RU2151114C1 - Use of catalyst for hydration of cement, method - Google Patents

Abstract

FIELD: building industry and building materials, more particularly compositions of cement containing concrete mixes with organic additives. SUBSTANCE: use of sodium salts of naphthalene polysulfonic acids makes it possible to reduce at least by two times duration of isothermal maintenance period during manufacture of concrete products. The same strength of concrete in the presence of said catalyst is achieved in much milder conditions and at considerably smaller amount of energy vehicle. Catalyst is added to cement-containing mixture with mixing water or in dry form directly to cement during grinding of clinker or additional grinding of cement. EFFECT: intensified effect of accelerating hardening of concrete in early periods. 4 cl, 4 tbl

Description

 The invention relates to construction and building materials, in particular to compositions of cement-containing concrete mixtures with organic additives, and can be used for the manufacture of monolithic and prefabricated concrete and reinforced concrete structures.

 Special catalysts for hydration (hardening) of cement are not described.

Known chemical additives to concrete mixtures, affecting the hardening process of cement. See Sat VNIINTIIIEPSM:
1. Building materials industry, series 3, Precast concrete industry, overview, issue 3, APPLICATION OF CHEMICAL ADDITIVES IN CONCRETE, M., 1982;
2. Scientific and technological achievements and best practices in the production of building materials, analytical review, ADDITIVES TO CELLULAR CONCRETE, M., 1990.

 The closest in technical essence to the proposed one is superplasticizer C-3 - based on the sodium salt of the condensation product of naphthalenesulfonic acid and formaldehyde. However, this chemical additive cannot be attributed to catalysts, since its minimum amount is at least 0.5% by weight of cement (see, for example, patents RU N 2026270, cl. 6 C 04 B 28/04 // (C 04 B 28 / 04, 24:30, 22:08), 1995; N 2029749, CL 6 C 04 B 7/52, 1995).

The objective of the invention is to find an effective catalyst for hydration of cement, which would allow:
- improve the molding properties of the cement-containing concrete mixture;
- increase the strength of cement-containing concrete in the early stages of hardening while maintaining or increasing strength at design age;
- increase the coefficient of efficiency of the use of additives (the ratio of concrete strength to the consumption of additives).

 The problem is solved by using as a catalyst for the hydration of cement sodium salts of naphthalene polysulfonic acids containing at least two sulfo groups. These salts can be used both in the form of an aqueous solution, and in dry form during processing in the process of preparing cement for hydration.

 Earlier, sodium salts of naphthalene polysulfonic acids were used as starting materials in the synthesis of intermediates and dyes, as well as surfactants and textile auxiliary substances (see Chemical enz., T. 3, p. 192, scientific publishing house "Big Russian Encyclopedia", M., 1992), moreover, the sodium salt of 1,3,5,7-tetrasulfonic acid naphthalene has not yet been used in industry.

 The technical essence of the invention lies in the fact that the sodium salt of any naphthalene sulfonic acid containing at least two sulfo groups can be used as a catalyst for cement hydration. The presence in the polysulfonic acid molecule of naphthalene of other substituents (for example, amino, nitro, hydroxy, etc.) does not adversely affect cement hydration.

 The activity of the catalyst depends on the number and location of sulfo groups in the sulfonic acid molecule. So, to obtain the same result, the consumption of sodium salt of 1,5-sulfonic acid of naphthalene is 40 mg per 1 kg of cement, the consumption of sodium salt of 2,6-disulfonic acid of naphthalene is 10 mg per 1 kg of cement, the consumption of sodium salt of 8-amino-4-naphthol -3,6-disulfonic acids (Al-acid) is also 10 mg per 1 kg of cement, the consumption of sodium salts of 1,3,5- and 1,3,6-trisulfo-, as well as 1,3,5,7-tetrasulfonic acids naphthalene is 4 mg per 1 kg of cement.

 The sodium salts of naphthalene polysulfonic acids are highly soluble in water and can be introduced into the cement-containing concrete mixture together with mixing water. In dry form, they can be injected directly into the cement when grinding clinker or when grinding cement.

 Their use as a catalyst for cement hydration enhances the effect of accelerating the hardening of concrete in the early stages.

 The proposed catalyst for cement hydration allows at least halving the duration of isothermal aging in the production of concrete products. At the same time, an increase in the strength of concrete at the design age and an improvement in the molding properties of the concrete mixture are achieved. The same concrete strength in the presence of a cement hydration catalyst is achieved under milder conditions, with a significantly lower energy consumption.

 The invention is illustrated by examples.

 Examples 1-14 show the results of using a catalyst in cement-containing concrete mixtures in comparison with the same mixtures without additives. The catalyst was introduced into the concrete mixture with mixing water. The amount of the remaining components of the concrete mixture was not changed either for the control (without catalyst) or for the sulfonic acid used. Specific examples of the composition of concrete mixtures are presented in table. 1, and the results of their tests are shown in table. 2. The effect of catalysts on cement hydration in cement-containing concrete mixtures was investigated under the conditions of OAO "LZKPD" p. Kotelniki, Moscow region.

 Examples 15-21 illustrate the results of using a catalyst when grinding cement clinker (see table. 3), and examples 22-23 - when grinding cement (see table 4). Clinker grinding and cement grinding were carried out on vibratory ball mills in the conditions of Voskresenskcement JSC.

 The composition of the catalysts in the conditions of the plants was not disclosed.

 The term "sodium salt" for each specific polysulfonic acid of naphthalene means that for all sulfo groups of this acid, the hydrogen atom is replaced by a sodium atom.

Claims (3)

 1. The use of sodium salts of naphthalene polysulfonic acids as a catalyst for cement hydration.  2. The method of hydration of cement using the catalyst according to claim 1, in the form of an aqueous solution during the mixing of cement-containing concrete mixture.  3. The method of processing cement using the catalyst according to claim 1 in dry form when grinding clinker or milling cement.

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