CS236116B1 - Liquefying additive for concrete mixes and method of its production - Google Patents

Abstract

Flowing admixture for concrete mixtures composed of aqueous solutions of salts of sulfonated polycondensates of formaldehyde and cyclic organic substances; which contains as cyclic organic substances in the dry matter 50 to 40% by weight of the distillation fraction of the methylnaphthalene portion from tar with a boiling point of 240 to 265 °C composed of 40 to 62% methylnaphthalene, 0.1 to 50% dimethylnaphthalene, 0.1 to 12% naphthalene, 0.1 to 10% thionaphthene, 0.1 to 15% dlphenyl, 0.1 to 15 dibenzyl, 0.1 to 6% phenol, 0.1 to 10% pyridine. It is produced by adding 70 to 80% by weight of concentrated sulfuric acid or the corresponding oleum equivalent to the distillation fraction of the methylnaphthalene portion of tar with a boiling point of 240 to 265 °C, while stirring at 100 to 180 °C, the mixture is cooled to 100 °C, 24 to 48% by weight of formaldehyde is added and, after polycondensation at 100 to 120 °C, the mixture is neutralized.

Description

The invention relates to a plasticizing additive for concrete mixtures and a method of its production, which improves the workability of the mixture and the quality of subsequent products.

In technological processes of products that start with water-miscible mixtures, the issue of the amount of water used is often addressed. In many cases, the technology promotes minimal water addition while maintaining good workability of the mixture, even if it is justified by energy savings in further processing of the product (vibration of concrete mixtures) or product quality (compressive and tensile strength of concrete during bending, shrinkage, content and quality of pores, etc.).

The most modern means of reducing the water content in concrete mixtures are alkaline salts of sulfonic acids of polycondensates of formaldehyde with melamine (Japanese Patent [JPP] 21659/68 and JP P 63015/75), or of polycondensates with β-naphthalenesulfonates or their derivatives. These plasticizers are also referred to as superplasticizers. In a number of products, the resins mentioned are the main plasticizing component in addition to other polymers or copolymers or polycondensates of other cyclic hydrocarbons with formaldehyde. Typical examples are the subjects of US patents^. 2 141 569 or 2 690 975 and Japanese patent No. P 115842/75*

Furthermore, to a limited extent, waste products from the processing of wood and leather are used as plasticizers, which consist of various lignosulphates or artificial tannins based on sulfonated polyhydric phenols or phenol-formaldehyde resins (e.g. plasticizer S, Silfix, Ralentol-, Umaform SF, etc.).

The quality of these additives is not always guaranteed, some have unsatisfactory retarding properties during the hardening of concrete and their rheological properties are usually low. Their wider use is also limited by other unfavorable properties, especially at higher dosages, e.g. increasing porosity and thus reducing the strength of concrete, unsatisfactory retarding properties or negative effects on corrosion of reinforcement in structural concrete.

The subject of the invention is a plasticizing additive for concrete mixtures composed of aqueous solutions of salts of sulfonated polycondensates of formaldehyde and cyclic organic substances, which contains as cyclic organic substances in the dry matter 30 to 40% by weight of the distillation fraction of the methylnaphthalene portion from tar with a boiling point of 240 to 265 °C, composed of 40 to 62% methylnaphthalene, 0.1 to 30% dimethylnaphthalene, 0.1 to 12% naphthalene, 0.1 to 10% thionaphthene, 0.1 to 15% diphenyl, 0.1 to 15% dibenzyl, 0.1 to 6% phenol, 0.1 to 10% pyridine.

The fluidizing additive according to the invention is produced in such a way that 70 to 30% by weight of concentrated sulfuric acid or the corresponding equivalent of oleum of any concentration is added to the distillation fraction of the methylnaphthalene portion of tar with a boiling point in the range of 240 to 265 °C, with constant stirring at temperatures of 100 to 180 °C, the resulting sulfonic acid mixture is cooled to 100 °C, 24 to 48% by weight of formaldehyde is added and, after polycondensation at 100 to 120 °C, the mixture of polycondensates is neutralized, preferably with an equivalent of diluted alkali metal hydroxides.

The plasticizing additive according to the invention has the advantage that it reduces the water content in concrete mixtures by up to 25% with the same workability, which appropriately increases the compressive strength of concrete, or saves 15 to 20% of cement with the same strength, depending on the type of mixture. It does not exhibit retarding properties. In summary of its properties, it is classified as a so-called superplasticizer. The method of producing the plasticizing additive according to the invention is simple, it can be carried out in one sequence in a single reaction kettle, without the use of organic solvents. The advantages mentioned include the fact that the additive can be produced from readily available raw materials.

