CS263289B1 - Complex additive for building materials - Google Patents

Abstract

Complex additive for building materials the solution comprises a sulfonated polycondensate urea with formaldehyde, oxidized starch with reactive aldehyde or / i carboxy groups, carboxymethylether starch, carboxymethylether of cellulose and urea and the ingredients that determine the additive affect the hydration reaction kinetics, rheological properties and mechanical-physical properties of building material. Ingredient it is suitable for the preparation of prefabricated dry building materials with inorganic binders, such as renders, sealants, casting and self-leveling materials, screeds, stucco or to prepare these materials in situ construction or construction parts. Perfect and fast solubility complex additives in water in a fraction of a minute does not require a delay to "settle" the building < mass after mixing with water and thus allows use of building materials in automated continuous mixing and coating applications facilities.

Description

The invention relates to a complex additive for building materials predominantly prefabricated with binder inorganic materials such as anhydrite, cement, gypsum, lime and mixtures thereof.

A number of additives which retard the setting and hardening of gypsum binders are known, in particular based on weak or poorly dissociated inorganic or organic acids and their salts, or complex or macromolecular natural or synthetic compounds.

Retention aids are also known, in particular based on cellulose or starch derivatives.

A disadvantage of these retarders is that their solutions behave predominantly as electrolytes due to dissociation in an aqueous medium. Electrolytes penetrate more easily into the porous substrate, thereby depleting the building material of process water, with subsequent accompanying phenomena such as shortening the pot life, lack of water in the boundary layer leading to deterioration or loss of adhesion. Easier penetration of the electrolyte into the porous substrate also reduces the effectiveness of the retention aids.

Conventional retention aids such as cellulose ethers, casein, dextrin, hydrolyzed starches affect the viscosity of the aqueous phase and hence the water retention in the building material depending on the pH of the aqueous phase, their swelling and dissolution in water is in most cases quite slow. For this purpose, mainly hydroxyethyl-, methylhydroxyethyl-, methylhydroxypropylcellulose with differently adjusted dissolution time is used abroad. The carboxymethylcellulose produced by us, which exhibits retention capacity, inhibits the hydration reaction of dehydrated calcium sulphate, i.e. anhydrite and gypsum, and is therefore not usable as a retention additive for these binders. Casein also commonly used as a retention additive for cementitious binder-based prefabricated building materials dissolves very slowly in water, the building material mixed with water requires retention and at a dose required for retention as well as hydrolyzed starches and dextrin slow down significantly (gypsum and anhydrite) inhibit the hydration reaction and also significantly reduce strength and increase contraction of the building material.

Plasticizing or liquefying additives are not all equally applicable. Phenolic polycondensates with aldehydes as well as ligninsulphonates with a greater or lesser proportion of halast carbohydrates have a negative effect on the kinetics of the hydration reaction over the entire hydration range and are selective in their desired effects for cement binders where their strongly retarding to inhibitory effect on binder based Calcium sulphate exhibits less strongly at temperatures above 15 ° C.

It is also known AO 257 517 by Chládek, Kodet, which solves this issue in a specific area of gypsum as a binder by optimizing the composition of a specially prepared complex additive, during preparation there are other products that synergize the effect of components.

The disadvantage of the complex additive formulated in this way is that it is specific for gypsum and already its use for building materials based on anhydrite (anhydrite XIX, as a binder) is excluded due to the significant retarding to inhibitory effect of trisodium phosphate and strong retarding effect of starch phosphoesters. The formation of voluminous salts of starch phosphates with calcium of the building material means a fairly rapid increase in thixotropy, advantageous for plaster or putty, disadvantageous for casting, self-leveling materials on both gypsum and anhydrite basis, all the more on the same cement-based compositions containing Another disadvantage of this formulation is the fact that in the alkaline area (building materials containing cement or lime or lime-contaminated gypsum fillers or excess lime neutralized by fluorine or phosphoric anhydride). or gypsum), the viscosity of the aqueous phase of both starch phosphates and oxidized starches decreases very significantly, thereby reducing water retention in the building material. Higher dosing has a negative effect on the mechanical properties of hardened building material. cracks.

The aforementioned disadvantages are overcome by the complex building additive according to the invention, which consists of 10 to 26 parts by weight of sulfonated urea polycondensate with formaldehyde, up to 40 parts by weight of oxidized starch containing at least 15% starch grains with reactive aldehyde and / or carboxy groups, 20 to 60% by weight. parts by weight of starch carboxymethylether, 4 to 17 parts by weight of cellulose carboxymethylether and 6 to 12 parts by weight of urea.

The complex additive may contain 0.1 to 4 parts by weight of a fungicidal and / or bactericidal additive, e.g. an organotin or boron compound.

