Mineral knitting substances

Napolniteli

Modifying additives

The price and quality

Features of national marketing

P.Kolosov Source: the Journal "Technology of building" #1 (2004)

It is introduced: on November, 15th, 2004

Last decade the XX-th centuries use of dry mixes at realisation building-finishing and repair work at last became norm and in our country. Materials for the system of floors, waterproofing and repair structures, glues for a ceramic tile and a natural stone, zatirki for seams (fugovki), plaster mixes most of different function — here it is far not the complete list of the products delivered in the form of dry mixes. Unfortunately, the great bulk of consumers has no the slightest concept that disappears for beautiful (or not so beautful) packing, and the basic criterion of a choice of this or that material quite often there is its cost, that basically is not true. Why? We will try to understand.

Modern dry mixes it is not simple cement with sand, and a product of the high technologies which application allows not only to increase considerably labour efficiency, but also to receive absolutely other qualitative results unattainable in case of use of traditional cement-sandy mixes. It is natural, that manufacturers store compoundings of the mixes in the deepest secret, but the general principles of formation of specific characteristics of materials, and also the components entering into them, well-known. As a part of the modified dry mixes it is possible to allocate four basic groups of components: mineral knitting, exicipients, additives for reception of special properties, including water-retaining, and also polymeric binding which work in the same direction, as mineral, but have absolutely other mechanism of action.

Mineral knitting substances.
As hydraulic mineral knitting are used portlandtsementyi (white and grey), byistrotverdeyuschie vyisokoalyuminatnyie cements, a - and.-polugidratnyj plaster, and also their combinations more often. At joint hydration of cement and plaster the considerable quantity of the mineral named ettringit which availability is capable to lead to destruction of the material received from a dry mix is formed, therefore such combination finds the limited application, for example for the system bezusadochnyih floors with a rigid surface. Gidratirovannaya izvest (pushonka) otverzhdaetsya as a result of reaction c carbon dioxide (CO2) that is why is air knitting.
Now izvest it is used as the additive (5—30 %) to the cement materials, allowing considerably to improve pererabatyivaemost the shut solution, and as the core knitting — only in the specialised structures intended for restoration of historical buildings. If napolnitel it is chosen correctly, that is has low porosity, dense packing and sufficient own durability durability and density of a received mineral composition depend only on properties of knitting substance.
Unfortunately, the cement technical characteristics, even one manufacturer, can essentially vary from a consignment to a consignment that conducts to change of properties of a dry mix at an invariable compounding. Despite availability in our country of a large quantity of deposits CaCO3, there are big problems and with quality to exhaust. In this connection it is necessary to mention the international system of quality management DIN ISO 9001. There is an erroneous opinion, that the availability of certificate ISO 9001 is an unconditional guarantee of quality of production. It not absolutely so. The ISO standard 9001 does not define qualitative characteristics of materials, and guarantees only stability of properties of manufactured production. The special commission conducts enterprise inspection, evaluates a condition of its equipment, the engineering specifications, the organisation of production and quality of initial raw materials.
The decision on issue (or failure in issue) the given certificate starts on the basis of the comprehensive analysis of the received results. Further at entering into the "know-how" of any changes, capable to affect conformity of production to requests of standard documents, the manufacturer is obliged to inform on it the commission which has issued the certificate. In turn, the commission, having considered the demand, has the right to make the decision on realisation of repeated certification.
Thus, sign ISO 9001 which are present on packing with a dry mix or in engineering specifications, means, that the product is produced at the enterprise, passed certification, and the information containing in the description, corresponds to the validity.

Napolniteli
By production of dry mixes in quality napolniteley the calcareous flour and quartz sand more often are applied. Use of dolomite instead of a calcareous flour is not recommended because of the contents in it bolshego quantities of soluble salts of magnesium that can lead to formation vyisolov.
Into structure teploizolyatsionnyih plaster mixes enter also porous napolniteli, such, as keramzit, perlit and vermikulit, and in some cases — the granulated expanded polystyrene. If necessity of application of cement of a choice quality does not cause also a doubt shade the expediency of use napolniteley and, in particular, sand of certain standards, from the point of view of the nonspecialist is absolutely not obvious.
And meanwhile quality of a dry mix depends not only from granulometricheskogo structure napolnitelya, but also on the contents of the extraneous additives which availability essentially influences an end result. In particular, even the small contents of impurity of clay is capable to reduce considerably adhesion of a solution, and presence of some soluble connections initiates destruction of expensive organic additives.
Besides, as a part of mineral napolnitelya chemical compounds (for example, active oksid aluminium), capable to influence process of hydration of cement can contain. To avoid similar troubles manufacturers aspire to use napolnitel from one deposit that allows to supply stable quality of an end-product.
For example, levelling weights of the trade mark «Vetonit», using invariable popularity among our builders, are made at factory of company Optiroc which is possessed in the open-cast mine centre, sand from which is used in quality napolnitelya.
Unfortunately, the volume of the journal article does not allow to consider in detail such important parametres napolnitelya, as hardness and porosity. We will shortly stay on influence sitovyih characteristics. The majority of solutions for tonkosloynogo drawings, such as tiled glues and thin plasters, contain, as a rule, grains not more largely 0,6 mm. The structures intended for tolstosloynogo of drawing including decorative, contain larger grains. The size to 0,1 mm is characteristic for such smooth solutions, as shpaklevki and rasshivochnyie weights. The maximum mechanical indicators, for example effort to a separation, at the minimum cost of chemical additives can be reached in that case when napolnitel has dense enough packing, that is contains about identical shares of various fractions.

