Method for producing a dimensionally stable concrete workpiece and dimensionally stable concrete workpiece
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Solution Overview
Problem
Concrete workpieces exhibit low dimensional stability and high geometric distortions due to hydration and thermal expansion, leading to defects and reduced strength, which limits their accuracy and usability in applications requiring precise geometry.
Innovation Solution
A method involving a predetermined temperature distribution within the mold during concrete hydration, ensuring complete surface contact and controlled heat management to prevent geometric distortions, combined with a controlled filling speed to prevent air pockets and maintain fiber alignment, results in a compressive strength of 10 MPa before demolding and dimensional tolerances of +/- 25 micrometers per meter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If concrete workpieces are produced with conventional methods, then production is simple and fast, but dimensional stability is poor and geometric distortions occur
Solution Approach 1:
The mold is pre-cooled to a specific temperature (e.g., 5-15°C) before concrete pouring to establish a temperature gradient that controls hydration. This preliminary temperature preparation enables precise dimensional control during the subsequent hydration process without requiring complex real-time adjustments.
Solution Approach 2:
The invention changes the temperature parameter of the mold walls during concrete hydration, maintaining a temperature gradient (e.g., mold wall temperature 5-15°C lower than concrete temperature) to control the hydration rate and thermal expansion, thereby achieving dimensional stability with tolerances of ±25 micrometers per meter.
2Manufacturing precision
If the mold is not completely filled with fresh concrete, then air pockets remain which prevent contact between temperature-controlled walls and concrete, but complete filling requires controlled filling speed to prevent turbulence
Solution Approach 1:
The filling process uses dynamic flow control where the filling speed is adjusted according to the mold geometry and concrete properties. The concrete is poured at a controlled speed that prevents turbulence in cross-sectional constrictions while ensuring complete filling, maintaining fiber orientation and preventing air pocket formation.
Solution Approach 2:
The filling process monitors the concrete flow and mold filling status to adjust the filling speed in real-time, ensuring complete contact between concrete and mold walls while preventing turbulence. This feedback control ensures dimensional accuracy without sacrificing productivity.
3Strength
If large grain size concrete is used, then material strength is improved, but heat transfer through hydrating concrete becomes chaotic causing geometric distortions
Solution Approach 1:
The invention changes the grain size parameter of the concrete aggregates, limiting the maximum grain diameter to less than 20% of the mold's smallest dimension. This parameter modification ensures uniform heat distribution during hydration while maintaining adequate compressive strength, preventing chaotic temperature fields and geometric distortions.
4Loss of time
If demolding is performed at low compressive strength, then early demolding is possible, but mechanical damage and defects occur
Solution Approach 1:
The concrete gains sufficient compressive strength (at least 10 MPa) through controlled hydration in the temperature-regulated mold, enabling self-supporting demolding. The mold design and temperature control facilitate demolding at the earliest possible time when the concrete has achieved adequate strength to avoid mechanical damage, eliminating the need for additional curing before demolding.
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
This approach produces dimensionally stable concrete workpieces with high precision, enabling their use in complex geometries and applications like solar collectors, with improved strength and accuracy, allowing for the creation of series parts with tight tolerances.
Implementation Method 1
By maintaining a predetermined temperature distribution in the mold walls during the hydration of the fresh concrete
Implementation Method 2
volume changes and hydration-induced structural changes caused by hydration and thermal expansion being manageable
Implementation Method 3
This can be accelerated by the heat supplied to the fresh concrete and then generated by the heat itself
Data Source
Figure 1
Figure 2a~2b
Figure 2c
AI summary
The invention relates to a method for producing a dimensionally stable concrete workpiece characterised in that to produce the concrete workpiece a fully-sealed dimensionally stable form (20) is filled with fresh concrete in a predetermined geometry, during the subsequent and undisrupted hydratation a predetermined temperature distribution of the walls (21, 22) of the form (20) surrounding the hydrated concrete is carried out and the concrete workpiece is shaped at a compressive strength of more than 10 MPa. The maximum size of the fresh concrete has a diameter of less than 20% of the smallest measurement of the shape.