In addition, the complex additive may enrich 30 to 57 parts by weight of phosphorone ester and / or phosphate ester of starch and / or salts of low dissociated inorganic acids and / or weak organic acids and / or salts thereof as gypsum solidification retardant, 100 to 500 parts by weight of salt and / or alkali anhydrite solidification catalysts, 15 to 65 parts by weight of liquefying additives, can be dispersed in an inert filler, e.g., limestone or calcium aluminosilicate having a free silica content of greater than 15%, and / or anchored on a porous aluminosilicate carrier and may also contain a dry redisper a dispersion in an amount of 0.3 to 2.5 times the weight of the sulfonated urea polycondensate with formaldehyde.

The complex additive according to the invention has a number of advantages in that its composition is chosen so that, for different types of binders or building materials, the individual desirable properties of the components do not deteriorate by mutual interaction. The preparation process eliminates the secondary cleavage of formaldehyde from plasticizers or liquids due to the pH of the building material, causing chemical binding of the components to each other and / or calcium of the building material, thereby causing a synergistic effect of the components. For example, the phosphate group of starch phosphesteres reacts with calcium and thus incorporates the structural starch grain into the binder cement structure. The interaction of the amino groups of the plasticizers and / or the liquid with the free (reactive) aldehyde- or carboxy groups of the oxidized starch forms a cross-linked sulfo-bonded product again on the calcium binder. Substitution of sodium in the sodium salt of carboxymethyl ether of starch and cellulose with calcium binder again results in chemical binding of the macromolecule to the binder. The negative effect of carboxymethylcellulose on the gypsum hydration reaction kinetics is utilized to synergize the effect of the starch phosphorus-carboxymethylcellulose combination to retard gypsum binder solidification. The formation of efflorescence of sodium salts contained in starch derivatives and emerging substitutions is successfully suppressed by urea (AO 252 105, Chládek), which also extends the workability of the binder or building material by the absence of rapid formation of voluminous flocculent or villous calcium salts of starch derivatives. but for the gradual formation of crystalline products. By the same mechanism, which prolongs the pot life, the rapid formation of similar voluminous salts of plasticizers or liquids with calcium is suppressed (AO 252 104, Chládek). The consequence of these processes is that the reduction in strength of building materials caused by the presence of macromolecular substances in the absence of urea is substantially less or zero. Tests have shown that optimum effects can be achieved! while maintaining the composition of the complex additive according to the invention and dosing the additive into the binder or the building material formed therefrom in the range of 0.5 to 6.5% by weight.

The specific composition and use of the complex additive is explained in more detail in several examples:

EXAMPLE 1 Gypsum binder, formed in a wet limestone scrubber of a thermal power plant, was prepared with a G5A III grade gypsum binder. From this gypsum binder, limestone flour up to 0.25 mm, calcium hydroxide and the complex additive, a dry prefabricated gravel sealant was prepared to compensate for the mixed masonry consisting of gas silicate, bricks, fittings and precast concrete. The deposited layer had a thickness of 3 to 10 mm.

The complex additive had the following composition:

Urea formaldehyde sulfonated polycondensate Starch carboxymethyl ether Cellulose carboxymethyl ether Oxidized starch Urea

Tartaric acid

Borax-acid mixture. boron (boronite) parts by weight 55 parts by weight parts by weight 12 parts by weight parts by weight parts by weight

The mass was applied to mixed masonry after mixing with water to a pasty consistency in an automatic mixing and spraying machine (Gipsomat G 78), flattened and smoothed with a trowel. Workability time on different substrates 35 to 50 minutes.

The resulting surface treatment had an adhesion to the base of 0.23 to 0.37 MPa, a tensile strength of 3.6 + 0.33 MPa, a bending tensile strength of about 1.2 MPa. Although mixed masonry had considerable unevenness, notches for wiring and joints were not discarded or repaired, there was no leakage or cracking even at 45 mm thickness.

Example 2

A dry prefabricated mass consisting of cement of class 400, limestone flour, sintrocorundum grit, crushed silicon carbide, quartz sand and a complex additive was prepared for the surface treatment of the floor with increased abrasion resistance:

Sulphonated urea-formaldehyde polycondensate Sulmonated melamine-formaldehyde polycondensate Starch carboxymethylether Cellulose carboxymethylether Oxidized starch Urea

Fungi- and mycocidal ingredients

20 May % by weight parts 30 % by weight parts 20 May % by weight parts 5 % by weight parts 25 % by weight parts 10 % by weight parts

weight parts

At the construction site, the premix was mixed with water at a ratio of 74:26 to 30 parts by weight, and pumped in a creamy consistency immediately after mixing, pumped to a wet concrete floor with an average thickness of 8 mm to form a surface.

