Page 4 - Open-Access-July-2019

TECHNICAL PAPER

strEngth BEhavIour of

rEInforcEd rEcYclEd

aggrEgatE concrEtE

columns confInEd

WIth fErrocEmEnt

lamInatE LEKShMI S. ThILAKAn, SAJI. K. P.

Abstract adopted confinement techniques. Among these methods,
retrofitting with ferrocement confinement is the oldest and the
In this study, attempts have been made for the use of recycled most cost-effective technique that can be used to strengthen
aggregate in place of normal coarse aggregate in reinforced the concrete structures.
concrete columns. It includes processing of recycled aggregates
and then obtaining their physical and mechanical properties. Ferrocement is defined as “a form of reinforced concrete
Both compressive and flexural strength of concrete mixes using closely spaced multiple layers of mesh and/or small
decrease with increase in the percentage of recycled aggregate diameter rods completely infiltrated with, or encapsulated, in
[1]
added. To analyse compression behaviour of ferrocement mortar” . The most commonly used reinforcement is steel
confined, reinforced recycled aggregate concrete columns, six mesh. Selected organic, natural, or synthetic fibres combined
column specimens were cast. Out of which, one column from with metallic mesh also can be used. It is used as a material for
each of the two size-groups is kept as control column, one building construction as well as a repair material. The unique
each is strengthened using ferrocement and the remaining properties of ferrocement such as good water proofing, higher
for assessing the effect of retrofitting with ferrocement. It fire resistance, low self- weight and better crack resistance make
is observed that ultimate strength of confined specimens it an ideal material for wider applications like roofing or flooring
increased significantly. A comparison with results of two elements, boats, water tanks, grain silos etc. The thicknesses
analytical models showed higher ultimate strengths than of ferrocement elements vary between 10 to 25 mm. It requires
obtained in the experiments. minimum number of skilled labours and utilises readily available
local materials. Ferrocement consists of matrix (mortar) and
1. INtrODUctION wire mesh which forms the reinforcement. A mixture of Portland
cement, water and fine aggregate forms the matrix (mortar)
Reinforced concrete is the most commonly used material for which constitutes more than 95% of ferrocement volume and
the construction of structures which are designed in accordance has a great influence on the behaviour of the final product.
with the specifications given in the standard codes to meet the Wire mesh forms the reinforcement part of ferrocement. It has
intended purpose. Based upon these specifications, the loads continuous or small diameter steel wire or welded mesh with
are taken into account for the design of the various elements of high volume fraction (2-8%) and specific surface of reinforcement
the structure like beams, columns and slabs. The deterioration is considerably higher for ferrocement than reinforced cement
of reinforced concrete structures may lead to the structure concrete.
becoming useless during its service life. Replacement of any
damaged structural element is difficult and costly and it creates Confinement using ferrocement can be done in reinforced
a risk to the integrity of other connecting members. Retrofitting concrete structures to increase the strength of columns, beams
can be done to restore the strength of the deteriorated and slabs. It also contributes towards resistance to formation of
structure. Specific member of the structure can be strengthened cracks. Previous studies showed that ferrocement confinement
or replaced by local retrofitting. Jacketing is the most preferred enhances the strength, ductility and energy absorption capacity
technique among the various retrofitting techniques. Fibre of concrete members. For confinement, the ferrocement can
reinforced polymers such as aramid, carbon and glass fibres; be attached to the specimen mainly in three ways. In the first,
external steel caging techniques and ferrocement are commonly wire mesh is attached to the specimen by means of epoxy resin

18 The IndIan ConCreTe Journal | JulY 2019