Modifying additives.
Application of special additives (modifiers) at creation of compoundings of the modified dry mixes is caused by necessity of reception certain technical and technical characteristics on these materials and, first of all, — requirement of deduction of water for the shut solution after its drawing. Water is absorbed in the basis and evaporates from a solution surface that leads to reduction of time of stay of cement in a gel phase, to reduction of degree of hydration and, as consequence, to durability decrease. The less thickness of a layer of a solution, the the indicated defects more affect quality of a formed cement stone.

In the beginning of the last century in Germany the method of reception of water-soluble aethers of cellulose has been developed. Researches have shown, that owing to weak intermolecular interaction with water molecules these polymers have magnificent water-retaining ability. Each molecule of polymer can keep to 20 thousand molecules of water.
Energy of this interaction is comparable to energy of evaporation and capillary diffusion in a basis that is an obstacle for water care. In turn, this energy is a little bit less, than energy of diffusion of water at cement hydration that allows it to select this water.
Actually water in a solution is replaced homogeneous zheleobraznyim with a solution metiltsellyulozyi in which cement and filler parts are weighed. High water-retaining ability of such system promotes complete hydration of cement and allows a solution to type necessary durability even at tonkosloynom drawing. After care of water polymer in the form of the most thin film remains on surfaces between a cement stone and napolnitelem, not influencing in any way on mechanical characteristics of the hardened solution. Thus, addition of insignificant quantity (0,02—7 %) water-soluble aethers of cellulose to cement-sandy mixes leads to essential increase in open time and gives the chance to a solution gidratirovatsya in regular intervals on all volume, and also supplies essential increase of adhesion to the basis and improvement of quality of a surface.
The more the thickness of a layer of a cement mortal, the less metiltsellyulozyi is required for maintenance of necessary degree of initial hydration, therefore on a label of a dry mix is minimum admissible thickness of drawing of structure should be accurately indicated. In turn, it is inadmissible and tolstosloynoe (10 mm and more) application of a solution with the high contents of an aether of the cellulose intended for tonkosloynyih of technologies. In this case the effect karameli »when a surface otverzhdaetsya it is normal can be shown«, and not hardened cement mortal is inside saved. For this reason for preparation of the rough bases (with differences more than 10-15 mm) are recommended application of system of the materials consisting of a dry mix for rough alignment and tonkosloynoy of the levelling weight, supplying reception of a smooth finishing layer on which surface floor cover keeps within. The system approach not only allows to avoid the transferred troubles, but also to lower level of expenses for materials.
Dispersive powders which, unlike water-soluble derivatives of cellulose concern the following group of additives, at zatvorenii water form not solutions, the diphasic systems consisting of polymeric particles (on the basis of copolymers vinilatsetata and etilena, vinilhlorida, styrene-akrilata, etc.), dispergirovannyih in water. Addition of these structures in products of building chemistry allows to influence actively characteristics of a final material and supplies reception of the results unattainable at use only of the traditional mineral knitting.
The first attempts of updating of cement mixes by polymers consisted in addition to water zatvoreniya dispersions vinilatsetata, izvest - ache as glue PVA. In the course of formation vinilatsetatnoy films occurs significant (to 10 %) usadka, that involves rastreski - vanie a polimerno-cement material, therefore application PVA have fast refused.
