CS205323B1 - Compound for manufacture of internal hydrophobized building material - Google Patents

Description

The invention relates to a composition for the production of an internally hydrophobized building material, in particular based on cement, lime, gypsum, anhydrite and combinations thereof comprising aqueous dispersions of cromolecular material with dispersed metal soaps.

Up to now, paraffin emulsion or oil based additives have been used for the internal hydrophobization of building materials, metal soaps dispersed in the mass by vigorous mixing, silicone preparations, finely ground substances with hydraulic properties capable of chemical reaction with calcium hydrate, etc. Paraffin emulsions or oils have a temporary effect and usually As a result of further exposure to moisture, metal soaps dispersed in the mass increase the pore volume due to the increase in the water number, reduce the mechanical strength and density of the composition. When exposed to moisture, they become washed out over time and the hydrophobic effect decreases. Silicone formulations are effective, but require special manufacturing equipment and technologically demanding processing. Additives with hydraulic properties permanently increase the hydrophobicity of building materials, but do not have general applicability, they are particularly suitable for some types of cement-bound materials. Surface hydrophobization of building materials has a temporary effect and is used to improve hydrophobic properties at an early stage of operation. Melted metal soaps dispersed using surfactants give better properties. This method has the disadvantage of having to disperse the mixture in concrete, mortar or plaster, which causes technological problems on construction sites.

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20S 323

The above-mentioned drawbacks are overcome by the internal hydrophobized composition according to the invention, which contains metal soaps having a specific surface area greater than 10 cm @ ² g @ -1 in aqueous dispersions of macromolecular substances. Particularly fine dispersions of metal soap in the dispersion system can be achieved by using surfactants operating in the hydrophilic region (HLB 8 to 18). The modified dispersions are added to the mixing water for the treatment of building materials such as cement, lime, gypsum, anhydrite, or a combination thereof in conjunction with fillers and modifiers and correction additives, and upon completion of the reaction, a permanently hydrophobic effect homogeneous throughout the material. The modified dispersion reduces the water number and thus reduces the total pore volume and achieves high mechanical strength. At the same time, the processability is facilitated, the capillary activity is improved, and the cohesion and adhesion properties of the building materials are increased. The hydrophobic properties of building materials eliminate the tendency of the macromolecules of the substance to alkaline hydrolysis, which takes place not only on the surface, but also due to the presence of pores and capillaries inside the mass. Internal hydrophobization causes increased surface tension of water throughout the mass and water in cement mineral gels as well as the remaining water in other building materials is dispersed into microscopically small droplets isolated from each other.

Examples

1. To 25 parts of SPC 250 cement and 75 parts of gravel sand 17.5 parts of water containing 2.5 parts of a water dispersion of styrene acrylate with a dry matter content of 50% by weight and 0.1 parts of calcium stearate with a specific surface area of 10 cm and g are added. % Of sodium dinaphthyl methane disulfonate all in parts by weight. After homogenization, the mixture is used as insulating concrete in a permanently wet environment. The concrete mixture without the addition of calcium stearate of said composition has a compressive strength of 25.0 MPa, a tensile strength of 1.8 MPa, an absorbency of 8% by weight,

2—1

An analogous mixture with the addition of calcium stearate having a specific surface area of 10 ^J cm g mixed into the mixture by vigorous stirring has a compressive strength of 22.0 MPa, a tensile strength of 1.4 MPa and a water absorption of 6.3% by weight. The composition of the example has a compressive strength of 32 MPa, a tensile strength of 2.4 MPa and a water absorption of 0.08% by weight,

2. 75 parts of gypsum and 25 parts of sand with a grain size up to 1.6 mm were added 42 parts of water dispersion of polyvinyl acetate having a solids content of 40 wt.%, Which are dispersed in 3.4 parts of zinc stearate having a specific surface of this 14 cm @ ² g @ and 1.7 parts by weight of an aqueous solution of potassium palmitate of 80% by weight. and 0.8 parts of exyetylated castor oil, all in parts by weight. The gypsum mixture is used to cast architectural elements for outdoor use. The water absorption after curing is 0% by weight. and the mechanical strengths are higher by 270% against gypsum without the addition of the dispersion mixture according to the example, but with the addition of the same amount of dispersion,

3. To 25 parts of a cement-lime mixture (1: 4 by weight) was added 3.0 parts of an aqueous dispersion of butyl acrylate-butyl methacrylate with a dry matter content of 45% by weight. and 0.2 parts of calcium stearate having a specific surface area of 12 cm @ ³ , 0.03 parts of sodium propylbenzenesulfonate and 0.05 parts of an aqueous solution of sodium palmitate having a dry weight of 60% by weight, all in parts by weight. After setting, the mixture is used as an insulating render and has a water absorption below 1.0% by weight.

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4. Κ 85 parts of anhydrite, 15 parts of ground chalk and 2 parts of dibutylnaphthalenesulphonate sodium add 8.5 parts of a 60% by weight aqueous dispersion of vinyl acetate-acrylate copolymer containing 0,3 parts of calcium stearate with a specific surface area of 10 cm and 15 g a part of water, all in mass parts. After homogenization, the mixture is used as a casting flooring which, after setting, has a water absorption of 0.2% by weight, low abrasion and high mechanical strength.

Experimentally, it has been found that as the specific surface area of the metal soaps increases, a non-linear decrease in water absorption occurs. cement flooring with cement composition:

: sand 1: 3 wt. have the following properties after processing according to the invention. Per 100 wt. 20 parts by weight of cement-sand mixture are used. parts by weight of water, 2.5 wt. % by weight of an aqueous dispersion of styrene-2-ethylexyl acrylate having a dry weight of 55 wt. and 0.04 wt. parts of sodium dinaphthyl methane disulfonate. Absorption of cement mortar beams after 24 hours of storage in water in mass. The% dependence on the specific surface area of the stearate is given in the following table:

Zinc stearate, 2 - 1 wt. parts Merny stearate surface cm g

per 100 wt. parts of the mixture 10 ² 10 ³ 10 ⁴ 10 ⁵ ID ⁶ 0.10 7.3% 6.8 6.1 0.08 0.06 0.15 7.1 6.2 5.5 0.07 0.06 0.20 6.8 5.4 4.7 0.04 0.03 0.25 6.2 4.6 2.9 0.01 0.01

The internally hydrophobised building materials can be used as waterproofing materials, as external and internal renderings, as joint sealants for building prefabricates, etc.

Claims (2)

SUBJECT OF THE INVENTION A composition for the production of an internally hydrophobised building material, in particular based on cement, lime, gypsum, anhydrite and combinations thereof, which may contain fillers and modifying additives such as plasticizers, aerators, solidification and retention regulators, characterized in that the mixing water contains aqueous dispersions % of macromolecular substances having dispersed Δ 2 5 2 - 1 metal soaps with a specific surface area above 10 cm g, preferably 10 cm cm in an amount of 5.0 to 22.0% by weight; due to the dry matter of the water dispersion of macromolecules! and the amount of dispersion is 2.0 to 30 wt. dry matter to binder content. 2. A composition according to claim 1, wherein the solid metal soaps are stearates, e.g. calcium, zinc or magnesium stearate.