RU2320592C1 - Cement containing mineral additives - Google Patents

Abstract

FIELD: building materials and industry.

SUBSTANCE: invention relates to compositions of cements and can be used in preparing novel species of cements used in building. Proposed cement containing mineral additives comprises Portland cement clinker, gypsum dihydrate and magnesium-silicate mountain rock wehrlite in the following ratio of components, wt.-%: wehrlite, 25-30; Portland cement clinker, 70-75, and gypsum dihydrate, 2 of mass of mixture of wehrlite and Portland cement. Cement is prepared by combined grinding in a core-type vibration device for 10 min. Invention provides enhancing strength and decreasing cost of cement.

EFFECT: improved and valuable properties of cement.

3 tbl, 5 ex

Description

The invention relates to compositions of cements and can be used to obtain mortars and concrete based on them.

Known astringent composition, including, wt.%:

Portland cement clinker 15-50 Tails of the Kovdorsky GOK 50-85

(The use of by-products of iron ore beneficiation in construction in the North. Leningrad, Stroyizdat. Leningrad Branch, 1986, pp. 80-97).

The disadvantage is that when it is received, the autoclave treatment method is used, which significantly increases the cost of the composite binder. The proposed cement eliminates this processing method, and also has a higher strength, higher by 67.3% compared with the known composition.

Closest to the claimed invention, the composition of the same purpose for the totality of signs is an astringent, containing, wt.%:

Dunite 30-40 Gypsum plaster 3 Portland cement clinker rest

(RF patent No. 2168472 of July 26, 1999, Bull. No. 16 of June 10, 2001). Known binder, taken as a prototype, differs from the proposed one in that it contains magnesium silicate rock - dunite as an additive. The proposed cement as a mineral additive contains magnesium silicate rock - verlite, is a finished product and has a higher strength, higher by 78.4% compared to the prototype.

The technical result of the invention is the production of new, ready-to-use types of cements with a mineral additive - verlite, which have increased strength and low cost.

The specified technical result is achieved in that the proposed cement with mineral additives containing Portland cement clinker, two-water gypsum and magnesium silicate rock, characterized in that it contains verlite as a magnesium silicate rock in the following ratio of components, wt.%:

Verlite 25-30 Portland cement clinker 70-75 Gypsum plaster 2 by weight of a mixture of verlite and portland cement clinker

with their joint grinding in a rod vibrating unit for 10 minutes.

The known mechanism of hydration and hardening of Portland cement based on magnesium-containing tailings of the Kovdor GOK, which is a rock of ultrabasic composition. An important role in the formation of the mechanical properties of the material is played here by the autoclave synthesis parameters. In hydrothermal synthesis under autoclave conditions, magnesium silicates and ferruginous magnesium silicates change their structure. In the system (Mg, Fe) ₂ SiO ₄ -CaO-H ₂ O, neoplasms of various calcium-magnesium composition are fixed, which provide strength to the autoclave.

A comparison of the invention with other technical solutions known from the prior art made it possible to establish the following. In the well-known technical solution for obtaining a binder used the tails of the Kovdorsky GOK, which are part of the known mixture. The raw material mixture was autoclaved at 1.7 MPa. The disadvantage is the use of this treatment, which leads to a large consumption of electricity and, as a result, a higher cost of the binder.

In the claimed cement, magnesium silicate rock in the form of verlite, which is a natural raw material of the Baikal region, is used as an additive. Joint grinding of the starting components provides not only their fine grinding, but also the activation of particles, and a change in the structure of their surface layers. Solid-phase reactions take place in the raw mix, which affects the hydration activity and the increase in strength indicators of the proposed cements.

The analysis of the prior art by the applicant, including a search by patent and scientific and technical sources of information and 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 analysis of analogues, as well as the prototype, as the closest in the set of essential features, allowed to identify the set of essential in relation to the perceived technical result - obtaining new types of finished cements with sufficiently high strength characteristics - the hallmarks 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 was not revealed from the prior art determined by the applicant. Namely: the interaction of verlite with minerals of cement clinker and gypsum during joint grinding in a rod vibrating installation provides a positive reaction to achieve a technical result - an increase in strength.

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

Verlite of the Yoko-Dovyrensky massif (Northern Baikal region), which is part of cement, is a magnesium-silicate rock of the following chemical composition, wt.% (See table 1). It is a type of peridotite, consisting of olivine and monoclinic pyroxene, and the fayalite molecule in olivine is 10-14%.

Verlites separate the dunitic zone of the massif from the plagiodunitic one. They are also widespread in the upper part of the dunite zone. Their stocks in the array are significant.

In this technical solution, this raw material is first used as an active binder component in joint grinding with Portland cement clinker and gypsum for 10 minutes.

To select the optimal composition, cement mixtures were prepared, differing from each other in the content of constituent components, wt.%: Verlite - 20, 25, 30, 35, 40; Portland cement clinker - 60, 65, 70, 75, 80; gypsum gypsum - 2 by weight of a mixture of verlite and Portland cement clinker.

The technology of cement of the proposed composition is as follows.

Portland cement clinker, two-water gypsum, verlite is mixed in the appropriate proportions and crushed in a 75T-DrM rod-type vibrating unit with shock-shear loading for 10 minutes. The mixture is shut with water at a water-solid ratio of 0.3, mix thoroughly for 5 minutes and prepare 2 × 2 × 2 cubic samples (cm). Samples are stored in normal humidity conditions for 7 and 28 days. Then they are tested for compression.

Example 1

Verlite, Portland cement clinker, two-water gypsum are crushed in a 75T-DrM rod-type vibrating unit for 10 minutes with the following ratio of components, wt.%:

Verlite twenty Portland cement clinker 80 Gypsum plaster 2 by weight of a mixture of verlite and clinker.

