Double Rustproof PC Strand Corrosion Resistance
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Solution Overview
Problem
Existing PC strands used in prestressed concrete and marine structures face issues with corrosion due to salt exposure, leading to surface damage and uneven twisting pitches, which compromise tensile strength and durability.
Innovation Solution
A double rustproof PC strand is developed with a plated layer and synthetic resin coating, where the core wire and surrounding wires are adjusted to specific diameters to ensure uniform twisting pitches and a secondary resin coating is applied to fill gaps and enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick resin coating is applied to protect against corrosion, then corrosion resistance is improved, but the strand becomes more susceptible to surface damage and uneven twisting pitches
Solution Approach 1:
The protection system is segmented into two independent layers: a plated layer on each individual wire and a resin coating on the entire strand. This segmentation allows each layer to perform its specific function without compromising the other, resolving the contradiction between thick coating protection and surface damage prevention.
Solution Approach 2:
The invention uses a composite protection system combining metallic plating (zinc or zinc alloy) and synthetic resin coating. This composite structure provides both the corrosion resistance of the plated layer and the protective barrier of the resin coating, while the plated layer prevents surface damage to the wire core.
2Strength
If the core wire and surrounding wires are twisted to provide flexibility and shear resistance, then mechanical performance is improved, but twisting pitch uniformity deteriorates
Solution Approach 1:
The resin coating is applied to the entire strand before the twisting operation. This preliminary coating action ensures that the twisting pitch uniformity is established before the final protective layer is applied, allowing the twisting process to proceed with controlled pitch while the resin coating provides subsequent protection without affecting pitch uniformity.
Solution Approach 2:
The invention changes the sequence of operations by applying the resin coating before twisting, rather than after. This parameter change in the manufacturing sequence allows the twisting pitch to be controlled during the twisting process itself, while the pre-applied resin coating ensures uniform protection throughout the strand.
3Reliability
If individual wire coating is applied to ensure rustproof function, then corrosion protection is improved, but the complexity of the manufacturing process increases
Solution Approach 1:
The invention merges the individual wire plating process with the subsequent strand-level resin coating process into a unified manufacturing sequence. The plated layer is first applied to each wire individually, then the entire strand receives a unified resin coating, combining both protection methods in a streamlined process that maintains rustproof function while managing manufacturing complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The double rustproof structure improves tensile strength to 1850 N/mm² or higher, stabilizes twisting pitches, and provides superior durability and semi-permanent corrosion resistance, significantly extending service life.
Implementation Method 1
a plated layer and a synthetic resin coating by a double rustproof processing treatment
Data Source
Figure 1~3
Figure 4~5
Figure 6
AI summary
Double rustproof PC strand comprising a core wire (8) and six surrounding wires (9) twisted around said core wire (8), the wires having the following diameters: (A) diameter of the core wire (8): 4.42 ± 0.05 mm, diameter of the surrounding wire (9): 4.25 ± 0.05 mm; or (B) diameter of the core wire(8): 5.22 ± 0.05 mm, diameter of the surrounding wire (9): 5.06 ± 0.05 mm; or (C) diameter of the core wire (8): 5.40 ± 0.05 mm, diameter of the surrounding wire (9): 5.25 ± 0.05 mm. The tensile strength of the strand is 1850 N/mm2 or higher. All wires were subjected to a wire drawing treatment and each wire comprises a plated layer (2). Additionally each plated wire or the strand is coated with a synthetic resin coating on an outer peripheral surface thereof. The PC strand has a uniform twisting pitch, durability and semi-permanent rustproof performance.