Application of complex solutions. Classification and scope of mortars. Penza State University
What is sea water, milk, steel wire - are they individual substances, or do they consist of several components? In our article we will get acquainted with the properties of solutions - the most common physical and chemical systems with variable composition. They may contain several components. So, milk is an organic solution containing water, drops of fat, protein molecules and mineral salts. What is a solution and how can it be obtained? We will answer this and other questions in our article.
Application of solutions and their role in nature
Metabolism in biogeocenoses is carried out in the form of interaction of compounds dissolved in water. For example, the absorption of soil solution by plant roots, the accumulation of starch as a result of photosynthesis in plants, the digestive processes of animals and humans - all of them are reactions that occur in chemical solutions. Can not imagine modern industries: space and aircraft construction, military industry, nuclear energy without the use of alloys - solid solutions with unique technical characteristics. Several gases can also form mixtures, which we can call solutions. For example, air is a physical and chemical system that contains components such as nitrogen, oxygen, carbon dioxide, etc.
What is a solution?
By mixing sulfate acid and water, we obtain its aqueous solution. Let's look at what it consists of. We will discover a solvent - water, a dissolved substance - sulfuric acid and the products of their interaction. These include hydrogen cations, hydrogen sulfate - and The composition of the physicochemical system consisting of a solvent and components will depend not only on what substance is the solvent.
The most common and important solvent is water. Great importance has also the nature of the soluble components. They can be roughly divided into three groups. These are practically insoluble compounds, slightly soluble and highly soluble. The last group is the most important. This includes most salts, acids, alkalis, alcohols, and monosaccharides. Slightly soluble compounds are also found quite often in nature. These are gypsum, nitrogen, methane, oxygen. Metals, noble gases: argon, helium, etc., kerosene, oils will be practically insoluble in water.
How to Quantify the Solubility of a Compound
The concentration of a saturated solution is the most important value, showing It is expressed by a value numerically equal to the mass of the compound in 100 g of solution. For example, disinfectant medical product- salicylic alcohol is sold in pharmacies in the form of a 1% alcohol solution. This means that 100 g of solution contains 1 gram active substance. What is the largest mass of sodium chloride that can be dissolved in 100 g of solvent at a certain temperature? You can find the answer to this question using a special table of solubility curves for solid compounds. So, at a temperature of 10 ⁰C you can dissolve 38 g of table salt in 100 g of water, at 80 ⁰C - 40 g of the substance. How to make a solution dilute? You need to add a certain amount of water to it. The concentration of a physicochemical system can be increased by evaporating the solution, or by adding to it a certain portion of a dissolved compound.
Types of solutions
At a certain temperature, the system can be in equilibrium with the soluble compound in the form of its precipitate. In this case we speak of a saturated solution. How to make a solution saturated? To do this you need to refer to the solubility table solids. For example, table salt weighing 31 g is introduced into water at a temperature of 20 ºС and normal pressure, then stirred well. With additional heating and the introduction of an additional portion of salt, its excess ensures the formation of a supersaturated solution. Cooling of the system will lead to the precipitation of sodium chloride crystals. Solutions will be called dilute in which the concentration of compounds compared to the volume of solvent will be sufficiently small. For example, saline solution, which is part of blood plasma and is used in medicine after surgical interventions, is a 0.9% sodium chloride solution.
Mechanism of dissolution of substances
Having considered the question of what a solution is, we will determine what processes underlie its formation. At the heart of the phenomenon of dissolution of substances we see the interaction of both physical and chemical transformations. The main role in them is played by the phenomenon of destruction of chemical bonds: polar covalent or ionic, in the molecules of the soluble compound. The physical aspect of breaking bonds is the absorption of energy. There is also an interaction between solvent particles and solute molecules, called solvation, or in the case of aqueous solutions, hydration. It is accompanied not only by the emergence of new connections, but also by the release of energy.
In our article, we examined the question of what a solution is, and also found out the mechanism of formation of solutions and their significance.
Mortars for masonry. The compositions of masonry mortars and the type of initial binder depend on the nature of the structures and their operating conditions. Construction masonry mortars are made in three types: Cement, cement-lime and lime.
Cement mortars are used for underground masonry and masonry below the waterproofing layer, when the soil is saturated with water, that is, in cases where it is necessary to obtain a mortar of high strength and water resistance.
Cement-lime mortars are a mixture of cement, lime paste, sand and water. These solutions have good workability, high strength and frost resistance. Cement-lime mortars are used for the construction of underground and aboveground parts buildings.
