RU2432335C1 - Method of enhancing plasticising and water-reducing capacity of naphthalene-formaldehyde-based superplasticisers - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to production of construction materials and can be used in preparing concrete and mortar. The method involves mixing cement, an aggregate, water and a superplasticiser in form of an aqueous solution. The naphthalene-formaldehyde-based superplasticiser is added together with a micro-dose of a polycarboxylate-based additive, taken in amount of 0.05-0.15% of the weight of the dry residue of the plasticising additive. The binder used can be different types and brands of portland cement, the plasticiser used is naphthalene-formaldehyde-based plasticising additives, the additive is polycarboxylate-based plasticising additives, optimum content of which is equal to 0.001 of the dry residue of plasticising additive, with allowable ratio of 0.001±0.0005.

EFFECT: high mobility of concrete mixtures, as well as strength of concrete and mortar.

6 dwg, 6 tbl, 5 ex

Description

The invention relates to the production of building materials, and in particular to methods for enhancing the plasticizing and water-reducing ability of superplasticizers on a naphthalene-formaldehyde basis. The technical result is an increase in the mobility of concrete and mortar mixtures, as well as the strength of concrete and mortar, or a decrease in the water-cement ratio (w / c).

The invention can be used to increase the mobility of a concrete or mortar, reduce the consumption of superplasticizer, to reduce the w / c ratio, which reduces the cost of plasticized concrete and mortar, improves workability of the mixture, or increases strength, water resistance.

Known concrete mixtures with complex additives modifying their properties (RU, No. 2078744, 04B 28/04, 1997).

Known concrete mixture containing (as a water-reducing surfactant) superplasticizer C-3 (RU, No. 2055034, C04B 28/02, 1996).

A known method of producing high-strength cellular concrete by sequential supply of a surfactant, water, cement to the mixture with the additional introduction of plasticizer C-3 in an amount of 0.2-0.4% by weight of cement (RU, No. 2133722, С04В 38/10, 1999).

A known method of preparing a concrete mixture by mixing cement and water with the subsequent introduction of superplasticizer in the form of a solution (RU, No. 20186885, С04В 40/00, 1994).

A well-known complex additive for concrete mix containing C-3 superplasticizer based on the sodium salt of the condensation product of naphthalenesulfonic acid with formaldehyde in an amount of 85.21-89.74% (RU, No. 2041863, С04В 28/04, 1995).

Known raw mix for the preparation of heavy concrete, containing a superplasticizer based on sodium salts of the condensation product of naphthalene sulfonic acid with formaldehyde in an amount of 0.5-1% by weight (consumption) of cement (RU, No. 2100304, С04В 28/00, 1997).

Known technical dispersant, which is a mixture of polymer compounds of different molecular weights, obtained by sulfonation of naphthalene followed by condensation with formaldehyde and neutralization with sodium hydroxide (RU, GOST 68481-79).

The closest solution in technical essence, selected as a prototype, is a method of increasing the plasticizing ability of a naphthalene-formaldehyde-based superplasticizer by co-administering C-3 with LST, including mixing cement, aggregates, water and a superplasticizer in the form of an aqueous solution. In the case of its application, an increase in the plasticizing ability of the C-3 superplasticizer taken in an amount of 0.5-0.7% by weight of cement, with the addition of LST in an amount of 0.2% by weight of cement, can reach 20% (Batrakov V.G. Modified Concretes. Theory and Practice. - 2nd ed., Rev. and add. - M., 1998., S.476-480).

The disadvantages of the described method are the slowdown of the cement setting process, which leads to a decrease in strength, and excessive air intake, leading to a deterioration in the strength and appearance of the product.

The essence of the invention lies in the fact that the task of increasing the plasticizing and water-reducing ability of the naphthalene-formaldehyde-based superplasticizer, as well as reducing the cost of plasticized concrete mix, is solved without reducing the strength of concrete and other negative consequences.

