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Posted by : Saurabh Gupta Saturday, September 12, 2015

 Polymer Concrete, Test and its Applications

ABSTRACT:
In Concrete Technolgy there are many types of Concretes here we are mainly discussing
about Polymer Concrerte. Polymer concrete is a composite material. A graded mixture
coarse and fine aggregates bound together by an appropriate organic resin system. Polymer
concrete is a relatively low-cost composite material system that has been developed to be a
technically viable alternative to porcelain for most high voltage electrical insulation
applications. Polymer composites appear as useful materials for repair and protection of
building structures, as well as for manufacturing pre-cast elements. In the case of pre-cast
elements as well as repair materials, the usefulness and durability of polymer composites
depend on the selection of the material composition for obtaining the composite with
controllable properties Polymer Concrete consists of a polymer binder which may be a
thermoplastic but more frequently is a thermosetting polymer, and a mineral filler such as
aggregate, gravel and crushed stone. PC has higher strength, greater resistance to chemicals
and corrosive agents lower water absorption and higher freeze-thaw stability than
conventional Portland cement concrete.

Polymer modified concrete may be divided into two classes; polymer impregnated
concrete and polymer cement concrete. The first is produced by impregnation of pre-cast
hardened Portland cement concrete with n monomer that is subsequently converted to solid
polymer. To produce the second, part of the cement binder of the concrete mix is replaced by
polymer Both have higher strength, lower water permeability, better resistance to chemical,

and greater freeze-thaw stability than conventional concrete.

INTRODUCTION
Polymer concrete is a composite material in which the binder consists entirely of a synthetic
organic polymer. It is variously known as synthetic resin concrete, plastic resin concrete.
Because the use of a polymer instead of Portland cement represents a substantial increase in
cost, polymers should be used only in applications in which the higher cost can be justified
by superior properties, low labor cost or low energy requirements during processing and
handling. It is therefore important that architects and engineers have some knowledge of the
capabilities and limitations of PC materials in order to select the most appropriate and
economic product for a specific application. The first polymer concrete construction in the
worldis Concrerte-Roman_colosseum_red.

NATURE AND GENERAL PROPERTIES:
Polymer concrete consists of a mineral filler and a polymer binder (which may be a
thermoplastic, but more frequently, it is a thermosetting polymer. When it is used as a filler,
the composite is referred to as a polymer mortar. Other fillers include crushed stone, gravel,
limestone, chalk, condensed silica fume, granite, quartz, clay, expanded glass, and metallic
fillers.
To produce PC, a monomer, a hardener and a catalyst are mixed with the filler. Other
ingredients added to the mix include plasticizers and fire retardants. To achieve the full
potential of polymer concrete products for certain applications, various fiber reinforcements
are used. These include
glass fiber,
glass fiber-based mats,
fabrics and
metal fibers.
The amount polymer binder used is generally small and is usually determined by the size of
the filler. Normal the polymer content will range from 5 to 15 percent of the total weight, but
if the filler is fine, up t 30 percent may be required.
Polymer concrete composites have generally good resistance to attack by chemicals and other
corrosive agents have very low water sorption properties. Portland cement concrete permits
the use of up to 50 percent less material. This puts polymer concrete on a competitive basis
with cement concrete in certain special applications. The chemical resistance and physical
properties are generally determined by the nature of the polymer binder a greater extent than
by the type and the amount of filler In turn, the properties of the matrix polymer are highly
dependent on time and the temperature to which it is exposed.

The polymers most frequently used are based on four types of monomers systems: methyl
methacryl , polyester prepolymer-styrene, epoxide prepoiymer hardener and furfuryl alcohol.

MATERIALS AND TESTING PROGRAM
Based on workability, polymer content for GFRPC and CFRPC were determined to be 18%
and 20% respectively. Fiber content for both the matrices was varied up to 6%. CIGMAT
standards (CIGMAT PC1-01, CIGMAT PC2-01, CIGMAT PC3-01) were followed for
specimen preparations, compression test and tension test. Destructive tests were performed in
displacement-controlled mode.
TEST RESULTS AND CONCLUSIONS
Based on the experimental study the following conclusions can be drawn:

Adding 6% glass fibers required 18% polymer in the GFRPC system for good
workability. Glass fibers increased the failure strain, peak strength and modulus in
compression and tension.
Adding 6% PAN based carbon fibers required 20% polymer to develop a workable
CFRPC. The addition of carbon fibers increased the failure strain, but strength and
modulus decreased. In tension, it increased the tensile strain, modulus and strength.
Carbon fibers also increased the failure strain in compression, but reduced the
strength and modulus.

