Crisis signals of prestressed steel strands --- yellow rust and red rust? (II)

May. 29, 2025

As the core bearing material of engineering structures, the durability of prestressed concrete steel strands is directly related to the safe service life of infrastructure such as buildings and bridges. The oxidation and rust morphology (yellow rust and red rust) on the surface of steel strands is an intuitive representation of the corrosion process. Scientifically identifying the characteristics of the two and taking targeted protective measures are of great engineering significance for extending the life of components and avoiding safety risks.

Ⅲ. Summary and comparison table

Items	Yollow Rust	Red Rust
Color	Yellowish-Brown, Light Brown	Reddish-Brown, Brownish Red
Ingredient	Fe₂O₃·nH₂O	Fe₂O₃·H₂O
Corrosion Stage	Early Stage/Middle Stage	Mid-Stage/Late Stage
Circumstance	Damp and short-term contact with water	Long-term humid, high-salt/acidic environment
Character	Relatively loose, Thin	Loose and easy to peel off, Thick
Harm	It has a mild impact and needs to be dealt with promptly.	The mechanical properties have significantly declined and the risk is high.
Key Points of Handling	Simple Rust Removal + Rust Prevention	Thorough Rust Removal + Inspection and Evaluation
Cross-sectional Area Loss Rate	≤5%，Local Rusting	10%~30%，It may Pass Through the Steel Wire
Tensile Strength	Basically No Change	Decrease by 10%~20%
Brittleness	No Obvious Change	Significantly Increased and Prone to Breakage
Fatigue Life	The influence can be ignored.	Shorten by more than 50%
Engineering Applicability	It can be used normally after rust removal.	It needs to be inspected and evaluated. In severe cases, it should be scrapped.

Key points: Red rust is more corrosive and more harmful than yellow rust. Red rust should be given priority in engineering and should be avoided from being used in load-bearing structures. Yellow rust is a corrosion warning signal, and timely treatment can avoid performance deterioration; red rust has caused substantial damage, and safety must be confirmed through professional testing. It is strictly forbidden to be used directly in key projects.

IV. Project Management Suggestions

On-site inspection: Use a 10x magnifying glass to check the surface of the steel strands when they enter the site. If the yellow rust area is greater than 5%, it needs to be derusted and re-inspected, and red rust needs to be directly removed from the site;
Process control: For steel strands piled in the open air with a construction period of more than 3 months, the rust level inspection is carried out every two weeks;
Technical files: Establish a "rust-treatment-detection" ledger to record the images before and after rust removal, detection data and protection process parameters.

Crisis signals of prestressed steel strands --- yellow rust and red rust? (II)

Conclusion

Yellow rust and red rust are "graded warning signals" of steel strand corrosion. In engineering practice, it is necessary to achieve "early identification---early treatment---system protection". Our steel strands provide reliable protection for the performance of prestressed components throughout the life cycle and provide solid support for infrastructure safety through the deep integration of refined management and advanced anti-corrosion technology. If you have any related needs, please feel free to contact us for consultation and negotiation!

What to do if there is a quality crisis of steel strands? ---- Strictly control the five core links of production and refuse to ship inferior products

Crisis signals of prestressed steel strands --- yellow rust and red rust?(I)

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