Repair and Protection of Reinforced Concrete

The protection of the steel reinforcement is ensured by the high alkaline pH of the concrete (~12.5).The penetration of substances such as CO2 and chlorides gradually destroys this protective layer that surrounds the reinforcing bars, resulting in the onset of their corrosion. The presence of oxygen and moisture are key factors in accelerating the rate of corrosion.

1.Substrate Preparation

The substrate must be structurally stable, clean, free from loose particles, oils, dusts, oxidation residues of reinforcement. The reinforcing bars are cleaned, by water jet/sandblasting and in cases of local interventions using a wire brush. The edges of the repair surface are cut vertically (90°) to a minimum depth of 10 mm.

2. Application of Corrosion Inhibitor / Adhesion Booster

After the completion of the above work, the reinforcement bars are applied with the spreadable, cementitious mortar for the anti-corrosion protection of exposed reinforcement BetonFix Kimifer SP or Sika Monotop 910 S or Sika Monotop 111 Anticorrosion.The contents of a container are mixed with clean water using a slow-moving mechanical stirrer to produce a homogeneous, creamy mortar-free mortar texture. Then the first layer is applied by applying the exposed reinforcement rods using a brush.The waiting time between the two layers is estimated to be approximately 30 minutes at 20°C, while the mortar is applied with a brush on the surface of the concrete that will receive the repair, as a bonding primer. In cases of high demands (reinforcement near the sea), for corrosion protection it is recommended to use the 3-component cement mortar SikaTop Armatec 110 Epocem.

3. Application of Repair Mortar

Immediately after the application of the second layer of corrosion inhibitor, the application of thixotropic, high performance, non-shrinking, polymer modified, repair mortar SikaRep 300 Classic or Sika MonoTop 627 HP or Kimia BetonFix FB is carried out. The contents of a bag are mixed with clean water using a slow-moving mechanical stirrer to produce a homogeneous, creamy, agglomerated mortar texture.It is applied by hand, with a trowel or using mechanical equipment.

The thickness of application in one layer, depending on the surface for each material is given below:

• Kimia BetonFix FB                     : 1.5-4 cm / layer
• SikaRep 300 Classic                 : 0.5-2 cm / layer
• Sika MonoTop 627 HP             : 1.5-8 cm / layer

4. Smoothing & Final Surface Finishing

After the above works are completed, the final finishing of the surface follows.This can be achieved by applying a fiber reinforced repair polymer spatula which will impart a waterproof finish. These spatulas are the Sika MonoTop 621 Evolution, BetonFix R30 or BetonFix RS, with a maximum thickness per layer of application of 5 mm. For increased requirements / durability in the final finish use the Sika MonoTop 723 Finiro polymer spatula.

• BetonFix RS                                   :  2-5 mm / layer
• BetonFix R30                                 :  2-5 mm / layer
• Sika MonoTop 723 Finiro           :  2-5 mm / layer
• Sika MonoTop 621 Evolution    :  2-5 mm / layer