Page 8 - Open-Access-July-2019

TECHNICAL PAPER

The column failed at a load of 406 kN. The mode of failure was ferrocement and tested under concentric loading. Type 2
compression. Cracks were formed at the top half portion of column also showed similar behaviour under loading. From
the specimen. In contrast, as the loading started, the confined the observations made, it is clear that the confinement using
column S2 showed less deflection as compared to control ferrocement in recycled aggregate concrete column can restore
column. The first crack appeared at a load of 235 kN followed by its strength and its strength is comparable with the strength of
failure of the column at load of 483 kN. Cracks started at the top normal aggregate concrete without confinement. The column R1
and extended towards the middle height. The failed columns, showed an ultimate load carrying capacity of 499 kN and column
after testing, are shown in Figure 2 and 3. R2 had a capacity of 407 kN.

3.2 Compression Tests on Retrofitted Columns Both the columns showed similar load values to that of the
aggregate concrete without confinement. The type 1 column
Control column specimens were initially subjected to a load showed an ultimate load carrying capacity of 499 kN and type
of 60% of ultimate load (assumed based on previous studies) 2 column had a capacity of 407 kN. Both the columns showed
for repairing. The loaded columns were then confined with
similar load values to that of the corresponding control columns.
A marginal decrease of 6.62% and 7.4% in load carrying capacity
is observed to comparison with control columns C1 and C2
respectively. The retrofitted columns after testing are shown in
Figure 4.

(a) (b)
Figure 2: (a) Control column C1 (b) Ferrocement confined column
S1 - after loading. (a) (b)
Figure 4: (a) Retrofitted column R1 (b) Retrofitted column
R2 - after loading.

3.3 Overall comparison of test results

3.3.1 Effect of Ferrocement Confinement on
Ultimate Load capacity
There is an increase in the ultimate load carrying capacity of
confined columns as compared to the control column. Figures
5 and 6 depict graphical representation of the test results.
The recycled aggregate concrete specimens confined with
ferrocement showed an increase of 22.35 % and 18.96% in
ultimate load carrying capacity, respectively for type 1 and type 2
columns as compared to unconfined natural aggregate concrete
specimens of same dimensions. The confinement effect is
more in type 1 column (250 mm x 700 mm) compared to type 2
(a) (b) column (250 mm x 1200 mm). Comparative analysis of control
columns and ferrocement confined columns with different
Figure 3: (a) Control column C2 (b) Ferrocement confined column
S2 - after loading. heights is given in Table 4.

22 The IndIan ConCreTe Journal | JulY 2019