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0Technobius, 2024, 4(3), 0064, DOI: https://doi.org/10.54355/tbus/4.3.2024.0064
Technobius
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e-ISSN 2789-7338
Article
Binding properties of synthesized CS glasses activated by alkaline components
Bakhytzhan Sarsenbayev1, Sultan Auyesbek1*, Meiram Begentayev2, Nuraly Sarsenbayev1, Erkin Khaltursunov3, Gaukhar Sauganova1
1M. Auezov South Kazakhstan University, Shymkent, Kazakhstan 2Kazakh National Research Technical University named after K. Satpayev, Almaty, Kazakhstan 3Turin Polytechnic University in Tashkent, Tashkent, Uzbekistan Correspondence: sultan 067@mail.ru
Abstract. The paper presents the synthesis and evaluation of hydration and binding properties of individual minerals with glass-like structures in silicate systems, most often found in technogenic materials based on phosphorus and blast furnace slags. This work aims to determine the optimum composition of CS glasses to obtain binders with given properties, the hydration of glasses of different silicate and aluminosilicate compositions in the presence of solutions of soda, sodium hydroxide, and sodium metasilicate was investigated. The results of X-ray phase and differential-thermal analysis, and infrared spectrum are given, and the hydration structure of the calcium oxide-silicon oxide-alkali component system has been studied. The analysis of hydrate neoplasms of the studied binding systems shows that the most optimal conditions for the synthesis of stone strength with stable physical and mechanical properties are created in the presence of gel-like phase reinforced by hydrosilicates and hydroaluminosilicates of alkaline and alkaline-alkaline-earth composition, characterized by fiber-like structure and possessing the ability to epitaxial fusion with each other, as well as gel-like phase, which they reinforce.
Keywords: low basic tobermorite-like hydrosilicates, heat and humidity treatment, alkaline components, differential thermal analysis, slag-alkali binders, hydration.
1. Introduction
The study of properties of individual glasses and minerals included in blast furnaces and phosphorus slags has been studied by many researchers: Lanzhvan S., Keil F., Lapin V.V., Butt Yu.M., and many others. However, the author and his collaborators conducted the most successful research in synthesized glasses and minerals [1], [2].
In [3] the results of studies of the hydraulic activity of one-calcium silicate (CaOSiO2) and gelenite (2CaOAhO3SiO2) were published. Testing of samples of 7*7x7 cm with and without the addition of activating components was carried out after storage in water for 28 days, steaming according to the regime of 4+8+2 h and autoclave treatment for 4 h at 0.8 MPa. Analyzing the data, it is possible to draw a conclusion that slowly cooled minerals do not possess binding properties. However, at their activation with lime, lime in combination with gypsum and Portland cement clinker the hydraulic activity of CS and C2AS slightly increases.
Researchers [4] found that the reactivity of glasses mainly depends on the CaO content because calcium depolymerizes the glass structure and increases the reaction rate of glasses. The reactivity of glasses is mainly related to the degree of depolymerization of the glass structure. In this work, eight calcium aluminosilicate glasses have been synthesized, whose compositions reflect the glassy phases of industrial ashes and slags. The selected composition ranges allow the roles of Ca and Al to be distinguished and identified. The effect of AhO3 on the reactivity of the glass is less pronounced and is based on the chemical weakening of the glass structure. However, an increase in
alumina content has a pronounced effect on hydrate phase assembly, bound water content, portlandite consumption, and heat of reaction. The compressive strength of composite cement mortars incorporating synthesized CaO-AhO3-SiO2 glasses was found to depend on both the degree of reaction of the glass and the actual composition of the phases.
In [5] the influence of vanadium oxide on the crystallization of CaO-Al2O3-SiO2 (CAS) glass was studied. Specifically, CAS glass-ceramics with deposited hexagonal lamellar particles of metastable CaAhSi2O8 (CASGC-H), which is a layered crystal that was prepared using metallic molybdenum (Mo) particles as a nucleation agent, was investigated. When the parent CAS GC-H glass was crystallized with the addition of vanadium oxide in the range of 0.052-0.21 weight %, the resulting lamellar particles of metastable CaAhSi2O8 showed an increase in aspect ratio from 20 to 15 compared to conventional CAS GC-H.
Furthermore, no crystallization occurred in CAS glass with vanadium oxide in the range of 0.052-0.21 wt% in the absence of metallic Mo particles. At the same time, in CAS glass containing 1.0 wt% vanadium oxide without the addition of Mo metal particles, the precipitation of metastable CaAhSi2O8 was observed. Thus, these results indicated that the aspect ratio of layered crystals in the glass is controlled by the addition of a relatively small amount of vanadium oxide, and a new nucleator was developed for the deposition of metastable CaAhSi2O8 in CAS glass using a relatively high vanadium oxide content.
