RU2125545C1 - Binding agent - Google Patents

Abstract

FIELD: manufacture of building materials. SUBSTANCE: binding agent based on Portland cement clinker contains also 30-35 wt % of synnerite and 3 wt % of calcium sulfate dihydrate. EFFECT: increased strength. 3 tbl

Description

 The invention relates to compositions of cements and can be used to obtain alkaline Portland cement, mortar and concrete based on them.

Known astringent, including, wt.%:
Portland cement clinker - 57 - 85
gypsum plaster - 3 - 5
granular high-calcium ash, calcined at 1150 - 1300 ^o C with a basic modulus of ≥1.8 and a free calcium oxide content of ≤2.0% - The rest
(see A.S. N 1183474, C 04 B 7/14, B.I. N 37, 1985) / 1 /.

The reasons that impede the achievement of the specified technical result when using a known substance include the fact that in the known composition the water demand of the cementitious mixture increases, the rate of hydration and structure formation slows down, which reduces the effectiveness and scope of its application in ground structures, in rooms with reduced air humidity, being limited obtaining low-quality concrete. In addition, the destructive manifestations of late quenching of burnt CaO _sv . In this substance, the negative effect of CaO _sv in ash is eliminated by the method of partial preliminary hydration - granulation of ash in a plate granulator followed by grinding of the granules. In our opinion, this additive will require additional energy costs for the specified firing at the specified temperature, as well as for granulation of ash with its subsequent grinding. The proposed binder has a higher strength higher by 6% at 28 days of hardening compared with the known composition.

Also known astringent, having in its composition, wt.%:
gypsum plaster - 3 - 5
dried cement raw material sludge - 1 - 5
Portland cement clinker - Other
The selection of raw sludge is carried out after processing in a raw mill. Then carry out the drying of sludge at 120 ^o C in an oven (see.with. N 992457, C 04 B 7/35, B. I. N 4, 1983) / 2 /.

 However, an essential disadvantage of the known binder is its insufficiently high strength, which is reduced compared to the proposed binder by 13.3%. In addition, an increase in the content of raw sludge of more than 5% leads to a further increase in strength compared with the proposed additive.

It is also known astringent, containing, wt.%:
two-water gypsum - 1-3
mineral additive of the specified composition - 3 - 15
Portland cement clinker - Other
Get the additive from the raw material mixture, which contains, wt.%:
limestone - 45 - 70
jarosite rock - 27 - 50
gypsum plaster - 3 - 5
After pre-mixing and firing the mixtures at 900 - 1200 ^o C with a holding time of 30 - 120 min, the resulting product contains calcium sulfoaluminoferrites (8 - 12%), alkali metal sulfates (5 - 9%), calcium silicates (8 - 15%) and ferrites calcium (the rest) (see.with. N 1127870, C 04 B 7/00, B.I. N 45, 1984) / 3 /.

 However, the strength of the known binder is reduced by 9.2% in contrast to the proposed composition.

Closest to the claimed invention, the composition of the same purpose for the totality of signs is a binder containing, wt.%:
Portland cement clinker - 88 - 94
gypsum plaster - 4 - 6
thermochemical product of alkali-containing aluminosilicate materials - 2 - 6
(see A.S. N 639828, MKI C 04 B 7/35, B.I. N 48, 1978) / 4 /.

 The reasons that impede the achievement of the specified technical result when using a known substance adopted for the prototype include the fact that in a known substance of known composition additional components complicate the system and increase the cost of the binder. An increase in the addition of nepheline concentrate of more than 6% leads to a decrease in strength, a reduction in the setting time, which complicates its use in Siberia.

Therefore, it is possible to create alkaline Portland cements without the addition of alkalis and additives - retarders to cement, and to use as such potassium alumina rocks containing up to 10 - 20% R ₂ O (see Slag cement cements, concretes and structures: Dokl. And abstract. Dokl. 3rd All-Union Scientific and Practical Conf., Kiev, 1989, vol. 1, p. 100 - 101, 114 - 116, 119 - 121). The composition "Synnyr" - Portland cement clinker - two-water gypsum "allows you to replace nepheline concentrates in a known binder.

 The problem solved by the invention is to increase the strength of the binder by quantifying the introduction of additives based on Transbaikalia rocks - sonnyrites in combination with Portland cement clinker minerals, which leads to the active participation of the rock in the hydration and hardening of cement due to the high concentration of alkaline oxides formed in the result of cation exchange reactions during mixing with water of a mixture of components.

