CC BY
16
https://doi.org/10.29013/AJT-21-1.2-49-53
Babayev Zabibulla Kamilovich, Department of Chemical Technology, Urgench State University,
Urgench, Khorezm, Uzbekistan E-mail: [email protected] Masharipova SharofatMuhammadova, Khorezm Academy of Mamun, Khiva, Khorezm, Uzbekistan E-mail: [email protected] Buranova Dinara Baxtiyarovna, Department of Chemical Technology, Urgench State University, Urgench, Khorezm, Uzbekistan
E-mail: [email protected] Ataeva Farida Abdusharipovna, Department of Chemical Technology, Urgench State University,
Urgench, Khorezm, Uzbekistan E-mail: farida [email protected]
IMPROVING THE STABILITY OF RESTORATION INORGANIC WALL MATERIALS IN THE MONUMENTS OF ANCIENT ^IVA
Abstract. The article is devoted to the study of the properties of ceramic brick waste as a technogenic mineral raw material for reuse in the production ofwall materials. The urgency of solving this problem is due, on the one hand, to environmental problems of reducing the resource intensity ofwall materials, on the other hand, to the problems of socio-economic development of the region. Possibility of obtaining clinker. a loess-like loam brick was created. To improve the forming properties of the ceramic mass, a method has been developed for producing a mechanically activated binder from a starting material. It has been proven that when it is introduced into the composition of the ceramic mass, the properties of semi-finished products improve. Polished slag of ceramic bricks is offered as a thinner for ceramic mass. It has been established that its introduction into the composition of the brick mass leads to a decrease in the shrinkage of the samples. the optimal amount is determined (15%).
Keywords: mineral raw materials, wall materials, diffractogram, clinker brick, loess loam, ceramic mass.
The Gorenje wall materials of ancient Khiva are cal world heritage sites [1], as well as monuments
ceramic bricks obtained by firing loess-like loams, of ancient Khiva, have been activated, as reported
while the firing was carried out in a reducing envi- in our early works. Restoration and preservation
ronment, where the heat source was the heat released of historical monuments, preserving its primitive
from the burning of various firewood, herbs, and appearance, is one of the most important tasks. In
shrubs. In recent years, under the influence of natural this regard, we set a goal to study the world expe-
forces, the processes of destruction of several histori- rience and develop on their basis the principles of
production of chemically resistant and mechanically strong materials for restoration.
The production of ceramic bricks in the Republic of Uzbekistan is accompanied by the formation of industrial waste, the issue of disposal of which is still an unsolved problem. These wastes include ceramic bricks and slags, the amount ofwhich varies between 10-15% and 8-12%, respectively. Until now, they are mostly taken to landfills of solid household waste or put in special designated places. At the same time, not only the volume of landfills increases significantly, but also the mineral raw materials, whose resources are limited in the conditions of the Khorezm region, are irretrievably lost. This work is devoted to the study of the properties of waste ceramic bricks as technogenic mineral raw materials for reuse in the production of wall materials. The urgency of solving this problem is caused, on the one hand, by environmental problems of reducing the resource intensity of wall materials, on the other - by issues of socioeconomic development of the region [1].
Many works are devoted to the study of the properties of ceramic bricks produced from mineral and man-made raw materials used in architectural monuments. In [2], a specially developed experimental setup is proposed for simultaneous and reliable monitoring ofhumidity, salts, and spontaneous electrical polarization in stone walls, based on the joint use of permanent sampling points and electrodes.
The results of testing the mass moisture content in salted baked solid clay bricks by non-destructive dielectric, resistive, and microwave methods are presented. [3] several groups of bricks were Tested, which were aged in aqueous nitrate, chloride, and sulfate media with different ion contents, and in saltfree water (as a reference), respectively. It is shown that the mineralization of bricks significantly affects the readings of the dielectric meter and the resistance meter, and this effect is similar for different salt concentrations, which leads to a significant overestima-tion of the calculated humidity relative to the actual humidity.
The paper [4] presents preliminary experimental studies conducted on samples of masonry from baked clay bricks and cement mortar joints to assess structural damage caused by salts. For this purpose, the samples were subjected to specially developed accelerated weathering procedures of various durations in solutions of sodium chloride and sodium sulfate (the most common salts in brickwork). Then, using a special experimental test, the shear behavior of artificially damaged masonry samples was studied.
Another source [5] reports the reuse of spent bricks by alkaline activation in a new geopolymer brick. The influence of the inclusion of crushed granulate of blast furnace slag, the molarity of sodium hydroxide (NaOH), and the ratio of silicate-sodium hydroxide (Na2SiO3/NaOH) on the mechanical properties of the final product is studied. The production of geopolymer bricks was carried out by mixing brick battle, crushed granulate ofblast furnace slag, sand with a solution of sodium hydroxide and silicate. Samples were prepared according to various recipes. The obtained optimal compressive strength is 89.91 MPa with a blast furnace slag/ bricklaying ratio of 80/20, molarity of 8 m NaOH, and a silicate/hydroxide ratio of 2/1.
