Closed-Mold 3D Concrete Casting for Bubble-Free Stair Surfaces
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Solution Overview
Problem
Traditional methods for manufacturing concrete stairs, whether on-site or in a factory, face challenges such as significant finishing work due to air bubbles, safety risks for operators, noise nuisance, and increased costs from additional smoothing and coating operations, which are not effectively addressed by existing techniques.
Innovation Solution
A method involving the use of self-compacting concrete injected into a closed mold with a vent and inclination, allowing for the production of monobloc concrete structures upside down, with features like draft angles and continuous curvature to prevent air bubble formation, eliminating the need for mortar and reducing manual vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional concrete pouring methods are used with vibration and manual leveling, then concrete can be placed and compacted, but air bubbles form on the surface requiring extensive finishing work and additional coating
Solution Approach 1:
The mold is inverted during the concrete pouring process, with the mold bottom positioned above the concrete level. This inversion causes air bubbles to rise away from the future functional surface and escape through the vent at the mold top, while concrete fills from the bottom up to create a bubble-free functional surface without requiring extensive finishing work
Solution Approach 2:
A vent is incorporated at the top of the mold to extract and allow escape of air bubbles during concrete pouring. This extraction mechanism removes the harmful air bubbles from the system before they can become trapped in the concrete, eliminating the need for subsequent bubble removal and surface repair operations
2Ease of manufacture
If operators perform manual leveling and smoothing of wet concrete on site, then steps can be formed, but operators face safety risks from precarious positioning at height
Solution Approach 1:
The mold is pre-configured with inverted geometry and integrated vents before concrete pouring begins. This preliminary setup eliminates the need for operators to perform dangerous manual leveling and smoothing operations on wet concrete at height, as the mold design itself ensures proper step formation and bubble-free surfaces
Solution Approach 2:
The inverted mold design with vents enables the concrete to self-level and self-compact without operator intervention. The concrete flows and settles automatically under gravity, with air bubbles escaping through the vent, eliminating the need for operators to physically manipulate wet concrete in hazardous positions
3Ease of manufacture
If vibration operations are performed during concrete pouring, then concrete compaction is achieved, but noise nuisance affects working conditions
Solution Approach 1:
The invention replaces mechanical vibration systems with a gravity-based passive compaction mechanism. The inverted mold design allows concrete to self-compact under its own weight as it fills from the bottom up, eliminating the need for noisy vibrating needles or mold vibration equipment while still achieving proper concrete densification
4Manufacturing precision
If multiple smoothing and coating operations are performed to conceal air bubbles, then aesthetic appearance is improved, but production time and costs increase significantly
Solution Approach 1:
The inverted mold with vent is configured before pouring to prevent air bubble formation on the functional surface in the first place. This preliminary preventive measure eliminates the need for subsequent smoothing and coating operations to conceal bubbles, significantly reducing production time and costs while maintaining aesthetic appearance
Solution Approach 2:
The vent, which could be seen as an additional component, actually benefits the process by providing a dedicated escape path for air bubbles. This converts the potential harm of trapped bubbles into a beneficial outcome where bubbles are systematically removed, eliminating the need for time-consuming corrective finishing operations
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 significantly reduces air bubbles at functional surfaces, simplifies the production process, enhances safety, and lowers costs by eliminating the need for additional coatings, while ensuring a robust finish resistant to wear and cracking.
Implementation Method 1
injecting into the volume defined by the two molds respectively lower and upper, and from the lower base of said volume, self-compacting concrete until the entire volume is filled
Implementation Method 2
the entire mold is inclined, typically at an angle of between 3 and 25 degrees to the horizontal, during the concrete pouring operation
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
This process employs a closed mold composed of a lower mold (2) and an upper mold or cover (3, 4) defining between them a volume intended to be filled with concrete, consisting of: ▪ installing the lower mold (2) intended, ultimately, to define said at least one horizontal flat surface; ▪ positioning the upper mold or cover (3, 4) opposite said lower mold (2), and fixing it onto said lower mold; ▪ injecting self-compacting concrete into the volume defined by the two molds respectively lower and upper, and from the lower base of said volume, until the entire volume is filled; ▪ after the concrete has set, removing the upper mold and the lower mold, and thus demolding the three-dimensional concrete structure or part of a structure;then to turn over the structure or part of the structure thus obtained, in order to have at least one horizontal flat surface in the operational position, that is to say in the upper position when said structure is erected in place on site.;