RU2122986C1 - Method of preparing additive to concretes and solutions - Google Patents

Abstract

FIELD: construction, particularly, manufacture of concrete and reinforced concrete products. SUBSTANCE: method comprises sulfonating original aromatic hydrocarbon stock, condensing sulfonated stock with formaldehyde and neutralizing the resulting product. Said original stock includes stillage residue resulting from production of aromatic hydrocarbons and process of catalytic reforming of gasoline that evaporates at temperature higher than 210 C. The present invention makes it possible to improve properties of additive, increase strength and frost resistance of concrete. EFFECT: more efficient preparation method. 1 tbl

Description

 The invention relates to the production of additives for concrete and mortar mixtures used in construction, as well as in the manufacture of concrete and reinforced concrete products.

A known method of producing sodium salts, petroleum sulfonic acids as an additive in a concrete mixture, including sulfonation of a prepolymerized fraction of 200 - 400 ^o C products of catalytic cracking or pyrolysis of crude oil, condensation of sulfomass with formaldehyde, followed by neutralization of the resulting product. (A.S. USSR N 1071036, class C 07 C 139/06, 1984).

 However, to obtain a stable and high-quality additive, additional operations are required to isolate undesirable components: from catalytic cracking gas oil - saturated hydrocarbons, from pyrolysis resin - resins and asphaltenes.

 The closest in technical essence and the achieved result to the claimed object is a method for producing an additive - superplasticizer C-3, including sulfonation of naphthalene, condensation of the obtained naphthalene sulfonic acids with formaldehyde, followed by neutralization of the obtained product (Batrakov V.G. Modified concretes. M., Stroyizdat, 1990, p. 134 - 135).

However, to achieve the greatest plasticizing effect of this additive, as well as the maximum reduction in water demand when producing high-strength concrete with increased frost resistance and water resistance, its increased dosage (up to 1.5%) is required, which negatively affects the strength of concrete from concrete mixture in the early stages of hardening (1 , 3, 7 days), as well as after heat-moisture treatment, especially at a temperature of isothermal exposure above 80 ^o C.

 In addition, the increased dosage of C-3 additive requires an increase in the time of preliminary exposure of the concrete mixture to heat and moisture treatment.

 It should also be noted that to increase the frost resistance of concrete, C-3 additive should be used in combination with air-entraining additives.

 The invention is aimed at improving the properties of additives that increase the strength of concrete in the early stages of hardening and after heat and moisture treatment, as well as increase the frost resistance of concrete.

 This is achieved by the fact that in the method of producing an additive in concrete and mortar, including sulfonation of the aromatic hydrocarbon feedstock, condensation of the sulfonated feedstock with formaldehyde, followed by product neutralization, bottoms of aromatic hydrocarbon production are used as feedstock.

 When using additives obtained by the claimed method, in the process of preparing the concrete mixture, disaggregation of cement particle flocs occurs due to the adsorption of molecules on the surface of cement grains, which leads to an increase in the plasticizing effect. Due to its stereochemical structure, a monolayer of adsorbed molecules does not interfere with the hydration of the monomineral components of cement clinker, which leads to a slowdown in the setting of the cement paste and, as a result, the increase in strength in the early stages of hardening proceeds at the same rate as in cement without additives.

 The plasticizing properties of the polycondensation product (additives) are due to the presence of alkylbenzenes, methylnaphthalenes, methyl diphenyls, anthracenophenanthrene hydrocarbons in the bottom residue. In addition, the bottom residue contains hydrocarbons, which, after sulfonation, are able to create “mixing” bridges between the above hydrocarbons, and this helps to reduce the consumption of the condensing component - formaldehyde. Due to the fact that in the polymer chain methylnaphthalene molecules that create the greatest “screening” effect for cement hydration are interspersed with molecules that do not prevent water molecules from entering the cement hydration reaction, hardening is not slowed down. This will allow the supplement to be used in higher dosages. In addition, the inventive method will allow to obtain an additive that slightly reduces the surface tension at the water / air border, which will ensure the involvement of a certain amount of air in the concrete mixture. This will give the concrete mixture, in addition to the plasticizing effect, increased frost resistance.

