RU2309133C1 - Dry plaster mix for covering cellular concrete - Google Patents

Abstract

FIELD: manufacture of building materials.

SUBSTANCE: invention concerns binder-based mixes containing mineral aggregate used for plastering walls, preferably of cellular concrete. Dry plaster mix according to invention comprises, wt %: lime-cement binder 35.6-48.9, quartz sand 3.5-13.1, cellulose ether(ester) 0.07-0.13, adhesion agent (re-dispersible powder) 1.1-2, and porous aggregate in the form of cellular concrete manufacturing waste with particle size up to 5 mm, 44.4-51.2, which has multifractional composition: fraction 2.5-5 mm 17.2-32.0, fraction 1.25-2.5 mm 14.6-22.6, fraction 0.63-1.25 mm 11.2-15.8, fraction 0.315-0.63 11.3-13.7, fraction 0.14-0.315 mm 9.2-15.2, and fraction 0-0.14 mm 9.1-28,1. Above-mentioned re-dispersible powder in the dry mix is based on vinyl acetate, versatate , and acrylate monomers.

EFFECT: reduced average density of plaster, increased water-retention capacity, and enhanced adhesiveness for porous cellular-concrete.

2 cl, 1 dwg, 2 tbl

Description

The invention relates to the field of manufacture of building materials, in particular to mixtures based on binders and mineral aggregate, used for plastering walls mainly of cellular concrete.

A known dry mixture for the preparation of a light mortar [1], containing Portland cement, silica sand, expanded porous aggregate and a surfactant as a binder. The disadvantage of the mortar mixture prepared from this dry mixture is its low water-holding ability and low adhesion to the cellular concrete base. Significant loss of water from the contact layer and low initial adhesion contribute to poor adhesion of the solution to the porous base.

The closest in purpose and technical essence to the proposed invention is a dry mix for the preparation of aerated concrete plasters [2], including a lime-cement binder, silicon oxide in the form of sand with a particle size of up to 1.25 mm, and the weight of the fraction with particle sizes up to 0, 5 mm is 50-70% of the weight of sand, and additionally cellulose ethers and sodium soaps of resin acids in the following ratio of components of the dry mixture, wt.%:

lime-cement binder - 30-38;

specified sand - 60-70;

polyvinyl acetate - 0.6-1.1;

cellulose ether - 0.9-1.6;

sodium soaps of resin acids - 0-0.2.

The disadvantage of this mortar is a relatively high average density, insufficient water holding capacity and low rates of normal adhesion to a cellular-concrete base.

The objective of the invention is to reduce the average density of the solution, increase water retention capacity and increase adhesion to a porous cellular concrete base.

The problem is solved by the proposed dry mixture for plastering on cellular concrete, which contains lime-cement binder, quartz sand, cellulose ether, an adhesive additive and an additional porous aggregate from cellular concrete waste with a particle size of up to 5 mm, contains a redispersible powder as an adhesive additive in the following ratio of components of the dry mixture, wt.%:

lime-cement binder - 35.6-48.9;

quartz sand - 3.5-13.1;

said porous aggregate 44.4-51.2;

cellulose ether 0.07-0.13;

redispersible powder 1.1-2;

moreover, the porous aggregate from the waste products of cellular concrete has a polyfraction composition in the following ratio of fractions, wt.%:

fraction 2.5-5 mm - 17.2-32.0%;

fraction 1.25-2.5 mm - 14.6-22.6%,

fraction 0.63-1.25 mm - 11.2-15.8%,

fraction 0.315-0.63 mm - 11.3-13.7%,

fraction 0.14-0.315 mm - 9.2-15.2%,

fraction 0-0.14 mm - 9.1-28.1%.

The use of the proposed dry mixture of porous aggregate from the waste products of cellular concrete can significantly reduce the average density of the solution by replacing most of the dense quartz sand with porous. In addition, the composition of the porous aggregate contains a significant proportion (9.1-28.1%) of grain size less than 0.14 mm, which increases the water-holding capacity of the solution.

The proposed fractional composition of the porous aggregate from cellular concrete waste is optimal for increasing water retention capacity, increasing adhesion to a cellular concrete base and reducing the average density of the solution. The optimal fractional composition was established experimentally, for which the authors prepared and tested a number of mixtures with different ratios of fractions of the porous aggregate. As a result of tests, it was found that the solutions with the screening curves of the porous aggregate lie in a certain optimal range have the highest water-holding ability, adhesion to a cellular concrete base and the lowest average density. The optimal range of sieving curves is shown in the drawing.

