Base
The brick surface and the plaster surface to be repaired must be clean and undamaged. Remove salt, dust, rust and compact cement paste, for example by water sand blasting. The dry surface should be wetted to be matte moist. However, the absorption capacity of the base must be maintained and no loose water must be visible. The quality of the repair patch plaster should be selected according to the strength of the base. The patches must be allowed to harden for at least a few days before plastering the surface evenly.
Mixing
Refer to the bag for how much water the plaster requires. Add the dry material to the water and mix with a concrete mixer for around ten minutes. With a power mixer or a drill paddle, around one to three minutes of mixing is sufficient. Allow the plaster to stand for around ten minutes and mix it again for a short while. Find the correct consistency at this stage by gradually adding the rest of the water. We do not recommend adding all of the water right at the start. Every batch must be mixed in the same way. The finished plaster remains workable for around two to three hours. Lowest usage temperature +5°C.
Work instructions
Slam or spray the adhesive plaster tightly to the base so that it fills 90-95% of the base. The adhesive plaster must be allowed to harden for at least one day before filling. The filling plaster is beaten into place by hand or sprayed. A suitable thickness of one layer of filling plaster is approximately 15 mm. If the layer thickness exceeds 20 mm, the work is carried out with several layers so that the previous layer has been allowed to dry for 1 or 2 days before making a new layer. The plaster must receive aftercare and the base must be moistened before adding a new plaster layer. The filling plaster is levelled using a wooden board. Also, careful wood rubbing to level the surface is possible.
The consumption of dry mortar with a layer thickness of 15 mm is approx. 30 kg/m². The lowest application temperature is +5°C and the recommended temperature is +10°C to +20°C. Plastering is not recommended in direct sunlight or in windy weather. Plastering nets mitigate the risk of cracking when mortar is drying. The net should be used especially at the connecting points of various materials, cracks in old brick walls, for reinforcing openings and corners, and plastering of various block surfaces (lightweight concrete, lightweight gravel, concrete). The correct position of the net in the plaster is 1/3 of the surface, however at least halfway outside.
Aftercare
Filling plastering should be treated for at least three days with water irrigation. Aftercare should be started as early as possible to prevent plasticity cracks in the fresh mortar. In dry or windy conditions, aftercare should be started almost as soon as the mortar has sufficiently adhered to tolerate irrigation. If necessary, adhesive plastering should also be treated with water irrigation.
Other considerations
- For pumping render mortars and vertical joint concretes with a maximum aggregate size of 3 or 4 mm, it is recommended to use a sufficiently powerful rendering pump with a minimum power output of 5.5 kW and a stator size suitable for 7 or 8 mm aggregates. The use of automatic mixing pumps is not recommended, as the mixing time in automatic systems is too short. This may negatively affect the solubility of the mortar admixtures and the performance properties of the mortar.
Storage and handling of waste
See the separate storage and disposal instructions https://www.fescon.fi/en/material-bank