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DOI: http://dx.doi.org/10.20534/AJT-16-9.10-55-57
Djandullaeva Munavara Saparbaevna, Tashkent chemical-technological institute, Senior staff scientist, Department of Technology of inorganic substances E-mail: djandullaeva@mail.ru. Turabdjanov Sadritdin Mahamatdinovich, Chancellor of Tashkent chemical-technological institute, Doctor of technical sciences, professor Atakuziev Temirjan Azim ugli, Tashkent chemical-technological institute, Doctor of technical sciences, professor, Department of Technology of inorganic substances Xusnitdinov Asomiddin Munnimovich, Tashkent chemical-technological institute, Senior staff scientist
Enhancement of adhesiveness of silicate brick on the basis of tuffit addition with masonry mortar
Abstract: Presented the results of research by investigation of possibilities enhancement of adhesiveness of silicate brick on the basis of barchan sands and steel making slag sand with masonry mortar due to introduction into the raw mixture hydraulic active addition — tuffit thermally processed at 600 °C in quantities of 10%, 20%, and 40%. It was established that the most effective is addition of tuffit 20% which enables enhancing its normal adhesion with masonry mortar already at 7 — day time of hardening, in more than 4-times as compared with brick without additions (0,115 MPa). Such brick has adhesion with masonry mortar almost 2 times more than requirements of Construction Rules and Regulations R > 0,18 (0,309 MPa).
Keywords: Tuffit, hydraulic active addition, adhesiveness, silicate brick, masonry mortar, hardening.
It is well known, that residual hydraulic activity of Input in composition of silicate mixture of burned silicate brick may change its properties via interactions tuffit rock, as opposed to rock in natural condition, does
of components which located inside of it with calcium hydroxide of masonry mortar, which affects technology of production of brick and on its basic construction and technical properties.
During autoclaving, first of all, occurs interaction between calcium hydroxide and active SiO2 and Al2O3 contained in fired at 600 ° C tuffit, which introduced in mixture for production of silicate brick. From now on the thermally processed at 600 ° C tuffit we shall refer
not affect negatively in deformation, shrinkage and swelling of silicate brick. When 10-20% of tuffit introduced shrinkage does not change, but while there is addition of30-40% tuffit, shrinkage reduces slightly as compared with mixture without additions of tuffit. Swellings of samplings practically do not change.
In laboratory mixer machine dry mixture with activity 8% were prepared from quicklime, tuffit addition, barchan sand and steel making slag sand (table. 1).
as tuffit.
Table 1. - Content of components in investigated mixtures
Tuffit thermally processed at 600 °C Quicklime Steel-making slag sand Barchan sand
10 10 20 60
20 10 20 50
40 10 20 30
Section 7. Technical sciences
Steel making slag sand with dimensions 0,350,60 mm we use as enlarger. Since barchan sands have homogenous granulometry (size 0,14 mm), which molded poor at currently functioning press machine.
Samples were molded in molds with sizes 4x4x4 mm by specific pressure — 20 MPa and different molding-moisture content. Optimal molding-moisture content of sample with addition of tuffit in quantities 10%; 20%;
Table 2. - Effect of tuffit addition on physical
40% accordingly is 10,5%; 11,5%; 13%, and molding-moisture content at samples without addition of tuffit is 9,5%. Addition of steel-making slag sand promotes reduction of moisture.
Molded samples were autoclaved at pressure of steam 0,8 MPa by cycle 2+8+2 hours. Before and after autoclav-ing physical and mechanical properties were measured (table 2).
and mechanical properties of silicate samples
Quantity oftuffit Bef ore autoclaving After autoclaving with pressure 0,8 MPa during 8 hours
Molding mois-ture,% Compression strength, MPa Volume-weight, g/sm 3 Compression strength, MPa Volume weight, g/sm3 Water absorp-tion,% Poros-ity,% Frost resis tance
0 9,5 0,4 1,940 12,8 1,682 17,8 35,02 25
10 10,5 0,6 1,990 20,0 1,678 16,9 35,3 30
20 11,5 0,8 1,930 27,0 1,646 16,0 35,9 35
40 13 0,12 1,920 21,0 1,593 18,1 37,8 30
Increasing the content ofhydraulic active addition of tuffit in mixture causes a slight rise of optimal molding moisture. It is due to higher water absorption of tuffit addition as compared with barchan sand, and also due to lower volume weight.
There is very important moment in technological view the positive effect of tuffit addition on strength of pressed silicate samples (0,8-0,12 MPa). Presence in mixture of tuffit addition and slag enlarger increases removable strength of silicate samples in some cases up to 250%, without increasing activity of mixture. Removable strength of silicate samples to a large degree is defined by activity of tuffit addition. The hardness of structure of samples is affected not only by increase of the forces on which interacts on surface which is brought about by tuffit addition with high specific surface, but also by development especially at beginning period of chemisorptive bond.
