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Turemuratov Sharibay Nauryzbaevich, Ph.D., Head of the Chemistry Laboratory Karakalpak Scientific Research Institute of Natural Sciences of the Karakalpak Branch of the Academy of Sciences
of the Republic of Uzbekistan E-mail: [email protected] Abylova Amina Zhanabaevna, researcher at the laboratory of chemistry Karakalpak Scientific Research Institute of Natural Sciences of the Karakalpak branch of the Academy of Sciences
of the Republic of Uzbekistan E-mail: [email protected]
STUDY OF THE PROCESSES OF HYDRATION STRUCTURE FORMATION IN LIME-BELITE BINDERS ON THE BASIS OF MARLS OF THE REPUBLIC OF KARAKALPAKSTAN
Abstract. The possibility of improving the physicochemical and physic-mechanical properties of dispersions of lime-ware binding materials obtained on the basis of Akburly and Porlytau marls was revealed for the first time by regulating the processes of hydration structure formation using local mineral fillers in normal and hydrothermal conditions; the dosages of the fillers were established, the mechanisms of their action were clarified.
Keywords: marl, carbonate first mineral, Karakalpakstan, lime-ware binding, binder, hydration, structure formation, coagulation, I, crystallization, structure and.
Introduction. A large number of papers are de- tunity use lime-ware binding materials for making
voted to the theory of hardening binders, but so far high-strength construction materials and products
there is no single, generally accepted point of view on autoclaved.
the processes of structure formation in the harden- Objects and research methods. The object of
ing of binders. Therefore, the study of the processes this study on lime-ware material (LWM) produced
of hardening and structure formation of binders is on the basis of carbonate minerals in Karakalpakstan.
relevant. LWM is close to the high-grade astringent substance,
It has been established that the formation of so it can be used to produce construction building x
strength is associated not only with the formation materials and products with high physical-mechan-
of different types of structures in the system - co- ical properties.
agulation and crystallization, with the transition of The work also studies the kinetics of hydration
the first to the second, but also different stages of structures and the physicochemical properties of
the formation of a crystallization structure. Based on LWM based on marl Akburly and Porlytau. studies of physic-chemical and physic-mechanical In accordance with the above, this work is de-
properties considered lime-ware binding materi- voted to the study of the fundamental possibility of
als and second article n It turned whether oppor- optimal heat treatment, the study of the phase com-
position and properties of the products obtained, the development ofways to regulate the processes of obtaining and hydration structure formation in the considered IBI, their rational use for the production of some silicate products.
The study of physicochemical and mechanical properties, as well as the brand of LWM based on carbonate minerals of Karakalpakstan, was carried out according to GOST 23789-04.
Discussion and research results. The processes of hydration of clinker minerals and other binding materials, as well as hydration structure formation (HS) in these systems are interconnected, the latter usually follow from the first, so their consideration together is of scientific and practical interest from the point of view of their role in controlling the properties of binding systems.
In our case, natural marls from the Akburly and Porlytau deposits (the Republic of Karakalpakstan) served as the raw material for the LWM.
It has been established [1; 2] that the optimal heat treatment conditions for the production of LWM based on the studied marls are temperatures within 1000 ° C with an exposure of 90 minutes. Under these conditions, the largest amount of free calcium oxide (50-60%) and ft - dicalcium silicate -whit
(25-30%) in heat treatment products are formed, in small amounts aluminates and calcium ferrites.
About the kinetics ofhydration structure formation was judged by the change in plastic strength (Pm) of the system, measured on a Geppler consis-tometer.
The study of the processes of HS in concentrated pasta LWM allows to reveal the role of the nature of the hydrating phase in the kinetics of the formation of strength and its creation in the emerging spatial structure.
The nature of the kinetic changes in the plastic strength of the system at W/S = 0.90 (Table 1.) Differs from the nature of the change in the strength of the system at W/S = 1.0 and W/S = 1.2; plastic strength first increases, then, after three days of exposure of the system, drops sharply, followed by another sharp increase after 14 days. For other W/S relationships, there is also a sharp increase in the strength of the system after 14 days.
