IMPROVEMENT OF FUNCTIONAL PERFORMANCE OF CONCRETE IN LIVESTOCK BUILDINGS THROUGH THE USE OF COMPLEX ADMIXTURES

In the study of cement stone, there are two levels: macroscopic and microscopic. The macroscopic level is made up of large air bubbles, cavities and pits formed, for example, by poor compaction of concrete mixture. These defects can be greatly reduced by using plasticizers. The whole spectrum of binders including the strongest fractions form IMPROVEMENT OF FUNCTIONAL PERFORMANCE OF CONCRETE IN LIVESTOCK BUILDINGS THROUGH THE USE OF COMPLEX ADMIXTURES


Introduction
In the study of cement stone, there are two levels: macroscopic and microscopic. The macroscopic level is made up of large air bubbles, cavities and pits formed, for example, by poor compaction of concrete mixture. These defects can be greatly reduced by using plasticizers. The whole spectrum of binders including the strongest fractions form
Ammonifying and sulfate-reducing bacteria actively proliferate in livestock buildings. Resistance of microorganisms to adverse environmental factors requires careful disinfection of buildings in which pathogens of infectious diseases of animals were identified. Chemical disinfectants are used in solid, liquid or gaseous forms. The most commonly used disinfectants include chlorine lime, alkalis, acids, chlorine-containing preparations and oxidizers, phenols and salts of heavy metals.
Numerous measures are taken to increase corrosion resistance of concrete structures. Service life extends through reduction of humidity in buildings and reconstruction of ventilation systems. Also, to repair old livestock buildings, such measures as partial repair and elimination of cracks and holes that aggravate danger of surface contamination with microorganisms can be taken. Plastering with bactericidal admixtures in mortar is used in major repair of buildings. This is intended to impart such surface form to the building structures that would prevent concentration of organogenic media on this surface. Also, outlet gutters are arranged and corrosive media are neutralized.
Currently, there is a wide range of choice of concrete admixtures and high-strength concretes are offered, however, most of them are of high cost and are down on demand in the agricultural industry. Bactericidal admixtures for concrete must retain their properties for a long time, that is they must not be prone to inactivation by other substances and products of cement hydration. At the same time, admixtures should not have a corrosive effect on concrete reinforcing bars nor impair physical and mechanical properties of concrete.