Use of the two-componental structures consisting of a cement-sandy mix, prepared industrially, and the polymeric dispersion delivered in the liquid state which mix up on a building site became a following stage. Two-componental solutions are applied till now, but the water dispersion loses the properties at freezing, therefore in a cold season its transportation and preparation of a working solution cause certain difficulties.
The beginning of production of unicomponent dry building mixes concerns 1953 when experts firms Wacker (Germany) managed to receive dry redispergiruemyiy a powder forming after zatvoreniya by water diphasic system, having properties of an initial polymeric dispersion.
Dispersions differ from metiltsellyulozyi and the action mechanism. In process of an expenditure water concentrates in a time of a cement stone and in the same place the dispersion, forming «elastic bridges» concentrates, working on a stretching and the bend incomparably is better, than cement. The combination of the mineral and polymeric knitting grants manufacturability of products of the building chemistry having not only raised prochnostnyimi properties and improved adhesion (including to such "problem" bases, as metal, a tree, plastic, glazurovannaya a tile, etc.), but also operated reologicheskimi (tiksotropnost, plasticity) and special (water repellency, fluctuation) characteristics.
For example, levelling solutions for floors contain a combination of special dispersive additives with the organic and synthetic softeners which availability defines such specific properties of these materials as ability to rastekaniyu and smoothness of a received surface. The dispersive modifiers which are a part of glutinous structures for tiled works, improve working conditions, prolong term of a life of the shut solution and raise tiksotropnost (ability to get thick in a condition of rest and to be diluted at hashing) a material.
Except adhesion increase to difficult bases, dispersive powders execute functions polymeric knitting when velichi on shift loads exceeds possibilities of the cement-sandy solutions modified only by an aether of cellulose. Plasticity of such glutinous structures allows to compensate, in particular, the thermal pressure arising between a facing material and the basis. First of all it concerns front systems where daily fluctuations of temperature can reach 70—80°S and to "warm" floors where differences of temperatures also are very great.
Very high (20—30 %) the polymer contents leads to that cement any more does not form a continuous crystal lattice, and separate fragments of a cement stone are connected among themselves only by elastic polymeric chains. Such materials are applied to the waterproofing system. The range of many manufacturers of components of building chemistry (CLARIANT, BAYER, WACKER, etc.) includes dispersive powders with temperature plenkoobrazovaniya an order 0°S, that allows to use dry mixes with the additive of these materials at low (but not negative) temperatures, and some marks of dispersive powders have temperature plenkoobrazovaniya at level-15°S. Solutions in which compounding such powders are used, are intended for realisation stroitelnootdelochnyih works during the winter period (at temperatures not more low-10°S).
Drawing up of a compounding of dry mixes is a difficult and long process, impossible without sharing of qualified personnel and assuming obligatory availability of modern laboratory for the analysis and test of the samples, equipped with the high quality equipment. In this connection it would be desirable to warn consumers against attempts of handicraft "updating" of simple cement mortals.
In particular, the practice of "improvement" of simple cement-sandy mixes extended in our country by a dispersion vinilatsetata (glue PVA) leads to rather pitiable results. Low firmness to the alkaline solutions, inherent vinilatsetatu, causes it omyilenie in places with the raised humidity (bathrooms, etc.). This circumstance is the reason of that the tile laid on a solution with addition of glue PVA falls off.