The result is ensured by the fact that in order to increase the plasticizing ability of the superplasticizer on a naphthalene-formaldehyde basis, a microdose of the superplasticizer on a polycarboxylate basis is added to its solution in an amount of 0.1 ± 0.05% by weight of the additive of the superplasticizer on a naphthalene-formaldehyde basis. The action of plasticizers on a naphthalene-formaldehyde-based and polycarboxylate-based is to use different effects:

- naphthalene-formaldehyde - electrostatic;

- polycarboxylate - steric.

It was previously believed that these additives do not combine at all, since a superposition effect occurs between them, and the effectiveness of the mixture is always deliberately lower than each of these additives separately. We found a ratio of 1: 1000 (acceptable ratio 0.001 ± 0.0005), in which a synergistic effect is observed: the combined action is stronger than the sum of the individual actions. Applicants from the technical field are not aware of the use of compositions in which naphthalene-formaldehyde-based additives are used in conjunction with polycarboxylate-based additives.

The claimed technical solution differs from the prototype in that the proposed method for increasing the plasticizing and water-reducing ability of superplasticizers on a naphthalene-formaldehyde basis does not have the disadvantages typical for the prototype described above.

This distinctive feature in comparison with the prototype allows us to conclude that the proposed technical solution meets the criterion of "novelty."

Obtaining a similar result in a way that eliminates the occurrence of harmful effects characteristic of the prototype, allows us to conclude that the proposed technical solution meets the criterion of "inventive step". These effects can be traced to different types and brands of Portland cement. In the examples, specific examples show the possibility of increasing the plasticizing and water-reducing ability of additives on a naphthalene-formaldehyde basis, on plasticized (Appendix No. 1, No. 2) and conventional (Appendix No. 4, No. 5) Portland cement. Appendix 3 and 6 show how concrete strength increases at different dosages of the additive when using plasticized PC 600 D0 and ordinary PC 400 D0, made according to GOST 30515, GOST 10178, GOST 31108. The mixture was mixed on a laboratory mixer. Water-reducing ability was determined by the method of GOST 30459 with constant mobility, determined by the spread of the cone on a shaking table. Plasticizing ability was determined at a constant flow of water according to the technique of TU 5743-083-46854090-98. Strength measurement was determined by the method of GOST 310.4 by manufacturing and testing at the age of 28 days samples - beams with a size of 40 × 40 × 160 mm Thus, the use of the invention allows to enhance the plasticizing and water-reducing abilities of superplasticizers on a naphthalene-formaldehyde basis, without slowing down the setting time, excess air entrainment and without reducing the strength of the mortar, or concrete.

Further, the claimed invention is illustrated by examples, but is not limited to. The results in the form of tables and graphs illustrating them are summarized in six applications.

Example 1 (control composition)

They mixed in a laboratory mortar mixer, 500 g, in the first case, plasticized cement ПЦ 600 Д0, in the second case, ordinary Portland cement ПЦ 400 Д0 with 1500 g of medium-sized silica feldspar sand according to GOST 8736 and, in the first case, 175 g of water according to GOST 23732 (w / c = 0.35), and in the second case, 200 g of water (w / c = 0.4). The resulting solution was tested on a shaking table according to the method of GOST 310.4. The cone spread was 108 mm.

Beam samples of 40 × 40 × 160 mm in size were made from the solution, they were held for 28 days under regulated conditions and tested in accordance with GOST 310.4. The compressive strength in the first case was 54.3 MPa, and in the second case 44 MPa.

Example 2 (plasticized composition)

The solution was prepared as in example 1, but together with water, 4 g of SP-1 superplasticizer were added according to TU 5870-005-58042865-05 (0.8% by weight of cement on dry residue).

The cone spread in the first case was 119 mm, in the second case, 145 mm. The increase in mobility in the first case was 10%, in the second case 34%. To determine the water-reducing ability, new batches were prepared with a reduced amount of water so that the cone diffusion corresponded to the control composition blur. Water reduction in the first case was 19%, in the second case 17%. The increase in compressive strength of samples aged 28 days in the first case was 20%, and in the second case 30%.