Literature review and problem statement
Structure of cement stone represents a solid phase and a pore space filled with liquid and gas. Concrete properties depend on physical and chemical characteristics of its solid phase and pore space.
Continuity is important for the solid phase and pH of liquids, moisture content and constant temperature are important for the pore space. A comprehensive approach to capillary-porous structure in concrete makes it possible to take into account formation of its solid phase and pore space on which physico-mechanical and deformation properties of concrete depend [1,2].
Interior surfaces of building structures (both for residential and livestock buildings) are usually of concrete or cement mortar plaster. It was established that concrete has bactericidal properties at the first stage of operation due to the alkaline medium of the cement stone pore fluids [3]. This is explained by presence of moisture and dissolved calcium hydroxide in the pores formed during hydration of clinker materials. However, a year later, the outer layer of concrete structures completely loses its bactericidal properties. This is explained by neutralization of alkaline medium of the cement stone pore fluid caused by carbonation of calcium hydroxide with carbon dioxide of air: Ca(OH) 2 +CO 2 =CaCO 3 +H 2 O. This impact can be regarded as one producing corrosive medium in livestock buildings [4,5].
Ammonia (NH 3 ) and hydrogen sulfide (H 2 S) are components of animal excrements. Ammonia has a negative impact on building structures: floors, fencing, walls and sewage. Sulphurated hydrogen has a pronounced corrosion effect on concrete and steel reinforcement bars as well. Over time, iron sulfides (FeS) are formed, especially in places where concrete layer is too thin [6].
Moisture content grows in livestock buildings and a constant use of disinfectants brings about change of concrete pH. In addition, lactic acid (CH 3 CHOHCOOH) is released from sour milk and silo. For example, fermentation of feeding staff in silo is associated with formation of organic acids (lactic, butyric, acetic acids in concentrations of 0.5-1.0 %) which is accompanied by temperature growth. In an anaerobic fermentation situation, temperature reaches 30-50 °C. Corrosive action of lactic acid on concrete is characterized by pH<5 [7,8].
Relative humidity is very high in almost all livestock buildings often reaching 85 %. Condensate of water vapor on the surface of building structures penetrates the pore spaces and eventually leads to dehydration and cracking. Ammonium hydroxide (NH 4 OH) is formed during interaction of ammonia (NH 3 ) with water and a basic medium arises [9].
Calcium carbonate (CaCO 3 ) is one of the most common substances found in the Earth's crust. It forms limestone and chalk rocks there and in building materials. Chemical and structural parameters of carbonates are immensely diverse which complicates their analysis. For example, it is difficult to isolate certain chemical ingredients, in particular, when producing carbon dioxide gas (CO 2 ) necessary for radiocarbon dating of samples by the content of carbon isotope 14C using accelerated mass spectrometry (AMS). To date, kinetics of CaCO 3 decomposition under the action of high temperature in accordance with reaction (1) has been studied in sufficient detail.
where s is the solid phase state of the substance, g is the gas phase state of the substance. In particular, influence of various experimental factors on the reaction course (1) was studied, namely, rate of heating, particle size, composition of the gas medium, presence of impurities in carbonates of organic and inorganic nature, course of reaction under isothermal and non-isothermal conditions [10]. Note that the studies have been limited in most cases to the study of kinetics of decomposition of chemically pure synthetic CaCO 3 . At the same time, detailed information is needed for applied studies, in particular quantitative evolution of carbon dioxide in accordance with reaction (1) for radiocarbon dating by the AMS method. This is the information on qualitative and quantitative reaction parameters associated with real samples having complex chemical and morphological structures. Based on the above, objective of [10] consisted in establishing limits of the temperature range and time of heating of concrete samples of complex composition for quantitative evolution of carbon dioxide from the samples to be subsequently used in radiocarbon dating by the AMS method. Phenomenon of corrosion is common in concretes with low cement content or low cement grade. This often takes place at agricultural enterprises and is caused by cutting construction costs. Chlorine compounds lead to calcium levitation from concrete. Magnesium chloride and aluminum chloride (MgCl 2 and AlCl 3 ) react with calcium lime which increases risk of concrete corrosion. Calcium chloride destroys concrete if it is not well fixed and compacted [11,12].
