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22
Section 6. Materials Science
Adilkhodjaev Anvar Ishanovich, professor, doctor of technical Sciences, Tashkent Institute of Railway Engineers, Uzbekistan, Tashkent Amirov Tursoat Jummaevich senior lecturer, Tashkent Institute of Design, Construction and Maintenance of Automotive Roads,
Uzbekistan, Tashkent E-mail: [email protected]
ADHESIVE COMPOSITIONS ON THE BASIS OF CHLOROSULPHONED POLYETHYLENE FOR PROTECTION OF CONCRETE AND REINFORCED CONCRETE PRODUCTS
Abstract: The article presents the results of research on the use of new materials based on chlorosulfonated polyethylene, epoxy resin and polysulfide rubber. The proposed adhesive compositions contribute to increasing the strength and frost resistance of concrete and reinforced concrete products when exposed to chloride salts.
Keywords: corrosion of concrete, strength reduction, frost resistance of concrete, epoxy compositions, chlorosulfonated polyethylene, adhesion, modifier.
Introduction
Despite the variety of building materials possessing more and more perfect qualities, the issues of ensuring reliability in the operating conditions of structures remain relevant. Reinforced concrete structures made with observance of all requirements of regulatory documents are free from corrosion problems of building materials. This process can occur absolutely in any systems where water and cement contact occurs. Therefore, the corrosive destruction of concrete and reinforced concrete structures and methods for their effective protection is important.
Consider the problem of corrosion of reinforced concrete, as well as methods of protection on the example of blocks of fencing barrier type of roads, the main purpose of which is the device of the separation barrier between the opposing lanes. The blocks of the fence, made with the observance of different technologies, have excellent aesthetic and physico-mechanical characteristics, which makes them relevant in ensuring the safety of vehicles. However, the climatic conditions of operation of such structures urgently require the development of effective methods of protection against the development of corrosion processes in them in order to ensure long-term operation.
The severity of this problem can be traced when analyzing the state of cement concrete pavements and various auxiliary
elements of the roads of the mountainous and foothill regions of the Republic of Uzbekistan.
High summer (+ 50 - + 55 °C), low winter (-20 - -30 °C) temperature leaves its mark on the development of destructive processes leading to their partial or complete destruction (Figure 1).
To ensure the smooth and safe passage of vehicles in the winter, various reagents are used.
The use of chemicals to combat snow and ice is based on the fact that when interacting with ice and snow, chemical substances, having internal energy, cause the destruction of the crystal structure of ice, as a result, the ice melts and forms a solution with the reagents. When moving the solution and snow wheels of vehicles, the resulting mixture is distributed over the surface of the crystals of unmelted snow and creates a kind of film-frost. At present, a mixture of sand and sodium chloride is used for icing. This technique contributes to the stable and uninterrupted operation of transport during the winter cold season, but does not guarantee the protection of structures from damage due to the development of corrosion processes.
Studies of the destruction of fencing blocks were carried out at sites: from 108 to 208 km of the A-373 "Tashkent-Osh" highway of the Kamchik pass.
ADHESIVE COMPOSITIONS ON THE BASIS OF CHLOROSULPHONED POLYETHYLENE FOR PROTECTION OF CONCRETE...
Figure 1. Ruined blocks of fencing on mountain roads
In the practice of road use, a polymer composition based on chlorosulfonated polyethylene is used. It includes chloro-sulfonated polyethylene and, as a modifying additive, epoxy resin and polysulfide rubber [1].
To mitigate the conditions conducive to the resolution of structures during operation, the road workers use glycerin, when applied to the surfaces of products, waterproof films are created.
The method used improves the corrosivity of products in sulphate environments. However, concrete and reinforced concrete products impregnated in this way are characterized by insufficient frost resistance in chloride salts. Due to the simultaneous action of negative temperature and anti-icing reagent - chloride salts, the road fence blocks are destroyed after 3-5 years of operation, without having served the service life (30-40 years), provided by the manufacturer. As a result, to ensure safety, operational road services are forced to replace the destroyed blocks with new ones. It should also be noted that the components of these compositions imported, expensive, are purchased for hard currency, from a technological point of view are complex and do not allow to fully solve the problem of providing frost resistance under the action of chloride salts.In order to eliminate the shortcomings inherent in film-forming compositions based on glycerol, the compo-
sition proposed is significantly different from those used in practice, not only by availability, but also by physical and mechanical parameters [2].
Comprehensive studies have shown that the coating of concrete and reinforced concrete products with modified chlorosulfonated polyethylene provides for a long time increased strength and frost resistance when exposed to chloride salts.
The mechanism for ensuring the above positive indicators in the proposed protective composition is examined as follows:
Chlorosulfonated polyethylene is modified with hemis-ulfide rubber and epoxy resin. The chlorine group provides polymer resistance to various salts and chemicals, the sulfur group improves weather resistance and oil resistance, and the epoxy group ensures good adhesion of chlorosulfonated polyethylene to concrete.
Results of the research
The proposed method of protection of concrete and reinforced concrete products as follows. After a set of concrete and reinforced concrete products of brand strength, a surface based on chlorosulfonated polyethylene and a modifier is applied onto the surface prepared and impregnated with glycerin.
The test results of the samples when determining the strength and frost resistance are presented in (Table 1).
Table 1.- Strength and cold resistance of impregnated samples
№ Name of indicators Indicators of samples
Soaked in glycerin Soaked with glycerin and composition consumption kg/u2
0.7 0.8 0.9 1.0 1.2
1. Ring crush resistance, MPa 350 365 385 400 410 410
2. Bending resistance, MPa 4.63-6.12 5.0 6.1 7.3 8.1 8.1
3. Frost resistance according to the second base method, cycle 250 260 275 285 300 305
In contrast to the three-layer glycerin coating, which tions, the coating based on chlorosulfonated polyethylene, cracks when cracking in concrete and reinforced concrete epoxy resin and polysulfide rubber, having a greater elastic-structures due to shrinkage, temperature and other deforma- ity, can withstand a crack in size 0.2-0.3 mm.
Conclusion
Impregnated with glycerin with the subsequent application to the surface of the product of the proposed composition - chlorosulfonated polyethylene and modifier, concrete
and reinforced concrete products have increased strength and frost resistance in chloride salts.
This composition also contributes to an increase in the service life of concrete and reinforced concrete products, ensures a reduction in operating costs.
References:
1. Adilkhodjaev A. I., Amirov T. J. Some ways to improve the durability of road concrete and reinforced concrete products of roads // Bulletin of TARI. Scientific and technical journal. - Tashkent. 2018.- No. 1.- P. 38-43.
2. Jalilov A. T., Karabaev A. M., Amirov T.J. et al. Method of protecting concrete and reinforced concrete products // IAP -05605.- Tashkent. Patent bulletin of Uzbekistan.- 06/29/2018.- No.s 6.
