RU2765620C1 - Dry plaster mix - Google Patents

Abstract

FIELD: building materials.

SUBSTANCE: invention relates to the field of building materials, in particular, to the production of dry building mixtures for finishing works using continuously operating mixing pumps. To achieve the specified effect, in addition to the main components of gypsum, light aggregate - perlite, limestone flour, lime, setting retarder - tartaric acid, cellulose ether, air-entraining additive, starch ether, additionally fractionated quartz sand with a particle size of up to 0.4 mm and palygorsk clay of the Melzansky deposit with the following ratio of the components of the mixture.

EFFECT: obtaining a dry plaster mixture with high adhesion of its mortar and an extended setting time of the mortar, which can be used for plastering walls using continuously operating mixing machines.

1 cl, 3 tbl

Description

The invention relates to the field of building materials, in particular, to the production of dry building mixes for the production of finishing works using continuously operating mixing pumps.

Known gypsum mixture according to the patent of the Russian Federation No. 2090533, including semi-aqueous gypsum and the addition of alkaline effluents from the production of caprolactam based on dicarboxylic acids SCHSPK, it additionally contains a polydentate chelating ligand and trisodium phosphate in the following ratio, wt.%: semi-aqueous gypsum 47-72; addition of alkaline effluents from the production of caprolactam based on dicarboxylic acids SchSPK 0.2-0.8; polydentate chelating ligand 0.03-0.15; trisodium phosphate 0.05-0.1; water is the rest.

The described composition has the following disadvantages: the stability of the existence of the composition due to its aqueous emulsion state is limited, the resulting coating has a low adhesive strength, and, therefore, is of little use for plastering walls using continuously operating mixing pumps.

A dry gypsum plaster mixture is known, which contains a gypsum binder, sand from expanded vermiculite, lime, a moderator - citric acid, cellulose ether in the form of carboxymethyl cellulose, an air-entraining additive - sulfonic acid, a superplasticizer (KZ patent No. 11511).

The disadvantage of this composition is that it does not provide high adhesive characteristics.

The closest analogue in terms of technical essence and the achieved result (prototype) is a dry plaster mixture (RF patent No. 2237035), which can be used for plastering walls using continuously operating mixing pumps. To achieve the specified technical result, the dry plaster mixture includes gypsum, lime, retarder, cellulose ether, an air-entraining additive, additionally contains perlite, limestone flour, technical sodium tripolyphosphate, redispersed latex powder and starch ether in the following ratio of components, wt.%: gypsum - 90- 92; lime - 1.2-1.5; moderator - 0.035-0.045; cellulose ether - 0.13-0.16; air-entraining additive - 0.008-0.015; perlite - 2.5-3.1; limestone flour - 4.0-5.0; technical sodium tripolyphosphate - 0.04-0.045; redispersed latex powder - 0.018-0.03; starch ether - 0.09-0.1.

The prototype is characterized by insufficiently high adhesion of the plaster solution and a short setting time.

The technical result of the claimed invention is the production of a dry plaster mixture with high adhesion of its solution and an extended mortar setting time, which can be used for plastering walls using continuously operating mixing machines.

To achieve the specified technical result, the dry plaster mixture includes semi-aqueous gypsum, light aggregate - perlite, limestone flour, lime, cellulose ether, starch ether, air-entraining additive, setting retarder - tartaric acid, and additionally, fractionated quartz sand with a particle size of up to 0.4 is introduced into the composition. mm and palygorskite clay of the Melzanskoye deposit in the following ratio of the mixture components, wt.%:

gypsum semi-aqueous 49.03-51.07 perlite 1.00-1.20 limestone flour 0.00-11.00 hydrated lime 3.50-3.60 cellulose ether 0.18-0.20 starch ester 0.02-0.03 air-entraining agent 0.01 setting retarder - tartaric acid 0.02-0.03 graded quartz sand 34.00-35.00 palygorskite clay 0.04-0.06

Semi-aqueous gypsum from the Arakcha gypsum plant was used as a gypsum binder.

As a filler, fractionated quartz sand (up to 0.4 mm) and limestone flour were used.

As a water-retaining additive - cellulose ether (hydroxyethyl methylcellulose).

As a setting retarder - tartaric acid.

As a co-binder - hydrated lime.

As an air-entraining additive - an anionic surfactant "Ufapore TCO", manufactured by the company "Unger", Norway, which contains alpha-olefin sodium sulfonate as an active substance, and the content of the active substance is 92%. [https://www.unger.no/functional-materials/applications/construction/mortars-plaster/]

As a light aggregate - perlite.

As a rheological additive - starch ether.

As a special rheological additive - palygorskite clay of the Melzanskoye deposit.

The palygorskite clay of the Melzanskoye deposit is distinguished by a peculiar chemical composition, in particular, a low content of silica and a high content of calcium and magnesium. The composition of palygorskite clay is shown in Table 1.

The content of trace elements was determined by spectral semi-quantitative analysis. Elements such as arsenic, scandium, phosphorus, tin, niobium, tungsten, germanium, cadmium, silver, cobalt were not detected by this method.

One of the main physical and chemical properties of palygorskite rocks, which determine their quality and possible areas of application, are: granulometric composition, content of natural radionuclides and toxic elements.