 To assess the quality indicators of the additives obtained by the present method, a fine-grained concrete mixture was obtained as follows.

Components of the concrete mixture: quartz sand with a particle size modulus M _cr = 2.3, Portland cement ПЦ 400 of the Sterlitamak Production Association "Soda", tap water, additive.

To prepare the additive, we used the bottom residue of the production of aromatic hydrocarbons in the process of catalytic reforming of gasoline from the aromatic complex of Ufaneftekhim JSC, which has the following physicochemical properties:
Density at 20 ^o C, kg / m ³ - 976
Coking ability, wt.% - 0.4
Refractive index, η $\genfrac{}{}{0ex}{}{\text{20}}{\text{D}}$ - 1,5675
Sulfur content, wt.% - 0.05
Fractional composition:
the beginning of the boil, ^o C 210
boils, vol.% at temperature, ^o С
10 - 252
50 - 285
90 - 360
According to the results of chromatographic analysis, the bottom residue contains, wt.%:
Alkylbenzenes - 7.4
Methylnaphthalenes - 56.0
Methyldiphenyls - 25.0
Indenotetraline, anthracenophenanthrene, fluorene and acenaphthenic hydrocarbons - 11.6
The specified bottom residue was subjected to sulfonation by treatment with concentrated sulfuric acid (monohydrate content of 92 - 98%) at 85 ^o C for 4 hours. The sulfonation product was diluted with water and condensed with a 35% aqueous solution of formaldehyde at 80 ^° C. The ratio of the components per mole was as follows: VAT residue: sulfuric acid: formaldehyde - 1: 1.6: 0.25. The condensation product was neutralized with an aqueous alkali solution to pH 10.

 The resulting additive in the form of an aqueous solution in various dosages was introduced into a fine-grained concrete mixture in which the cement: sand ratio was 1: 3 by weight. The waterproof ratio is 0.45 (see examples 1 to 4). The content of the components of the concrete mixture and its quality indicators are summarized in the table.

For comparison, a control sample of concrete mixture (without additives) was obtained - example 5 and concrete mixture using additives according to the prototype: superplasticizer C-3 according to TU 6-14-625-80 of Pervouralsky Production Association “Khrompik” in the form of an aqueous solution of 32% concentration (examples 6 and 7). The ratio of the components of the concrete mixture is the same as in the previous examples 1 to 4. The content of the components and quality indicators of concrete mixtures according to examples 5 to 7 are also summarized in the table. The mobility of the obtained concrete mixtures was determined by the melt of the cone on the shaking table and by the draft of the cone according to GOST 10181-81. The frost resistance of concrete was determined by an accelerated method by alternately freezing at a temperature of -20 ^o C and thawing at +20 ^o C in a 5% aqueous solution of sodium chloride.

From the prepared mixtures, samples 10 × 10 × 10 cm in size were formed, some of which hardened under natural normal humidity conditions, and some were subjected to heat and humidity treatment according to the 3 + 3 + 8 + 4 mode at an isothermal holding temperature of 85 ^o C. The compressive strength was determined according to GOST 10180 -90.

 As can be seen from the test results (see table), the proposed additive in comparison with the prototype provides concrete with improved physical and mechanical properties: it will increase the strength of concrete in the early stages of natural hardening and after heat and moisture treatment, an increased dosage of the additive will not affect the quality of concrete. At increased dosages (1.0 - 1.8% by weight of cement - see examples 1-4), the strength of concrete in the early stages of natural hardening is 36 - 102% higher at 3 days old, and 19 - 73 at 7 days old % than the prototype.

 After heat and moisture treatment, the strength of concrete (after 4 hours) is 51–186% higher, and after 27 days of hardening it is 51–70% higher than that of the prototype. The frost resistance of concrete with the use of the proposed additives increased 2.7 - 5.3 times.

Claims (1)

A method of producing an additive in concrete and mortar, including sulfonation of an aromatic hydrocarbon feedstock, condensation of a sulfonated feedstock with formaldehyde, followed by neutralization of the resulting product, characterized in that the bottoms used are boiling above 210 ^° C from the production of aromatic hydrocarbons in the catalytic process gasoline reforming.

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