Studies [13] have found that destruction of concrete and loss of its strength over a large surface area took place in exposure of test specimens to environment of microorganisms. In addition to bacteria effect, concrete is very vulnerable to the effects of microscopic fungi. Appropriate admixtures should be introduced to provide concrete with long-lasting bactericidal activity.
No effective admixture has been developed so far to improve concrete service and antimicrobial properties and make it resistant to alkalis and acids used in livestock facilities. Another important aspect consists in environmental safety of building materials obtained: they should not emit substances toxic to animals and humans [14].
An option to overcome this problem may consist in introduction into the concrete used for flooring in the livestock buildings such admixtures that would protect it against biological damage and animals against pathogenic microflora [15,16].
When thickness of the carbonized concrete layer and the protective layer becomes the same, corrosion of reinforcement bars starts. Steel corrosion products that have a larger volume than metal cause concrete cracking along the reinforcement bars and facilitate gas penetration. Destruction of structures caused by gas corrosion can occur both as a result of failure of reinforcement bars and concrete destruction [17,18].
Analysis of importance of the factors determining fulfillment of the given conditions makes it possible to state that the most important contribution to ensuring reliability and durability of concrete is made by cement component. This is also confirmed by the data of cement importance in adaptive evolution of concrete. The modern notion of cement stone structure makes it possible to classify it with regard to such important characteristics as level and dispersion of the solid phase, size of pores, energy and forms of water binding. Particular place in concrete industry, in terms of providing specified properties, is taken by the study of the solid phase formed during hydration and curing of cement. It is formation of cement stone and its genesis that will determine, first and foremost, reliability and durability of the material under influence of variable factors [19,20]. This problem is solved by introducing a composition of yellow iron oxide (Fe 2 O 3 ) pigment, liquid glass, cuprous sulfate and acetic acid into concrete for floors of livestock buildings as basic components.
Admixtures are those ingredients that are added to the concrete mixture immediately before or during stirring. Iron oxides attributed to the coloring mixture improve certain mechanical properties [21]. Scientists prove that the use of nano ZrO 2 , Fe 3 O 4 , TiO 2 and Al 2 O 3 at a constant content enhance mechanical properties of fresh and cured concrete, for example, compressive strength [22].
Composition of the experimentally developed biocidal admixture to concrete was selected due to physicochemical characteristics of its components. Liquid glass is known as the substance commonly used in construction to coat build-ing structures. Its addition to concrete improves insulating and strength properties of the latter [23].
Acetic acid (CH 3 COOOH) is formed by interaction of concentrated hydrogen peroxide with glacial acetic acid. Under the action of peracetic acid, the cell membrane and enzyme system of bacteria are destroyed and they die at high concentrations. The range of action of acetic acid is quite wide. Peracetic acid concentration in a range of 0.005-0.2 % is sufficiently effective for action duration from 30 s to 30 min to ensure complete destruction of fungi and their spores. Peracetic acid has a corrosive effect, so low acid concentrations were used in the studies and cuprous sulfate was added [24,25].
Copper tailings have a slight negative effect on sedimentation when time and porosity of mixtures are determined. However, mixtures containing copper tailings have improved mechanical strength and abrasion resistance, as well as reduced chloride penetration. In general, there is a potential in the use of copper tailings as a zero eco-friendly admixture to concrete, especially at a 5 % addition level [26].
Current trends in disinfectology served as a theoretical basis for designing the biocidal admixture. In particular, this is a combination of different active substances in one preparation to enhance beneficial (biocidal activity) and inhibition of undesirable properties (corrosive activity) as regards synergistic dependences.
Therefore, use of the proposed admixture based on yellow iron oxide pigment, liquid glass, peracetic acid and cuprous sulfate is advisable to increase strength and improve corrosion and biocidal resistance of concrete for flooring.

