3.6. Scanning electron microscope (SEM) tasks
E2 ¼ Ds=D3 ¼ ð0:90su  0:60su Þ=ð3 2@0:90 su  3 2@0:60 su Þ (3)
In order to observe the quality of the interface between carbon
fabric and surrounding cement paste (especially in the presence of
3.4. Double shear tests impregnation with epoxy resin), observations by means of SEM
were carried out on samples taken from specimens after tensile
A total of 21 double shear tests were performed in order to testing at magnifications ranging from 30 to 100.
analyze the effect of different coatings, using the same mortar type
(Mortar-15). The bond length was kept constant and equal to 4. Experimental results and discussion
150 mm. The load was applied under displacement control at
0.5 mm/min. The fabric was wrapped around a steel cylinder with a 4.1. Mortar characterization
diameter equal to the thickness of the brick plus twice the first layer
of mortar in order to apply the load parallel to the face of the brick. The mortar characteristics are of fundamental importance and
The double shear test set-up as well as the different failure modes its compatibility with the substrate needs to be accounted for in
(fibers breakage and slippage) is shown in Fig. 3. design. Three different kinds of mortars were examined, labeled
‘Mortar-15’, ‘Mortar-30’ and ‘Mortar-45’ and corresponding to a
3.5. Pull-off tests mortar class strengths of 15, 30 and 45 MPa, respectively. The
compressive and splitting tensile strengths were evaluated ac-
28 pull-off tests were performed following recommendations cording to ASTM C109 [24] and ASTM C496 [25] at 28 curing days,
described in the AC434 and ASTM C1583 [23]. The mortar was the on (50  50  50 mm) cubes and (∅50  100 mm) cylinders,
same used in tensile and double shear tests (Mortar-15), coupled respectively. The Elastic modulus was evaluated according to ASTM

Fig. 7. Tensile test (Mortar-45): comparison among different coatings applied to car- Fig. 8. Tensile test: comparison among different mortars reinforced with MS carbon
bon fabrics. fabric.
226 J. Donnini et al. / Composites Part B 88 (2016) 220e228

Fig. 9. SEM observations: bonded area of dry fabric within the mortar.

Fig. 10. SEM observations: bond with mortar of light (a) and medium (b) impregnated fabric.

Table 4
Results of the double shear test [according to RILEM TC250-CSM].

Mortar Fabric Peak load (per side), Slip at peak Peak stress in the Exploitation ratio of textile's Failure mode
Lmax (N) load (mm) textile, sf ¼ Lmax/Af (N/mm2) strength, smax/ft (%)

Mortar-15 Dry Average 1495 2.31 479 26.63 S

CoV (%) 1 9
L Average 1636 2.38 524 28.35 S
CoV (%) 2 10
M Average 2640 4.54 846 45.74 S
CoV (%) 6 3
H Average 2629 4.71 842 45.56 S/F
CoV (%) 9 4
LS Average 2039 3.51 653 35.33 S
CoV (%) 15 18
MS Average 2329 4.10 746 40.36 S
CoV (%) 3 6
HS Average 3247 5.31 1040 56.3 S/F
CoV (%) 1 2

S) Slippage of the fabric within the matrix; F) Fabric failure (out of the bonded area).

C580 [26] and the average and COV results of 5 repetitions are re- performances. FRCM ultimate tensile strength was greatly
ported in Table 2. improved by increasing the impregnation level of the fabric, from
dry to completely impregnated (see Fig. 7), even without the use of
4.2. Tensile tests a quartz sand layer. In fact, when the fabric is dry, only the external
filaments that are in contact with the matrix carry the load, while
The parameters calculated for each matrix and fabric tested are the inner filaments easily slip because of the low friction between
reported in Table 3, as averages of 5 specimens for each combina- the fibers. This phenomenon was clearly observed by SEM as shown
tion fabricematrix. The two failure modes detected in this experi- by pictures taken at different magnification (Fig. 9). Even for
mental work are shown in Figs. 5 and 6. Results obtained were also partially impregnated fabric, the external coating guaranteed a
expressed as stressestrain curves and reported in Figs. 7 and 8. The more uniform bonded surface between yarns and matrix (see
polymer coating was able to improve the bond between fabric and Fig. 10 showing SEM on light and medium impregnated fabrics at a
matrix, and consequently to increase the FRCM mechanical magnification of 30). As well shown in Fig. 8, the first segment of
 J. Donnini et al. / Composites Part B 88 (2016) 220e228 227

turning into a hardening behavior when the fabric is impregnated.

