Page 1 of 5

European Journal of Business &

Social Sciences

Available at https://ejbss.org/

ISSN: 2235-767X

Volume 07 Issue 05

May 2019

Available online: https://ejbss.org/ P a g e | 771

An Experimental Study on Enhancement of Strength of Concrete

Members using Wrapping Technology

B. ALAGU SUNDARAM

SCHOOL OF ENGINEERING AND TECHNOLOGY

DEPARTMENT OF CIVIL ENGINEERING

PRIST (Deemed to be University)

THANJAVUR.

ABSTRACT

Fiber-reinforced polymer (FRP) application is a very effective way to repair and strengthen

structures that have become structurally weak over their life span. FRP repair systems

provide an economically viable alternative to traditional repair systems and materials. In this

study experimental investigation on the flexural behavior of RC T-beams strengthened using

glass fiber reinforced polymer (GFRP) sheets are carried out.

Reinforced concrete T beams externally bonded with GFRP sheets were tested to failure

using a symmetrical two point static loading system. Seven RC T-beams were cast for this

experimental test. All of them were weak in flexure and were having same reinforcement

detailing. One beam was used as a control beam and six beams were strengthened using

different configurations of glass fiber reinforced polymer (GFRP) sheets. Experimental data

on load, deflection and failure modes of each of the beams were obtained. The effect of

different amount and configuration of GFRP on ultimate load carrying capacity and failure

mode of the beams were investigated.

INTRODUCTION

Deterioration in concrete structures is a

major challenge faced by the infrastructure

and bridge industries worldwide. The

deterioration is mainly due to

environmental effects, which includes

corrosion of steel, gradual loss of strength

with ageing, repeated high intensity

loading, variation in temperature, freeze- thaw cycles, contact with chemicals and

saline water and exposure to ultra-violet

radiations. This problem, coupled with

revisions in structural codes needed to

account for the natural phenomena like

earthquakes or environmental deteriorating

forces, demands development of

successful structural retrofit technologies.

The structural retrofit problem has two

Page 2 of 5

European Journal of Business &

Social Sciences

Available at https://ejbss.org/

ISSN: 2235-767X

Volume 07 Issue 05

May 2019

Available online: https://ejbss.org/ P a g e | 772

options, repair/retrofit or

demolition/reconstruction.

Traditionally, the trend within the US

construction industries has been towards

the latter option. This solution has become

increasingly unacceptable due to changing

economic and

social attitudes concerning existing

structures. This fact leads to the necessity

for development of appropriate structural

retrofit/repair systems.

Retrofitting of concrete structures with

wrapping FRP sheets provide a more

economical and technically superior

alternative to the traditional techniques in

many situations because it offers high

strength, low weight, corrosion resistance,

high fatigue resistance, easy and rapid

installation and minimal change in

structural geometry. In addition, FRP

manufacturing offers a unique opportunity

for the development of shapes and forms

that would be difficult or impossible with

the conventional steel materials. Although

the fibers and resins used in FRP systems

are relatively expensive compared with

traditional strengthening materials, labor

and equipment costs to install FRP

systems are often lower. FRP systems can

also be used in areas with limited access

where traditional techniques would be

impractical.

However, the use of these materials for

retrofitting the existing concrete structures

cannot reach up to the expectation due to

lack of the proper knowledge on structural

behavior of concrete structures retrofitted

by fiber reinforced polymers (FRP)

composites. Successful retrofitting of

concrete structures with FRP needs a

thorough knowledge on the subject and

available user-friendly technologies/

unique guidelines. Beams are the critical

structural members subjected to bending,

torsion and shear in all type of structures.

Similarly, columns are also used as various

important elements subjected to axial load

combined with/without bending and are

used in all type of structures considering

from building to bridge as piers or

abutments.

EXPERIMENTAL STUDY

It is composed of Portland cement and

water combined with sand, gravel, crushed

stone, or other inert material such as

expanded slag or vermiculite. A strong

stone-like mass is formed from a chemical

reaction of cement and water. The concrete

paste is plastic and can be easily molded

into any form or trowelled to produce a

smooth surface. Hardening starts

immediately after mixing, but precautions

are taken, usually by covering, to avoid

Page 3 of 5

European Journal of Business &

Social Sciences

Available at https://ejbss.org/

ISSN: 2235-767X

Volume 07 Issue 05

May 2019

Available online: https://ejbss.org/ P a g e | 773

rapid loss of moisture since the presence of

water is necessary to continue the

chemical reaction and increase the

strength. Excess of water, however,

produces a concrete that is more porous

and weaker. The quality of the paste

formed by the cement and water largely

determines the character of the concrete.

Proportioning of the ingredients of

concrete is referred to as designing the

mixture, and for most structural work the

concrete is designed to give compressive

strengths of 15 to 35 MPa. Concrete may

be produced as a dense mass which is

practically artificial rock, and chemicals

may be added to make it waterproof, or it

can be made porous and highly permeable

for such use as filter beds. An air- entraining chemical may be added to

produce minute bubbles for porosity or

light weight. Normally, the full hardening

period of concrete is at least 7 days. The

gradual increase in strength is due to the

hydration of the tri-calcium aluminates and

silicates. Sand used in concrete is

originally specified as roughly angular, but

rounded grains are now preferred. The

stone is usually sharply broken. Concrete

is stronger in compression than in tension,

and steel bar, called rebar or mesh is

embedded in structural members to

increase the tensile and flexural strengths.

In addition to the structural uses, concrete

is widely used in precast units such as

block, tile, sewer, and water pipe, and

ornamental products.

The T-beams are tested in the loading

frame of the “Structural Engineering”

Laboratory of National Institute of

Technology, Rourkela. The testing

procedure for the all the specimen is same.

First the beams are cured for a period of 28

days then its surface is cleaned with the

help of sand paper for clear visibility of

cracks. The two-point loading arrangement

is used for testing of beams. This has the

advantage of a substantial region of nearly

uniform moment coupled with very small

shears, enabling the bending capacity of

the central portion to be assessed.

The load is transmitted through a load cell

and spherical seating on to a spreader

beam. The spreader beam is installed on

rollers seated on steel plates bedded on the

test member with cement in order to

provide a smooth leveled surface. The test

member is supported on roller bearings

acting on similar spreader plates. The

specimen is placed over the two steel

rollers bearing leaving 150 mm from the

ends of the beam. The remaining 1700 mm

is divided into three equal parts of 567 mm

as shown in the figure. Two point loading