In the following description, the invention is illustrated by means of exemplary embodiments. For examples 1 to 5, the basic raw material, methylnaphthalene fraction from tar, has the composition according to the following table.

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example 1 ΖΞΊ ΞΊ Γ7Ξ % methylnaphthalene 40.0 62.0 49.9 52.8 55.0 dimethylnaphthalene 27.9 0.5 15.5 0.1 30.0 naf talent •10.9 0.7 6.0 12.0 0.1 thionaphthene 10.0 0.5 4.1 0.1 8.9 diphenyl 0.6 15.2 9.7 14.2 0.2 dibenzyl 0.5 14.6 7.2 15.0 0.1 phenol 0.2 6.0 3.5 5.7 5.2 pyridine 9.9 0.5 4.5 0.1 0.5

Example 1

A mixture of 500 g of methylnaphthalene fraction from tar and 370 g of conc. sulfuric acid was heated to 160-170 °C and stirred for 30 min. After cooling to 100 °C, 290 g of 37% formalin was added and stirred for 50 min at 100-120 °C. The reaction mixture was neutralized with 150 g of sodium hydroxide in 700 ml of water. A dark brown product with a specific gravity of 1.12 g/cm^ and a dry matter content of 46% was obtained.

Example 2

To 500 g of methylnaphthalene fraction from tar was added 360 g of 10% oleum at 115°C over 20 minutes. The reaction product was cooled to 100°C and 450 g of 37% formalin was mixed with it.

After 25 minutes of stirring at 100 to 110 °C, the polycondensate was neutralized with 230 g of potassium hydroxide in 800 ml of water. A black product with a specific gravity of 1.15 g/cm^ and a dry matter content of 49% was obtained.

Example 3

To 500 g of methylnaphthalene fraction from tar was added dropwise 335 g of 10% oleum at 165 °C over 25 minutes and after 10 minutes of stirring cooled to Ϊ00 °C. To the reaction mixture was added 880 g of 25% formalin and after 25 minutes of stirring at 100 to 115 °C the mixture was neutralized with 145 g of sodium hydroxide in 1000 ml of water. A dark brown product with a specific gravity of 1.1 g/cm ^J and a dry matter of 44% was obtained.

-4Example 4 238 no

A mixture of 500 g of methylnaphthalene fraction from tar and 360 g of conc. sulfuric acid was heated to 140-160 °C and stirred for 40 minutes. After cooling to 120 °C, 290 g of 37% formalin was added and stirred for 20 minutes at the same temperature. The reaction mixture was neutralized with 145 g of sodium hydroxide in 600 ml of water. It was

A black product with a specific gravity of 1.13 g/ ^cm3 and a dry matter content of 47% was obtained.

Example 5

A mixture of 500 g of methylnaphthalene fraction from tar and 360 g of conc. sulfuric acid was heated to 160 °C and stirred for 30 minutes.

‘ After cooling to 120 °C, 280 g of 37% formalin was added, stirred for 20 minutes at a temperature of 120 to 130 °C. The reaction mixture was neutralized with 150 g of sodium hydroxide in 700 ml of water. A product with a specific gravity of 1.12 g/cm and a dry matter content of 46% was obtained.

Concrete mixtures and products had the same processing properties at the same dosage of dry matter of the plasticizing additives according to the invention from the examples given. At a dosage of 0.5 to 2% by weight of dry matter per cement, water savings were 12 to 25% with the same workability as the standard and an increase in concrete strength after 28 days of hardening under the same conditions by 10 to 20%, with the hardening time of the samples at 95 °C being 50 to 85 minutes (standard 50 minutes).

Claims (2)

CLAIMS 1. A liquefying additive for concrete mixtures consisting of aqueous solutions of salts of sulphonated polycondensates of formaldehyde and cyclic organic substances, characterized in that it contains 30 to 40% by weight of dry matter as cyclic organic substances. distillation. a fraction of the methylnaphthalene fraction from the tar boiling point of 240 to 265 ° C composed of 40 to 62% methylnaphthalene, 0.1 to 30% dimethylnaphthalene, 0.1 to 12% naphthalene, 0.1 to 10% thionaphthene, 0.1 to 30% 15% diphenyl, 0.1-15% dihenzyl, 0.1-6% phenol and 0.1-1β% pyridine. 2. A process according to claim 1 wherein 70 to 80% by weight of the distillate fraction of the methylnaphthalene fraction of tar at a boiling point of 240 DEG-265 DEG C. is added to the distillation fraction. % sulfuric acid or an equivalent oleate of any concentration, the resulting sulfoacid mixture is cooled to 100 ° C and 24-48 wt. formaldehyde and po. by polycondensation at 100 to 120 ° C, the polycondensate mixture is neutralized.