The slope of the curve increased, when a medium or high impreg-
nation level was used. The ultimate strain capacity increased with the
level of impregnation, leading to an enhancement in the pseudo-
ductility of the FRCM system. The failure mode was by slippage of
the fabric within the matrix after the formation of one or two cracks
perpendicular to the direction of the load (see Fig. 5). Using a medium
or high level of impregnation, the interface fabricematrix bond was
capable of bringing the fibers to failure, minimizing the fabric slip-
page within the matrix (see Fig. 6). The use of epoxy impregnation
without sand may negatively modify the FRCM behavior, avoiding
the fiber slippage within the matrix and consequently reducing the
FRCM pseudo-ductility. By increasing the mortar mechanical prop-
erties, the FRCM capacity increased, in particular the peak stress after
the first crack formation, as shown in Fig. 8.

Fig. 11. Double shear bond test: comparison between dry and pre-impregnated fabrics. 4.3. Double shear tests

The results of double-shear tests are reported in Table 4. As

expected, the coating had an influence in both the peak load and
the ultimate slip. The use of a coating increased the bonding at the
matrixefiber interface, and it was able to partially avoid the so-
called telescopic-effect.
The peak load increased by 75% when the fabric was fully
impregnated (H), and by 117% when a quartz sand layer was applied
to the fabric surface (HS). The slip at peak load increased due to the
coating (see Fig. 11), but the addition of sand improved the pseudo-
ductility and maintained higher strength passed the peak load (see
Fig. 12).

4.4. Pull off tests

Results of pull-off tests are shown in Table 5. The predominant

failure mode was at the interface mortarefabric (see Fig. 13). The
use of different coatings did not change the failure mode. Higher
Fig. 12. Double shear bond test: comparison between dry and sanded-impregnated
fabrics.
impregnation performed worse at times, because the fabric, acting
as a bond breaker, reduced the contact area between the two layers
the curve (i.e. linear portion before the cracking of the matrix) is not of mortars surrounding it.
influenced by the fabric, but rather by the quality of the mortar and
its tensile strength and stiffness. Results variability was mainly due 5. Conclusions
to the non-constant thickness of the coupons cross-section [27].
The load drop after the first crack was due to a low amount of fabric From the experimental results obtained on FRCM using different
area which was not sufficient to absorb the energy released at first mortar matrices and different coating treatments applied to the
crack: the higher the tensile strength of the mortar, the greater the carbon fabric the following conclusions can be drawn:
drop after first crack.
As shown in the curves of Fig. 7, the second segment, after the 1. The use of a polymer coating applied on carbon fabric showed to
matrix first crack, presents a softening behavior for the dry fabric, be promising in increasing the mechanical capacity of FRCM

Table 5
Pull off test [according to AC434, ASTM C1583].

Mortar Fabric Maximum load (kN) Maximum stress (MPa) Failure mode

Mortar-15 Dry Average 1.15 0.79 C

CoV (%) 19
L Average 1.82 0.93 BeC
CoV (%) 16
M Average 1.05 0.54 C
CoV (%) 21
H Average 0.75 0.38 CeD
CoV (%) 28
LS Average 1.14 0.58 C
CoV (%) 3
MS Average 1.34 0.68 BeC
CoV (%) 17
HS Average 1.18 0.60 C
CoV (%) 14

A) Failure in the substrate; B) Bond failure at the FRCMesubstrate interface; C) Failure at the mortarefabric interface; D) Bond failure at the epoxyeFRCM.
228 J. Donnini et al. / Composites Part B 88 (2016) 220e228

Fig. 13. Pull-off test: predominant failure mode at the mortarefabric interface.