Tension Test
Acrylic Polymer Concrete:
The most common acrylic polymer is poly, obtained by polymerization of methyl
methacrylate. PC made with this acrylic polymer as a binder is versatile material,has excellent weathering resistance
good waterproofing properties
good chemical resistance and
relatively low setting shrinkage
its coefficient of thermal expansion is equivalent to that of Portland cement concrete.
Because of its very low tendency to absorb water, acrylic PC has a very high freeze-thaw
resistance.
Polyester Polymer Concrete :
Because of low cost, the most widely used polymer-binders are based on unsaturated
polyester polymer. In most applications, the polyester binder is a general purpose,
unsaturated polyester prepolymer formulation. The chemical reaction is called cross-linking,
the production process associated with it is referred to as curing, and the resulting polymer
binder is a thermosetting polymer.
Polyester PC has good mechanical strength, relatively good adhesion to other materials, and
freeze-thaw resistance. Polyester PC is used in various pre-cast and cast-in place applications
in constructs works, public and commercial buildings, floor tiles, sewer pipes and stairs.
Epoxy Polymer Concrete :
Epoxy binder like polyester, is a thermosetting polymer. The epoxy polymer can be hardened
with a variety of curing agents, the most frequently used being polyamines. The use of
polyamine hardeners results in PC products with the highest chemicals resistance. Other
curing agents are polyamides and polysulfide polymers. Epoxy PC products cured with
polyamides give greater flexibility.

Epoxy PC exhibits high strength, low-setting and post-setting shrinkage, high chemical
resistance, good fatigue and creep resistance. Because they are relatively expensive, epoxy
polymers have not been used very widely as binders in PC products. Therefore, epoxy PC is
used for special applications. Epoxy PC reinforced with glass, carbon or boron fiber is used
in the fabrication of translucent panels, boat hulls and automobile bodies.
Furan Polymer Concrete :
Furan polymers are based on furfuryl alcohol, which is derived from agricultural residues
such a corn cobs, rice hulls, oat hulls or sugar cane bagasse. The furan pre-polymer is usually
cross-linked with furfuryl alcohol, furfuraldehyde to yield thermosetting polymers, high
resistant to most aqueous acidic or basic solutions and strong solvents such as ketones,
aromatics, and chlorinated compounds. The furan polymers are used as binders in mortars
and grouts to achieve chemically resistant brick floors and linings. In addition to exhibiting
superior chemical resistance, these floors have excellent resistance to elevated temperatures
and extreme thermal shock.
Polymerization :
Polymer- modified cementitious materials date back more than 70 years. In the 194G's they
were developed for use on ships' decks and bridges. Polymers arc made from simple organic
molecules that combine to form more complex structures through a process called
polymerization. The polymers are dispersed in water. These are added to hydraulic cement,
with or without aggregate or admixtures, depending on trip desired result.