Lime mortars have high plasticity and workability, adhere well to the surface, and have low shrinkage. They are characterized by fairly high durability, but are slow-hardening. Lime mortars are used for structures operating in the above-ground parts of buildings experiencing low stress.
Finishing solutions.
There are finishing solutions - ordinary and decorative.
Finishing mortars are prepared using cement, cement-lime, lime, lime-gypsum binders. Depending on the area of application, finishing solutions are divided into solutions for external and interior plasters. The compositions of finishing solutions are established taking into account their purpose and operating conditions. These solutions must have the required degree of mobility, have good adhesion to the base and change little in volume during hardening, so as not to cause the formation of cracks in the plaster.
For external plastering of stone and monolithic concrete walls of buildings with a relative indoor air humidity of up to 60%, cement-lime mortars are used, and for wooden and gypsum surfaces in areas with a persistently dry climate, lime-gypsum mortars are used. For external plastering of plinths, rims, cornices and other sections of walls that are subject to systematic moisture, cement and cement-lime mortars based on Portland cement are used. For internal plastering of walls and floors of a building at a relative air humidity of up to 60%, lime, gypsum, lime-gypsum and cement-lime mortars are used.
Decorative colored solutions are used for factory finishing of the front surfaces of wall panels and large blocks, for finishing the facades of buildings and elements of urban improvement, as well as for plastering inside public buildings.
For cooking decorative solutions The following are used as binders: Portland cement (regular, white and colored) - for finishing layered reinforced concrete panels and panels made of concrete on light porous aggregates; lime or Portland cement (regular, white and colored) - for the front finishing of silicate concrete panels and for colored plasters of building facades; lime and gypsum - for colored pieces inside buildings.
Washed quartz sand and sand obtained by crushing granite, marble, dolomite, tuff, limestone and other white or colored stones are used as fillers for colored decorative mortars. rocks. To add shine to the finishing layer, up to 1% mica or up to 10% crushed glass is added to the solution. Alkali-resistant and light-resistant natural and artificial pigments (ochre, red lead, mummy, chromium oxide, ultramarine, etc.) are used as dyes.
Special solutions.
Special ones include solutions for filling joints between elements of prefabricated reinforced concrete structures, injection solutions, floor solutions, waterproofing grouting, acoustic and X-ray protective.
Solutions for filling joints between prefabricated elements reinforced concrete structures prepared using Portland cement and quartz sand with a mobility of 7...8 cm.
Injection mortars are cement-sand mortars or cement paste used to fill the channels of prestressed structures.
Waterproofing solutions are prepared using high-grade cements (400 and higher) and quartz sand or artificially produced sand from dense rocks.
Grouting solutions are used for plugging oil wells. They must have high homogeneity, water resistance, and mobility; setting times, corresponding conditions for injection of the solution into the well; sufficient water yield under pressure, resistance in aggressive environments.
Acoustic solutions are used as sound-absorbing plaster to reduce noise levels.
X-ray protective solutions are used for plastering walls and ceilings of X-ray rooms.
Liquid dosage forms(Formae medicamentorum fluidae) They are free disperse systems in which medicinal substances are distributed in a liquid dispersion medium. Medicinal substances in these forms can be in three states of aggregation: liquid, solid and gaseous. Depending on the size of the particles of the dispersed phase and the nature of its connection with the dispersion medium, liquid dosage forms can be true solutions of low-molecular and high-molecular substances, colloidal solutions, suspensions, emulsions and combined systems– usually mixtures of the above systems, most often – extraction dosage forms.
According to medical purposes, liquid dosage forms are divided into dosage forms for internal, external and parenteral (dosage forms for injections) use.
Solutions
Solution (Solutio, Genitive – Solutionis) – a liquid dosage form prepared by dissolving a solid drug substance or liquid in a solvent. Solutions are used for external and internal use, as well as for injection.
The solvent used is:
- distilled water ( Aqua destillata);
- ethanol ( Spiritus aethylicus 70%, 90%, 95%);
- glycerin ( Glycerinurn);
- liquid oils ( Oleum Vaselini, Oleum Olivarum, Oleum Persicorum and etc.).
Accordingly, aqueous, alcoholic, glycerin and oil solutions are isolated. True solutions are always transparent; they should not contain suspended particles or sediment. Solutions are used for external and internal use, as well as for injection.
Solutions for external use are solutions that are used as eye and ear drops, nasal drops, as well as for lotions, rinsing, and douching.
A solution in drops is prescribed in a volume of 5-10 ml, solutions for other purposes - in an amount of 50-100 ml or more. Presented in the recipe in shortened or expanded form.
