How to repair cracks in concrete or screed
Before installing the floors certain preparations have to be made. Foundation should be checked for cracks, excess humidity, abrasions or porosity. Climate conditions, under floor heating and humidity standards for floor heating should also be taken in to consideration.
Cracks that appear as a result of drying process of concrete foundation, construction settling of the building or panels, heat or mechanically induced deformities, should be permanently repaired.
Cracks should be coated, evened out and interconnected in to screed making a compact sub floor panel that can equally sustain burden through out the whole floor.
Cement foundation should be prepared for coating with appropriate resins according to technical standards and regulations.
Epoxy and PMM resins
Epoxy or Polymethylethacrylate resins for coating and smoothing are used for firm filling of cracks and evening out rough uneven surfaces on concrete, stone and other building materials. Resins show great impregnating abilities – abilities to fill up deep openings in the surface achieving high resistance to pressure (90 N/mm).
They are easily applied in combination with appropriate density fillers (aerosol, quartz sand…). Every type of mortar can be prepared this way.
Epoxy resin filled with ceramic sand creates high quality epoxy mortar suitable for filling bigger cracks. High results are obtained by mixing sand grains of different sizes.
Epoxy resins used for filling and repair of floor foundations (concrete, screed)have the following characteristics:
- High resistance to chemical and mechanical influences
- Good contact with different types of surfaces
- Small percentage of shrinking
- They are odorless
- High flexibility
- Long period of bondage
PMMA resins show certain advantages when compared to epoxy resins:
- Low viscosity which allows better and quicker filling of narrow cracks.
- Highly resistant, they harden in less then 10 minutes
- They can be applied on low temperatures up to – 30 oC
- They show good results mixed with quartz sand and other fillers
Every crack, no matter how small it may be, can become a big obstacle to installing the final flooring layers. There fore, every crack in cement foundation has to be repaired in the phase of preparation.
Repaired foundation is than sprinkled with quartz sand and coated with primer like UZIN creating a good foundation suitable for further treatments.