The preparation of the stucco mortar from the dry mixture is as follows: the required amount of water is poured into a clean container to obtain the mobility of the solution P _k = 6-7 cm (400-450 ml of water per 1 kg of dry mixture). Water temperature t = + 5 ... + 25 ° С. Then the dry mixture is poured with constant stirring of the mass with a drill with a mixer nozzle, 250-300 rpm. Mixing is carried out until a homogeneous consistency is obtained. Then the solution is allowed to stand for 5-7 minutes to dissolve the cellulose ethers and redispersible powder. Then the solution is thoroughly mixed again, after which it is ready for use.

To verify the proposed dry mix, three compositions were prepared with different component ratios (see table 1).

Table 1.
The ratio of components in the dry mixture Name of components The content of components, wt.%. one 2 3 Lime and cement binder 35.6 42.3 48.9 Quartz sand 11.13 8.3 4,57 Aerated concrete fight: 51,2 47.8 44,4 fraction 2.5-5 mm - 17.2%; fraction 1.25-2.5 mm - 14.6%; fraction 0.63-1.25 mm - 11.2%; fraction 0.315-0.63 mm - 13.7%; fraction 0.14-0.315 mm - 15.2%; fraction 0-0.14 mm - 28.1%. Cellulose ether 0,07 0.10 0.13 Redispersible powder 2 1,5 2.0

The specified dry mixture contains a redispersible powder based on monomers of vinyl acetate, versatate and acrylate, as well as, for example, based on monomers of vinyl acetate, vinyl versatate and ethylene based on monomers of vinyl acetate and acrylate.

The prepared solutions were tested to determine the water-holding ability of the mixtures, the average density of the hardened mortar, the adhesion to a foam concrete and aerated concrete base and, in addition, the coefficient of structural quality in terms of adhesion strength of CCC _sc , taking into account the positive effect of reduced density and increased bonding strength: CCC _sc = R _sc / ρ ² , where R _sc - the adhesion strength of the solution with a cellular concrete base, kgf / cm ² ; ρ is the average density of the solution, t / m ³ .

To determine the same properties of the solution from the dry mixture of the prototype, a solution was prepared and tested in accordance with the prototype [2]. The test results are shown in table 2.

table 2
Physico-technical indicators of plaster mortars The name of indicators Compositions one 2 3 Prototype The average density, kg / m ³ 800 900 1000 1550 Water retention capacity,% 98.3 99.0 99.5 98.0 The strength of adhesion with a porous base, kgf / cm ² : on aerated concrete 4.6 5.1 6 4,5 on foam concrete 4.3 4.8 5,4 4.2 Coefficient of structural quality in terms of adhesion, CCC _sc : on aerated concrete 7.19 6.30 6.00 1.87 on foam concrete 6.72 5.93 5.40 1.75

From the table it follows that the average density of the solutions of the proposed compositions is in the range of 800-1000 kg / m ³ , while the average density of the prototype is about 1550 kg / m ³ , which is 1.55-1.94 times higher. In this case, the water-holding ability and adhesion to a cellular concrete base of the claimed solutions of any composition exceeds the similar parameters of the prototype. The KKK _sc , comprehensively taking into account the positive effect of reducing the average density and increasing adhesion strength, of the proposed compositions is also higher than that of the prototype, 3-3.5 times.

From the data obtained it also follows that with a decrease in the average density of the proposed solutions, the adhesion strength decreases, although it remains higher than the adhesion strength of the prototype solution. The growth of a favorable factor (decrease in average density) outstrips the growth of an unfavorable (decrease in adhesion strength), as evidenced by the increase in CCC _sc upon transition to less dense solutions.

Information sources

1. RU 2251539, publ. 2005.05.10., 4 p.

2. RU 2191166, publ. 2002.10.20., 3 p.

Claims (2)

1. A dry mixture for stucco mortar on aerated concrete, including lime-cement binder, silica sand, cellulose ether and an adhesive additive, characterized in that it additionally contains porous aggregate from cellular concrete waste with a particle size of up to 5 mm as an adhesive additives contains redispersible powder in the following ratio of components of the dry mixture, wt.%: lime cement binder 35.6-48.9 quartz sand 3,5-13,1 specified porous aggregate 44.4-51.2 cellulose ether 0.07-0.13 redispersible powder 1.1-2 moreover, the porous aggregate from the waste products of cellular concrete has a polyfraction composition in the following ratio of fractions, wt.%: fraction 2.5-5 mm 17.2-32.0 fraction 1.25-2.5 mm 14.6-22.6 fraction 0.63-1.25 mm 11.2-15.8 fraction 0.315-0.63 mm 11.3-13.7 fraction 0.14-0.315 mm 9.2-15.2 fraction 0-0.14 mm 9.1-28.1 2. The dry mixture according to claim 1, characterized in that it contains a redispersible powder based on monomers of vinyl acetate, versatate and acrylate.

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