Base
Excellently suited to recasting structural members. Where the newly cast mass joins old concrete, the base must be undamaged, rough, damp enough to be darker in colour and sufficiently strong (see compression strength). There must be no cement paste on the surfaces. Begin wetting the base on the previous day. The required amount of wetting depends on the weather conditions and, for instance, the strength of the base. You must always ensure that there is no standing water on the base when starting rendering. If necessary, reinforce the structure.
Mixing
Total water requirement is around 2.6 l/25 kg of dry product. Add the dry material to the water and mix with a power mixer for around one to two minutes allow to stand for five minutes and mix again for a short while. Find the final consistency at this stage by adding water when necessary. However, keep the total amount of water below 11% of the dry product. The finished plaster remains workable for around one hour.
Work instructions
Adhesion to the base concrete is ensured through careful compacting and, if necessary, by applying a separate adhesion layer on the base with a brush. Do not allow the adhesion layer to dry before spreading the plaster. If necessary, use the separate Adhesive Plaster. The minimum thickness of a casting layer is 30 mm. (Maximum around 200 mm as a continuous surface, unless cooling is separately taken care of.) Casts must always be moulded and, when necessary, reinforced. The lowest working temperature is +5°C.
After treatment
The aftercare must be begun immediately after the plaster has been spread and must continue for at least seven days. We recommend using plastic covering / curing compound and a hood. The aftercare is stopped in stages. When a casting connects to old concrete, you must pay special attention on not only aftercare but also the preparation of the base and the casting work itself to avoid cracks. The importance of planning is also increased, and the need for reinforcement must be considered on a case-by-case basis.
Storage and handling of waste
See the separate storage and disposal instructions https://www.fescon.fi/en/material-bank