CFRP Lining for PCCP Refurbishment Without Cut-and-Patch Ends
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Solution Overview
Problem
Pre-stressed concrete cylinder pipes (PCCP) can fail due to breakage of pre-stressing wire, leading to structural integrity issues, and existing refurbishment methods using CFRP linings can compromise the integrity due to the need for cutting and patching.
Innovation Solution
A method for refurbishing PCCP involves removing concrete from the inner core to expose the metal core, cleaning and filling the exposed areas with a reinforced epoxy filler, and applying a carbon fibre reinforced polymer (CFRP) liner that remains substantially cylindrical with unbent ends, ensuring secure adhesion and minimizing the need for cutting and patching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the CFRP lining is applied as sheets that are cut and bent to conform to annular ramps, then the lining can cover the repaired ends, but the integrity of the CFRP reinforcement is compromised
Solution Approach 1:
Instead of cutting and bending the CFRP sheets to fit the annular ramps, the patent inverts the approach by forming the CFRP lining in its final cylindrical shape first, then installing it over the annular ramps. This is achieved by applying the CFRP lining to a mandrel or form that maintains its cylindrical shape during curing, eliminating the need for post-installation cutting and bending that compromises integrity.
Solution Approach 2:
The patent applies preliminary action by preparing the inner concrete core surface and forming the annular ramps before applying the CFRP lining. The surface is cleaned, roughened, and primed in advance, and the annular ramps are formed with appropriate geometry beforehand, allowing the CFRP lining to be installed in its final shape without requiring subsequent modifications that would damage its structural integrity.
2Ease of repair
If the inner concrete core is chipped away to expose the metal core for repair, then the metal core can be cleaned and reinforced, but the structural integrity of the PCCP segment is compromised during the repair process
Solution Approach 1:
The patent employs the flexible shell principle by using the CFRP lining as a thin, flexible reinforcement layer that can be applied over the exposed metal core and annular ramps. This CFRP shell provides structural reinforcement while being adaptable to the repaired geometry, restoring and enhancing the structural integrity of the PCCP segment without requiring extensive removal of the inner concrete core.
Solution Approach 2:
The patent applies composite materials by combining the metal core, epoxy mortar annular ramps, and CFRP lining into a composite reinforcement system. The metal core provides structural strength, the epoxy mortar provides bonding and geometry formation, and the CFRP lining provides additional tensile strength and corrosion protection, creating a multi-material composite structure that restores structural integrity.
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 method effectively refurbishes PCCP by enhancing structural integrity, reducing the risk of further failures, and maintaining the cylindrical shape of the CFRP liner, thus avoiding the complications associated with cutting and patching.
Implementation Method 1
applying a carbon fibre reinforced polymer (CFRP) liner to the inner surface of the inner concrete core and to the filler at each end of the PCCP. The CFRP liner conforms to the inner surface of the inner concrete core and to the filler, and the CFRP liner remains substantially cylindrical with substantially unbent cylindrical ends.
Data Source
AI summary
A method for refurbishing a pre-stressed concrete cylinder pipe (PCCP) comprises removing concrete from an existing inner surface of the PCCP at each end thereof to expose a metal core, cleaning the exposed metal core and depositing filler over the exposed metal core at each end of the PCCP to a thickness wherein the filler is substantially flush with the existing inner surface. One or more layers of carbon fibre reinforced polymer (CFRP) liner are applied to the existing inner surface of the PCCP and to the filler at each end of the PCCP. Each layer of CFRP liner conforms to the inner surface of the PCCP and the filler and remains substantially cylindrical with substantially constant diameter along a length of the PCCP with substantially unbent cylindrical ends. After curing all layer(s) of CFRP liner, each terminus of the layer(s) of CFRP liner is sealed.