Cast terrazzo - renovation
Terrazzo floors, stairs, precast-renovation
Terrazzo floors are made from a mixture of cement and crushed marble. When mixing the mixture with water it comes to an aeration of the mass. This is then reflected when grinding terrazzo so that pores are visible on the sanded surface of the floors. On older floors, due to improper maintenance and wear and tear of the floors, these pores may reappear. These small holes get penetrated by dirt and chemical compounds (during normal operation and maintenance), which are very difficult to remove. It is important that a floor for a simple and effective maintenance does not have these deficiencies.
It is necessary to grind the terrazzo floors throughout to about -2 mm - depending, however, on the extent of damage and wear of the floor. Subsequently fully cement with cement screed containing marble powder and water-borne epoxy binder (guarantees consistency and hardening of cement). Otherwise, the cement would be burned and subsequently washed out.
After fine grinding (grinding of filler) the floor is hydrophobicized and waxed. This is very important because the wax can protect the floor and facilitates its maintenance. There is a very wide variety of waxes that can be used. Waxes can create both wet- and transparent look. There is a variety of anti-slip waxes for public spaces such as stairwells. It all depends on agreement and requirements and must be consulted.
Terrazzo floors are usually dilated, in order to create the so-called “controlled crack”. Such dilatations were usually not used on older buildings, and therefore they were created spontaneously, including substrate. The dilating is not effective under the existing state (it is not possible to dilate the substrate). Terrazzo floors are being warped due to thermal changes. But the cracks can occur even when imperfect processing of the substrate, or at shock and settlement of the building
It is necessary to thoroughly clean and wash the cracks exceeding 1 mm. It is then necessary to putty the cracks by a sandable polyester sealant that has elastic abilities, possibly using the polymer-cement matrix. Marble aggregate is added to the cement in order that the crack is optically lost as much as possible. (We have very good experience with it; additional cracks no longer appear.) Other cracks and micro-cracks will be filled up at cementing the floors.