Deformable Core Molding for UHPC Tubular Piles
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Solution Overview
Problem
Existing methods for molding Ultra-High Performance Fiber Concrete (UHPC) tubular elements face issues such as segregation of concrete constituents, leading to heterogeneous distribution, and significant shrinkage that can cause cracking, especially in large diameter or long length elements, making them unsuitable for constructions in developing countries with limited engineering resources.
Innovation Solution
A method involving the use of a prestressing device and a core with a progressively modifiable shape to control the deformation of UHPC as it sets, allowing for the absorption of shrinkage and easy extraction of the tubular element without draft angles, using materials like wax for deformation control and surface roughening to improve grip for subsequent concrete injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional gravity pouring with auger rotation is used to mold tubular concrete elements, then the concrete can be introduced into the mold, but the constituents of the concrete segregate and are heterogeneously distributed
Solution Approach 1:
The mold is made deformable rather than rigid, allowing it to adapt its shape dynamically during concrete setting. The deformable mold can modify its shape progressively to accommodate concrete shrinkage and prevent segregation by maintaining optimal contact pressure throughout the mold cavity during the setting process.
Solution Approach 2:
The invention changes the physical state or properties of the mold from rigid to deformable, allowing the mold material to undergo controlled deformation. This parameter change enables the mold to respond to concrete shrinkage and maintain homogeneous concrete distribution without the adverse effects of rigid confinement.
2Shape
If a rigid inner core is used to define the inner wall of tubular casting space, then the mold structure can be established, but UHPFRC shrinkage causes cracking and deterioration of the element
Solution Approach 1:
The inner core is made deformable rather than rigid, allowing it to change shape progressively during concrete setting. This dynamic adaptation enables the core to accommodate UHPFRC shrinkage without causing cracking, while still maintaining the tubular casting space definition throughout the process.
Solution Approach 2:
The deformable core provides a cushioning effect that absorbs the shrinkage stresses of the setting concrete before they can cause cracking. The core's ability to deform creates a buffer zone that protects the element integrity during the critical shrinkage phase.
3Ease of manufacture
If draft angles are provided for easy demolding, then the element can be removed from the mold, but small diameter elements develop a strongly flared shape
Solution Approach 1:
The mold maintains a cylindrical shape during concrete setting, and the deformable nature of the mold allows for easy demolding without requiring draft angles. The mold can slightly deform during demolding to facilitate element removal while preserving the true cylindrical geometry of small diameter elements without flaring.
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
Enables the production of long, high-quality UHPC tubular elements with reduced risk of cracking and easier handling, suitable for various construction applications, including pile driving and soil injection, without the need for extensive machinery or skilled personnel.
Implementation Method 1
installation of at least one prestressing device in a first element
Implementation Method 2
control of a gradual modification of the shape of one of the elements as the material comprising cement sets
Implementation Method 3
According to a particular embodiment, the core is made at least partially out of wax
Implementation Method 4
whose deformation control is easy
Implementation Method 5
The outer surface of the core is shaped to imprint a rough surface state and/or cavities on the inner surface of the tubular pile
Data Source
AI summary
The invention relates to a method for moulding a part (100), comprising the following steps: placing at least one prestressing device in a first element; placing the first element (20, 60) such that it faces a second element (1); prestressing of the at least one prestressing device; introducing ultra-high performance fibre-reinforced concrete (51) into the receiving space; controlling a progressive modification of one of the elements (20); and demoulding the tubular element (20).