The specified technical result in the implementation of the invention is achieved by the fact that a substance of known composition, consisting of Portland cement clinker, two-water gypsum, additives, according to the invention as an additive contains alkaline aluminosilicate rock - synyr, in the following ratio, wt.%:
Synnyr - 30 - 35
two-water gypsum - 3
Portland cement clinker - Other
The known mechanism of the process of hydration and hardening of alkaline Portland cement based on feldspar rocks, which can be represented as follows. Due to the hydration of Portland cement clinker, the alkalinity of the medium increases, which contributes to the destruction of rocks and the removal of alkali from their composition into a dispersion medium, which further determines the hydration process along the way to reduce the basicity of Portland cement hardening products and the synthesis of alkaline hydroaluminosilicates from the products of degradation of Portland cement and aluminosilicate rocks. The presence in the composition of the hardening products of low-basic calcium hydrosilicates and alkaline hydroaluminosilicates of the zeolite type is the fundamental difference between the proposed cementitious composition from the known developments.

Comparison of the invention with other technical solutions known from the prior art made it possible to establish the following. In the known technical solutions for obtaining the binder used various mineral additives obtained by thermochemical processing of raw materials included in the known mixture. As an additive, the product of the interaction of acid with alkali-containing aluminosilicate materials, for example nepheline concentrates at 120 - 150 ^o C. was used. This temperature is achieved due to the heat of reaction of the interaction of nepheline with acid, without initial heating of the components. A disadvantage of the known substance is the quick setting and high heat release of the binder. In addition, an increase in the addition of nepheline concentrate of more than 6% does not lead to a further increase in the strength of cement. Such an astringent is characterized by an increased alkali content (2.5% P ₂ O). Curing occurs not earlier than after 50 minutes, which additionally requires the use of additives - hardening inhibitors.

In the claimed binder, an ultrapotassium aluminosilicate rock in the form of synsyrite, which is a natural alkaline raw material of Transbaikalia, is used as an additive. Portland cement based on this raw material contains up to 1.4% R ₂ O in the following formulations.

 The analysis of the prior art by the applicant, including a search by patent and scientific and technical sources of information, and the identification of sources containing information about analogues of the claimed invention, allowed to establish that the applicant did not find an analogue characterized by features identical to all the essential features of the claimed invention. The definition from the list of declared analogues of the prototype, as the closest in the set of essential features of the analogue, allowed to identify the set of essential in relation to the perceived technical result - increased strength of the binder, distinctive features in the claimed substance set forth in the claims.

 Therefore, the claimed invention meets the condition of "novelty."

 The search results showed that the claimed invention does not derive explicitly from the prior art for the specialist, since the influence of the transformations provided for by the essential features of the claimed invention is not revealed from the prior art determined by the applicant, namely, the interaction of the synergite with cement clinker minerals provides a positive reaction to achieve technical The result is increased strength.

 Therefore, the claimed invention meets the condition of "inventive step".

Synnyrt of the Sakunskoye deposit (Chita region), which is part of cement, is a natural alkaline aluminosilicate of the group of alkaline feldspars of the KAlSi ₃ O ₈ series, which are an important component of igneous rocks, such as granites, syenites, minerals of the nepheline and mariupolitic group, of the following chemical composition , wt.%: (see table. 1).

 The Sakunskoye deposit is associated with the largest alkaline massif, composed in the central part of nepheline syenites, between which there is a zone of development of high potassium pseudo-lepite nepheline syenites with large bodies of calcite-potassium feldspathic rocks - sonnyrites. The main mineral components of synsyrites are potassium feldspar, calsilite, and secondary minerals. At present, it is very relevant to solve the problem of prospective reserves of synsyrites, as well as the similarity of these raw materials with other sodium and potassium aluminosilicates widely distributed in the earth's crust (nepheline, mariupolite, kaolinite, zeolite, etc.).

Based on the chemical composition, the synergy contains 17 - 18% K ₂ O, in contrast to the known nepheline concentrate, the chemical composition of which is shown below for comparison, wt.%: (See table. 2).

 Typically, potassium feldspar is used as a raw material for the thermochemical processing of various raw materials, and not for the production of hydraulic binders based on it (see A.S. N 1421693, C 01 F 7/26, B.I. N 33, 1988). Judging by the material composition, it is only known that synergy can be used in various sectors of the national economy - for the production of high-grade ceramics, refractories, and for the production of potassium salts.

 In this technical solution, this raw material is used as an active binder component in cement in an amount of 30 - 35% for the first time. We use the mineral complex of calsilite and potassium feldspar compounds created in synsyrite. Small calsilite crystals in combination with Portland cement clinker minerals form hydration products such as alkaline aluminosilicates, as well as siliceous gel shells, which promote the germination and bonding of potassium feldspar grains into a durable cementitious framework (natural fine crystallinity of calsilite and potassium feldspar).