After 28 days, the coating had the following characteristics:

Adhesion to the substrate Compressive strength Abrasion (DIN 52 108)

0.57 + 0.037 MPa 35 to 43 MPa

3.6 to 4.4 cm ^{3/50 cm2}

Example 3

Dry blending of 40 parts by weight of a G 2 s II gypsum binder, 50 parts by weight of dry sand of grain size up to 0.5 mm with 10 parts by weight of a complex additive containing 15% by weight and 85% by weight calcium aluminosilicate was prepared. gypsum plaster. The active ingredient content of the complex additive was as follows:

Starch phosphorus ester Sulfonated urea polycondensate with formaldehyde Oxidized starch

Starch carboxymethyl ether parts by weight parts by weight 19 parts by weight 18 parts by weight

263789

Cellulose carboxymethyl ether Urea

Sodium phosphate

Fungicidal additive (Lastanox) parts by weight 8 parts by weight 5 parts by weight 0.15 parts by weight

This plaster was mixed on site with 7: 3 water with water to a slightly pasty mass. After being applied to a precast concrete substrate with an average thickness of 5 mm, it had a pot life of 75 minutes, a setting time of 90 minutes, a setting time of 110 minutes. The mortar samples taken for testing showed a compressive strength of 3.87 MPa on the beam and 4.15 MPa on the plaster cut-out. The adhesion test on the untreated surface of the prefabricates showed a adhesion of 0.33 ± 0.07 MPa, on the prefabricated surface treated with an adhesive interlayer of 0.56 ± 0.05 MPa.

The parallel test of render without complex additive showed the following values:

Workability 2.5 minutes, start of setting 6 minutes, end of setting 11 minutes, compressive strength on beam 5 ', 53 MPa, on plaster cut-out 1.12 MPa, adhesion less than 0.02 MPa, but mostly not measurable.

Example 4

Dry prefabricated was prepared plaster mixture consisting of lime, cement, limestone grit 0 to 4 mm and complex additives that had this composition; Sulfonated polycondensate urea formaldehyde 26 wt parts Oxidized starch 40 wt parts Starch carboxymethyl ether 60 wt parts Cellulose carboxymethyl ether 17 wt parts Urea 10 wt parts The compound was under the same conditions prepared plaster of the same composition without complex additives for comparative tests. Results Testing for mortar spray consistency: without additive with an additive Adhesion to brick MPa 0.17 0.31 of concrete MPa 0.09 0.22 Siporex MPa 0.14 0.32 Dry density kg.m ^-3 1,723 1,487 Compressive strength MPa 1.32 2.21 bending tension MPa 0.62 1.12 Flow rate in the layer above mm 14 32 Cracks at you. 10 mm Yes No

EXAMPLE 5 Lightweight gypsum ceilings formed from a mixture of G5-II gypsum binder and diatomaceous earth in a 2: 1 ratio by weight and a complex additive of the composition given in Example 3, supplemented with a flowing component of sulfonated melamine-formaldehyde. parts by weight of the complex additive at a dose of 2.25 parts by weight of the mixture, mixed with water in a weight ratio of 5: 3, were cast into separate silicone molds after 20 minutes of foaming of the prepared suspension.

The start of solidification of the thus prepared mass was 35 minutes, the end and drying of the gypsum views had a density of 476 + 11 1.95 + 0.18 MPa, a flexural tensile strength of 1.23 + 0.2 MPa.

solidification 55 minutes. After molding-3 kg.m, compressive strength

Example 6

For additional thermal insulation of the building it was decided to use lightweight plaster gypsum plaster. Prior to application on site, a dry premix was prepared in the mixer consisting of 62 parts by weight of gypsum binder G 5 Β II, 36.5 parts by weight of expanded perlite and 1.5 parts by weight of a complex additive, which was mixed with water at the site 1: 1,2. The lightweight mortar thus prepared was sprayed onto a concrete substrate treated with an adhesive bridge.

The complex additive was formulated as follows:

Starch phosphorone ester Sulphonated urea-formaldehyde polycondensate Oxidized starch Starch carboxymethyl ether Cellulose carboxymethylether Ammonium phosphate secondary Fungicidal additive parts by weight parts by weight 13 parts by weight 13 parts by weight parts by weight 4 parts by weight 1,5 parts by weight

The base was masonry consisting of precast concrete and brick fittings, plaster thickness of 4 to 5 cm in a single-layer design. After comparison and setting, the plaster thus formed was smoothed with a steel trowel.

Pot life 160 minutes, setting time 180 minutes, setting time 210 minutes. Plaster compressive strength 1,3 MPa, density 380 + 7 kg.m ”^, thermal conductivity coefficient 0,06 + 0,004 W.m. ° K, adhesion greater than 0,23 MPa (failure in render).