The mixture is shut with water at a water-solid ratio of 0.3 and the samples are molded. After 7 and 28 days of hardening under normal humidity conditions, they are tested for compressive strength. The samples had strength after 7 days of hardening - 36.8 MPa. The compressive strength after 28 days was 51.5 MPa. The average density is 2253 kg / m ³ .

Example 2

Similar to example 1 with the following content of components, wt.%:

Verlite 25 Portland cement clinker 75 Gypsum plaster 2 by weight of a mixture of verlite and clinker.

The compressive strength after 7 days of hardening in normal humidity conditions is 43.8 MPa. After 28 days, the compressive strength was 54.9 MPa, and the average density was 2241 kg / m ³ .

Example 3

Similar to example 1 with the following content of components, wt.%:

Verlite thirty Portland cement clinker 70 Gypsum plaster 2 by weight of a mixture of verlite and clinker.

The compressive strength after 7 days of hardening in normal humidity conditions is 59.6 MPa. After 28 days, the compressive strength was 61.0 MPa, and the average density was 2216 kg / m ³ .

Example 4

Similar to example 1 with the following content of components, wt.%:

Verlite 35 Portland cement clinker 65 Gypsum plaster 2 by weight of a mixture of verlite and clinker.

The compressive strength after 7 days of hardening in normal humidity conditions is 40.7 MPa. After 28 days, the compressive strength was 53.2 MPa. The average density is 2280 kg / m ³ .

Example 5

It is carried out analogously to example 1 in the following ratio of components, wt.%:

Verlite 40 Portland cement clinker 60 Gypsum plaster 2 by weight of a mixture of verlite and clinker

The compressive strength after 7 days is 38.5 MPa, after 28 days - 47.9 MPa. The average density is 2345 kg / m ³ .

As a result of the studies (see Table 2), it was possible to establish that when grinding in a rod vibrating unit for 10 minutes, the raw mix consisting of 25-30% verlite, 70-75% Portland cement clinker and 2% two-water gypsum (by weight of the mixture verlite and clinker) strength is increased in comparison with the known types of cements of conventional composition.

Characteristics of the obtained binders are given in table 2 (examples 1-5). For comparison, the indicators of the known prototype are shown in table 3 (examples 1-7). In tables 2, 3 the following designations of the main components are adopted:

K - Portland cement clinker;

G - two-water gypsum;

D - mineral supplement;

R _cr - ultimate compressive strength.

An analysis of the results of Table 2 shows that

- the proposed cement, incorporating a mineral additive - verlite, has increased strength compared to conventional Portland cement grade M 400;

- the optimal composition is 30% verlite, 70% Portland cement clinker and 2% two-water gypsum (based on the weight of verlite and clinker);

- with an increase in the consumption of verlite additives, starting from 40%, a decrease in clinker to 60%, the strength of cement decreases;

- all cement compositions gain strength in 7 days of storage of samples in normal humidity conditions;

- the strength of cement increases during storage of samples for 28 days in normal humidity conditions, which allows us to make a conclusion about the set of strength in the later stages of hardening.

Therefore, when receiving cement with mineral additives by joint grinding in a core vibratory installation of incoming components, the optimal composition is, containing, wt.%: Verlite - 25-30, Portland cement clinker - 70-75, two-water gypsum - 2 from the mass of verlite and clinker, providing good strength indicators under normal humidity conditions of hardening.

Table 1 The chemical composition of verlite, wt.% Component Verlit SiO ₂ Al ₂ O ₃ FeO Fe ₂ O ₃ Cao MgO K ₂ O + Na ₂ O 39.70 1.80 10.70 0.42 0.81 43.83 0.19

table 2 Indicators of physico-mechanical properties of cement with the addition of verlite The composition of cement, wt.% Compressive strength Average density MPa, aged kg / m TO D G 7 days 28 days (by weight of the mixture K + D) 80 twenty 2 36.3 51.5 2253 75 25 2 43.8 54.9 2241 70 thirty 2 59.6 61.0 2216 65 35 2 40.7 53,2 2280 60 40 2 38.5 47.9 2345 one hundred - 2 36.9 42.3 2032

Table 3 The physical and mechanical properties of the known prototype The composition of the binder, wt.% The ultimate tensile strength, MPa, aged The average density, kg / m ³ TO D G 7 days 28 days 77 twenty 3 8.8 8.9 1431 72 25 3 13.7 14.3 1519 67 thirty 3 28.8 30.1 2029 62 35 3 31,0 32.1 2076 57 40 3 33.3 34.2 2248 52 45 3 29.8 30,2 2239 47 fifty 3 26.7 27.1 2226 97 - 3 29.6 30,0 2095

Thus, the proposed cement with mineral additives has the following advantages compared with the known:

- increased strength indicators by 78.4% compared with the prototype and by 44.1% compared with the control sample;

- there is no hydromechanical activation of verlite, which leads to a reduction in certain technological costs in the production of the proposed cement;

- cost reduction through the use of waste rock, which is verlite;

- obtaining the finished end product.

The proposed cement differs from the prototype in that it contains magnesium silicate rock - verlite - and has increased strength characteristics.

The proposed cement with mineral additives was developed at the Laboratory of Chemistry and Technology of Natural Raw Materials, BIL 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)

Cement with mineral additives, containing Portland cement clinker, two-water gypsum and magnesium silicate rock, characterized in that it contains verlite as magnesium silicate rock in the following ratio of components, wt.%: Verlite 25-30 Portland cement clinker 70-75 Gypsum plaster 2 by weight of a mixture of verlite and   portland cement clinker