To select the optimal binder composition and heat treatment mode, binders were prepared that differ from each other in the alkaline content (synsyrite) in percent by weight: 10, 15, 20, 25, 30, 35, 40, 45; clinkers - 52, 57, 62, 67, 72, 77, 82, 87; gypsum content up to 3% by weight of clinker. The resulting mixture was shut with water. The binders of the proposed compositions were prepared in two ways: 1) Steaming or heat and moisture treatment according to the mild hardening mode: 1 + 5 + 2 hours at t = 90-95 ^o C. Storage for one day in laboratory conditions. 2) Storage of samples for 28 days in normal humidity conditions (24 hours in a humid environment, 27 days in air).

The technology for producing a low-cement binder of the proposed composition is as follows. Portland cement clinker, gypsum and synshire separately sieved through a sieve with a mesh N 005, which meets the requirements of GOST. Then the finished mixture is ground in a laboratory rod mill type 75T-DrM to the optimum specific surface area S _beats = 2900-3200 cm ² / g Fine aggregate — quartz — feldspar sand with M _cr = 1.05–2.08, is introduced into the mixture prepared in this way, after which the mixture is thoroughly mixed for 5 minutes, and then the required amount of water is introduced. Samples - beams of size 4x4x4 (cm) are prepared from the prepared cement mortar with a composition of 1: 3, consisting of 1 parts by weight binder and 3 wt. including sand, with a water-cement ratio of at least 0.4 and the consistency of the solution, characterized by the melt of the cone on the shaking table at least 105 mm. The samples are molded in a vibratory compactor. Samples in the molds are stored for 24 hours in humid conditions or in a special bath with a hydraulic shutter, after which the samples are steamed according to the 1 + 5 + 2 (h) mode (1 hour - raising the temperature to 100 ^o C, 5 hours - isothermal heating in boiling steam water, 2 h - cooling of the deformed samples and storage in the laboratory during the day) or stored for 28 days in the laboratory after daily exposure of the samples in a humid environment. To determine the coefficient of water resistance, the samples were additionally stored for 2 days in water after heat and moisture treatment and normal hardening.

 Example 1

Synnyr grind with clinker and gypsum in a core mill type 75T-DrM to S _beats = 2900-3200 cm ² / g in the following ratio of components, wt. %:
Synnyr - 10
Portland cement clinker - 87
two-water gypsum - 3
The mixture is stirred and shut with water, after which it is left for 24 hours to be stored in molds in humid conditions. After steaming, the samples are additionally stored for 1 day in the laboratory, then tested for strength. To determine the coefficient of water resistance, the samples after heat treatment were stored for 2 days in water. The samples had a compressive strength of 43.3 MPa, an average density of 2050 kg / m ³ , K _water = 1.06. Samples were also stored for 28 days under normal conditions (24 hours in a humid environment, 27 days in air). Moreover, the compressive strength was 44.8 MPa, the average density did not change. There is no false setting in this composition.

 Example 2

Similar to example 1 with the following content of components, wt.%:
Synnyr - 15
Portland cement clinker - 82
two-water gypsum - 3
Compressive strength after TVO = 28.8 MPa, P _cf. = 2010 kg / m ³ , K _water = 0.89. Compressive strength after 28 days = 34.3 MPa. In this composition, a false setting is observed.

 Example 5

It is carried out analogously to example 1 in the following ratio of components, wt.%:
Synnyr - 30
Portland cement clinker - 67
two-water gypsum - 3
Compressive strength after TVO = 51.2 MPa, average density = 2050 kg / m ³ , K _water = 1.02. Compressive strength after 28 days = 58.5 MPa, R _ex . = 6.3 MPa.

 Example 6

Example 6 is similar to example 1 with the following content of the main components, wt.%:
Synnyr - 35
Portland cement clinker - 62
two-water gypsum - 3
R _sr. after TVO = 39.8 MPa, P _cf. = 1990 kg / m ³ , K _water = 1.0, P _compress. after 28 days = 41.2 MPa, R _ex. = 5.03 MPa.

 Example 8

Example 8 is carried out analogously to example 1 with the content of the main components, wt.%:
Synnyr - 45
Portland cement clinker - 52
two-water gypsum - 3
R _sr. TVO = 30.8 MPa, average density = 2010 kg / m ³ , K _water = 0.99. Compressive strength after 28 days = 35.6 MPa, R _ex. = 3.55 MPa.