system for both the tensile strength and the shear bond strength [6] Garmendia L, San-Jose  JT, García D, Larrinaga P. Rehabilitation of masonry
arches with compatible advanced composite material. Constr Build Mater
when applied to masonry. The use of a sand applied during the
2011;25(12):4374e85.
manufacture process was able to further increase mechanical [7] Ascione L, Mancusi G, D'Aponte A. Fabric-reinforced cementitious matrix
characteristics, while maintaining a certain level of pseudo- (FRCM): a new Italian guideline under development. Key Eng Mater 2014;624:
ductility. 3e10.
[8] Ascione L, De Felice G, De Santis S. A qualification method for externally
2. Fabric impregnation, especially if realized with rigid epoxy, may bonded fibre reinforced. Compos Part B Eng 2015;78:497e506.
negatively impact ease of applications, particularly around cor- [9] Valluzzi MR, Modena C, de Felice G. Current practice and open issues in
ners of masonry or concrete structures. strengthening historical buildings with composites. Mater Struct 2014;47(12):
1971e85.
3. The tensile failure mode of these systems was found to be pre- [10] Papanicolaou CG, Triantafillou TC, Karlos K, Papathanasiou M. Textile rein-
dominantly slippage of the yarns inside the matrix. However, by forced mortar (TRM) versus FRP as strengthening material of URM walls: in-
using a coating made of flexible epoxy and sand the adhesion plane cyclic loading. Mater Struct 2007;40(10):1081e97.
[11] Corinaldesi V, Donnini J, Mazzoni G. Experimental study of adhesion between
developed at the interface mortarefabric resulted in fibers FRCM and masonry support. Key Eng Mater 2015;624:189e96.
rupture. [12] Hegger J, Will N, Rüberg K. Textile reinforced concrete e a new composite
4. The transition point between the uncracked and cracked phase material. Adv Constr Mater 2007:147e56.
[13] Curbach M, Ortlepp R. TRC for rehabilitation. In: Textile reinforced concrete e
showed a capacity drop because the amount reinforcement was
state-of-the-art report of RILEM TC 201-TRC, vol. 36; 2006. p. 221e36.
not sufficient to support the load transfer after the formation of [14] Xu S, Krüger M, Reinhardt HW, O zbolt J. Bond characteristics of carbon, alkali
the first crack. Future work could be devoted to establish a min- resistant glass, and aramid textiles in mortar. J Mater Civ Eng 2004;16(4):
356e64.
imum amount of fabric area based on the mortar properties, in
[15] Yin S, Xu S, Li H. Improved mechanical properties of textile reinforced con-
order to guarantee a bilinear tensile behavior of the FRCM system. crete thin plate. J Wuhan Univ Technol Mater Sci Ed 2013;28(1):92e8.
5. FRCM performances at high service temperature, as well as fire [16] Silva FA, Butler M, Hempel S, Filho RDT, Mechtcherine V. Effects of elevated
resistance, could be compromised by fabric impregnation. This temperatures on the interface properties of carbon textile-reinforced con-
crete. Cem Concr Compos 2014;48:26e34.
important issue could be investigated by further studies. [17] Kockritz U, Offermann P, Jesse F, Curbach M. Influence of textile
manufacturing technology on load bearing behavior of textile reinforced
concrete. In: Proceedings of the 13th international techtextil-symposium;
Acknowledgment 2005 [Paper n. 24].
[18] ACI 549.4R-13. Guide to design and construction of externally bonded fabric-
reinforced cementitious matrix (FRCM) systems for repair and strengthening
The authors acknowledge the National Science Foundation concrete and masonry structures. Farmington Hills, MI: American Concrete
(NSF) for the support provided to the Industry/University Center for Institute; 2013.
[19] Xu S, Li H. Bond properties and experimental methods of textile reinforced
Integration of Composites into Infrastructure (CICI) at the Univer- concrete. J Wuhan Univ Technol Mater Sci Ed 2007;22(3):92e8.
sity of Miami, Fondazione Marche, ISSNAF and ECTSystem s.r.l. for [20] Peled A, Zaguri E, Marom G. Bonding characteristics of multifilament polymer
the financial support under Grant No. IIP-IIP-1439543. yarns and cement matrices. Compos Part A Appl Sci Manuf 2008;39(6):930e9.
[21] AC 434-13. Acceptance criteria for masonry and concrete strengthening using
fabric-reinforced cementitious matrix (FRCM) composite systems. 2013.
[22] Arboleda D. Fabric reinforced cementitious matrix (FRCM) composites for
References infrastructure strengthening and rehabilitation: characterization methods
[Doctoral dissertation]. University of Miami; 2014. p. 22.
[1] Naaman AE. Textile reinforced cement composites: competitive status and [23] ASTM C1583. Standard test method for tensile strength of concrete surfaces
research directions. In: International RILEM conference on material science, and the bond strength or tensile strength of concrete repair and overlay
vol. 1; 2010. p. 3e22. materials by direct tension (pull-off method). 2013.
[2] Hegger J, Voss S. Investigations on the bearing behaviour and application [24] ASTM C109. Standard test method for compressive strength of hydraulic
potential of textile reinforced concrete. Eng Struct 2008;30(7):2050e6. cement mortars. 2013.
[3] Ombres L. Analysis of the bond between fabric reinforced cementitious mortar [25] ASTM C496. Standard test method for splitting tensile strength of cylindrical
(FRCM) strengthening systems and concrete. Compos Part B Eng 2015;69: concrete specimens. 2011.
418e26. [26] ASTM C580. Standard test method for flexural strength and modulus of
[4] D'Ambrisi A, Feo L, Focacci F. Experimental analysis on bond between PBO- elasticity of chemical-resistant mortars, grouts, monolithic surfacings, and
FRCM strengthening materials and concrete. Compos Part B Eng 2013;44(1): polymer concretes. 2012.
524e32. [27] Carozzi FG, Poggi C. Mechanical properties and debonding strength of fabric
[5] Nanni A. FRCM strengthening e a new tool in the concrete and masonry repair reinforced cementitious matrix (FRCM) systems for masonry strengthening.
toolbox. Concr Int 2012;34(4):43e9. Compos Part B Eng 2015;70:215e30.