When using the abbreviated form of the copybook after the letters Rp.: indicate the name dosage form, then the name of the medicinal substance, the concentration of the solution and its amount in milliliters. The concentration of the solution is indicated by:
- as a percentage (most often);
- in relationships (1: 1000; 1: 5000);
- in mass-volume ratios (0.1 – 200 ml).
An abbreviated form of prescription of solutions is used in cases where
when the choice of solvent is determined by factory technology or provided to the pharmacy worker. If the solution is aqueous, then the type of solvent is not indicated in the abbreviated recipe. If the solution is oily or alcoholic, then the name of the medicinal substance is followed by the designations - oleosae(oil) or spirituosae(alcohol).
Depending on the type of structure (wall, foundation, etc.) and the conditions in which it will work, based on the requirements of SNiP, the basic requirements for mortars (grade, water resistance, frost resistance) for the construction or installation of this structure are established.
Masonry mortars are used depending on the design stresses and operating conditions of the masonry. It is recommended to lay masonry of above-ground structures operating under low stress using mortars containing cheap local binders: lime-slag, lime-pozzolanic, lime. In mortars for laying foundations in aggressive sulfate waters, sulfate-resistant cements are used, for the installation of large-block and large-panel walls - Portland cement, Portland slag cement, as well as Portland cement with organic additives. The mobility of the mortar mixture is selected taking into account the purpose of the solution. When laying walls from hollow brick or ceramic stones mobility is assigned 7...8 cm, for rubble masonry -4...6 cm, for masonry from solid brick and concrete stones - 8... 12 cm, installation of walls from panels and large blocks - 5... 7 cm, for filling voids in the masonry and feeding with a mortar pump - 12... 14 cm.
Mounting solutions. When installing walls, horizontal joints between panels of heavy concrete are filled with a mortar of a grade not lower than Ml00; made of lightweight concrete - not lower than M50. When installing walls made of large blocks, the grades of mortar for filling horizontal joints are indicated in the project (usually M10...M50). For jointing vertical joints of panel and large-block walls, the grade of mortar must be at least M50.
To install load-bearing reinforced concrete structures, the grade of cement mortar must be no lower than the grade of concrete for this structure.
As a filler for heavy masonry and installation mortars, quartz sand is used in accordance with GOST 8736-93, which should not contain particles larger than 5 mm, and the particle size modulus should be 1.5...2.5.
When laying mortars in winter, the hardening rate slows down. For example, at the age of 28 days. the strength of solutions hardening at a temperature of 1 °C is half that at a hardening temperature of 20 °C. Therefore, in winter, for masonry and grouting joints in prefabricated elements, a mortar with a grade one or two levels higher is used than for the mortar used for the same purposes in the summer. Solutions for winter work can be produced heated. The temperature of the solution at the time of its use must be at least 10 °C at an outside air temperature of minus 10... 15 Khin less than 20 °C - at an air temperature below minus 20 °C.
The temperature of mixtures for installation of structures should be 10 ° C higher than for masonry.
In construction, monolithic plaster, obtained from plaster mortars, is most often used. The plaster coating consists of two or more layers. Adhesion to the base surface is ensured by a preparatory layer, or spray, no more than 5 mm thick on brick and concrete surfaces and 9 mm - on wood. The main layer (primer) with a thickness of 5...7 mm is used to obtain a flat surface. An improved appearance is achieved through a covering layer no more than 2 mm thick.
Natural sand of the “very fine”, “fine” and “medium” groups is used as a filler for plaster mortars (fineness modulus - up to 2.0).
The maximum permissible grain size of sand for the preparatory layers of spray and soil should not exceed 2.5 mm, for the finishing layer (covering) - 1.2 mm.
The properties of the various layers of the plaster system must be coordinated with each other in such a way that stresses do not arise at the interfaces between the layers and the base due to shrinkage and thermal expansion. To do this, it is necessary that the strength of the upper layer be less than the strength of the lower one or that both layers have the same strength.
Solutions for ordinary plasters subdivided into cement, lime, gypsum, cement-lime, lime-gypsum, gypsum and clay-lime. The binder for solutions of conventional plasters is selected depending on the humidity operating conditions.
Cement mortars are used for external plasters that are subject to systematic moistening (external walls, cornices, etc.), and internal ones - in rooms with relative humidity air over 60%. To increase their water resistance, it is desirable to use water-repellent additives, for example, organosilicon liquids.
Cement-lime mortars are used for plastering both building facades (structures that are not subject to systematic moisture) and interior spaces. The introduction of lime dramatically increases the plasticity of solutions. The content of lime paste depends on the purpose of the layer.
