Strengthening Corrosion of Steel Reinforcement in Concrete

Steel reinforcement corrosion can cause volume expansion, which in turn can crack the concrete cover and reduce the load-bearing capacity of the structural members. Reinforcement must follow the principle of "first removing the corrosion hazard, then restoring structural performance," and involves three core steps: pretreatment, reinforcement construction, and post-reinforcement protection. Specific methods are as follows:

I. Pretreatment: Thoroughly eliminate the root cause of steel reinforcement corrosion

This is the foundation of reinforcement. If the source of corrosion is not treated, the subsequent reinforcement will quickly fail.

1. Defect Detection and Assessment

Detecting the extent of corrosion: Visual inspection (crack width, rust seepage points), concrete strength testing using the rebound hammer method, and rebar scanner location to pinpoint the rebar position and extent of corrosion.

Assessing the damage level of the component: Determining whether the corrosion is localized or widespread, and whether rebar replacement is necessary.

2. Removing the Corrosion Layer and Damaged Concrete

Remove cracked, loose, and peeling concrete cover until a solid concrete base is exposed. For corroded rebar, use a wire brush, angle grinder, or sandblasting to remove surface rust and scale, exposing the metallic luster.

If the rebar cross-sectional area loss exceeds 10%, or the corrosion depth reaches 1/6 of the diameter, the corroded section must be cut off, replaced with new rebar, and lap welded or mechanically connected.

3. Rust Prevention Treatment

Apply a rust inhibitor (organic or inorganic) to the surface of the derusted reinforcing bars to form a protective film and prevent further corrosion. If the environment is highly corrosive (e.g., coastal areas or chemical industrial zones), hot-dip galvanized or epoxy-coated reinforcing bars can be used to replace the original bars.

Clean the concrete substrate surface of dust and debris to ensure a firm bond between subsequent repair materials and the substrate.

II. Reinforcement Construction: Restoring and Enhancing the Load-Bearing Capacity of Components

Based on the degree of corrosion and component type, select the appropriate reinforcement method:

Reinforcement methods	Applicable scenarios	Advantages	Disadvantages
Polymer mortar repair	For minor rust and cracked protective layer	Fast application, low cost	Suitable only for small-area damage
Strengthening by increasing the cross-section	Significant steel reinforcement loss and decreased load-bearing capacity	Long-lasting strengthening effect and significantly improved load-bearing capacity	Increases the structure's self-weight and cross-sectional dimensions
CFRP bonding reinforcement	Moderate corrosion, original dimensions must be preserved	Lightweight, easy to install, corrosion resistant	Requires high-quality substrate preparation
External prestressing reinforcement	Severely corroded, large-span components	Significant increase in load-bearing capacity	Complex process, high cost

III. Post-reinforcement Protection: Preventing recurrence of corrosion

After reinforcement, long-term protection is necessary to prevent recurrence of corrosion:

Surface protection treatment: Apply a concrete anti-carbonation coating or water-repellent agent to the component surface to prevent corrosive media such as carbon dioxide and chloride ions from penetrating the concrete.
Regular monitoring and maintenance: Inspect the appearance of the components annually and monitor changes in crack width; for components in highly corrosive environments, inspect the steel reinforcement for corrosion every 3-5 years and address any potential problems promptly.
Improving the usage environment: For components in basements or damp environments, ensure proper drainage and moisture prevention; components in chemical industrial areas require anti-corrosion isolation measures.