 As a result of studies (see Table 3), it was possible to establish that when Sonnyrite additives were added to Portland cement in an amount of 10 to 30%, false setting is observed, which reduces the strength of the cement stone, and in some cases causes cracks. The phase composition of the hardening products of such Portland cement within the indicated limits is mainly represented by calcium hydrosulfoaluminates, which lead to a loss of strength. When introducing into Portland cement 30-35% of the additive of synsyrites of false setting is not observed. Strength in this case increases compared with the known types of cements of conventional composition. Thus, an increase in strength is achieved only within the above ranges.

Also note that the obtained alkaline Portland cement has a positive sulfate resistance. As studies, samples were considered - beams with a size of 4x4x4 (cm) of a similar composition of the mixture discussed above. The resistance of cements in an aggressive environment was evaluated by their resistance coefficient in a 5% K ₂ SO ₄ solution. The final products of hydration of sonnyrite in a sulfate medium are potassium alum, the solubility of which at 20 ^o C in water is 5.6 g. This explains the specific sulfate resistance of the binder based on sonnyrite (K _c = 1.0).

Characteristics of the obtained binders are given in table. 3, 4 (examples 1-8). For comparison, the indicators of the known prototype are given in table. 5 (examples 1-5). In the table. 3-5 the following designations of the main components are accepted:
K - Portland cement clinker,
g - two-water gypsum
d - mineral supplement - synsyr.

n - nepheline concentrate,
S _beats - specific surface area,
W / C - water-cement ratio,
THAT - heat treatment,
TVO - heat and moisture treatment,
R _cr - ultimate compressive strength,
R _izg - ultimate strength in bending.

Analysis of the results of the table. 3 and 4 shows that
- binder, consisting only of Portland cement clinker and gypsum, has a reduced strength compared to the proposed binder, which has in addition to these components a mineral additive - synyr,
- with an increase in the consumption of synergite additives, starting from 40%, a decrease in clinker to 52%, the strength of the binder decreases
- all binder compositions gain strength in 8 hours of heat treatment and 1 day of storage of samples in laboratory conditions. When steaming samples for more than 8 hours of heat treatment, there is no significant increase in strength,
- the strength of the binder increases significantly during storage of samples for 28 days under normal conditions, which allows us to conclude on the set of brand strength of the binder at a later hardening time compared to traditional types of binders.

Therefore, optimal are the binder compositions containing, by weight. %: synsyr - 30-35, clinker - 62-67, gypsum - 3, providing good strength indicators both under conditions of heat and moisture treatment at t = 90-95 ^o C, and under normal conditions of hardening for 28 days.

Thus, the proposed binder has the following advantages compared with the known:
- the amount of additive with an increase in strength indicators by 3.2% is 30-35% compared with the prototype (6% of the additive),
- the content of the clinker component is reduced by 1.5-2 times without deterioration of the strength properties of cement due to the use of synsyrite,
- reduced TVO time by 1.5 times as a result of preliminary mechanical processing of materials,
- reduced isothermal exposure time by 3 hours (1 h - temperature rise to 100 ^o C, instead of 2 hours in the prototype and 5 hours of isothermal exposure instead of 8 hours in the prototype),
- the proposed binder is water resistant (K _water = 1.0) compared with the known in the prototype (K _water = 0.8),
- reduction of energy consumption due to the replacement of nepheline concentrate activated with acid at a temperature of 120-150 ^o C in the composition of the binder, by synsyr, the production of which is supposed to be open-cast
- the proposed binders have good sulfate resistance (K _s = 1,0),
- the cost of the additive used is 14 times cheaper at a higher consumption than the cost of a nepheline supplement at a lower dosage.

 Known binder includes an expensive component - nepheline concentrate worth 1 ton 47.8 rubles. in prices of 1981. The cost of synergy is 3.29 rubles per 1 ton in prices of 1981.

 The proposed composition differs from analogues in that it does not contain ash, raw sludge from cement production, a mineral additive of the specified composition; from the prototype - in that it does not contain nepheline concentrate and acid.

 The proposed binder was developed at NILSTROM VSTU in conjunction with the Laboratory of Chemistry and Technology of Mineral Raw Materials, BIEN SB RAS.

 The foregoing indicates the feasibility of the invention to obtain the specified technical result, which allows us to conclude that the proposal meets the condition of "industrial applicability".

Claims (1)

A binder, consisting of Portland cement clinker, two-water gypsum, additives, characterized in that as an additive it contains an alkaline aluminosilicate rock - synsyr - in the following ratio of components, wt. %:
Synnyr - 30 - 35
Two-water gypsum - 3
Portland Cement Clinker - Other

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