Page 15 - Open-Access-June-2020

TECHNICAL PAPER

eCC
type of sl. type of dimensions loCation
speCimen no. referenCe reinforCement (b×d×l) (mm) of eCC thiCkness oBservation
*
(mm)
15. Yu et al. [73] GFRP/ECC 150 × 250 × i) tension 30 & 80 The application of GFRP/ECC formwork
Formwork 1800 face significantly increases the failure load and
Formwork ii) U-shape shifts the failure mode from debonding to
form concrete crushing under flexure.
work.

16. Afefy and Steel reinforcement i) 300 × 100 × tensile zone 150 × 20 × The strengthened slab showed enhanced
Mahmoud [61] 900 500 ultimate and ductility of 37% and 25%,
Slab
ii) 600 × 100 × respectively than unstrengthen slab.
2000
17. Esmaeeli 20 105×805 tension face 15 & 20 Strengthened beams showed comparable
et al. [74] load carrying capacity and enhanced
deflection than ECC beams.
18. Singh et al. [75] _ 230 × 110 × i) tension 35 The ECC thickness recommended for epoxy
860 face and cement bonding agent for tension-
ii) tension & strengthened beams were 45 & 50 mm
Masonry beams
compression respectively and for sandwich beam is 45 &
face. 20 mm respectively.
19. Dehghani _ 450 × 9450 × tension face 20 ECC increases the shear strength of about
et al. [76] 9105 1.5–2.8 times and at least 35 times for the
energy absorption capacity of the masonry
panels than plain masonry.
* (b-breadth, d-depth, l-length & r -height replacement ratio in beam)
h

Strengthened ECC beams without reinforcement showed In ECC strengthened RC beams, the failure modes of under-
increased deflection compared to unstrengthened beams reinforced and over-reinforced beam were flexural-tension and
without reinforcement due to its more stable fracture flexural-compression, respectively . The presence of ECC
[60]
behavior [59, 67] . layer decreases the stress of reinforcement, which delays the
flexural failure of the structure . Even after observed initial
[63]
ECC strengthened beams without reinforcement showed debonding of ECC layer, the deflection of the strengthened
increased ductility with increase in layer thickness compared [68]
to unstrengthened beam without reinforcement due to kinking beam increased significantly until failure .The beams failed
of micro-cracks in the ECC layer [58, 66] . On the contrary, the by rupture of the strengthened layer near midspan and no
ductility of composite beam decreased with increase in height delamination was observed [60,65] . In addition, no delamination
replacement ratio . at the interface between ECC layer and the substrate was
[62]
observed.
7.1.3 Cracking Behavior and Failure Modes
7.1.4 Influences of ECC Layer Thickness
ECC strengthened plain concrete beams (without steel
reinforcement) showed different cracking behavior than The application of ECC layer on the tensile side of the flexural
unstrengthened beams. The cracks initiated at the ECC layer beam exhibits increased flexural strength and the degree of
tensile zone between the interface of ECC layer and concrete improvement increases with the increase in thickness of ECC
substrate. Eventually, it propagated into the ECC layer and the layer applied [58,59,66] .
compression zone of concrete [58, 66] .
In the case of plain beams, increase in ECC layer thickness
The crack width of the ECC strengthened RC beams increased the deflection of the strengthened ECC beams
decreased due to the multiple cracking behavior of ECC [63,65] . than unstrengthened beams due to ECC’s fiber bridging
In addition, presence of steel reinforcement in ECC layer property [58,66] . Increase in ECC layer thickness, which in turn
increases the number of cracks to the great extent . The increases the initial stiffness of the strengthened RC beams .
[69]
[65]
ECC layer significantly reduces the stress concentration in the In case of under-reinforced ECC strengthened RC beams,
reinforcement compared to the plain beam, which eliminates the ductility improves with the improvement of ECC layer
the yielding of reinforcement . thickness .
[60]
[63]
16 The IndIan ConCreTe Journal | June 2020