Repair concrete RKB
Fescon Corro Shotcrete RKB is a multi-purpose, strength-rated, non-sag and fibre-reinforced special concrete. It can be used for the repair and coating of concrete structures on floors, walls and ceilings. Suitable for indoor and outdoor use. It is also suitable for use as cast concrete and sprayed concrete in applications where high strength and good weather-resistance are required. Maximum grain size 3.0 mm.Layer thickness on wall and ceiling surfaces 30–40 mm, for hole patching up to 150 mm, for concrete casting 20– 100 mm.
- Excellent workability
- Can be applied manually or by pumping or spraying
- No sagging on vertical surfaces, fibre-reinforced
- Strength class C30/37
- Frost-resistant after drying
- SILKO approved
- Good adhesive properties (adhesive class R3)
- Repair and coating of concrete structures indoors and outdoors
- Excellent choice for repairing foundations and stairs
- Suitable for concrete casting, refills, levelling and tilting both indoors and outdoors
- Can be used as a base in prefabricated unit construction
- Suitable for insulation plastering in areas where high mechanical strength is required, e.g. foundations
- Jointing of natural stone structures
- Suitable for increasing structural strength in load-bearing structures
- Increasing the safety distance of steel rebars
- Concrete balcony repairs
- Repair and shotcreting of concrete bridges, tunnels and pools
- Vertical grouting of concrete elements
The product is listed in the portal for building products that can be used in Nordic Swan Ecolabelled buildings.
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Repair concrete RKB
Repair concrete RKB
- The temperature should be above +5 °C
- Concrete base or an insulating sheet
- The surface of the base must be clean, solid and dust-free. The base must be sufficiently strong, immobile and have sufficient carrying capacity
- Loose layers, cement paste and other impurities should be mechanically removed in order to ensure the proper adhesion of Corro Shotcrete RKB to the base. Adheres best to porous surfaces
- When outdoors, it is recommended to use a pressure washer for cleaning the concrete base. This will also add moisture to the base, which prevents the concrete from drying too quickly.
- The reinforcing steels should be cleaned from loose rust and, if necessary, treated with Fescon Adhesive Plaster TL
- Apply reinforcing if necessary. In insulation plastering, steel mesh reinforcement should always be applied.
- If the base is of weak concrete (tensile strength <0.5 MPa) or an insulating sheet, casting must be done by using a floating reinforcement structure. A floating floor structure must be separated from the underfloor by using Fescon Separation Fabric and from the vertical structures by using Fescon Bordering Strip.
- The concrete base should be sufficiently moist before applying Corro Shotcrete RKB.
- The base is moistened with water to prevent the water in Corro Shotcrete RKB from absorbing into the base too quickly. Corro Shotcrete RKB must remain moist while hardening to ensure proper hardening and to achieve the desired strength. This and subsequent moistening prevent plastic cracking and detachment from the surface
- Before applying the product, wet the concrete base until it darkens. Allow any excess visible water to dry before continuing. Begin wetting the base well in advance, e.g. the night before, so that the water is absorbed deep enough into the base
- If necessary, apply Fescon Adhesive Plaster TL for better adhesion and to protect the reinforcements. Refer to the instructions on the product card
- Liquid adhesion promoters should not be used with Corro Shotcrete RKB
- In renovation sites with an old and dry substructure, it is recommended that the base is moistened several times
- The working area should be protected from strong wind, sun and rain
- During the casting and hardening of the concrete, the temperature should be 5–25 °C
- A bag (25 kg) of dry material is mixed into 3.5–4.1 litres of clean water. Start by adding the minimum amount of water, gradually adding more water until the desired consistency is achieved. The correct water ratio in the mixture is achieved when the paste does not sag when applied to the base.
- Excessive water in the mixture reduces the product’s strength values, increases the risk of segregation and
- extends the drying time of the product
- Mix Corro Shotcrete RKB until a uniform paste is formed by using a paddle mixer, concrete mixer, horizontal pan-mixer, or continuous mixer.
- When mixing with a paddle mixer or a concrete mixer, allow the mixture to stand for approx. 5 minutes, followed by a short re-mixing
- Corro Shotcrete RKB can be applied manually or by pumping or spraying. After application, it is compacted and levelled with a screeding level. The concrete surface can be bull floated with a polyurethane float or a steel trowel to achieve the desired quality required for the application. Bull floating is performed when Corro Shotcrete RKB has slightly solidified
- Use planks or screed rails to guide the screeding level when levelling the concrete. When levelling corners, use a plank as a guide so that the RKB is applied at a right angle
- The recommended layer thickness on large surfaces is 30–50 mm. Thicker layers are made in several layers so that the lower layer is allowed to dry for 24 hours before applying the next layer. Maximum hole depth that can be patched is 150 mm.
- After adding water, the concrete remains workable for 1 hour
- Wash all tools with water immediately after finishing the work
- Dried Corro Shotcrete RKB is removed mechanically.
- After casting, the concrete’s surface is kept moist for 2–5 days by spraying water, covering with a plastic film or using Fescon Curing Compound.
- Especially in the spring, pay attention to the starting time of the aftercare and do it with care, as the relative humidity of the air is often less than 40 % RH. Low relative humidity combined with sunlight and wind dries the surface very quickly
- Corro Shotcrete RKB can be left uncovered or uncoated
- Outdoors, the surface can be covered with ceramic tiles, natural stones, epoxy, polyurethane, paint or facade coatings
- Indoors, the surface can be covered with ceramic tiles, plastic coatings, textile mats, vinyl tiles, parquet/laminate board or cork. If necessary, the surface can be sanded and/or levelled with Fescon’s wall and floor levelling products
- Corro Shotcrete RKB’s strength values and other technical characteristics are sufficient to provide an adequate underlay structure for almost all coating materials. However, it must be ensured that the paste meets the technical requirements of the coating manufacturer, including the moistening of the base
The surface is moistened for 2–5 days after casting, depending on the conditions and location.
- In floor structures where RKB is cast onto the base concrete, the layer thickness is 20–100 mm
- Can be used in floating floors with a reinforcing mesh size of e.g. # 150/5 mm. In this case, the layer thickness is 50–100 mm
- It is recommended that no more than 15 m² of floor area is cast at a time. When casting areas larger than 15 m², the risk of cracking increases. To prevent cracking, a sufficient number of contraction joints should be added by following the instructions in the concrete floor installation manual (BY45/BLY 7 Betonilattiat 2014). The maximum size of a floor area to be cast at a time is approx. 50–100 m2.
- When casting wide floor surfaces onto a base, the tensile strength of the base must be >1.5 MPa. The concrete slab may shrink and consequently become detached from the base. To avoid this, it is important to size the slab correctly.
Storage and handling of waste. See the separate storage and disposal instructions https://www.fescon.fi/en/material-bank
appr. 2,0 kg / mm / m².
3.5-4.1 l/25 kg
12-13 l/25 kg
|Maximum grain size
25 kg and 1000 kg
storage time in a dry location approx. 1 year
Substances improving workability.
+ 5°C - +25°C
approx. 1 h
approx. 24 h
> 37 MPa (28 day +20 °C, RH 50 %)
> 1.5 MPa
XC4, XF4, XS1, XD2 (50 years) XC4, XF3, XS1, XD2 (100 years)
The information is based on tests and practical experience. We cannot affect conditions at the work site so we cannot assume responsibility for the end result affected by local conditions.