RU2550775C1 - Complex additive for concrete mixtures - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: complex additive contains, wt %: caprolactam oligomers recovered by filtration from extraction waters from the stage of granulated polyamide-6 extraction after preparing by hydrolytic polymerisation of caprolactam - 60-75; sodium sulphate - 2-5; polyvinyl alcohol - 15-20 and water - 8-15.

EFFECT: higher strength, lower water absorption and improved plasticising ability of the additive.

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Description

The invention relates to the construction industry, namely, additives for concrete mixtures.

Known additive for concrete mix, including alkaline runoff of caprolactam production from benzene based on sodium salts of carboxylic acids of fraction C ₁ -C ₆ and bottoms of its purification at the distillation stage, containing, wt.%:

sodium hydroxide 1-4 aminocarboxylic acid sodium salt 2-8 caprolactam oligomers 5-10 caprolactam rest

(A.c. SU 1414825 C04D 24/06. Publ. 1988).

The disadvantages of this additive are its toxicity and the need for special precautions when using it, high consumption and low increase in concrete strength, not exceeding 12.4%.

Known complex additive for concrete mixtures, the closest to the invention in technical essence. It contains, wt.%:

bottoms of synthetic production fatty acids based on higher fatty acids 1.25-47.62 sodium hydroxide 4.76-6.25 bottoms of the caprolactam regeneration workshop based on caprolactam and its oligomers 7.62-62.5

(Patent RU No. 2072971 C04B 28/04, C04B 24/04. Publ. 10.12.1997).

The disadvantages of the prototype are:

- insufficient strength and high water absorption of concrete;

- insufficient plasticizing ability, characterized by the mobility of the concrete mixture in its manufacture. For the prototype, it does not exceed 18 cm;

- high alkalinity of the additive and the formation of crystalline precipitate, extremely complicating its transportation, storage and use.

SUMMARY OF THE INVENTION

The objective of the invention is to search for the composition of a complex additive for concrete mixtures, including caprolactam oligomers, which would provide increased strength and reduced water absorption of concrete, would have a higher plasticizing ability and would be convenient in transportation, storage and use.

The problem is solved by a complex additive for concrete mixtures, including caprolactam oligomers, which additionally contains sodium sulfate, polyvinyl alcohol and water, and as caprolactam oligomers it contains caprolactam oligomers isolated by filtration from extraction water from the extraction stage of granular polyamide-6, upon its hydrolytic production the polymerization of caprolactam, with the following components, wt.%:

Caprolactam oligomers 60-75 Sodium sulfate 2-5 Polyvinyl alcohol 15-20 Water 8-15

The advantages of the additives according to the claimed invention are:

- increase in concrete strength by 23.82-32.83%;

- reduction of concrete water absorption 2.9-4.0 times;

- higher plasticizing ability of the additive, providing increased mobility of the concrete mixture. So, the cone draft is not lower than 22 cm;

- the absence of harmful effects on the human body during its preparation and use, since the additive does not contain toxic components. The paste-like consistency of the additive eliminates the formation of a crystalline precipitate or delamination during transportation, storage, use.

INFORMATION CONFIRMING THE POSSIBILITY OF PLAYING THE INVENTION

The following components are used to prepare the additive:

- oligomers of caprolactam. They are obtained in the form of a white microcrystalline powder with a particle size of 2-25 microns as a result of filtration from extraction water from the extraction stage of granular polyamide-6 upon its production by hydrolytic polymerization of caprolactam;

- sodium sulfate GOST 6318-77;

- polyvinyl alcohol GOST 10779-78;

- technical water GOST R 53128-2003.

The additive is prepared as follows. Caprolactam oligomers, sodium sulfate and a suspension of polyvinyl alcohol in water are loaded into the mixer with a mixer in the required quantities. The mixture is stirred at 20-40 ° C for 30-40 minutes, then a screw is fed into the receiving chamber of a homogenizer, for example, a rotary-pulse one, through which the mixture is circulated through the mixer for 15-20 minutes until a homogeneous paste-like mass is obtained.

The resulting additive in the preparation of concrete mix is used with mixing water.

Concrete products obtained using the additive prototype and the inventive additives were made and tested the same way. The composition of the additive prototype used the following, wt.%:

bottoms of synthetic production fatty acids based on higher fatty acids acids 1.25 sodium hydroxide 6.25 bottoms of the caprolactam regeneration workshop based on caprolactam and its oligomers 20,0

The strength of concrete was judged by compressive strength, determined according to GOST 10180-2012. The water absorption of concrete was determined according to GOST 12730.0-78.

The plasticizing ability was judged by the index of mobility of the concrete mixture, determined by the value of sediment cone according to GOST 10181-2012.

Physico-chemical properties of the concrete mixture and products from it with different quantitative content of the components of the inventive additives are given in the table.

These tables indicate the clear advantages of the claimed additives.

Table Physico-chemical properties of concrete mix and products from it No. Name of components Component Content one 2 3 Prototype one Caprolactam oligomers 60 70 75 - 2 Sodium sulfate 5 four 2 - 3 Polyvinyl alcohol twenty 16 fifteen - four Water fifteen 10 8 - Physicochemical properties one Compressive strength, MPa 49.8 51.5 53,4 40,2 2 Water absorption, wt.% 0,086 0.102 0.118 0.346 3 The mobility of the mixture by sediment cone, cm 22.0 23.0 25.0 18.0

Claims (1)

A complex additive for concrete mixtures, including caprolactam oligomers, characterized in that it additionally contains sodium sulfate, polyvinyl alcohol and water, and as caprolactam oligomers it contains caprolactam oligomers isolated by filtration from extraction water from the extraction stage of granular polyamide-6 upon receipt hydrolytic polymerization of caprolactam in the following components, wt.%:
caprolactam oligomers isolated from extraction water from the extraction stage granular polyamide-6 when it hydrolytic polymerization caprolactam 60-75 sodium sulfate 2-5 polyvinyl alcohol 15-20 water 8-15