The presence of differences (W/S = 0.90) in the values ofPm is apparently connected not only with the formation of different types of structures in the system - coagulation and crystallization, with the transition of the first to the second, but also different stages of formation of the crystallization structure [3].
Table 1.- The kinetics of structure formation (Pm , MPa) in dispersions of LWM, depending on the water-solid ratio
Marl based LWM Timing of measurement
No W/S minutes clock day
1 15 30 1 3 6 1 3 7 14 28 40
1. Akburly 0.90 0.9 4.1 6.4 8.7 9.3 13.9 15.6 20.5 16.6 14.2 20.4 28.7
2. Akburly 1.00 0.6 5.5 6.1 7.7 9.2 12.2 13.2 13.4 14.5 14.5 18.3 23.4
3. Akburly 1.20 0.4 4.3 5.8 7.7 9.0 10.4 12.1 13.0 14.0 13.8 17.9 21.3
4. Porlytau 0.90 0.9 4.4 6.5 8.9 9.3 13.5 15.5 20.4 17.1 16.4 21.0 30.3
5. Porlytau 1.00 0.6 5.1 6. 1 7.3 9.4 12.9 12.1 13.5 14.6 14.8 18.5 28.4
6. Porlytau 1.20 0.5 4.1 5.9 7.8 9.1 10.6 11.6 12.9 14.2 13.8 17.7 24.7
During the first two stages of the formation of the crystallization structure, i.e. respectively, the emergence of crystalline nuclei of hydro silicates and an increase in their number without accretion, as well
as the formation of a crystalline intergrowth of the embryos, increases the strength of the system, which reaches a maximum, when going to the third stage of structure formation, the formation of crystalline
particle contacts begins to weaken due to the destruction of the aggregations and recrystallization of contacts; the subsequent sharp increase in the strength of the system after the minimum is due to the formation of crystalline contacts, giving the system sufficiently high strength properties. This area coincides in time with the system's 14-day shutter speed, which is relevant to all W/S variants.
The fact that the minimum extreme point at 14 days corresponds to the beginning of crystal contacts is evidenced by the fact that the increase in strength after 14 days' exposure is sharp, since the strength parameters of crystallization structures usually always have relatively large indicators than coagulation structures, which is due to the nature of the forces that determine the contacts of the particles in these structures. It is known [4] that the contacts of particles in the first (coagulation) structures are formed due to low-strength van der Waals forces of intermolecular interaction through thin interlayers of the dispersion medium and therefore have relatively low rates; secondly (crystallization) structures, contacts
are formed due to chemical forces with significantly higher binding energy, they arise in the process of formation of new phases from metastable supersaturated solutions, and these structures are accretion structures that differ from coagulation by several orders of magnitude higher strength due to the formation of phase accretion.
Systems based on heat treatment products of a marl from the Akburlinsk field at W/S = 0.90 under conditions of moisture-air storage have a maximum strength of about 28.75 MPa, and Porlytau deposit -30.25 MPa after 40 days of exposure.
Table 2 shows the results of physical studies of dispersion based on LWM.
From the presented data it is clear that the water demand for LWM obtained on the basis of the studied marl more than that of Portland cement or gypsum. This is due to the fact that in the composition of LWM, together with dicalcium silicate (8-C2S), free calcium oxide CaO (58.24 and 50.30%) is also contained in large quantities, which, upon hydration with a great need of water, passes in calcium hydroxide.
Table 2.- The results of physical research pastes LWM
No Marl based LWM normal density,% setting time, min specific surface, cm2 /g
Start end
1. Akburly 90 48 131 3200
2. Porlytau 90 46 144 3500
Table 3 presents the dependence of the mechani- ditions of moisture-air and thermo-moisture harden-cal strength of the LWM samples on the duration of ing, the mechanical strength of the samples increases hardening. As can be seen from the table, as in the con- with time, its greatest value takes place after 28 days.