It has been established that palygorskite microcrystals make up the bulk of this clay, have a high degree of dispersion, and have an acicular-lamellar habitus. According to the granulometric composition, palygorskite clay of the Melzanskoe deposit belongs to highly dispersed systems containing more than 80% of particles less than 0.01 mm, including more than 60% - less than 0.001 mm. According to the results of the performed radiation assessment, the palygorskite clay of the Melzanskoye deposit can be assigned to the first class and used in all types of construction. The content of toxic elements (fluorine, arsenic, lead, mercury, cadmium, benzopyrene, etc.) in palygorskite clays does not exceed the permissible concentrations given in the technical specifications for zeolite raw materials used for feeding birds and animals.

Dry plaster mixture according to the invention is obtained by mixing all the constituent components in an industrial mixer. The composition of the mixture fully provides the specified properties. The components and content of the components of the claimed composition, control composition No. 1 (without the addition of palygorskite clay) and control composition No. 2 (according to the prototype) are shown in table 2.

The proposed dry plaster mixture was tested at construction sites for plastering walls using continuously operating mixing machines. To prepare the plaster mortar, the dry mixture is poured into the hopper of the plastering machine and the required water flow is set to obtain the required mortar consistency. The recommended ratio is 0.4-0.45 l/kg of the mixture. The resulting solution is applied in one layer with a thickness of 30 mm to 45 mm, leveled using a rule with a preliminary installation of beacons. After the start of setting, the surface of the laid plaster is rubbed with a grater with a polymer or rubber coating for final leveling.

Technological indicators of the claimed composition, control composition No. 1 (without the addition of palygorskite clay) and control composition No. 2 according to the prototype are shown in table 3.

As can be seen from table 3, the claimed composition showed an extended setting time with a higher adhesive strength. Control sample No. 1, where there is no addition of palygorskite clay, showed lower results. As for the prototype (control sample No. 2), its suitability as a plaster composition for machine application is questionable. The determining indicators when using plaster compositions when feeding them with the help of continuously operating mixing machines are the mobility of the mortar mixture after mixing and its setting time. According to the standards for machine-applied gypsum plaster, the setting time of the solution must be at least 90 minutes (GOST 31377-2008). However, the prototype only has 80 minutes. The mobility of the resulting solution is not indicated at all. In addition, in terms of technological indicators, the prototype does not have very important for plaster solutions: water-holding capacity, crack resistance, the volume of air involved. It can be assumed that the developer of the composition did not determine these indicators at all.

The obtained higher strength characteristics of the prototype are not necessary in this case, because according to the standards in accordance with GOST 31377-2008 (clause 4.6.2 and clause 4.6.3), they are normalized as follows: adhesive strength during mechanical separation is not less than 5 kg / cm ² (not less than 0.3 MPa), compressive strength is not less than 25 kg/cm ² (not less than 2.0 MPa).

It should be noted an important fact that speaks of the unconditional advantage of the plaster composition we offer. Due to the needle-lamellar structure and granulometric composition of the palygorskite clay of the Melzanskoe deposit, the friction of the particles of the gypsum plaster solution against the walls of the hoses of continuously operating mixing machines is reduced. This allows you to significantly increase the efficiency of their work in the process of plastering.

The mixture does not release harmful chemicals into the environment and belongs to class 1 in terms of the specific activity of natural radionuclides.

The proposed composition has the following advantages:

- high non-delaminability of the resulting dry plaster solution due to the high water-holding capacity of 98-99%, and the delamination index is not more than 1-2%. Due to this, this mortar mixture practically does not separate water during the entire period of hardening and does not give water to the base on which it is applied, which creates a favorable moisture regime for the hardening of the binder;

- convenient setting time (life resistance) of the gypsum mixture solution, which is expressed in sufficient mobility during its processing in a plastering machine and application to the surface to be plastered, the possibility of leveling and smoothing the plaster solution on the surface;

- the presence of palygorskite clay in this dry mixture gives it special mobility, high plasticity and the ability to adhere more firmly to the treated surface.

Thus, according to this invention, a dry mix based on gypsum with additives with enhanced adhesion, increased mobility, plasticity, workability with an extended setting time was obtained, which can be used for plastering walls using continuously operating plastering machines, can also be used if necessary for manual application. The use of this gypsum mixture allows you to get a smooth surface without additional puttying of the walls.

Claims (2)

Dry plaster mixture, including semi-aqueous gypsum, light aggregate - perlite, limestone flour, lime, cellulose ether, starch ether, air-entraining additive, setting retarder - tartaric acid, characterized in that an anionic surfactant "Ufapore TCO" is used as an air-entraining additive ”, as lime - hydrated lime and additionally the mixture contains fractionated quartz sand with a particle size of up to 0.4 mm and palygorskite clay of the Melzan deposit in the following ratio of the mixture components, wt.%: gypsum semi-aqueous 49.03-51.07 perlite 1.00-1.20 limestone flour 10.00-11.00 hydrated lime 3.50-3.60 cellulose ether 0.18-0.20 starch ester 0.02-0.03 specified air-entraining agent 0.01 wine acid 0.02-0.03 graded quartz sand 34.00-35.00 specified palygorskite clay 0.04-0.06