RU2031882C1 - Concrete mixture - Google Patents

Abstract

FIELD: building materials. SUBSTANCE: concrete mixture has, wt.-%: portland cement or slag-portland cement 12.8-16.00; crushed stone 45.9-48.4; sand 28.8-31.4; neutralized secondary mother liquid of pentaerythritol production on the basis of sodium formate and carbohydrates 0.43-0.80; soda-alkaline melt 0.06-0.34, and water - the rest. Concrete strength after 28 days is 22.4-35.0 MPa. Mixture is used for making of concrete and ferroconcrete articles and structures. EFFECT: enhanced quality of mixture. 2 tbl

Description

 The invention relates to compositions of concrete mixtures used for the production of concrete and reinforced concrete products and structures.

Known concrete mixture, including cement, gravel, sand, water and an additive that accelerates hardening - sodium sulfate (Na ₂ SO ₄ ). Sodium sulfate is introduced into the concrete mixture in an amount of 0.5-2% by weight of Portland cement [1].

 A concrete mixture was selected for the prototype, including cement, crushed stone, sand, water and a neutralized secondary mother liquor for the production of pentaerythritol based on sodium salt of formic acid and carbohydrates (technical names according to TU 84-1067-85 - formate-alcohol stabilizer (aqueous solution) - SPS or a formate-alcohol plasticizer (aqueous solution) - PPS.

 The neutralized secondary mother liquor for the production of pentaerythritol based on the sodium salt of formic acid and carbohydrates is a multifunctional additive. Its introduction into the concrete mixture in an amount of 0.6-1% by weight of cement improves the plasticizing properties of the mixtures [3], and in an amount of 1-4% by weight of cement it causes a slowdown in the setting and hardening of the binder [2].

The disadvantage of these concrete mixtures is that the additives used in them do not provide an increase in the compressive strength of concrete sufficient to replace high-quality cements with low-quality (cement grade 500 to cement grade 300). The specified disadvantage is especially significant at low cement consumption in concrete mixtures - 300 kg / m ³ . In addition, structures made from these concrete mixtures have significant porosity (λBar = 2.23-6.75), which increases water absorption and therefore reduces water resistance.

The essence of the invention lies in the fact that the concrete mixture, including Portland cement or slag Portland cement, crushed stone, sand, a neutralized secondary mother liquor for the production of pentaerythritol based on sodium salt of formic acid and carbohydrates and water, additionally contains soda ash in the following ratio, wt.%:
Portland cement
or slag Portland-cement 12.80-17.00 Crushed stone 45.90-48.40 Sand 28.80-31.40
Neutralized
secondary uterine
production solution
pentaerythritol based
sodium salt ant
acid and carbohydrates 0.43-0.80 Soda-alkaline melt 0.06-0.34 Water Else
Soda-alkaline melt is a waste product obtained, for example, during thermal treatment of wastewater.

According to the technical conditions of TU 84512-19-86, the alkaline melt has the following composition, wt.%:
Mark A Brand B
Water-insoluble residue, not more than 5 10
Alkaline components in terms of
on sodium carbonate (Na ₂ CO ₃ ),% 10-33 60-90
Sodium sulfate (Na ₂ SO ₄ ) 40-76 8-18
Sulfur compounds in terms of
on sodium sulfide not more than 6-11 6
The proposed concrete mixture can significantly increase the compressive strength of concrete structures made from it. So, for example, after 28 days of hardening and heat-moisture treatment, structures made of the proposed concrete mixture using Portland cement or slag Portland cement of the M300 grade have a compressive strength exceeding the strength of structures made of non-admixture mixture using similar M500 cements, 1.1-1 , 2 times (at a cement consumption of 300 kg / cm ³ ) and 1.2-1.4 times (at a cement consumption of 400 kg / s ³ ). Thus, the proposed concrete mix allows the replacement of 500 grade cements with significantly less scarce 300 grade cements, which are 1.2 times cheaper. In addition, the proposed concrete mixture allows to obtain a finer-grained concrete structure and reduce water absorption by 1.1-1.3 times in comparison with the concrete mixture selected for the prototype, and 1.3-1.7 times in comparison with the non-admixture concrete mixture.

 The recipe for concrete mixtures: proposed, selected for analogue, and the prototype and control (no additives) are given in table. 1. Physico-mechanical characteristics of concrete - in table. 2.

The compressive strength of concrete (R _cr ) was determined according to the method described in GOST 10180-90 (Art. CMEA 3978-83).

 Water absorption and porosity were determined according to the methods described in GOST 12730.0-78. Concrete General requirements for methods for determining density, humidity, water absorption, porosity and water resistance; GOST 12730.3-78. Concrete Method for determining water absorption.

 GOST 12730.4-78. Concrete Methods for determining porosity.

 Concrete mixture is prepared as follows.

The alkaline melt is introduced into the mixing water, and the resulting mixture is thoroughly mixed until the melt is completely dissolved, and then filtered. To accelerate the dissolution process vessel in which stirring was made, can be preheated to 45-50 ° ^C. After complete dissolution of the melt in the resulting neutralized solution is added a secondary mother liquor pentraeritrita production based on formic acid sodium salt carbohydrates and stirred again.

 The alkaline alkali melt is introduced into the neutralized secondary mother liquor of pentraerythritol production based on sodium salt of formic acid and carbohydrates, and the resulting mixture is thoroughly mixed until the melt is completely dissolved and filtered, after which mixing water is added to the resulting solution.

 Then, Portland cement or slag Portland cement, sand, gravel are loaded into the concrete mixing plant in accordance with the recipe, and then mixing water with additives dissolved in it is poured. The resulting mixture is thoroughly mixed for 3-5 minutes.

Claims (1)

CONCRETE MIXTURE, including Portland cement or slag Portland cement, crushed stone, sand, a neutralized secondary mother liquor for the production of pentaerythritol based on sodium salt of formic acid and carbohydrates and water, characterized in that it additionally contains soda ash in the following ratio, wt.%:
Portland cement or slag Portland cement - 12.80 - 17.00
Crushed stone - 45.90 - 48.40
Sand - 28.80 - 31.40
Neutralized secondary mother liquor for the production of pentaerythritol based on sodium salt of formic acid and carbohydrates - 0.43 - 0.80
Alkaline alkaline melt - 0.06 - 0.34
Water - Else

Images