The authors [6] carried out microstructural control of CaO-AhO3-SiO2 (CAS) glass-ceramics which was achieved by oxidation and mixing with nucleating agents. The CAS glass-ceramics were deposited with hexagonal lamellar particles of metastable layered CaAhSi2O8 (CAS GC-H) crystals, which are usually prepared in a reducing atmosphere forming metallic Mo or W particles as nucleating agents.
The average crystal particle size decreased significantly from 50 to 11 p,m when CAS GC-H containing metallic W particles was prepared in an oxidizing atmosphere. Compared with this CAS-GC-H, the crystal particle size increased from 8-20 to 10-30 p,m when CAS GC-H was prepared by mixing the glass mass containing metallic Mo and the glass mass containing metallic W particles. These results indicate that the microstructure of CAS GC-H is controlled on a micrometer scale from the parent glass with the same composition by varying the experimental conditions related to the melting state of the glass.
According to the author [7], hydration and hardening of unfired slag binders occur through the formation of silicic acid, which further interacts with calcium hydroxide. This physicochemical process results in the formation of calcium hydrosilicates in gel, subcrystalline, and crystalline forms. As they accumulate, these new formations bind together the particles of the hardening system, which, thickening over time, acquires density and strength.
The closest to our ideas about the mechanism of hydration and hardening of slag-alkali binders are the authors of works [8], so further we consider his vision of this mechanism. Processes of hydration of slag-alkali binders develop differently depending on the type of slag and alkaline component of curing systems.
Irrespective of the ways of their development, it is unrealistic to realize hydration only through the dissolution of slag-alkali binder components. In hydration processes occurring in solidifying slag-alkali systems, the formation of hydrogels, rather than the dissolution of silicate components, plays a decisive role.
It follows that the synthesis and evaluation of hydration and binding properties of blastfurnace and phosphorus slag constituents and the development of binding materials on their basis is an urgent problem.
The goal of current research is to investigate and determine the optimum composition of CS glasses for obtaining binders with given properties hydration of glasses of different silicate and aluminosilicate compositions in the presence of solutions of soda, sodium hydroxide, and sodium metasilicate.
2. Methods
Synthesized glasses were obtained by abrupt cooling of melts of the corresponding chemical composition, which were ground in porcelain mills to a specific surface of 350m2/kg. The materials thus obtained were grouted with solutions of soda, caustic soda, and liquid glass. The test specimens with the size of 1 x 1 x 1 cm from a dough of normal density were hardened in natural conditions, in water, and hydrothermal conditions at temperatures of 95 and 175oC under the regime of 1.5+2+4+2 h.
Natural and water-cured specimens were tested after 3, 28, 90, and 360 days, and steamed and autoclaved specimens 24 hours after hydrothermal treatment.
X-ray phase analysis was carried out on a diffractometer URS 50 IM and DRON-3M in the range of angles 2 = 10...+60° at a counter and sample rotation speed of 2° per minute. The decoding of X-ray radiograms was carried out by identification of the obtained data with the characteristics of natural and artificial minerals. DTG, DTA, and TG curves were recorded on a derivatograph of the Paulik R. and Erden L. system of the MOM Budapest company. Spectral analysis was carried out on a Specord-80
3. Results and Discussion
3.1 Calcium oxide-silicon oxide-alkali component system 3CaO 2SO2C3S2)
During the hydration of pure C3S2 in water, the formation of weakly crystallized low basic hydrosilicates like tobermorite 11,3A and insignificant amounts of afvillite is observed.
When gelled with NaOH and Na2SiO3 solutions, the composition of hydration products is represented by afvillite CSH(1), plombierite and sodium-calcium compound NaCa2Si3OgOH2Na8Ca8Si5O26H14 (d/n = 3.09; 2.26 and 2.01 A) of cryptocrystalline structure (Figure 1a).
On IR spectrograms the presence of lines at 3340, 1658, 1280, 1100, 883, 673, and 512 cm-1 (Figure 1c) is identified with absorption lines characteristic of afvillite, and the formation of low-base hydrate phases is confirmed by the shift of absorption bands at 1000, 1070 cm-1 to lower frequencies due to polycondensation of silicon-oxygen groups.