Input of tuffit and steel making slag sand positively effects on hardening parameters of silicate samples, autoclaved at 175 ° C during 8 hours (Table 2). Maximal enhancement of strength of silicate samples corresponds to mixture with tuffit addition of 20-40% and steel-making slag sand 20% (21-27 MPa).
Crucial role of tuffit in forming of strength after au-toclaving is due to its specific feature as hydraulic active addition, which affects not only speeding up of formation of calcium hydrocilicate by autoclaving, but also on crystallization of hydratation products.
Efficient effects of highly active (in absorption of CaO) addition such as tuffit, is center of crystallization
new formation by autoclaving treatment of silicate materials. The properties of tuffit as crystallization priming may be due to more perfect structure of crystallite, formed in process cooling of alum silicate molten mass under high pressure.
Steel-making slag sand in given conditions also is active component participating in forming hard silicate rock. That obtained thanks to improving of fraction composition of barchan sand with steel-making slag with sizes 0,35-0,60 mm, which favors obtaining pressed silicate product with high grade strength by hydrothermal processing.
Autoclaved samples with tuffit addition have its optimum in content of addition from point of view of maximal mechanical strength (20%). With introduction of tuffit from 20% to 40% volume weight of autoclaved samples decreases.
Water absorption and porosity of autoclaved pressed silicate samples with tuffit addition and slag sand meets the qualifying standards to walling materials. Type of dependency ofwater absorption and porosity of autoclaved samples from their composition is analogous to changing of specific volume of samples.
Frost resistance is one of defining properties of material, which to large extent depends from structure and composition of samples. Autoclaved samples with tuffit addition containing up 20% has endured over 35 cycles of alternating freezing and thawing. Samples with tuffit addition — 10 u 40%, has endured less than 30 cycles of alternating freezing and thawing and proved that their sufficiently frost resistant (table 2).
Data obtained in principle corresponds to concept of effect of hydraulic active additions to frost resistance of autoclaved materials.
Introduction into mixture composition of hydraulic active addition — tuffit, even in relatively big quantities (up to 40%) enables to obtain autoclaved silicate materials with good physical mechanical parameters.
The research of normal adhesion of surface of silicate samples with tuffit addition which has residual hydraulic activity with masonry mortar as actual consequence of chemical interaction is of certain interest.
The adhesiveness has been studied on samples with sizes 4x4x16 mm; they were stuck together with the masonry mortar of the grade 50. We have applied complex
From the results of the research it is evident, that normal adhesion of1 sm 2 of surface of silicate materials with tuffit addition, which has residual hydraulic activity, is far above, than of silicate material without addition. Obtained parameters of normal adhesion not in direct proportion with residual hydraulic activity of investigated materials. Quite the contrary, when the quantity of tuffit addition in composition is raised up 40% the normal adhesion with masonry mortal has slightly decreased.
masonry mortar from portlandcement M -100, hydrated lime (activity 70%) and beach sand with size modulus (micrometer) 1,24.
Water-solid ratio in masonry mortar is equal 0, 25 and in accordance with results earlier conducted researches and can be considered optimal.
Masonry mortar was prepared according to the requirements of standard.
After sticking samples during 28 days were stored in moisture-air conditions in bath with hydraulic valve and afterward were tested on normal adhesion.
In table 3 is given calculated value of normal adhesion of autoclaved silicate samples with residual hydraulic activity due to input of tuffit addition.
Introduction of tuffit in silicate mass is due to the presence of residual hydraulic activity of autoclaved material and this contributes to enhancement of normal adhesion with masonry mortar.
Application of tuffit thermally processed at 600 ° C for the production of silicate material enhances the technology of its production and vastly improves qualitative parameters of these materials.
Table 3. - Normal adhesion with masonry mortar, MPa
Content of tuffit,% Samples after
7days 28 days 3 months 6 months 12 months
0 0,029 0,034 0,039 0,041 0,046
10 0,093 0,205 0,238 0,246 0,287
20 0,115 0,214 0,253 0,265 0,309
40 0,121 0,210 0,245 0,254 0,290
References:
1. GOST 7025-91. Bricks and ceramic and silicate stones. Methods of defining of water absorption, hardness and control of frost resistance.
2. GOST 379-95. Bricks and silicate stones.
3. Kabulova L. B., Djandullaeva M. S., Atakuziev T. A. Atmospheric stability of Portland cement with 20 and 30% of tuffie additives which were burnt under 600 °C.//Austrian Journal of Technical and Natural Sciences. - Vienna. -2015, -110-113 p.
4. Tairov A. A., Nudelman B. I. Improvement of adhesion of silicate bricks with masonry mortar.//Construction materials. - M.:- 1969.
