CS260085B1 - Liquefying admixture into concrete batches - Google Patents

Abstract

The solution relates to liquefying additive to concrete mixes and solves the problem of improvement properties, especially stability and ability reduce the water content of concrete mixes with the same workability, so-called superplasticizers. The essence of the solution is the ingredient, composed of aqueous polycondensate solutions of formaldehyde with alkali salts of sulfonated cyclic organic matter type phenol, naphthalene, and derivatives thereof; mixtures thereof, wherein the polycondensation chain is present it consists of three to ten basic Members and is terminated on methylol members by coupling NOj, H2PO2, HSO3 or anion mixtures thereof, wherein 1 mole of formaldehyde, bound in polycondensates corresponds to 0.1 to 0.3 mole of NO $, H 2 PO 2, HSO 3 or mixtures thereof.

Description

BACKGROUND OF THE INVENTION The present invention relates to a fluidizing additive for concrete mixtures which can be classified as a group of highly effective formaldehyde condensates with sulfonated cyclic hydrocarbons.

In the technological processes of products which initially are water-miscible mixtures, the question of the amount of water used is often addressed. In many cases, the technology promotes minimal addition of water while maintaining good processability of the mixture, whether it is justified by energy savings in further processing of the product or product quality.

The most modern water-reducing agents in concrete mixtures are the alkali metal sulfonic acid salts of polycondensates of formaldehyde with melamine (JP patent 21 659/68 and JP patent 63 015/75) or polycondensates of formaldehyde with beta-naphthalenesulfonates or derivatives thereof.

These plasticizers are also referred to as superplasticizers. In many products, said resins are the main fluidizing component in addition to other polymers, copolymers or polycondensates of cyclic hydrocarbons with formaldehyde (U.S. Pat. No. 2,141,569, U.S. Pat. No. 2,690,975, JP Pat. salts of sulphonated polycondensates of formaldehyde and cyclic hydrocarbons with a high content of methylnaphthalene (cf. AO 236 116).

In addition, wood and leather waste products based on various lignosulfonates or artificial tannins based on sulfonated polyhydric phenols or phenol-formaldehyde resins, such as plasticizer S, Silfix, Ralentol, Umaform SF and the like, are used to a limited extent as plasticizers.

These additives are not always guaranteed for quality, some have unsatisfactory retarding properties for concrete hardening and their rheological properties are usually low. Their use on a larger scale also limits other adverse properties, especially at higher dosages, eg by increasing porosity and thus reducing the strength of the concrete or the negative effect of corrosion in the reinforcement of structural concrete. Long-term storage of the additives may also result in further polycondensation of the components, since the methylol members of the polycondensate molecules are highly reactive, thereby reducing the quality of the additive.

The above-mentioned disadvantages are overcome by the liquefying additive according to the invention, which consists in that the additive consists of aqueous solutions of formaldehyde polycondensates with alkali salts of sulfonated cyclic organic substances of the phenol, naphthalene and their derivatives, respectively. mixtures thereof, wherein the polycondensation chain comprises three to ten members and is essential for the members of the methylol ended anion binding NOx, HjPOj, HSO _3, or mixtures thereof, wherein 1 mole of formaldehyde bound in the polycondensates corresponds to 0.1 to 0.3 moles of NO ₂ , H ₂ PO ₂ ,

HSO 3 or mixtures thereof. Thus, the methylol members of the additive molecule are reacted with the anion NO ₂ , H ₂ PO 3 or a mixture thereof, e.g. according to the equation:

-CH 3 OH + HSO "- CH ₂ SO ₃ + H ₂ O, with no further polycondensation.

The liquefying agent of the invention can be obtained by reacting the alkali salts of said anions with aqueous neutral solutions of formaldehyde polycondensates with the alkali salts of sulfonated naphthalenes, phenols or derivatives thereof, and mixtures thereof by boiling. The dosage of said free electron pair alkali salts on the central atom is controlled by the formaldehyde bound in the additive. Per mole of formaldehyde, 0.1 to 0.3 mol of one or more of the above salts or equivalent is used.

The additive according to the invention is considerably more stable than the additive used so far, its rheological properties have increased, it does not foam, it reduces the water content of concrete mixtures with the same workability, thus increasing the compressive strength of the concrete, does not show retarding properties. In summary, it is one of the so-called superplasticizers and can be produced from readily available raw materials.

The preparation of the additive is illustrated by way of example, but these do not limit the invention in any way.

He did

A mixture of 1000 g of the methylnaphthalene tar fraction and 830 g of conc. The sulfuric acid was heated to 150 ° C and stirred for 3 hours. After cooling to 90 ° C, 400 mL of 38% formalin was added and stirred for 30 min at 90-120 ° C. After diluting with 5 L of water, the polycondensate was neutralized with 441 g of potassium hydroxide and boiled for 30 min with 50 g of sodium pyrosulfite. A brown product having a density of 1.14 g / cm @ 2 and a dry weight of 30% was obtained.

Example 2

Mixture of 1000 g of naphthalene and 840 g of sulfuric acid conc. The mixture was heated to 165 ° C and stirred for 1 hour. After cooling to 90 ° C, 450 cn? 38% formalin and stirred for 30 min at 100-115 ° C. After diluting the sulfonate with 3 L of water, the polycondensate was neutralized with 320 g of sodium hydroxide, made up to 7000 g with water and boiled with 150 g of sodium nitrite. A light green product having a density of 1 ', 12 g / cm @ 3 and a dryness of 28% was obtained. The additive in Ex. 1 and 2 has the same rheological properties when the water coefficient of the concrete mixture is reduced from 0.5 to 0.4 at 1.5% of the additive dosing by weight of the cement.

Example 3

Executed as Ex 2, however, sodium nitrite was replaced by 230 g sodium phosphate / Na ₂ HPO ₂ .

• I ^ O /. A product with a density of 1.14 g / cm @ 2 and a dry matter content of 28.2% with the same rheological properties in the concrete mix as in Example 2 was obtained.

Example 4

By substituting sodium nitrite in Example 2200 g of sodium pyrosulfite, a product with the same rheological properties was obtained.

Example5>

Executed as Ex. 1. A mixture of 35 g sodium nitrite with 25 g sodium pyrosulfite was used instead of sodium pyrosulfite. The additive had identical rheological properties.

Claims (1)

OBJECT OF THE INVENTION Liquefying additive for concrete mixtures, consisting of aqueous solutions of formaldehyde polycondensates with alkali salts of sulfonated cyclic organic substances of phenol, naphthalene and their derivatives, or mixtures thereof, wherein the polycondensation chain of these substances consists of three to ten basic members, characterized in that the polycondensation chain is terminated on the methylol members by coupling of the anions NO3, H2O3, HSO3 or mixtures thereof, wherein 1 mole of formaldehyde bound in the polycondensates corresponds to 0.1 to 0.3 moles of NO3, H3PO4, HSO3 or mixtures thereof.