Multi-layer mineral lime plaster system based on lime

Abstract

(Main claim) 1. Multi-layer mineral plaster system, characterized in that it comprises: a) a base coat based on a hydraulic lime binder containing at least one pozzolanic additive, b) a first treatment of the base coat with an aqueous alkali silicate solution, applied after the base coat has set, for partial silicification and strengthening of the base coat surface, c) a fine plaster based on slaked lime, applied to the treated base coat and containing mineral aggregates and at least one zeolitic additive, d) a mechanical surface treatment of the fine plaster after it has set, e) and a second treatment of the fine plaster with an aqueous alkali silicate solution, applied after mechanical surface treatment, wherein the alkali silicate is not used as a film-forming binder, but serves to subsequently strengthen a porous, load-bearing mineral matrix.

Description

[0001] The present invention was developed by Niklas Rau. 1. Technical field

[0002] The invention relates to a multi-layered mineral plaster system based on lime.

[0003] In particular, the invention relates to a lime plaster system which provides a hardened, sandable and diffusion-open surface through a targeted combination of hydraulic lime base coat, zeolite-containing slaked lime fine coat, mechanical surface treatment and subsequent alkali silicate treatment. 2. State of the art

[0004] Current technologies include hydraulic lime plasters, slaked lime plasters, and silicate-based mineral coatings. Hydraulic lime plasters are often modified with pozzolanic additives, such as metakaolin, to influence the plaster's structural properties. Slaked lime plasters are used as finishing plasters to create vapor-permeable surfaces.

[0005] It is also known to treat mineral substrates with alkali silicate solutions, especially water glass solutions, to achieve silicification and surface hardening. Such treatments are used particularly in the field of silicate paints and silicate primers, where the alkali silicate serves as a film-forming or binding coating agent.

[0006] A disadvantage of known systems is that either only surface hardening occurs without a structure-forming effect, or that mineral plasters tend to surface abrasion during mechanical processing, especially grinding.

[0007] Furthermore, known systems lack a targeted combination of multi-layered structure, controlled pore structure, mechanical workability and permanent consolidation across multiple plaster layers. 3. Object of the invention

[0008] The invention is based on the objective of providing a mineral lime plaster system that • is mechanically machinable, in particular grindable, • exhibits reduced surface sanding, • an improved structural bond between multiple plaster layers enables, • remains open to diffusion, • can provide additional functional properties through porous additives, • and is clearly different from pure silicate coatings. 4. Solution to the task

[0009] The problem is solved by a multi-layered mineral plaster system according to claim 1.

[0010] The plaster system according to the invention comprises a base coat based on a hydraulic lime binder with at least one pozzolanic additive. After the base coat has set, a first treatment with an aqueous alkali silicate solution is carried out, resulting in partial silicification and hardening of the base coat surface.

[0011] A finishing plaster based on slaked lime, containing mineral aggregates and at least one zeolitic additive, is applied to the treated base coat. After the finishing plaster has set, its surface is mechanically treated, in particular by grinding, and then subjected to a second treatment with an aqueous alkali silicate solution.

[0012] The alkali silicate is not used as a film-forming binder, but serves as a subsequent functional agent to strengthen a porous, load-bearing mineral matrix. 5. Preferred embodiments 5.1 Flush mounting

[0013] The base coat is preferably based on a natural hydraulic lime binder. Metakaolin is preferably used as a pozzolanic additive, resulting in a denser microstructure of the base coat and improved interface compatibility with the subsequent finishing coat.

[0014] The plaster may contain further additives known to those skilled in the art, for example for rheology or processing control, without departing from the basic concept of the invention. 5.2 First alkali silicate treatment

[0015] After the base coat of plaster has set, it is treated with an aqueous alkali silicate solution. Preferably, this is a lithium silicate solution.

[0016] This treatment partially silicifies and mechanically strengthens the surface of the plaster without forming a closed coating or significantly closing the pore structure of the plaster.

[0017] In an optional embodiment, a mineral-based, silicifiable, and vapor-permeable primer can be applied to the substrate before the base coat. The alkali silicate treatment of the base coat can contribute to additional strengthening at the interface between the substrate, primer, and base coat. 5.3 Fine plaster

[0018] The fine plaster is based on slaked lime as a binder and contains mineral aggregates. Additionally, the fine plaster contains at least one zeolitic additive, preferably a natural zeolite, in particular clinoptilolite.

[0019] The zeolitic additive increases the internal surface area of ​​the fine plaster and contributes to the formation of a porous structure.

[0020] The fine plaster can also contain further fine-pored silicate aggregates, especially diatomaceous earth, which can further improve the specific surface area and the adsorptive properties of the plaster matrix.

[0021] The finishing plaster may additionally contain at least one porous, carbon-based adsorbent, in particular activated carbon in granular or powder form. The addition of activated carbon further increases the specific surface area of ​​the finishing plaster and improves its adsorption capacity against airborne organic compounds, with the activated carbon being embedded in the mineral matrix. 5.4 Mechanical surface treatment

[0022] After the fine plaster has set, its surface is mechanically treated. This mechanical treatment is preferably carried out by grinding.

[0023] Grinding is not merely for optical post-processing, but is a procedurally planned step for exposing mineral aggregates and for the targeted adjustment of the surface structure. 5.5 Second alkali silicate treatment

[0024] After mechanical surface treatment, the fine plaster surface is treated with an aqueous alkali silicate solution, preferably with a lithium water glass solution.

[0025] This second alkali silicate treatment strengthens the treated surface, reduces surface sanding and leads to partial silicification of the near-surface zone of the fine plaster, while maintaining the open porosity of the system.

[0026] In a further optional embodiment, the surface, hardened after the second alkali silicate treatment, can be mechanically processed again, in particular ground, and then treated once more with an aqueous alkali silicate solution. This can further enhance the exposure of the mineral aggregates and accentuate the surface appearance.

[0027] In a further optional embodiment, a lime wash, particularly in the form of a lime-wash coating, can be applied to the surface hardened after the alkali silicate treatment. The lime wash preferably serves to enhance the surface's appearance and forms a vapor-permeable, mineral-based finish without altering the fundamental structure and function of the plaster system. 6. Differentiation from silicate coatings

[0028] Unlike pure silicate paints or silicate coatings, the alkali silicate solution in the plaster system according to the invention is not used as a film-forming or primary binder.

[0029] Rather, the alkali silicate treatment is applied subsequently to strengthen an existing, porous, load-bearing plaster matrix. The alkali silicate treatment is specifically combined with mechanical surface treatment, which is not technically possible with silicate coatings. 7. Effects and Benefits

[0030] The combination according to the invention of hydraulic lime plaster, pozzolanic additive, zeolite- and optionally carbon-based fine plaster, mechanical surface treatment and repeated alkali silicate treatment results in the following advantages in particular: • reduced surface sanding, • improved mechanical strength of the surface, • improved interface stability between base coat and finish coat, • Preservation of water vapor diffusion capacity, • Porous surface structure with increased internal surface area.

[0031] The combination of porous additives and alkali silicate treatment also promotes the adsorption, binding and immobilizing fixation of airborne pollutants on the plaster surface. 8. Summary

[0032] The plaster system according to the invention is based on a combination of a hydraulically bound base coat, a pore-active fine coat and at least one subsequent alkali silicate treatment.

[0033] The combination of porous aggregates, mechanical surface treatment and subsequent silicification results in a solidified, diffusion-open and structurally bonded mineral plaster matrix with increased surface stability.