The authors constructed a mathematical model of the kinetics of phase transformations ofsalts in pores in combination with a program for modeling the transfer of heat, moisture, and salts in capillary-porous materials. This unique equation describes the kinetics of all five-phase transformations (hydration, dehydration, deliquescence, crystallization, and dissolution) [6].
Sources [7] report that in old buildings, increased humidity in walls that are in direct contact with the ground leads to migration of soluble salts, which are responsible for many of the observed pathologies. The authors concluded that the most effective way to handle rising dampness is to ventilate the base of the wall.
The paper [8] analyzed the state of historical brick buildings in Poland and concluded that most of them are in poor technological condition due to lack of proper insulation from moisture and water,
so they need immediate reconstruction. The article describes some selected problems that arose during the design and manufacture of wet insulation in two huge historical priceless Baroque buildings located near the Odra hive in wroclaw, namely the main building of the University of wroclaw and the building of the National Institute of Ossolinski in wroclaw.
The phenomenon of increasing humidity with a discussion of the controlling mechanisms and contributing factors, such as capillary effect, water absorption, evaporation, and salt formation. As discussed in [9] it also presents the results of a study on increasing humidity based on a practical annual test. Measurements were made on rising dampness on walls made of various solutions, and observations were compared with theoretical models. It was found that the characteristics of the solution will significantly affect the height of the moisture rise. It was also noted that there is a strong correlation between humidity growth and the sharp front model, and the rate of water absorption in solution was a key factor in determining the height of the rising wet front. Also, walls with ascending wet treatment are warmer than their control counterparts due to a reduction in the surface humidity of evaporative cooling.
X-ray phase analysis is the main method of diagnosing clay minerals. Compared with other minerals, they have significantly larger interplane distances, especially along with one of the crystallographic directions - the C-axis. To register large interplane distances, a survey is carried out in the area of small angles, since it follows from the Wulf-Bragg formula that the larger the value of d/n, the smaller the reflection angle 0. Identification of clay minerals is made mainly by reflections from the so-called basal planes, which have indices 001. Many clay minerals give a similar set of reflexes on radiographs. To correctly identify them, a system of treatments is used: saturation of mineral aggregates with organic liquids (glycerin or ethylene glycol), calcination at different temperatures, saturation with various cations. Since the crystal lattices of various clay minerals react dif-
ferently to these treatments, this technique allows for a more accurate diagnosis of the minerals in the mixture. Minerals of the montmorillonite group give different x-ray reflections in the air-dry state and after processing the sample with organic liquids. In mag-nesian and aluminum chlorites, all reflections remain unchanged after calcination. Mixed-layer minerals are alternating layers of different types in the normal direction to these layers (for example, illite-mont-morillonite, chlorite-vermiculite, etc.). the Study and identification of this group of clay minerals are carried out only by basal reflections. The interplane distances (d/n) and reflex intensities (I) depend on the type of components and the nature of layering.
The type of clay raw material determines its behavior in drying. The selected raw materials are highly sensitive to drying, which makes it necessary to select lean additives. From an economic point of viewoTomHTeAa, brick slag, which is formed when firing ordinary ceramic bricks, the volume of which reaches 10-15% ofthe output, is recommended as an otoshitel.
According to the studied data, the slag of ceramic bricks has a dark brown color, resulting in the melting of the low-melting part of the raw material and cools down in the form of stone. Density 1600-2100 kg/m3, the mechanical strength of 20-30 kg/cm2. Until now, ceramic brick slag is not used in brick enterprises and is stored in factories. In the experiments, a crushed slag fraction of 0.5-1 mm was used. The chemical composition of ceramic brick slag is as follows (in mass.%): Si02-60,30; Al2O3-13,65; Ti02-0,49; Fe203-6,08; CaO- 13,05; MgO-3,24; Na20-1,05; K2O-2,14.
The identification of samples was performed based on diffractograms, which were taken on XRD-6100 (a computer-controlled XRD-6100 (Shimadzu, Japan). CuKa-radiation (^-filter, Ni, 1.54178 modes of current and voltage of the tube 30 mA, 30 kV) and a constant speed ofrotation of the detector 4 deg/min in increments of 0.02 deg were used. (« / 20-coupling), and the scanning angle varied from 4 to 80o.
Figure 1. x-ray Phase images of ceramic brick slag
X-ray phase analysis of a sample of ceramic brick slag is shown in Fig. 1, indicating that its composition Andesin-49.4%, diopside-41.8%, Kinart-8.8%.