The aim and objectives of the study
The study objective was to develop an admixture to enhance corrosion resistance, increase strength and extend service life of concrete in livestock buildings.
To achieve this objective, the following tasks were solved: -to determine physical and mechanical properties of concrete (pH, heat resistance, permeability) exposed to organic media; to study chloride penetration into concrete applying temperature-programmed mass spectrometry (TPMS) technique; to determine antimicrobial properties of the building materials obtained.

The materials and methods used in making concrete
with bactericidal admixtures 4. 1. The procedure of studying the bacterial effect on corrosion resistance of concrete exposed to organic media The studies were conducted at Sumy Oblast Veterinary Laboratory (Sumy, Ukraine). The test specimens were prepared in Laboratory of Architecture and Engineering Studies of Sumy National Agrarian University during 2019. The studies were performed using M 400 Portland cement produced in Kryvyi Rih (Ukraine) and river sand and gravel excavated in Sumy.
Improvement of service performance of floors and their protection against biological damage (effect of corrosive environment and biological corrosion) occurred due to the use of yellow iron oxide pigment (Fe 2 O 3 ) produced by Sumykhimprom PJSC (Ukraine), liquid glass, cuprous sulphate and peracetic acid as main mixture components.
The proposed composition of the biocidal admixture to concrete, wt. %, was as follows: yellow iron oxide pigment (DSTU GOST 30333:2009): 1.5-2.0; liquid glass: 2-3; -cuprous sulfate: 0.5-1.0; -peracetic acid: 0.2-0.3; -water: up to 100 wt. %. In order to study the effect of bacteria on corrosion resistance of concrete in organic media, five nutrient media were prepared: the medium for ammoniating bacteria of Bacillus, Pseudomonas and Achromobacter species was prepared in distilled water (peptone: 5 g; K 2 HPO 4 : 1 g; MgSO 4 ·7H 2 O: 0.5 g; NaCl: traces per 1,000 ml at pH=7.5). The end product of life activity of these microorganisms is carbon dioxide, water, ammonia and salts of sulfuric and phosphoric acids; the medium for ammoniating bacteria of Bacillus, Micrococcus and Sporosarcina species was prepared in distilled water (CO (NH 2 ) 2 : 5 g; potassium citrate (K 2 C 6 H 5 O 7 ·H 2 O): 5 g; K 2 HPO 4 : 1 g; MgSO 4 ·7H 2 O: 5 g per 1,000 ml at pH=8.0). In the course of life activity of these bacteria, decomposition of urea with urease enzyme with formation of ammonium carbonate and then final products: ammonia, carbon dioxide and water; the medium for nitrous bacteria of Nitrosomonas, Nitrosolobus, Nitrosococcus, Nitrosopira species was prepared in distilled water ((NH 4 ) 2 SO 4 : 2.0 g; K 2 HPO 4 : 1 g; MgSO 4 ·7H 2 O: 0.5 g; NaCl: 2.0 g; FeSO 4 ·7H 2 O: 0.4 g; CaCO 3 : 5 g per 1,000 ml at pH=7.6). During the life activity of these bacteria, oxidation of ammonium salts to salts of nitrous acid (nitrites) takes place. This is the process of nitrification, phase 1: NH +1,5O NO +H O+2H . → -the medium for nitrate bacteria of Nitrobacter, Nitrispina species, was prepared in distilled water (NaNO 2 : 1 g; NaCO 3 : 1 g; NaCl: 0.5 g; K 2 HPO 4 : 0.5 g; MgSO 4 ·7H 2 O: 0.5 g; FeSO 4 ·7H 2 O: 0.4 g per 1,000 ml at pH=7.8). During the life activity of these bacteria, conversion of nitrites to nitrates, that is salts of nitrous acid are oxidized to salts of nitric acid. This is the process of nitrification, phase 2; specimens were exposed to a medium imitating that of livestock buildings (distilled sterile water at pH=7.0 was served as a control sample).
Physical and mechanical properties of concrete were determined applying the conventional procedure [27].
Concrete specimens in a form of 70×70×70 mm cubes were prepared in laboratory of the Department of Architecture and Engineering Studies of Sumy National Agrarian University. An appropriate admixture was introduced based on yellow iron oxide pigment (Fe 2 O 3 ) produced by Sumykhimprom PJSC (Ukraine), liquid glass, cuprous sulfate and peracetic acid according to the weight of cement and the control sample which did not contain admixtures.

2. The method used in determining chloride penetration into concrete and temperature-programmed mass spectrometry (TPMS)
Actual penetration of chloride ions into concrete specimens was assessed by immersion of concrete cubes with all their sides except one exposed to a 3 % NaCl solution for 28 days. After that, the samples were split and sprayed with a 0.1 % solution of silver nitrate to determine depth of chloride penetration [28]. These depths were determined as points in the samples where free chlorides exceeded 0.15 wt. % of cement. They reacted with the 0.1 % solution of silver nitrate (AgNO 3 ) forming a white precipitate of silver chloride (AgCl). Absence or a limited presence of free chloride was indicated by a brown precipitate of silver oxide (AgO) formed by reaction of the AgNO 3 solution and hydroxides in the concrete specimens.
A temperature-programmed mass spectrometry (TPMS) unit consisting of a high-temperature oven and an MX-7304A gas mass spectrometer (SELMI OJSC, Sumy, Ukraine) was used in the studies (Fig. 1).

2-3 mg samples were taken for the experiment.
The technical details of the experiment are presented in detail in [29].
Peaks of ions with molecular weights (m/z) of 2 for hydrogen; 16 for oxygen; 18 for water; 28 for carbon monoxide (CO) and 44 for carbon dioxide (CO 2 ) were subjected to unique identification in the obtained mass spectra.

