Polymer Impregnated Concrete Manufacture

Operations involved in the impregnation process to develop polymer impregnated concrete are:

1. A well-designed cement concrete is made available. They must adequately moist cured and gain an

optimum strength.

2. The moisture is removed by drying the concrete. The drying is carried out by heating the structural

element to surface temperature of the order 120 to 150 degree Celsius. An air oven can be used to dry

small specimens.

If the element has large surface, a thick blanket can be used, say, 10mm thick, to prevent from any

thermal gradient. Another sophisticated application is the use of Infrared heaters.

For complete removal of moisture from the concrete, 6 to 8 hours of heating is required.

3. After the complete removal, the concrete surface is cooled to safe levels. This can go to a temperature

of 35 degree Celsius. This temperature will avoid flammability.

4. The concrete is now taken to a vacuum sucker, where the whole air within the concrete structure is

removed. The quantity of the monomer that is impregnated will decide the time and the degree of

application of vacuum.

5. The concrete after adequate removal of air is dipped in a solution of monomer. It is soaked for a long

time till the desired depth of penetration of monomer is obtained.

The soaking time is dependent on the viscosity of the monomer, the preparation of the specimen and the

main characteristics of the concrete.

To reduce the time taken to acquire the desired penetration, it is preferred to use external pressure like

air or nitrogen gas. This facilitates speedy penetration.

6. After the above procedure, the surface is covered with plastic sheet. This helps to prevent the

evaporation of the monomer.

7. The thermal catalytic method of polymerization is carried out. This method involves the

polymerization by heating the catalyzed monomer to the required temperature level. This will range

from 60 degrees to 150 degree Celsius. The temperature range chosen depends on the type of monomer.

The heating can be carried out under the water or by low-pressure steam injection, or by means of

infrared heaters or in an air oven. The heating decomposes the catalyst and hence initiate the

polymerization reaction.

Once the monomer has penetrated the concrete, the polymerization can also be initiated using the

ionization radiation such as the gamma rays. The polymers when fully polymerized or when they are

cross-linked, they act as solids that occupy the voids into which they are impregnated.

8. The concrete structure is then allowed to cool.

The whole procedure from 1 to 8 can only be carried out in a precast factory. The Monomers like acrylate, styrene and the vinyl chlorides etc are used commonly for impregnating into concrete. Another widely used monomer is Methyl Methacrylate (MMA).