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700 700 600 600
600 600 500 500
500 500
400 400
400
400
Load (kN) 300 Load (kN) 300 C1 C1 Load (kN) 300 Load (kN) 300 C2 C2
S2
S2
S1
S1
200 200 200 200
100 100 100 100
0 0 0 0
0 0 2 2 4 4 6 6 8 8 0 0 5 5 10 10 15 15
Displaceme nt ( mm) Deflection Deflection (mm)
(mm
Displacement (mm)
)
Figure 5: Load Vs. Mid-Height deflection graphs for control column Figure 6: Load Vs. Mid-Height deflection graphs for control column
C1 and confined column S1. C2 and confined column S2.

3.3.2 Effect of Ferrocement Confinement on With ferrocement confinement on recycled aggregate columns
(type 1), for the first crack load, the column behaved in a similar
Lateral Deflection
manner as the control column. Zone of rupture is observed as at
Lateral deflection tends to decrease with confinement for the one fourth height from top. The first crack appeared in the outer
same load. In case of confined column S1, the deflection upto periphery and propagated vertically, thereby first separating
ultimate load is considerably reduced to 4.61 mm as compared the mortar layer from the wire mesh followed by failure of core
to that of control column i.e, 5.78 mm. Similar patterns was concrete. (Figure 2b)
observed with other column specimens also. The ultimate
deflection of long, control column C2 was again observed as In case of long, control column, the failure zone was observed
a higher 10.31mm as compared to a deflection of 8.82mm for to be above the one- fourth height. After the confinement, the
confined specimen S2. Thus, there is a reduction of 20.24% column showed first crack near the top corner which became
and 14.45% in ultimate lateral deflection for type 1 and type 2 wide with increase in load. The crack propagated vertically
columns respectively. near the outer periphery and the ultimate failure was followed
by delamination of the ferrocement layer up to mid height. It
3.3.3 Effect of Ferrocement Confinement on shows that the confinement is better in the centre of the width
and reduced strength of confinement is observed near corners.
First crack And crack pattern
(Figure 3a and 3b)
In case of unconfined type 1 columns, which fail in compression,
the first crack load value was observed nearer (approx. 70%) 3.3.4 Effect of Ferrocement Confinement on
to the ultimate load value. The zone of rupture was observed
nearer to the middle height of the column than to the top. Ductility
Typically, in case of unconfined control columns, the first crack Ductility is a desirable feature of any structural design as
appeared on the outer portion and diagonally propagated it safeguards a structure against unpredicted overloading
towards the middle of the width (Figure 2a). and/or load reversal. Ductility factor is calculated to assess

Table 4: Test results of control and ferrocement confined columns

spEcImEn % ra slEndErnEss fIrst cracK ultImatE % IncrEasE ultImatE
ratIo load (kn) load (kn) In ultImatE latEral
load dEflEctIon (mm)

C1 0 3 382 531 - 5.78
S1 100 3 414 672 22.35 4.61
C2 0 5 172 406 - 10.31

S2 100 5 235 483 18.96 8.82

The IndIan ConCreTe Journal | JulY 2019 23