1
2
3
4
1
2
3
4
c
a) X-ray images b) Thermograms
n
3,18 3.02 cc
rT\ r- r p fSI
M S - ?" <=> ft o\ m M"! »il CS 2.275 '2.175 OO
tci £ m U c cr> 0 n ,7 ^ -¿Jl <N ^Np/^o A S*"! <NV 3 H II CS o^ CO CN p H 00 iN ^00 CO
1 - 28 1 1 1 1
20 30 40 50 60 c
10
°4000 3200 2400 1600 800 400
The wave number, sin-1 c) IR spectrograms
Figure 1 - Results of the analysis of a stone based on a glass-like analog of C3S2
On DTA according to Figure 1(b), the presence of endothermic effects at 240, 320, 520, and 800 °C is due to stepwise dehydration, and endothermic effects at 100, 130 °C and exo-effect at 850 °C tobermorite dehydration and a-CS crystallization. The phase composition of the firing products of the composition based on C3S2 and NaOH according to Figure 2.2 is represented by P-C2S and Na2OCaOSiO2, and the composition based on C3S2, Na2OSiO3-P-CS, C3S2 and an insignificant amount of a - CS (Figure 2).
Comparison of phase compositions of hydration and dehydration products of glass-like C3S2 hydrated with NaOH and Na2SiO3 solutions shows that in the first case, more intensive destruction of glassy substance and formation of more mixed sodium-calcium compounds are observed, while at the hydration of C3S2 in the presence of Na2SiO3 afvillite and low-basic tobermorite-like hydrosilicates with inclusions of alkali ions are formed.
After heat and humidity treatment, the phase composition of hydration products of glass-like C3S2 in the presence of NaOH and Na2SiO3 along with compounds formed during curing under normal conditions in accordance with Figure 3 includes low-basic hydrosilicates of scautite type (d/n=3.03; 2,78; 2,39 and 2,29 Â), and transformations of calcium hydrosilicates within isomorphous phases (CSH(I)^scoutite) almost does not affect physical and mechanical properties of dispersed structures, as the new phase forms good contacts of aggregation with the disappearing one.
On the DTA curve according to Figure 1b the formation of C3S2H3 is confirmed by the presence of endo-effect at 360...400 °C and exo-effect at 780 °C, the shift of which in the low-temperature region is due to the presence of Na+ ions, and the synthesis of tobermorite-like calcium
hydrosilicates by the presence of endo-effects at 90...220 °C, 300...340 °C and exo-effect at 900 °C, associated with the crystallization of P - C3S.
The formation of sodium-calcium compounds during hydration of C3S2 with NaOH solution under conditions of heat and humidity treatment is confirmed by the presence of endo effects at 540-550-600 °C on the DTA curve.
At mixing of glass-like C3S2 with NaCO3 solution in the composition of hydration products (after the heat and humidity treatment) in addition to compounds formed at hydration in the presence of NaOH - a phase of pyrsonite type Na2Ca(CO3)2 25H2O was identified, the formation of which is confirmed by the presence of endothermic effect at 760 °C on the DTA-curve in accordance with Figure 3b.
3.2 The system of CaO-SiO2(CS)
During hydration of the glass-like analog under normal conditions, the degree of hydrolytic degradation is insignificant.
After heat and humidity treatment the composition of hydrate neoplasms is represented by C3S2H3 and partially crystallized tobermorite-to-like calcium hydrosilicates, the formation of which is confirmed by the presence on the DTA-curve of endothermic effects at 240 .... 260, 320, 470 °C (dehydration of C3S2H3), endo effect at 240 °C and exo effect at 880...960 °C (dehydration of low-base calcium hydrosilicates).
a) Mineral C3S b) Glass-like analogs of C3 c) Analogue of CSI
Figure 2 - X-ray images of a stone dehydrated at N = 1000 °C: 1 - water; 2 - solution NaOH;
3 - solution Na2CO3; 4 - solution Na2SiO3
During hydration of the glass-like analog of CS in the presence of NaOH, the phase composition of neoplasms after 28 days of hardening in accordance with Figure 4a is represented by low-base phases of the cryptocrystalline structure: gyrolite (d/n = 3.36; 3.15; 3.02; 2.52; 2.45; 2.25 Â) and pectolite.
On the DTA curve, in accordance with Figure 4 (b), the appearance of endothermic effects at 140...180 ° C, 500...780 °C, and the exo-effect at 820 °C is due to dehydration of gyrolite, and the exo-effect at 860...880 °C is due to dehydration of CSH(I) and crystallization of P-CS. The displacement of the exo-effect to the region of elevated temperatures is explained by the high content of calcium in the composition of the hydrosilicate phases.