Solutions based on airborne lime and gypsum are used for plastering indoor surfaces with relative humidity up to 60%. The main disadvantage of lime mortars is slow hardening. To speed up their hardening, building gypsum is added. Lime-gypsum mortars are most convenient for plastering wooden surfaces indoors. To increase their water resistance, hydraulic additives are introduced into the solution: tripoli, diatomite, slag, ash, etc.
All types of plaster mortars must have a given mobility (9... 14 cm - for spraying during mechanized application, 7... 8 cm - for primer and covering); do not delaminate during the production process; provide specified strength and adhesion to the base.
Protective and decorative solutions and compositions are intended for outdoor and interior decoration various porous surfaces, performing plastering and putty work. Depending on the type, dry and mortar mixtures, as well as paste compositions, and depending on the composition of the incoming components - mineral, polymer-mineral and polymer compositions.
Protective finishing plasters must satisfy a number of specific requirements related to their purpose and operating conditions. The most important are the strength of adhesion to the base and frost resistance. The main quality indicators of protective and finishing plasters according to STB 1263-2001 are given in table. 22.
The stability of these indicators over time depends mainly on the properties of the solution components. Binders for decorative mortars and compositions applied to the external surfaces of buildings include white and colored Portland cement, Portland cement with organic additives. In addition, for protective coating solutions with a polymer binder are often used. For interior decoration, lime, gypsum, gypsum-polymer cement and polymer cement binders are most often used.
Coloring additives are light-, alkali- and acid-resistant pigments of natural or artificial origin, for example chromium oxide, red lead, graphite, ultramarine, ocher. The most commonly used white pigments are lime, marble flour, white portland cement, titanium dioxide.
Fillers for decorative mortars are washed natural and artificial sands, ceramic, glass, plastic and crushed rock chips with a particle size of 2...5 mm. In necessary cases, to obtain sparkling surfaces, mica or crushed powder is added to the solution.
Polymer protective and finishing acrylic plaster produced by the Apimix enterprise has high physical and mechanical properties, comparable to foreign analogues. Decorative plasters"Apimix-Sh" are produced on the basis of 100% acrylic copolymer, quartz sand or marble chips and additives (antistatic, antifungal and antimold) and are painted with inorganic pigments. Acrylic plasters do not contain cement and have increased water resistance compared to mineral or polymer-mineral plasters, while having vapor permeability within the required limits; can be applied to any prepared base. Apimix-Sh plasters are very resistant to abrasion, resistant to impacts and scratches, and are difficult to ignite. They are recommended for finishing wall surfaces on stairwells, in lobbies, ticket halls, for prestigious finishing office buildings and decoration of facades.
Solutions for special purposes. Waterproofing (waterproof) solutions are ordinary fatty solutions with a composition of 1: 1-1: 3.5, into which sealing agents (aluminum sulfate, calcium nitrate, ferric chloride, bitumen emulsion, water-soluble resins) or water-reducing (plasticizing) additives are introduced. Solutions with the addition of soluble glass or sodium aluminate set quickly, which allows them to be used to seal cracks from which water oozes.
For waterproofing solutions, Portland cement, pozzolanic, sulfate-resistant and hydrophobic Portland cement, aluminous and expanding cements of grades no less than M400 are used. Sand with a fineness modulus of 2...3 is used as a fine aggregate in waterproofing mortars for screeds.
Waterproofing mortars applied by shotcrete are especially reliable; their sand fineness modulus should be 2.5...3.5. Such solutions are used to cover the walls of swimming pools, pipelines, tunnels, and basements exposed to aggressive environments.
Thermal insulation and acoustic solutions are used instead of conventional plaster solutions in order to increase the heat-insulating properties of enclosing structures or give them sound-absorbing properties.
As fillers for thermal insulation and acoustic solutions, dug sands are used: perlite - grades 100, 150 and 200, expanded clay - grades 500...700 and agloporite - grades with a density of up to 600. In this case, perlite sand must contain fractions with a dispersity of less than 0 .16 and larger than 2.5 mm - no more than 15%, agloporite and expanded clay sand - respectively less than 0.16 and larger than 5 mm - no more than 5%.
For acoustic solutions, single-fraction sands with a grain size of 3... 5 mm are used.
X-ray protective solutions. This heavy solutions with a density of more than 2200 kg/m3, used for plastering X-ray rooms and rooms in which work involving X-ray or y-radiation is carried out. This plaster replaces the cladding with lead sheets. Portland cement or slag-Portland cement and special heavy aggregates (barite), iron ores (magnesite, limonite) and others in the form of sand and dust with a particle size of no more than 1.25 mm are used as binding materials. The following composition of barite solution (may. parts) can be recommended: ground barite concentrate - 4; quick-hardening Portland cement - 1; polyvinyl acetate dispersion - 0.1; water - to the required mobility.