Example 3 (plasticized composition with a minimum content of additives)

The solution was prepared as in example 2, but together with the superplasticizer SP-1, 0.002 g (0.05% of the dry residue of the plasticizing additive) of Sika ViscoCrete 120 R additive was added according to TU 5745-004-13613997-2005 (Swiss-made). The cone spread in the first case was 137 mm (mobility increased by 21%), and in the second case 160 mm (mobility increased by 48%).

Water-reducing ability in the first case increased by 23%, and in the second case by 22%. The compressive strength of the samples at the age of 28 days in the first case increased by 25%, in the second by 51%.

Example 4 (plasticized composition with optimal additive content)

The preparation of the solution was carried out as in example 3, but the proportion of the additive was 0.004 g (0.1% of the dry residue of the plasticizing additive). The cone spread in the first case was 154 mm (mobility increased by 43%), and in the second case 166 mm (mobility increased by 54%).

Water-reducing ability in the first case increased by 25%, and in the second case by 26%. The compressive strength of the samples at the age of 28 days in the first case increased by 28%, in the second by 51%.

Example 5 (plasticized composition with a maximum additive content)

The preparation of the solution was carried out as in example 3, but the proportion of the additive was 0.006 g (0.15% of the dry residue of the plasticizing additive). The cone spread in the first case was 147 mm (mobility increased by 36%), and in the second case 156 mm (mobility increased by 44%).

Water-reducing ability in the first case increased by 22%, and in the second case by 25%. The compressive strength of the samples at the age of 28 days in the first case increased by 25%, in the second by 57%.

Information sources

1. Batrakov V.G. Modified Concrete. Theory and practice. - 2nd ed., Revised. and add. - M., 1998., S. 476-480.

2. GOST 30515-97. Cements. General specifications. Introduced on 10/01/1998. - M .: GUPTSPP, 1998.

3. GOST 10178-85. Portland cement and slag Portland cement. Technical conditions Introduced on 01/01/1987. - M.: TsITP Gosstroy of the USSR, 1989.

4. GOST 31108-2003. Cements are general building. Technical conditions Introduced on September 1, 2004. - M .: GP TsPP, 2004.

5. GOST 30459-2003. Additives for concrete and mortar. Methods for determining the effectiveness. Introduced on March 1, 2004. - M .: GP TsPP, 2004.

6. TU 5743-083-46854090-98. Concrete modifier MB-S. Introduced on 01/01/1999. - M .: NIIZHB, 1998.

7. GOST 310.4-81 *. Cements. Methods for determining the tensile strength in bending and compression. Introduced 07/01/1983. Reprint 1992. - M .: IPK Publishing House of Standards, 2006.

8. GOST 8736-93 *. Sand for construction work. Technical conditions Introduced on July 1, 1995. - M .: Publishing house of standards, 1995.

9. GOST 23732-79. Water for concrete and mortar. Technical conditions Introduced on 01/01/1980. - M .: Publishing house of standards, 1979.

10. TU 5870-005-58042865-05. Superplasticizer "POLYPLAST SP-1".

11. TU 5745-004-13613997-2005. Superplasticizers for Sika ViscoCrete concrete. Introduced on 08.08.2008. - M .: ZIKA OJSC, 2005.

Claims (1)

A method of increasing the plasticizing and water-reducing abilities of naphthalene-formaldehyde-based superplasticizers, comprising mixing cement, aggregates, water and a superplasticizer in the form of an aqueous solution, characterized in that the naphthalene-formaldehyde-based superplasticizer is introduced together with a micro dose of a polycarboxylate-based additive, taken in an amount of 0 , 05-0.15% by weight of the dry residue of the plasticizing additive, while different types and brands of Portland cement can be used as a binder, as a plasticizer - plasticizing additives on a naphthalene-formaldehyde basis, as an additive - plasticizing additives on a polycarboxylate basis, the optimum content of which is 0.001 of the dry residue of the plasticizing additive, with an acceptable ratio of 0.001 ± 0.0005.

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