3. Methods used in assessment of the antimicrobial action of building materials
After a 28-day curing, the samples were placed in Petri cups on MPA with test microbes. 20 ml of sterile MPA was poured into the cups and after complete cooling, 1 ml of a 2 billion exposure of one-day E. Coli or S. Aureus broth culture was applied and evenly spread over entire surface of the cup. After 40-60 min, excess cultures were aspirated and samples of building materials were introduced. Cups were placed in a thermostat for 18-24 hours at a temperature of +37.6 °C. Museum strains of Escherichia Coli and Pseudomonas Aeruginosa were used [30].

Results obtained in the study of concretes with bactericidal admixtures 1. Results of studying the physical and mechanical properties of concrete exposed to organic media
Specimens for corrosion resistance studies were made in which the biocidal admixture content was 0; 0.5; 1; 2 % of cement weight. After 28 days of normal curing, the samples were placed in flasks with nutrient media and sterilized in an autoclave at 121 °C and pressure of 0.1 MPa. Half of the nutrient media were infected with bacteria corresponding to each nutrient medium. The rest of the media were left for control. The medium pH was measured once a month. Initial pH values ranged from 4.5 to 5.0. The study results are given in Table 1. The pH level in media with nitrating (2 nd phase nitrification) and ammoniating (urea ammonifiers) bacteria decreased by 10-15 % compared to the initial level. In media with microorganisms, pH should be reduced by 50-60 % compared to the initial pH of 4.5-5.0. This change in pH is due to the life activity of bacteria that create an acidic medium and, as a consequence, corrode concrete. The study results are presented graphically in Fig. 2.
Thus, it can be concluded that a concrete admixture of 1 and 2 % concentration does not change pH in corrosive bacteria media.
At the next study stage, strength properties of concrete specimens exposed for 6 months to media with and without microorganisms were assessed ( Table 2).
For example, compressive strength of control specimens having no admixtures exposed to various media was lower than that of the test specimens having a complex admixture.
Strength of the test specimens grew with an increase in concentration of the admixture relative to the cement weight despite the corrosive effect of various media. This is especially pronounced in the media with ammoniating bacteria (protein ammonifiers). No influence of microorganisms in the media with nitrating and ammoniating urea was observed which is confirmed by the pH values ( Table 1).
As noted earlier, this effect is caused by the adsorption reaction when surface of the iron oxides is covered with OH ions. These types of ions are called surface functional groups. Due to this effect, peculiar adsorption of various anions occurs. This reaction limits electrostatic interactions between ions. Surface adsorption acts through Fe-OH groups. These groups obtain negative or positive charge by dissociation or association of protons depending on pH of the ions surrounding them. On the other hand, the occurrence of different degrees of iron oxidation and creation of different phases must increase compressive strength of concrete.
Introduction of biocidal admixtures in amounts of 0, 0.5 and 1 % of cement weight has shown the same increase in the specimen strength. Most of all, this was evident from the results of studies in a medium imitating the livestock medium and in a medium with nitrous bacteria. Introduction of a biocidal admixture in an amount of 2 % of cement weight improved strength properties of concrete specimens compared to the standard specimen. Studies of biocidal properties have shown that the most pronounced bactericidal properties were in samples with a biocidal admixture in an amount of 2 %.
Concrete admixture can significantly increase strength and corrosion resistance, improve biocidal resistance of building materials for flooring the livestock buildings (Fig. 3, 4).

Fig. 2. pH values in various nutrient media with and without microorganisms during 180 days
For example, when 0.5 % of the admixture is introduced to concrete, strength of the specimens exposed to the medium with bacteria has reduced by only 4-5 % compared to the control specimens. Concentration of 1-2% of the admixture maintained the strength of concrete specimens exposed to corrosive medium by 98-99 %.