Acid-resistant solutions. These are solutions based on acid-resistant liquid glass binder, used for the installation of anti-corrosion coatings on structures that are exposed to acids during operation.
Liquid glass is used as a binder in these solutions: sodium glass with a silicate module of 2.4...2.8 and a density of 1.38...1.40 g/cm3 and potassium glass with a silicate module of 3...3.2 and density 1.30... 1.32 g/cm3 (paragraph 9.6). The filler is natural quartz or artificial sand obtained by crushing acid-resistant rocks (andesite, beshtaunite, granite). The sand should not contain clay impurities, grains of carbonate rocks and impurities of organic substances.
In addition to sand, a finely ground filler is added to acid-resistant solutions - powder from acid-resistant rocks (andesite, diabase). The filler must contain at least 70% grains up to 0.075 mm in size.
To increase water resistance, special finely ground additives are used that contain reactive silica - silica gel, diatomaceous earth, tripoli, agloporite, and acidic ash from thermal power plants. The acid resistance of fillers must be at least 96%, while active silica (capable of interacting with alkali) must be 84...97%. The consumption of the active additive is approximately 5...22% by weight of the finely ground filler.
To increase the water resistance of acid-resistant materials, polymer additives are used, for example furyl alcohol.
K category: Pool construction
Solutions used for facing work
Tiles can be mounted on wall surfaces various solutions, mastics and adhesives. Each type of tile has its own type of mortar or mastic.
Let's take a closer look at some of them.
It consists of Portland cement, sand and water. This solution is used for laying ceramic tiles and for sealing seams.
Portland cement is a binding material and must be grade M400 or M500 gray when using it for laying tiles; the solution used for sealing joints must contain white or colored Portland cement of the same grades.
Sand is a filler. It can be mountain, river and sea.
Mountain sand, due to the size of the sand grains, is considered the best for making solutions.
Mastics prepared before starting work
They contain bitumen and polymers, which is why mastics are bitumen, polymer, casein and bitumen-polymer.
For bitumen mastics petroleum bitumen of the BN 50/50, BN 70/30 and BN 90/10 grades is usually used. The first number in the marking indicates the softening temperature.
Such qualities of bitumen as hydrophobicity, water resistance, plasticity, frost resistance are transferred to mastics based on them.
Casein mastics are prepared on the basis of casein glue OB (“Ordinary”), V-105 (“Special”), V-107 (“Extra”).
All polymers on the basis of which mastics are prepared are divided into organic (these are oil varnishes, resins, drying oils), thermosetting (epoxy polymers), thermoplastic (PVA dispersion, indene-coumaron polymers).
The filler in the manufacture of mastics is Portland cement grades M400 and M500, asbestos, talc and limestone flour.
To give mastics good performance qualities You can add crumb rubber, rubber glue, coumaron resin, rosin and turpentine into their composition.
Ready-made mastics
In addition to those described above, you can purchase ready-made mastics in stores, which cannot be prepared at home due to the complexity of the technological process.
Adhesives
All types of adhesives used for facing work are manufactured industrially and sold in specialized building materials stores.
Joint fillers
For these purposes, specially produced industrial grout is used for joints.
Cementing materials V pure form are used very rarely. When dry, they shrink, form large cracks and do not have sufficient strength. To reduce the cost of binders and give them increased strength, various fillers are used.
They are divided into heavy - weighing more than 1000 kg/m3 and light - weighing less than 1000 kg/m3.
There are three types of sand: mountain, river, sea. The purer the sand, the higher the quality of the solution. Sand comes in different grain sizes: coarse - grain size from 1.2 to 5 mm, medium - from 0.5 to 2.5 mm and fine - from 0.3 to 1.2 mm. Volume weight equal to 1500-1700 kg/m3.
No matter how tightly the sand is compacted, there are still voids between its grains. The average void rate is 30-40%. Before starting work, contaminated sand is washed or washed in special washing machines. Sand mixed with more than 5% clay or more than 2% silt plastering works does not apply.
Slag is obtained by burning coal in boiler furnaces. It consists of porous sintered pieces weighing from 700 to 900 kg/m3. To obtain slag sand, the slag is ground in mills and sifted.
Pumice is hardened lump-shaped lava left after a volcanic eruption. Its volumetric weight is up to 600 kg/m3.
Asbestos is a mineral with a fibrous structure. It is mined in the mountains of the Urals, Siberia, and the Caucasus.
- Solutions used for facing work