The shaft of the eco effect to the region of elevated temperature is explained by the high content of calcium in the composition of the hydrosilicate phases.
After heat and moisture treatment at T=100 °C, the presence of C6S6H (d/n) carbonatite was noted in the phase composition of hydration products along with CSH(I) and tobermorite = 3.23; 3.0; 2.83; 2.72; 2.51 and 2.04 Â) (Figure 3d).
The formation of low-basic tobermorite-like phases is confirmed by the presence on the DTA curve of endothermic effects at 90 ...120 °C, 300...340 °C, and an exo-effect at 900°C, and xonotlite by the appearance of endoeffects at 800 ...880 °C.
During hydration of glassy CS in the presence of Na2CO3, regardless of the hardening conditions, in accordance with Figure 4a, the composition of the neoplasms is represented by CSH(I), gyrolite, pectolite and NaCa(CO3)2 2H2O (d/n = 4.92; 3.16; 2.88; 2.65; 2.57; 2.5; 2.02; 1.89; 1.82 Â).
The DTA curve in accordance with Figure 4b shows weak endothermic effects at 740, 820, and 960 °C, corresponding to the dehydration of CaCO3.
During the hydration of glass-like CS in the presence of Na2SiO3, the composition of the hardening products is represented by compounds of cryptocrystalline structure: CSH(I), gyrolite, pectolite, and tobermorite. On the IR spectrogram, the presence of law-o basic calcium hydrosilicate is confirmed by the presence of absorption bands at 3365, 1635, 1173, 1075, 997, 897, and 524 cm-1 (Figure 4).
On the DTA curve, in accordance with Figure 4b, the main endothermic effect of tobermorite dehydration at 128 °C is shifted toward low temperatures due to the introduction of Na+ ions into its composition.
The thermogravimetric curve has no sharp fractures, and mass loss is observed in the temperature range of 20...800 0 C. In the composition of the dehydration products at a temperature of 1000 0 C, the predominance of P-CS was noted and with an insignificant content in accordance with Figure 4b. During the heat and moisture treatment of CS, closed with a solution of Na2SiO3, a clearer crystallization of low-base hydrosilicate phases is observed.
M) TO V) 60
C 20 30 40 50 60
a) Mineral CS
b) Mineral C3S2
-'-'-1-'-'--I ■ . . ■ ■
20 30 40 50 60 C 20 30 40 50 60 C
c) Glass-like analog CS d) Mineral C3S2
Figure 3 - Radiographs of a stone: 1-with water; solutions: 2 - NaOH; 3 - Na2CO3; 4 - Na2SiO3 (heat and moisture treatment at N = 95 ± 5 °C according to the regime 3+6+3+2)
a) X-ray images b) Thermograms
С
400 600 1000 2400 3200 4000
The wave number, sni-1
c) IR spectrograms
Figure 4 - Results of the analysis of a stone based on a glass-like analog of CS closed with 1 - water; 2 - solution NaOH; 3 - solution Na2CO3; 4 - solution Na2SiO3 (28 days
of storage in water)
Thus, the reduced strength and water resistance of an artificial stone based on glass-like CS, compared with the strength of a stone based on glass-like C3S2, are due to the phase composition of hydration products represented by girolite, CSH(I) and pectolite, which do not possess crystallochemical affinity and belong to various categories of compounds.
According to the data of physico-mechanical tests given in Table 1, binders based on glass-like C3S2 hydrated with Na2SiO3 solution are characterized by the greatest hydraulic activity. The high strength (55...113 MPa) and its constant growth over time are due to the formation of epitaxially fused compounds in the hydration products: afvillite (monoclinic) and tobermorite-like hydrosilicates (orthorhombic) syngony.
Consequently, the most optimal conditions for the synthesis of strength artificial stone in the Na2O-CaO-SiO2-H2O system are created by hydration of binders of the glass-like analogue C3S2 with the formation of artificial stone, characterized by high rates of strength gain in the early stages of hardening and strength up to 125 MPa during long-term storage. This is due to the peculiarities of the structure of glassy calcium silicate, as well as the phase composition of hydration products: the ratio of gel-like and crystalline phases and the ability of hydrate compounds to form strong epitaxial accretions.