Example 7

A dry prefabricated gypsum sealant with the following composition was prepared for cementing masonry from precast concrete under the wallpaper:

Gypsum binder G 2 Β II

Dust from crushed limestone up to 0.125 mm Complex addition of parts by weight 56 parts by weight parts

At the construction site, the dry premix was mixed with water in a 2: 1 weight ratio.

The complex additive had this composition

Mixture of starch phosphors

Sulphonated urea-formaldehyde polycondensate

Oxidized starch

Starch carboxymethyl ether

Cellulose carboxymethyl ether

Urea

Sodium phosphate

Tartaric acid

Mixture of fungicidal and bactericidal additive (BORONIT) parts by weight parts by weight 17 parts by weight 17 parts by weight parts by weight 6 parts by weight 0.33 parts by weight 5.8 parts by weight parts by weight

Workability of the sealant on the precast concrete 50 minutes, the setting time 105 minutes. The gluing of the wallpaper started 3 hours after bonding.

Example

To compensate for unevenness of the floor face of the ceiling prefabricates in the range of 5 to 15 mm, a dry prefabricated anhydrite mass with the following composition was prepared:

Ground Fluorohydride 62 parts by weight

Finely ground limestone class IV / 6 33 parts by weight

Complex additive 5 parts by weight

At the construction site, the dry premix was continuously mixed with water in a 7: 3 weight ratio and pumped to the floor face of the ceiling structure where the creamy liquid formed a smooth and leveled surface.

The complex additive had this composition

Sulphonated urea-formaldehyde polycondensate

Sulfonated melamine formaldehyde polycondensate

Oxidized starch

Starch carboxymethyl ether

Cellulose carboxymethyl ether

Salt solidification catalyst mixture Urea parts by weight parts by weight 33 parts by weight 38 parts by weight parts by weight 205 parts by weight 12 parts by weight

The flow rate of the self-leveling leveling compound was 0 _fe > 24 cm, maintained for a minimum of 30 minutes, and the mass solidified after 16 hotspins at 18 + 5 ° C. After a week, a compressive strength of 27 to 35 MPa was achieved, adhesion to the substrate of 1.45 + 0.15 MPa.

Example 9

A dry prefabricated building material consisting of cement class 400 as a binder, quartz sand 1.6 / 3.15 mm, amberphide silicon carbide 0/4 mm, sintered corundum grit and cast iron scrap was prepared for surface treatment of the concrete floor in the production hall of the heavy engineering plant. 0/2 mm and complex additives.

The prefabricated material was spread on just wilted concrete, containing liquid, after wetting with rising damp, spread and smoothed with a rotary trowel and combed with asphalt brushes to expose the anti-abrasive grains.

The complex additive had this composition

Sulphonated urea formaldehyde polycondensate

Sulfonated melamine formaldehyde polycondensate

Starch carboxymethyl ether

Cellulose carboxymethyl ether

Oxidized starch

Urea

Redispersible dry dispersion of organic copolymers

10 parts by weight 60 % by weight parts 20 May % by weight parts 4 weight parts 10 % by weight parts 6 % by weight parts 25 % by weight parts

Samples taken from this mass for testing showed the following mechanical-physical properties:

Compressive strength + 3.5 MPa

Bending strength 21 + 2.3 MPa

Abrasion (DIN 52 108) 1,3 cm ^ .50 citT ^

Coherence with the substrate higher than 2.5 MPa (above the instrument range).

The complex additive according to the invention can be advantageously used for the preparation of plaster and temples based on inorganic binders, in the presence of liquid and casting of gypsum products throughout the cross-section homogeneous with perfect surfaces and absorbent compressive strengths and more than double flexural tensile strength against pure gypsum binder . Another field of application is the preparation of building materials on an anhydrite or cement basis as self-leveling liquid screeds.

Claims (1)

Complex additive for building materials, predominantly prefabricated, based on inorganic binders such as anhydride, cement, gypsum, lime and / or a combination thereof, which may contain fungicidal, mycocidal and bactericidal components, substances affecting hydration reaction kinetics, liquids, redispersible dry dispersions organic polymers or copolymers may be dispersed in an excess of inert filler or anchored on an inert or / or reactive carrier, characterized in that it consists of 10 to 26 parts by weight of sulfonated urea polycondensate with formaldehyde, 10 to 40 parts by weight of oxidized starch containing at least 15% by weight of starch grains having reactive aldehyde and / or carboxy groups, 20 to 60 parts by weight of carboxymethyl ether of starch, 3 to 17 parts by weight of carboxymethyl ether of cellulose and 6 to 12 parts by weight of urea.