Advantages of adding polymers to concrete :
In Polymer- Modified Concrete, a report by the American Concrete Institute. Lists these
advantages to polymer concrete:
• Increased bond strength
• Freeze/thaw resistance
• Abrasion resistance
• Flexural and tensile strengths
• Reduced permeability and elastic modulus
How it works :
To the normal process of cement hydration, polymer modifications add a process of
coalescence. As cement hardens, there form small spaces between the aggregate particles.
These spaces arc what allow water to penetrate, and do damage in freezing conditions.
Polymer particles coalesce to fill these voids. Thai's why the concrete becomes less
permeable and better protected against freeing. Interestingly, polymer concrete does not
produce bleed water. It makes an excellent overlay because it needs very little finishing. It is
more accurate to say that it dries, than to call it curing. For that reason that it is used to
resurface concrete.
Applications & Advantages :
There are several chemical systems for polymer concrete and mortar. Acrylic binders provide
excellent environmental resistance and fast setting times. Epoxy resins exhibit high strength
and low shrinkage during curing. They also provide toughness and resistance to chemical and
environmental damage. Furan resins are formed from the polymerization or poly
condensation of furfural, furfural alcohol, or other compounds containing a furan ring. They
are commonly used in foundry binders, grinding wheels, refractories and other high-temperature applications Polymers resins are used in place of phenolics fiberboard binder
applications. Polyurethane provides excellent flexibility, impact resistance and durability.
Other chemical systems for polymer concrete and mortar include silicone, polyester, and
vinyl ester.
The subject of polymer concrete has generated a lot of interest among researchers during the
past decade. This is due to the many advantages that polymer concrete pavement offers
compared to regular portland cement concrete. The advantages of polymer concrete, when
compared to portland cement concrete include, quick curing and setting, reduced moisture
sensitivity and permeability and improved mechanical properties resulting in reduced
pavement thickness to support the same load. These advantages will lead to attractive life
cycle cost benefits. Material properties and mix designs for PC with epoxy,
methylmethacrylate and Polyester as the binder material have been investigated. It has been
shown in this study that increased material cost of PC can be offset by the reduced thickness
of the pavement. In order to develop life cycle cost information, it is necessary to obtain field
performance data of PC pavement, especially in the composite design mode.
Applicaton of Polymer Impregnated Concrerte:
Keeping in view the numerous beneficial properties of PIC it is found useful in a
large no of applications some of which have been listed &discussed below
a) Prefabricated structural elements
b) Prestressed Concrete
c) Marine works
d) Desalination plants
e) Sewage works – Pipe & Disposal Works
a) Prefabricated structural elements:
For solving the tremendous problems of Urban housing shortage,
maintaining , quality econmy and speed ,builders had to fall back on prefabricated
techniques of construction. At present due to the low strength of conventional concrete, the
prefabricated sections are large and heavy ,resulting in costly handling and erection. These
reasons have prevented wide adoption of prefabrication in many countries.
At present, the technique of polymer impregnation is ideally suited for precast concrete .It
will find unquestionable use in industrialization if building components .Owning to strength ,
much thinner &lighter sections could be used which enables easy handling and erection.

b) Prestressed Concrete :
Further development in prestressed concrete inability to produse high strength
concrete, compatible with the high tensile steel available for prestressing .Since PIC provides
a high compressive strength of the order of 100 to 140 Mpa will be possible to use it for
larger spans and for heavier loads.Low creep properties of PIC willl also make it good
material for prestressed concrerte
c) Marine Works :
Aggressive nature of sea water ,abrasive and leaching action of waves and
inherent porosity ,impair the durability of conventional concrerte in marine works. PIC,
possessing high surface hardness ,very low permiabilty and greatly increased resistance to
chemical attack is a suitable material for marine works.
d) Deslination Plants :
Deslination if sea water is being resorted augment the shortage of surface and
ground water in many countries .The material used in the construction of flash distillation
vessels in such works has to withstand the corrosive effects of distilled water ,brine and
vapour upto a temp of 143 C. Carbon steel vessels which are currently in use are
comparatively costly .
e) Sewage Disposal Works :
It is common experience that concrete sewer pipes deteriorate due to attack of
effluents and when buried in sulphated infested soils. Further, in the sewage treatment plant,
concrete structures are subjected to severe attack from corrosive gases particularly in sludge
digestion tanks.
f) Impregnation of Ferrocement Products :
The Ferrrocement techniques of construction is being extensively used in
manufacture of boats, fishing trawlers , domestic water tanks .Application of Polymerimpregate
concrete due to its high sulphate and high resistance will prove to suitable
material in the ssituations .
References :
1. A. Blaga and J.J. Beaudoin. "Polymer Modified Concrete", Division of Building
Research, National Research Council Canada, Canadian Building Digest 241, Ottawa,
2. A. Blaga. "Plastics", Division of Building Research, National Research Council Canada,
Canadian Building Digest 154. Ottawa, 1973
3. A. Blaga. "Thermoplastics" , Division of Building Research, National Research Council
Canada, Canadian Building Digest 158, Ottawa, 1974.



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