2. Results obtained in the study of chloride penetration into concrete and temperature-programmed mass spectrometry (TPMS)
Depths of chloride penetration into the specimens immersed in a 5 % NaCl solution for 28 days were assessed (Fig. 5). These results have shown that chloride penetration was higher in control samples of concrete compared to the experimental ones. Penetration depth was 19.5 % in the concrete specimens without admixtures.
When admixtures were introduced to the concrete in amounts of 0.5 % to 2 %, depth of chloride penetration has decreased from 8.9 mm to 3.2 mm, respectively. Reduced depths of chloride penetration are due to a decrease in absorption of concrete water by introduction of admixtures of iron oxide, cuprous sulfate, peracetic acid and sodium silicate which caused decrease in specimen porosity. Therefore, due to the admixtures, the formed structure had intermittent pores and significantly reduced penetration of chlorides in the specimens.
The use of the TPMS method for predicting the direction and intensity of influence of some biocidal admixtures on physical and chemical properties of concrete has confirmed effectiveness of the developed admixture (Fig. 6). Fig. 6 shows curves of dependence of carbon monoxide (CO) and carbon dioxide (CO 2 ) evolution from specimens of carbon-containing substances on temperature. A detailed examination of the curves of dependence of CO and CO 2 evolution from the samples on temperature (Fig. 6) shows a clearly pronounced tendency to the shift of maximum evolution of gaseous substances in the direction of the heating temperature growth depending on presence of admixtures in the specimens. In particular, a concrete enriched with iron oxide gives a clearly delineated intense peak at 500-650 °C. At the same time, the reference sample of concrete begins to evolve carbon dioxide as soon as temperatures reach 400 °C which causes a looser concrete structure.
Thus, it was found in the experimental studies that the temperature range of heating for quantitative evolution of calcium carbonates from all studied specimens of concrete was 400-500 °C. At the same time, shape of the thermograms of carbon dioxide evolution intensity differs significantly in width and intensity depending on the temperature for each of the concrete specimens compared to the control sample (chemically pure synthetic CaCO 3 ). It can be assumed that different behavior of concrete samples when heated relates to the presence of different chemical admixtures.
The method of temperature-programmed desorption mass spectrometry (TPMS) has shown that addition of yellow iron oxide pigment to concrete increases its thermal resistance which is a positive property for building materials used in the construction of livestock buildings.

3. Results obtained in the study of antimicrobial properties of the obtained building materials
The studies have shown that concrete admixtures in a concrete improve its corrosion and biocidal resistance and strength. In order to provide these characteristics, an aqueous solution of environmentally friendly admixture with bactericidal properties based on yellow iron oxide pigment (1.5-2.0 wt. %), liquid glass (2-3 wt. %), peracetic acid (0.2-0.3 wt. %) and cuprous sulfate (0.5-1.0 wt. %) has to be introduced into concrete.
To study bactericidal properties of the obtained concrete, the concrete samples were immersed in cups with a nutrient medium and microorganisms ( It was proved that concrete with addition of admixtures in 1 and 2 % concentrations retains its bactericidal properties and as a result, is not amenable to biological corrosion (Fig. 7, 8).
It was found in the study that microscopic fungi grow well on concrete. Renicillis, Aspergillus, Cladosporium, Fusarium were most commonly detected [31,32]. Therefore, studies were conducted to identify fungicidal effect of the obtained concrete with a biocidal admixture. Duration of exposure of the experimental and control specimens in the livestock buildings was six months. During this time, specimens of building materials were contaminated. The specimens were crashed and examined in the laboratory for the presence of colonies of microscopic fungi ( Table 4).
The experiment has confirmed presence of antifungal action of the admixture added to concrete as the number of fungi colonies decreased by 98 % compared to the control samples (without admixtures). All isolated fungi germinating in the concrete pores can have a significant destructive effect on the concrete. Their spores are toxic to animals and humans ( Fig. 9-11).   Therefore, introduction of admixtures can significantly increase strength of concrete floors, improve their functional performance, reduce the amount of microflora on the surface and inside.

