Repair mortar
Preparatory work
The prerequisite for a successful concrete repair is correct preparatory work. The repair area must first be thoroughly cleaned. All damaged concrete and reinforcement corrosion must also be removed. This can be done by hand or with the help of mechanical aids such as water jetting or blasting. Choose the cleaning method considering the extent of the damage. Damaged reinforcement is supplemented or replaced.
Cover layers should never be less than 20 mm and depending on the type of construction, the layer may need to be much larger than that. To avoid voids, the repair site should have an appropriate shape.
Without shape
The repair site must be watered until it is moist, i.e. absorbent but not soaked. The cleaned concrete and reinforcement are then covered with a suitable cement-based slurry. The slurry should protect the reinforcement and increase the adhesion between the substrate and the repair mortar. Concrete slurry and repair mortar are applied wet on wet. The damage can be built up with different repair materials depending on the requirements. Examples of repair mortars are Bemix R50 or Bemix Conrep SR, both are easy-to-work and malleable repair mortars. Repairs with lower requirements and in thinner layers can be repaired with Bemix Betongspackel, which is excellent for many repair locations as it has a long processing time and a smooth consistency.
With shape
The repair site must be watered until it is moist, i.e. absorbent but not soaked. For smaller repairs and for thin cover layers, concrete and reinforcement can be pre-treated with a suitable cement-based slurry. Larger castings normally do not need to be pre-treated, if the watered concrete has a rough, clean and chipped surface. Castings can be carried out with, among other things, Bemix S3 or A3, depending on requirements and layer thickness. These products have a high resistance to frost, chemicals and mechanical wear. In addition, they give the reinforcement good protection.
Spray concrete
Water-treated surfaces normally do not need further pre-treatment. Dry-cleaned surfaces are washed with high pressure and water. When applying shotcrete, the surface must be slightly absorbent. Bemix SP40 is then applied with dry spray equipment. The mortar is based on building cement and adapted to repairs with low shrinkage and cracking requirements.
Finishing
After a repair, the mortar or concrete must be protected against too rapid drying out. This can either be done by water sprinkling or, if possible, by covering with plastic, alternatively wet cloth, for about a week. The treatment is adapted based on which product has been used and the prevailing climate.