Cement composition with adhesive concrete admix having fungicidal properties

The invention relates to a cement-based composition with adhesive and fungicidal properties.

In the specialized literature, it is reported that plasticized concrete can be obtained, with various substances that allow a reduction of the water-cement ratio.

Usually, when an additive is introduced into the concrete, a certain purpose is pursued, and for this reason, the classic additives for concrete perform individual functions. Therefore, the classification of additives is based on their main functions, namely: plasticizing additives, fluidizing additives, water reducing additives, air trainer additives, hydrophobizing additives.

These additives are used to eliminate some of the shortcomings encountered in the manufacture of concrete and they aim to increase the productivity of labor, increase the performance of concrete, reduce unnecessary expenses.

Also known are substances that are used in concrete, in the form of aqueous solutions, such as: polyvinyl alcohol solutions, cellulose derivatives solution, formic aldehyde resins. For precise purposes, calcium lignosulfonate, ammonium, calcium chloride, stop water, antigero is also used.

Also in the concrete, aqueous dispersions of the peanut are used, as well as aqueous solutions of bone glue, starch glue, casein, dextrin, which can also be used as paper adhesives and as additives in concrete.

Regardless of the type of organic material, natural organic substances are subject to aging and degradation. Due to hydrolytic degradation, they can generate other acid reaction substances, which can degrade the concrete. A first manifestation of the change in the chemical composition of these products is the change of color over time and the loss of elastic properties at negative temperatures. For this reason, the fields of application are limited, namely: the use of these products in confined spaces or in a humid environment. For example, a building that has been used as a mortar that cracks in freeze-thaw cycles, requires additional maintenance costs (the concrete is reduced, and the ceramic tiles fall).

To all these disadvantages can be added those related to the loss of adhesive properties, the release of unpleasant odors, the appearance of molds.

The composition according to the invention removes the mentioned disadvantages, in that it consists of 43 ... 47%. preferably 45.9% Portland cement, 43 ... 47%. preferably 45.9% quartz sand or quartz flour, 1 ... 3%, preferably 1.5% vinyl polyacetate copolymer with a hydrolysis degree of at least 69% and a saponification index of at least 30 mg KOH / g, 1 ... 3%, preferably 1.5% cellulose derivative modified with 20 ... 40% methoxy groups, 4% oxyethylene groups and up to 7% hydroxypropyl groups, 0.2 ... 0.5% . preferably 0.2% tetramethylthiuramdisulfide and 3-7%, preferably 5% ground chalk, usable in combination with

20 ... 25%, preferably 22 ... 23% water.

In the cement-quartz mixture - ground chalk (of controlled granulation), synthetic polymeric substances and natural polymeric substances, chemically modified, are introduced, together with a fungicidal agent that prevents fungus, spores and bacteria from occurring. The cement used is Portland type and has the quality provided in SR - 7055/1996 and SR 388/1995. Quartz sand and silica flour are characterized by SiO content₂ of a minimum of 98% (according to STAS 318/2 - 88) and a granulation of 0,16 ... 0,2 mm according to the sort M (50) 02, class N05. The quartz flour is of indigenous origin and corresponds to STAS 11095 - 78. The calcium carbonate (limestone filler, ground chalk) used contains at least 90% CaCO₃ and has a passage of 72% through the 0.071 mm sieve. The product quality is controlled by STAS 539/1979. The synthetic polymer used is a copolymer based on vinyl polyacetate, which confers elasticity on the concrete and great resistance to freeze-thaw cycles, making it possible to use the product in open (outdoor) spaces. polymer

RO 120968 Β1 is characterized by a hydrolysis degree of minimum 69% and a saponification index, 1 expressed in mg KOH / g, of minimum 30. The natural cellulose derivative has a modified chemical structure, containing 20 ... 40% groups methoxy, up to 4% oxyethylene groups and up to 7% 3 hydroxypropyl groups. Tetramethylthiuramdisulfide [(CH₃)₂N -CSSC- N (CH₃)₂] used is a fungicide with multipurpose action and with maximum efficiency at small dosages.5 In the adhesive composition, according to the invention, all the mentioned additions act synergistically and at small dosages. In addition to the adhesion on the substrate, the mixture gives the concrete 7 elastic friendships with vibrations and tripods, and due to the structural shape of the rock, of the macromolecular chains, it favors that under the influence of certain weather conditions (rain, frost, thaw) there are 9 splinters (hot). ) and return (to the cold), giving elasticity and resistance to freeze thaw cycles. The cellulose derivative and the copolymer based on vinyl polyacetate have the property of 11 to strongly bind water in their solid state, in which they are in concrete, favoring the uniform formation of the monolithic structure of the concrete, as a result of favoring the complete hydration of 13 cements in the first 3 ... 7 days.

The adhesive composition according to the invention consists of equal quantities of cement - 15 sand (quartz flour), in weight ratio 1: 1, having a mixture of 3 ... 7% crushed chalk, copolymer based on vinyl polyacetate proportion of 1,0 ... 3%, modified cellulose derivative in 17 proportion of 1,0 ... 3% and tetramethylthiuramdisulfide in proportion of 0,2 ... 0,5%.

