Cementitious Roof Tile Casting with Disposable Liners
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Solution Overview
Problem
Current methods for manufacturing concrete roof tiles, such as extrusion and casting, fail to produce tiles with both flexible shapes and weather-resistant surface coatings, due to issues like rough surfaces, release agent residues, and poor adhesion of coatings.
Innovation Solution
A method involving the admixing of a cementitious composition with water, sand, pigment, reactive fine filler, cement, and additives, followed by curing, surface preparation, and application of a primer and subsequent coatings, utilizing a plant with mixing, moulding, curing, and coating zones to achieve smooth, durable, and aesthetically appealing surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If extrusion method is used to manufacture roof tiles, then production efficiency is improved, but surface quality deteriorates (rough surface) and shape flexibility is limited
Solution Approach 1:
The patent changes the fundamental manufacturing parameter from extrusion to casting method, allowing the concrete mixture to be poured into moulds where it sets and cures. This parameter change enables smooth surface quality matching the mould interior while maintaining production efficiency through continuous casting processes
Solution Approach 2:
The casting method uses moulds as templates to copy the desired tile shape and surface finish. The mould interior surface serves as a master pattern that is replicated onto the tile surface during curing, achieving consistent high-quality surface finishes without the roughness inherent in extrusion
2Manufacturing precision
If re-usable moulds are used in casting process, then surface quality is improved (smoother surface), but manufacturing complexity increases (cleaning and release agent application)
Solution Approach 1:
The patent employs disposable liners made of release paper or similar materials that are placed inside re-usable moulds. These liners prevent concrete adhesion, eliminate the need for complex cleaning operations, and can be easily replaced between production cycles, reducing mould maintenance complexity while preserving surface smoothness
Solution Approach 2:
The patent introduces an intermediary release agent or release paper between the mould surface and the concrete mixture. This intermediary layer prevents direct adhesion of concrete to the mould, facilitating easy demoulding and eliminating the need for extensive cleaning operations while maintaining the smooth surface quality provided by the mould
3Ease of operation
If re-usable moulds with release agent are used, then de-moulding is facilitated, but coating adhesion deteriorates (release agent prevents proper adhesion)
Solution Approach 1:
The patent extracts the release function from the mould surface itself by using disposable liners or release papers. This separation allows the mould to maintain its smooth surface for high-quality tile finishing while the liner handles the release function, preventing release agent residues that would interfere with subsequent coating adhesion
Solution Approach 2:
By using disposable liners instead of reusable release agents, the patent eliminates the problem of release agent residues on the tile surface. The liners are removed with the tile, taking any potential adhesion-interfering substances away, thereby ensuring proper coating adhesion while still facilitating easy demoulding
4Ease of manufacture
If lost moulds made from aggregated material are used, then mould handling is simplified, but surface quality deteriorates (rough surface requiring coating)
Solution Approach 1:
The patent uses smooth interior surfaces of re-usable moulds as master patterns to copy the desired tile surface finish. This copying process transfers the smooth mould surface characteristics to the tile, producing high-quality surface finishes without requiring complex mould handling procedures
Data Source
AI summary
A plant and method for the manufacture of cementitious products, viz. cast concrete roof tiles (T), the plant comprising a mixing station (2) where the constituents of a cementitious composition, less an air entraining agent, are admixed under atmospheric pressure and further mixed under a partial vacuum of 200 to 340 mBar after the addition of an air entraining agent, the plant also comprising a molding station (4) where the tiles (T) are cast in a gang-mold (6) before being cured in a conventional autoclave for up to 10 hours at 45 degrees C. The cured concrete roof tiles (T) are de-molded after curing and conveyed to a surface preparation zone (12) where a primer coat of a water based epoxy and a surface coating of a water based emulsion paint are applied to at least an upper surface in use of the cast concrete roof tiles (T). The admixed cementitious composition has a Ford Cup flow of between 40 and 60 seconds and a slump test of between 180 and 220 mm. In an alternative method, instead of applying a primer coat, the upper surfaces, in use, of the roof tiles T are subjected to abrasion by grit-blasting to remove a thin layer from the upper surfaces thereby facilitating the subsequent application thereto of a surface coating.