The price and quality.
The comparative analysis of cost of the dry mixes presented in the Russian market, the large part of production made on open spaces of the post-Soviet territory shows, that, is much cheaper than the West European analogues. The domestic consumer perceives this fact as something, self-evident. Really, cheap labour, local raw materials, minimum cost of transportation and absence of the customs duties, are, at first sight, real preconditions for decrease in price characteristics of construction materials. However on closer examination the situation looks absolutely differently.
Production redispergiruemyih powders — process extremely difficult, requiring application of the unique specialised equipment and preliminary processing of initial dispersions, therefore all over the world exists no more than ten the companies manufacturing unconditionally qualitative modifiers for products of building chemistry. Recognised manufacturers of chemical additives are such foreign firms, as Bayer, Wacker, Clariant, Henkel-Nopco, Finndisp, etc. which production it is impossible to name cheap.
Cost of dry mixes is largely caused by cost of components, and at a high level of updating of an expense for mineral components can have rather small share, and chemical additives become tsenoopredelyayuschimi.
For example, one of the most simple and cheap structures — tiled glue of the Russian production in cost to 100—110 rbl. — represents a cement-sandy mix with the additive metiltsellyulozyi in number of 0,4 % (on weight). With allowance for that the cement ton costs about 1000 rbl., and 1 kg metiltsellyulozyi — 220—230 rbl. approximately half of cost of initial materials is necessary on additives. Technical (prochnostnyie characteristics, water resistance, frost resistance, adhesion to materials with low water absorption) and technological (open time) properties of these glues do not meet the requirements of the European normals, nevertheless, such materials are in demand not only in Russia, but also in countries of Western Europe. Come nearer to class S1 (on classification EN 12004) more expensive (110—200 rbl.) The glutinous structures containing (along with metiltsellyulozoy) to 2 % redispergiruemogo a powder. Materials of class S2 (high-quality elastic glue) differ raised (about 4 %) the polymer contents (more elastic, than in structures of class S1) and use metiltsellyulozyi other type (more viscous), and their cost exceeds 200 rbl.
Self-levelled weights concern number of the most difficult (from the point of view of a compounding) materials for tonkosloynogo drawings. For the control rastekaemosti the following technology is used: two identical metal rings in diameter fill of 40-70 mm with a working solution. One ring raise at once, allowing a solution to spread on a control surface, and the second — in fifteen minutes. The areas of stains should differ no more than on 10—15 %. Other important property of these materials it is possible to characterise as «ability to running off»: two "puddles" of a solution poured with an interval of 15 minutes, should merge in a uniform stain without formation of visible border.
Except ability to rastekaniyu self-levelled solutions should have good adhesion to the basis and stability to istiraniyu, not to be stratified at pouring, to supply necessary durability even in very thin layer etc. For this reason self-spreading mixes quite often include to 20 and more components, "chemistry" cost transfers for 90 %, and the share portlandtsementa and napolniteley in pricing is not so essential. In this connection economy attempts on mineral components are deprived practical sense, and to achieve some depreciation of a product it is possible only at the expense of competent drawing up of a compounding.
The conclusion is simple: cost of two specialised dry mixes with a high level of the updating, having identical technical and technical characteristics, cannot differ several times even if one of them is manufactured in the next street, and other — in far Germany.
Than the wide margin in cost of materials (even one manufacturer), having identical final quality performances (adhesion, durability on compression, a stretching etc.) and recommended for the same operating conditions speaks? The matter is that assortimentnaya the policy of the majority of foreign firms accurately traces the inquiries of consumers caused economic, and is frequent, and national features of the given region.
In the advanced countries any construction firm does not presume such luxury, as idle times of executors lasting many hours. Such organisation building-finishing and repair work assumes unconditional use byistroshvatyivayuschihsya the dry mixes, allowing to reduce to a minimum inevitable technological breaks between operations. These structures differ the raised contents of modifying additives and, as consequence, — a seller’s price.
For example, according to the standard documents acting in Germany, on a surface levelled with the help niveliruschey of weight, it is possible to go in three hours. These requests are answered with all materials manufactured by German firms (Henkel, Knauf, Uzin UTZ AG, Dyckerhoff etc.) and intended for realisation in home market and in a number of the West European countries. At the same time in Russia where similar norms in general are absent, it is possible to acquire an import material of similar appointment with the same technical characteristics, but suitable for circulation only in eight hours. Thus its cost in 3 times more low.
Domestic manufacturers offer cheaper materials of this group. In particular, the levelling weight «YUnis Gorizont-2» assumes possibility of foot circulation only in 36 hours. Decrease in the contents of the modifying additives accelerating shvatyivanie and tverdenie of a solution, has allowed experts of company JUNIS to create inexpensive, and consequently, the accessible material having fine technical characteristics. The customer engaging sufficient financial assets and interested in reduction of terms of building, most likely will stay on the first variant of the levelling weight. The one whom excites a problem of reduction of estimated expenditures more, will prefer the second variant. In both cases it is possible not to worry about an end result, as service properties of the levelled bases will be close enough.
The resulted example visually illustrates necessity of an exact formulation of the requests presented to a material in each concrete case, and attentive studying of technical, technological and price characteristics of dry mixes.
Perfectly understanding importance of reduction of the time expenses, some Russian companies also have run in production of levelling mixes in due course otverzhdeniya 3—4 hours («Glims-S3X» and «Glims-SL»), but miracles do not happen, and under the price characteristics these materials closely come nearer to foreign mixes of the given class.
It would be desirable to warn and against thoughtless use of universal structures. The universal mix is in most cases worse, and at equal technical characteristics — is more expensive highly specialised as contains the raised quantity of modifiers. What for to the system of a tiled apron at a kitchen sink to apply universal cold-resistant glue with a considerable quantity elastomernyih the additives, the raised adhesion and stability to effect of aggressive chemical compounds? This structure is much more expensive some the specialised glues recommended for facing of walls of kitchens and bathrooms, and the majority of its properties in this case remain dead.
Easier speaking, thoughtless acquisition of materials as the maximum, and the lowest price category is deprived practical sense.