Corrosion and destruction prevention of concrete and reinforcement at the dock

1. Purpose of concrete crack repair

Concrete crack repair is necessary to ensure the integrity of structural elements, allowing them to function normally and prevent the penetration of harmful agents that can affect the service life of the structure.

2. Causes of concrete cracking due to steel corrosion

When steel corrodes, the iron atoms (Fe) are oxidized to form rust (xFeO.yFe2O3.zH2O). These rust products have a porous nature and increase in volume by 4-6 times compared to the original Fe. This increase in volume causes pressure on the protective concrete layer, resulting in cracking and loss of bond between the steel and concrete.

3. Measures to address concrete cracking caused by corroded steel reinforcement

a. Signs of identifying concrete cracking due to corroded steel reinforcement:

- Concrete surface exhibits cracks, swelling, or localized spalling.

- Cracks are present in the protective concrete layer along the steel bars.

- Spalling of the protective concrete layer exposes corroded steel.

- Presence of reddish-yellow rust stains seeping through the concrete

b. Method of addressing concrete cracks caused by corroded steel reinforcement

The cause of concrete cracking is due to rusting of the steel reinforcement. Therefore, to address concrete cracks, it's essential to clean and prevent rust formation on the steel. Repair and treatment can be carried out partially in specific areas or entirely, depending on the extent of damage to the structure.

Treatment Method

- Remove the cracked and spalled concrete surrounding the corroded steel area, roughen the concrete surface, wash the surface with water, and allow it to dry.

- Remove rust from the steel: Use brushes, wire brushes, or specialized rust removal equipment to eliminate rust from the steel.

- Use rust converter chemicals to transform remaining adherent rust particles on the steel that couldn't be entirely removed.

- In locations where the steel has corroded beyond 20%, install new steel, bonded to the old steel through welding or tying.

- Apply epoxy adhesive to the steel and concrete: capable of corrosion resistance, bonding old and new concrete.

- Install reinforcing bars, pour new concrete containing DCI corrosion-inhibiting compounds by Grace. Incorporating corrosion inhibitors into the concrete is considered a protective measure against steel corrosion.

- Apply a waterproofing layer on the external concrete surface to prevent water seepage.

Illustration of the process for treating concrete cracks caused by rusty steel

 

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