Discussion of results obtained in the study of concretes with bactericidal admixtures
Studies have shown that concrete is destroyed and signs of corrosion occur in livestock buildings. This problem can be solved by introduction of admixtures that increase corrosion resistance of concrete, extend to some extent duration of its bactericidal activity. This is due to neutralization of the concrete surface layer. Therefore, in order to provide concrete with long-lasting antimicrobial activity, it is necessary to add bactericidal admixtures. This will not only protect animals against re-infection with diseases but also increase durability of structures by eliminating biological corrosion [33]. Introduction of bactericidal admixtures reduces microbiological pressure on animals [34].
It has been experimentally proven that the use of yellow iron oxide pigment improves strength characteristics of concrete, heat resistance and reduces penetrability. Biocidal action of this component is based on Fenton's advanced oxidation processes (AOP) and the combination of hydrogen peroxide (H 2 O 2 ) and ions of ferric and ferrous iron (Fe (III), Fe (II)). This reaction leads to the formation of highly reactive ions: OH -, O 2-, and oxygen molecules (O 2 ) capable of destroying microorganisms by oxidation [35,36].
In addition, it was proved by the studies that an effect of surface adsorption occurs due to the addition of iron oxide to concrete. This reaction limits electrostatic interactions between ions. The presence of different degrees of iron oxidation in concrete and creation of different phases contributes to the growth of its compression strength.
A method of studying properties of building materials with the help of TPMS technique was also used in the work. As a result of temperature-programmed mass spectrometry of concrete samples, it was found that introduction of an admixture based on iron oxide increases thermal stability of concrete compared to the control samples.
Disadvantage of this method consists in chemical differences of artificial carbonates as well as their low content in concrete compared with limestone. Therefore, comparison of different concretes and interpretation of the data obtained is a time-consuming process.
When tested for penetration of 5 % NaCl solution into concrete, possibility of its reduction was proven by adding a 2 % admixture based on yellow iron oxide pigment, peracetic acid, liquid glass and cuprous sulphate to 3.2 mm compared to the control specimen (19.5 mm). Such changes in concrete occur due to the introduction of fine crystalline powder of yellow iron oxide pigment as a filler and liquid glass, as a plasticizer reducing the pore holes. Introduction of admixtures changes concrete structure and reduces absorption of water and various chemical disinfectants used in cattle breeding. However, destruction of concrete will occur if sodium hydroxide (NaOH) and non-hydrated lime are used if the livestock buildings.
At the same time, studies [31,37,38] note that microorganisms live and actively reproduce on the surface of building structures destroying them and secreting toxic products and allergens. This leads to deterioration of environmental situation in buildings and structures. Thus, in agricultural buildings affected by pathogenic microorganisms, animal weight gain is reduced and death of animals is noted.
It has been established experimentally that corrosion of concrete in the livestock buildings is caused by microscopic fungi of Penicillium, Fusarium and Cladosporium, Aspergillus species and Escherichia coli and Pseudomonas aeruginosa bacteria. Microscopic examination with immersion of concrete samples in agar proved that the proposed concrete admixtures (based on yellow iron oxide pigment (1.5-2.0 wt. %), peracetic acid (0.2-0.3 wt. %), liquid glass (2-3 wt. %) and cuprous sulfate (0.5-1.0 wt. %) demonstrate antimicrobial properties. However, the problem consists in a limited term of antimicrobial properties. Therefore, the aim of further studies is to determine limits of bactericidal properties of concretes with complex admixtures and correct their composition taking into account previous disadvantages.
It should be noted that the use of the proposed measures can improve corrosion resistance of concrete by improving its physical, mechanical and antimicrobial properties. This is a prerequisite for the use of this concrete admixture in the construction of new livestock buildings.
2. It was established that when adding admixtures in concrete in a quantity from 0.5 % to 2 %, depth of chloride penetration decreases from 8.9 mm to 3.2 mm, respectively, and application of the TPMS method to predict direction and intensity of impact of some biocidal admixtures on physical and chemical parameters of concrete has confirmed effectiveness of the developed admixture.
3. This admixture exhibits bactericidal properties directed against microflora: the number of fungi colonies is reduced by 98 %, which gives grounds for its use in the livestock buildings.