Experimental samples of bricks based on optimal compositions had the following indicators: water absorption of bricks-2,5-9.0%; npegeAbmaximum compressive strength- 40-50 MPA; frost resistance- 50-60 cycles; abrasion resistance- 0,45-0,52 g /cm3; chemical resistance-9.7, 3-99, 0%. These characteristics of the new composition of clinker bricks allowed us to suggest recommendations for their use in extreme climatic conditions and in areas characterized by high salinity of the soil.
In the part devoted to the study of the binder extracted from the feedstock, data on the method
of separating the binder are given - the liquefaction of loess loam followed by gravitational separation, the use of mechanical activation of the selected plastic part to improve its binding properties. The optimal content of crushed powder in the composition of the mass of ceramic bricks is 20-30 wt.%. at an increase of more than 30 wt. the compressive strength decreases below the normalized value and water absorption of the resulting samples increases, and when its content decreases by less than 10 wt.% there is no significant decrease in the thermal conductivity coefficient. Products made from loess-like loam with an additive within the range of changes in the composition of the ceramic mass of the mass fraction of powder or ceramic bricks have sufficient color saturation and clarity of color tone.
Thus, as a result of the experiment, the possibility of using the waste of ceramic bricks as an otoschitel is established. This man-made raw material is recommended after appropriate grinding.
The possibility of obtaining clinker bricks from loess loam has been established. To improve the molding properties of the ceramic mass, a method for obtaining a mechanically activated binder from the feedstock has been developed. it is proved that
with its introduction into the composition of the ceramic mass, the molding properties of semi-finished products improve. oTo^meAaGround slag of a ceramic brick is offered as an otoschitel of a ceramic mass. It is established that its introduction into the composition of the brick mass leads to a decrease in the shrinkage value of samples. The optimal ero amount of it (15%) has been determined.
Referennces:
1. Babayev Z. K., Masharipova S. M., Musayev A. A. and Ataeva F. A. "Waste from ceramic bricks, as a raw material for the production of restoration materials," Int. J. Emerg. Trends Eng. Res., - Vol. 8. - No. 8. P. 4390-4393. 2020. [Online]. Available: URL: http://www.warse.org/IJETER/static/pdf/file/ ijeter56882020.pdf.
2. Franzoni E., Sandrolini F. and Bandini S. "An experimental fixture for continuous monitoring of electrical effects in moist masonry walls," Constr. Build. Mater.,- Vol. 25.- No. 4.- P. 2023-2029. Apr. 2011. DOI: 10.1016/j.conbuildmat.2010.11.047.
3. Abdollahnejad Z. et al. "Microstructural Analysis and Strength Development of One-Part Alkali-Activated Slag/Ceramic Binders Under Different Curing Regimes," Waste and Biomass Valorization,- Vol. 11.-No. 6.- P. 3081-3096.- Jun. 2020. DOI: 10.1007/s12649-019-00626-9.
4. Gentilini C., Franzoni E., Bandini S. and Nobile L. "Effect of salt crystallization on the shear behavior of masonry walls: An experimental study," Constr. Build. Mater.,- Vol. 37.- P. 181-189. Dec. 2012. DOI: 10.1016/j.conbuildmat.2012.07.086.
5. Youssef N. et al. "Reuse of waste bricks: a new generation of geopolymer bricks," SN Appl. Sci.,-Vol. 1.- No. 10.- P. 1-10. Oct. 2019. DOI: 10.1007/s42452-019-1209-6.
6. Espinosa R. M., Franke L. and Deckelmann G. "Phase changes of salts in porous materials: Crystallization, hydration, and deliquescence," Constr. Build. Mater.,- Vol. 22.- No. 8.- P. 1758-1773. Aug. 2008. DOI: 10.1016/j.conbuildmat.2007.05.005.
7. Torres I. and de Freitas V. P. "The influence of the thickness of the walls and their properties on the treatment of rising damp in historic buildings," Construction and Building Materials,- Vol. 24.- No. 8.-P. 1331-1339. Aug. 2010. DOI: 10.1016/j.conbuildmat.2010.01.004.
8. Adamowski J., Hola J. and Matkowski Z. "Probleme und lösungen beim feuchtigkeitsschutz des mauerwerks von baudenkmälern am beispiel zweier großer barockbauten in wroclaw," Bautechnik,- Vol. 82.- No. 7.- P. 426-433.- Jul. 2005. Doi: 10.1002/bate.200590148.
9. Hirsch E. and Zhang Z. "Rising damp in masonry walls and the importance of mortar properties," Constr. Build. Mater.,- Vol. 24.- No. 10.- P. 1815-1820. Oct. 2010. DOI: 10.1016/j.conbuildmat.2010.04.024.