This composition responds to the proposed purpose, namely to obtain a synergistic 19 mixture with fungicidal properties, which can be used as an adhesive mortar, for ceramic cladding, on flat, horizontal and vertical surfaces. 21

The variation of the proportions of the component materials outside the mentioned limits does not dramatically change the physical-mechanical indices. 2. 3

This mixture, with the ratio of weight between the components specified and with standardized granulation, responds to a precise dosage of the water when it is put into operation. The adjustment of the 25 viscosity of the environment is done not on account of the quantities of materials in the synergetic mixture, but on the amount of water introduced into the mass of powders. 27

An amount of water of 20% compared to the mass of powders favors obtaining a viscous mortar, an amount of 25% water favors obtaining a fluid mortar, the corresponding dose of water for obtaining a workable mortar is 22 ... 23 %.

The composition of mixture with adhesive properties, described in the invention, has the following 31 advantages:

- the products they work with are dry and are not used, when transporting, 33 solutions or aqueous dispersions;

- being dusty, it can be packed in bags, in airtight containers and has no temperature restrictions, 35 for storage and transport, compared to the pencil;

- presents precise uses: concrete coatings with ceramic materials (tiles, tiles 37 etc.) on horizontal and vertical surfaces, in closed and open spaces, at positive and negative temperatures; 39

- the thiuram in the composition gives the mixture properties of fungicide, sporicide, bactericide and disinfectant; 41

- the synthetic copolymer based on vinyl polyacetate is slightly soluble in the aqueous mass, at the temperature of the working conditions, having high adhesion power on the porous and hydrophilic surfaces 43;

- the modified cellulose derivative and the vinyl copolymer, besides their properties of 45 binders, also play the role of generating the water of the mineral particles, as it is consumed as a result of the hydration process of the cement, guaranteeing a uniform distribution of 47 forms. water in the entire mixing mass, avoiding the occurrence of internal stresses and cracks in the mass of material; 49

RO 120968 Β1

- the chalk, ground to micronization, does not behave in the synergetic mixture as an inert product, due to the strong adhesion of the hydration products of the cement, to the surface of the micronized limestone particles, by the phenomenon of epitaxy; this addition of about 5% slightly accelerates the setting and reinforcement reactions, due to the chemical reactions it modifies and consequently increases the rate of release of the heat of hydration of the concrete cement and the increase of the initial strengths of the concrete by 10 ... 15% and the final ones with

3...12%;

- the quartz sand and the quartz flour (of controlled granulations) introduced in the designed mixture, apart from the pyrolysis activity, contribute to the sensitive reduction of the porosity of the concrete cement paste, by filling the pores of the cement paste (in particular, the capillary pores). , ensuring the increase of the compactness of the cement pastes and the sensitive increase of the resistances of the pastes, mortars and concretes prepared with cement and with the addition of quartz sand.

The following is an example of making the composition according to the invention.

A mixture of Portland cement, quartz sand (or quartz flour), ground chalk, vinyl polyacetate copolymer with a hydrolysis degree of at least 69% and a saponification index of at least 30 mg KOH / g, cellulose derivative is made. with 20 ... 40% methoxy groups, 4% oxyethylene groups and up to 7% hydroxypropyl groups and a fungicide based on thiuram (tetramethylthiuramdisulfide).

Table 1 presents two composition recipes.

Table 1

<td>Nr. crt.</td><td>Component name</td><td>Example 1 (kg)</td><td>Example 2 (kg)</td>

<td> 1</td><td>Portland cement</td><td> 459</td><td> 459</td>

<td> 2.</td><td>Quartz sand</td><td> 459</td><td> -</td>

<td> 3</td><td>Quartz flour</td><td> -</td><td> 45,9</td>

<td> 4</td><td>Vinyl polyacetate copolymer</td><td> 15</td><td> 15</td>

<td> 5</td><td>Modified cellulose derivative</td><td> 15</td><td> 15</td>

<td> 6</td><td>tetramethylthiuram</td><td> 2</td><td> 2</td>

<td> 7</td><td>Micronized chalk</td><td> 50</td><td> 49</td>

<td> 8</td><td>Silicone water repellent</td><td> -</td><td> 1</td>

Tables 2 and 3 show the characterization of fresh mortars and the characterization of hardened concrete.

Table 2

<td>Apparent density, kg / m3</td><td>about 1780</td>

<td>Consistency (cm)</td><td>5 min - 8.5; 15 min-7.5</td>

RO 120968 Β1

Table 3 1

Hardened mortar characterization 3

<td>The age of the mortar</td><td>3 days</td><td>7 days</td><td>14 days</td><td>28 days</td>

<td>Compressive strength (N / mm²)</td><td> 10,3</td><td> 15,0</td><td> 20,0</td><td> 27,0</td>

<td>Bending resistance (N / mm²)</td><td> 3,5</td><td> 3,9</td><td> 5,6</td><td> 9,3</td>

<td>Adhesion on the support (N / mm²)</td><td> 1,2</td><td> 1,35</td><td> 1,45</td><td> 1,58</td>

Claim 9