SU796212A1 - Complex additive to cement-concrete mix - Google Patents

Description

one

The invention relates to the production of building materials, namely the production of concrete mixtures containing modifying additives.

Known complex additive 1J for cement concrete mixture, including, wt.%:

Sulfite Yeast

mash 2, 7-12, 7

Bottoms

synthetic

fatty acids 2.7-12.7 Nitrite, or nitrate

calcium chloride 72-82

WaterEverything

Closest to the proposed Technical Subject and the achieved result is a complex additive 2 for a cement-concrete mixture, including a stock of vegetable oil, a sulphite-yeast mash in a 1: 1 ratio by volume and water. The additive allows preserving the mobility of cement-sand mortar mixes for 4-5 hours.

A disadvantage of the known additive is the short shelf life of the concrete mix.

The purpose of the invention is to improve the workability of the cement-concrete mixture while maintaining the strength of concrete. The goal is achieved by the fact that the complex additive is for cement concrete. mixtures, including sulphite-yeast brew, soap stock of vegetable oil and water, additionally contain

sodium or potassium hydroxide and nitrite

0 sodium in the following ratio, wt.%: Sulfite-yeast mash 1.5-5.0

Soapstock vegetable oil 5-3-3.3 Sodium or potassium hydroxide 0.002-0.01 Sodium nitrite 45-55 Water Else

0 Soap stock of vegetable oils is a by-product of oil and fat production.

Complex additive is envisaged in the amount of 1-20%

5 by weight of cement.

The preparation of the additive is carried out as follows.

An aqueous solution of a sulphite-yeast brew is prepared first and potassium or sodium hydroxide is gradually combined with it, the resulting stock is heated to 45 ° C preheated soap and then sodium nitrite. The sulphite yeast brew (RRM) has an acidity pH of 5-6, which prevents the formation of soap stock emulsion in an aqueous RRM solution. In this case, float stock flakes are formed, the emulsion is heterogeneous in composition, which makes it difficult to apply it to the first concrete mix. Therefore, it is necessary to preliminarily neutralize the excess acid by additional addition of potassium or sodium hydroxide.

In addition, the hardened concrete has a lack of strength due to the blocking of the hydration of the cement grains by the fat flow of soap stock.

Soap stock of vegetable oils consists mainly of sodium salts of unsaturated (unsaturated) fatty acids, in molecules of which between carbon atoms there are double and triple bonds, and is a water-soluble surfactant.

Combining soap stock with an aqueous solution of a pre-alkalized sulphite-yeast brew. Can be carried out in a paddle mixer (soap stock is heated to 45-50 ° C; shaft speed of the mixer is 100-120 rpm; mixing time is 8-10 min). The presence of alkali metal hydroxide suppresses the float-foaming process and helps to obtain a homogeneous emulsion with low energy consumption.

Inorganic acid salt — sodium nitrite, besides accelerating the hardening of concrete, forms water associates that contribute to the liquefaction of the constituents of the concrete mix.

The prepared complex additive is introduced into the cement-concrete mixture with cement water.

Three compositions of the proposed complex additive with boundary contents of the components and one composition of the known complex additive are prepared. The consumption of cement and aggregate in all compositions is the same. As raw materials of concrete use slag Portland cement M 400 Podolsky plant; crushed stone fr. 5-10 and 10-20 Zaporozhye quarry and sand 1.8-2.0 from the Kursk base.

The consumption of materials for the preparation of concrete mixtures in all the compositions are assumed to be the same and amount to IM-, kg:

Cement480

Sand720

Crushed stone1020 and water cement

ratio 0,43

The dosage of the proposed additive in all compositions is 2% by weight of cement, and the known additive is 0.2% (an increase in dosage leads to a strong slowdown in the setting and hardening of the concrete).

The table shows the results of tests of concrete mixes and concrete with additives.

offer

 1.53.3

55.0 Ost- 21-22

0.01

52.5 27-28

0,003

3.152.1 45.0 24-25

..5,01.0 0,002 known

3,153,15

52.5 27-28

0,0036

3.152.1 (KOH) Concrete mixes are prepared in a forced mixer. five

32.9 all up to 100%

34.6 32.6

The rest is 9-10

27.4% to 100% 34.6 Of these concrete mixes, molded sample cubes are subjected to

heat and humidity treatment according to the 2 + 3 + 8 + 2 h mode. Steamed cubes were tested 4 hours after the end of the heat and moisture treatment cycle.

The proposed complex additive allows to obtain highly liquefied mixtures without reducing the strength of the concrete and is able to retain its properties for a long time — more than 3 months.

The known additive is a non-uniform emulsion (layering of stock flow and SDB occurs 12 minutes after their combination). Soap stock, when combined with RDB, forms a flake due to increased QC; RRB. This is the reason for the slight plasticizing effect of the known additive and the reduced strength of the concrete.

Claims (2)

1. USSR author's certificate for application number 2578184 / 29-33, 0 cl. From 04 To 13/24, 1978. 2. Higerovich M. I., Salidjanov S. B., Bayer V. E, Teshabaev R. D., Improving the properties of building solutions with complex organic 5 additives, - Building and Architecture of Uzbekistan, 1971, No. 8, pp.15-17 (prototype).