130
Curing time, day
Figure 5 - Dependence of the strength of the binder based on C3S2 on the curing time with alkaline component: 1 - NaOH; 2 - Na2CO3; 3 - Na2SiO3; 4 - H2O (*after aqueous storage)
Table 1 - Results of physical and mechanical tests of artificial stone based on hydrated glasses
Glass Hardener _Compressive strength, MPa_
composition After natural storage After water storage for After heat and
for a day
a day
humidity treatment at a temperature of, °C
3 28 90 360 3 28 90 360 95 175
CS H2O 7.4 13.2 31.5 34.0 P P P P 5.8 22.0
NaOH 10.7 13.5 32.3 37.0 15.0 16.6 16.0 28.0 15.0 36.5
Na2CO3 2.5 5.8 34.9 36.0 2.5 19.9 30.0 33.7 26.5 34.9
Na2SiO3 23.2 34.8 69.7 72.0 33.0 35.7 45.0 69.0 50.0 66.0
C3S2 H2O 1.0 1.5 3.3 5.8 2.5 15.0 59.4 63.0 1.5 30.0
NaOH 5.0 20.0 43.0 48.0 12.5 49.5 57.0 62.0 20.0 35.0
Na2CO3 8.0 12.5 35.0 42.0 5.0 21.5 113.2 121.0 35.0 55.0
Na20Si03 37.5 57.5 59.4 63.0 33.0 55.0 113.5 125.0 62.5 71.0
Note: P is the soaking of the samples
4. Conclusions
1. The phase composition of hydration products plays a leading role in the formation of the structure of artificial stone of alkaline-alkaline-earth composition and determines its physical and mechanical properties. The analysis of the hydrate formation of the studied binder in the CS system shows that the most optimal conditions for the synthesis of stone strength with stable physical and mechanical properties are created when the hydration products contain a gel-like phase reinforced with hydrosilicates and hydroaluminosilicates of alkaline and alkaline-alkaline earth composition, characterized by a fibrous structure and having the ability to epitaxial fusion with each other, as well as the gel-like phase that they reinforce.
2. In the "calcium oxide - silicon oxide - alkaline component" system, high-strength stone (28 days - 53-58 MPa, 1 year - 125 MPa) is synthesized based on calcium silicates 1.5 < C/S < 2
and the phase composition of hydration products is represented by low-basic hydrosilicates of the
amitobermorite group, afvillite and alkaline-alkaline-earth hydrosilicates various degrees of
crystallization (NaCO2 Si030g0H; Na2CagSi5O26H14).
Acknowledgment
This research was funded by the Science Committee of the Ministry of Science and Higher
Education of the Republic of Kazakhstan (Grant No. BR21882292).
References
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[3] P. P. Budnikov and B. C. Gorshkov, "Investigation of hydrated synthetic minerals of alumina slags," in Chemistry and technology of silicates, Kiev: Naukova dumka, 1964, pp. 437-445.
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[7] M. M. Sychev, Hardening of binders. L: Stroyizdat, 1974.
[8] B. K. Sarsenbayev, Z. A. Estemesov, J. T. Aimenov, N. B. Sarsenbayev, and A. J. Aimenov, Slag-alkali binding concretes. Shymkent, 2016.
Information about authors:
Bakhytzhan Sarsenbayev - M. Auezov South Kazakhstan University, Shymkent, Kazakhstan, stroitelstvo uku@mail.ru
Sultan Auyesbek - M. Auezov South Kazakhstan University, Shymkent, Kazakhstan, sultan 067@mail.ru
Meiram Begentayev - Kazakh National Research Technical University named after K. Satpayev, Almaty, Kazakhstan, m.begentayev@satbayev.university
Nuraly Sarsenbayev - M. Auezov, South Kazakhstan University, Shymkent, Kazakhstan, nurali777 @mail.ru
Erkin Khaltursunov - Turin Polytechnic University in Tashkent, Tashkent, Uzbekistan, e .khaltursunov@polito.uz
Gaukhar Sauganova - M. Auezov, South Kazakhstan University, Shymkent, Kazakhstan, stroitelstvo uku@mail.ru
Author Contributions:
Bakhytzhan Sarsenbayev - concept, editing, drafting. Sultan Auyesbek - data collection, testing, modeling. Meiram Begentayev - editing the article and raising funds. Nuraly Sarsenbayev - methodology, resources, analysis. Erkin Khaltursunov - analysis, interpretation, modeling. Gaukhar Sauganova - visualization, interpretation, methodology.
Conflict of Interest: The authors declare no conflict of interest.
Use of Artificial Intelligence (AI): The authors declare that AI was not used.
Received: 12.08.2024 Revised: 28.09.2024 Accepted: 29.09.2024 Published: 30.09.2024
Copyright: @ 2024 by the authors. Licensee Technobius, LLP, Astana, Republic of Kazakhstan. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY-NC 4.0) license (https://creativecommons.org/licenses/by-nc/4.0/).
