Polymer Concrete

· The polymers are used in the concrete due to the following reasons:

· Polymers improve the strength and durability of hardened concrete

· The chemical resistance and the impermeability of hardened concrete is increased

· The flow properties of fresh concrete can be modified based on the required specifications

· The bond characteristics between old and new concrete can be improved

Polymers that are used popularly

Urethanes: Urethanes are produced by the reaction of isocyanates with the polyols

Acrylics: These are esters of acrylic and methacrylic acids

Vinyl

Epoxies: These are type of synthetic fibers

SBR or Styrene Butadiene Resins: These are synthetic rubbers in the solution

Different ways

The different ways in which the polymer is introduced into the concrete (hardened concrete) will vary

widely based on the commercial objective. The polymers can be employed in concrete in different ways.

They are:

· Polymer Impregnated Concrete (PIC)

· Polymer-Modified Concrete (PMC)

· Polymer Concrete (PC)

· Polymer as Protective Coating

· Polymer as Bonding Agent

Properties of Polymer Modified Concrete

· The addition of polymers makes the concrete mix to become more workable. This can hence reduce the amount of water that is added to the concrete mix.

· The crushing strength of the concrete is increased using the polymer in concrete. This is because the polymer reduces the water cement ratio which in turn increase the crushing strength.

· The bond between the aggregate and the matrix is improved.

· The polymer modification increases the flexural strength of the concrete.

· The polymer modified concrete consist of at least 3 % more amount of entrained air than the plain

· concrete. This additional amount of entrained air will reduce the modulus of elasticity of the concrete (PMC).

· The polymer addition increases the setting time of concrete.

· The resistance of the concrete against abrasion is increased using the polymer.

· Freezing and thawing resistance of the concrete structure is improved by polymer modification.

· The penetration of chlorine ions and other deleterious materials is restricted. The PMC gain higher resistance against such undesirable effects.

· The PMC gains superior shear bond strength.

· The ductility property of the polymer modified concrete is more compared with the conventional concrete.

· These gain a superior tensile and flexural strength compared to the conventional concrete.

Polymer Impregnated Concrete

In the case of polymer impregnated concrete, the prepolymers or the low viscosity liquid monomers are

partially or completely impregnated with the pore system of the hardened cement composite structure.

After this procedure, the whole treated structure is allowed to polymerize.

The normal curing procedure of the hardened concrete results in the gain of a considerable amount of

free water in its voids. These water-filled voids account for a significant amount of the total volume of

the component. It ranges from 5% in the case of dense concrete and 15% in the case of gap-graded

concrete.

In the case of polymer impregnated concrete, it is these voids (water filled pores) that must be filled

with the chosen polymer. Hence the major factor that affects the monomer loading is the: moisture

content in the hardened concrete and the air voids in the concrete.

Applications of Polymer Modified Concrete

· The polymer modified concrete can be used in the repair and the rehabilitation of old damaged concrete.

· The floor construction in frozen – food factories gains great application. This is because of the higher freeze and thaw resistance of PMCs.

· For floor construction of factories were chances of the splitting of chemicals and oils more prone to happen.

· For the preparation of steel bridge and ship decks surfaces.

· For the concrete structure that is more subjected to large doses of de-icing salts.

For the cementing ceramic tiles to concrete.