Table 3.- The results of the study of the mechanical compressive strength of specimens of LWM in moisture-air and thermo-wet hardening
No LWM based marl deposits W/S Compressive strength, MPa
moisture-air hare ening thermo-wet hare ening
3 days 7 days 28 days 3 days 7 days 28 days
1. Akburly 0.90 0.98 2.83 7.35 4.05 6.40 14.26
2. Porlytau 0.90 1.86 4.77 9.41 4.30 7.81 14.53
Comparison of the strength values shows that the greatest difference in their values during compression is observed in LWM based on the marl from the
Porlytau deposit, which indicates a relatively higher content of silicates, aluminates and calcium ferrites
in the heat treatment products of the marl from this deposit compared to the marl Akburly.
The initial strength of LWM is provided by the hydration of free lime and belite with the formation of the corresponding hydrates. A further, very slow increase in strength (under normal conditions) is
mainly due to the carbonization processes of unbound calcium hydroxide. Therefore, with an increase in the content of the active form of SiO2 it is possible, up to known limits, not only to intensify the hardening processes, but also to obtain a significantly greater strength of the hardened product.
Figure 1. Diffraction patterns of products of LWM1 hydration obtained on the basis of marl No. 1. and No. 2
Diffraction patterns of LWM hydrated for 28 days are characterized by the presence of more intense lines ofhillebrandite (0.302; 0.276; 0.260 nm), portlandite (0.487 and 0.191 nm), calcium hydro silicate ofC-S-H type (II ) (0.308 nm), as well as less intense lines ofto-bermorite 5CaO • 6SiO2 • 5H2O (0.252 and 0.246 nm). Lines 0. 330; 0.204 nm and 0.186; 0.179 nm refers to
Activity, temperature and quenching time for LWM are presented in (Table 4).
Based on the data in the table, it can be assumed that LWM can be used in the production of high-strength silicate autoclaved products (cellular concrete, blocks, etc.), since The above properties of LWM meet the requirements for autoclaved products.
hydroaluminate and calcium hydroferrite, respectively.
Table 4.- Activity, temperature and quenching time LWM
No Marl based LWM Quenching temperature, °C Blanking time, min Activity%
1. Akburly 44 14 71.89
2. Porlytau 43 15 70.30
Conclusion. Thus, the processes of HS in LWM by the formation in the system of different types of dispersions obtained on the basis of marl Akburly structures - coagulation and crystallization, with and Porlytau deposits, are characterized not only the transition of the first to the second, but also by
different stages of the formation of a crystallization The introduction of LWM in the production structure. Based on studies of the physicochemical of building materials can bring greater economic and physico-mechanical properties of the examined efficiency, since the binders are obtained by low-
LWM, it can be concluded that they are an effective temperature calcination and fine grinding of raw
binder for the preparation of high-strength auto- materials without waste and, accordingly, the cost
claved products. of building materials will be relatively low and the
raw material base will be used rationally.
References:
1. Turemuratov S. N., Nurymbetov B. C. H. Synthesis and research of LWM on marl from the Akburlinskoye field // Science and the formation of Southern Kazakhstan. - Shymkent. 2000.- No. 11.- P. 223-225.
2. Turemuratov Sh. N., Kurbaniyazov S. K., Akeshova M. M. Influence ofHydrothermal and Physical Properties for Lime Ware Binding Materials // World Applied Sciences Journal, 23 (9): 2013; 1151-1156. ISSN1818-4952.
3. Turemuratov Sh. N., Kurbaniyazov S. K., Akeshova M. M. Physical-mechanical properties of chemicals and undergone hydro-thermal treatment // Journal of Materials and Applications, 2013.- P. 1179-1185.
4. Turemuratov Sh. N., Zhukov A. D., Asamaddinov M. O., Nurymbetov B. Investigation of the kinetics of hydration structure formation and properties oflime-whitewash binders on the basis of marls // Vestnik MGSU, Building Materials,- M. 2016.- No. 4.- P. 62-68.
5. Turemuratov Sh. N., Zhukov A. D., Asamaddinov M. O., Nurymbetov B. The effect of fine-dispersed filler on the formation of calcium silicates // Vestnik MGSU, Stroitel'noyematerialovedenie,- M., 2017.- No. 4.-P. 446-451.
