RU2439015C1 - Polyfunctional superplasticiser for concrete mixture and mortar - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to composition of a polyfunctional superplasticiser for concrete mixture and mortar. The polyfunctional superplasticiser for concrete mixture and mortar, containing a water-reducing organic component, a mixture of sodium thiosulphate and sodium thiocyanate and water, contains the water-reducing organic component in form of superplasticiser SUPRANAFT and an additional mixture of resorcin, pyrocatechol and hydroquinone in ratio of (0.3-0.5):(6.45-8.01):(0.04-0.07), with the following ratio of components of the superplasticiser in wt %: superplasticiser SUPRANAFT 45.5-70.0, mixture of sodium thiosulphate and thiocyanate 13.48-15.4, said mixture of resorcin, pyrocatechol and hydroquinone 6.79-8.67, water - the rest. The invention is developed in subclaims.

EFFECT: wider range for regulating plasticising and air-entraining action of the polyfunctional plasticiser, as well as high strength in the early stages of hardening at higher doses of said plasticiser, high frost resistance.

3 cl, 2 tbl

Description

The invention relates to the technology of additives used as modifiers of the properties of concrete and mortars, manufactured on binders based on Portland cement clinker.

Concrete in the near future remains one of the main building materials and its annual global production has already reached two billion cubic meters, while the share of production of precast and reinforced concrete, mainly produced using steaming technology, is constantly growing.

For concrete, the urgent problem remains to achieve high early strength with normal moisture curing on ordinary Portland cement. The introduction of pre-steamed precast technology is due to the emergence of effective superplasticizers, which allowed to significantly reduce the water-cement ratio and the capillary porosity of cement stone. An obstacle to the production of quick-hardening concrete is the blocking effect of superplasticizers at an early stage of hydration, the mechanism of which requires further study, and the manifestation of false setting of cement systems with plasticizing additives.

The use in construction of additives for regulating the properties of ready-mixed concrete and mortar mixtures, as well as additives that change the properties of concrete and mortars, is determined by the provisions of the Interstate Standard for Additives for Concrete and Mortar - GOST 24211-2003, and the range of recommended additives is presented in the Guide to the Use of Chemical Additives in concrete (M .: Stroyizdat, 1980).

Taking into account the real tasks of construction, the main choice was made in favor of surfactants with a superplasticizing and air-removing effect, among domestic ones of which the product based on the condensation of naphthalene sulfonic acid and formaldehyde, known as C-3 superplasticizer, was initially the most promising, taking into account technological factors and the application effect. Silina E.S. et al., Effect of the quality of S-3 superplasticizer on its effectiveness in concrete and mortar, M .: NIIZhB Gosstroy USSR, 1985, p. 84-92).

However, the practical use of the C-3 superplasticizer revealed its shortcomings, namely: the instability of the properties of the C-3 product obtained at various enterprises, the reason for which is the formation of oligomers of different molecular weights during the synthesis of the additive, which in concrete is expressed in inadequate final technological effects.

Repeated attempts have been made to create additives for concrete for various purposes on the basis of C-3 plasticizer by introducing target additives into the plasticizer, such as, for example, an alkaline component, hardening accelerator - sodium nitrite or sodium formate and a mixture of ballast salts of coke oven gas purification based on thiosulfate and thiocyanate sodium (RU 2270815, C1, 02.27.2006); finely dispersed filler - silt, hydrophobizing agent - soot and hardening accelerator - potash (RU 2273612, C2, 05.07.2004). However, the resulting plasticizers did not receive the necessary distribution, because they did not fully meet the requirements for hardening accelerators, and also did not have a sufficient raw material base.

By its technical nature and the achieved result, the closest analogue prototype to the invention is a complex additive in concrete mixes and mortars (RU 2228306, C1, 12/9/2002).

The specified additive contains a mixture of ballast salts, desulphurization of coke oven gas based on thiosulfate and sodium thiocyanate (thiocyanate) and an organic component C-3 superplasticizer, in the following ratio, wt.%: Mixture of ballast salts of desulphurization of coke oven gas based on thiosulfate and rhodanide (thiocyanate ) sodium - 61-95 and superplasticizer C-3 - the rest.

The disadvantage of this complex additive is that in the C-3 superplasticizer even when modified with thiosulfuric and thiocyanic acid salts, the blocking effect of the superplasticizer at the early stage of cement stone hardening is maintained, which is confirmed by the degree of hydration of the latter. This leads to the formation of a looser structure of crystalline hydrate intergrowth at the age of 12 hours, as a result of which the concrete strength in the early stages of hardening is lower than the calculated one, and when the S-3 superplasticizer is added to the additive, it is up to 5 wt. ) the plasticizing effect should be minimal, especially in concrete on slag Portland cement.

The objective of the invention is to develop the optimal composition of a multifunctional plasticizer with the possibility of expanding the range of regulation of plasticizing and air-entraining effects, as well as increasing strength in the early stages of hardening at higher dosages of complex plasticizer for concrete systems on cements of various types, increasing frost resistance and reducing corrosion of reinforcement in concrete.

This problem is solved in that a multifunctional superplasticizer for concrete mix and mortar, including a water-reducing organic component, a mixture of sodium thiosulfate and sodium thiocyanate and water, contains as a water-reducing organic component a superplasticizer SUPRANAFT and additionally a mixture of resorcinol, pyrocatechol and hydroquinone in the ratio 3-0.5) :( 6.45-8.01) :( 0.04-0.07) in the following ratio of superplasticizer components, wt.%:

Superplasticizer SUPRANAFT 45.5-70.0 A mixture of thiosulfate and sodium thiocyanate 13.48-15.4 The specified mixture of resorcinol, catechol and hydroquinone 6.79-8.67 Water rest

The superplasticizer may contain the specified mixture of resorcinol, pyrocatechol and hydroquinone in the form of tar resin waters of coke production.

The superplasticizer may contain the specified mixture of thiosulfate and sodium thiocyanate in the form of a solution of wet desulfurization of coke oven gas after separation of arsenic-antimony compounds, heavy metal salts and cadmium and zinc salts from it.

SUPRANAFT, being a high molecular weight surfactant actively involved in the regulation of hydration and structure formation of cement systems, can be modified by modification to enhance the already known and give additional properties that improve the physicomechanical characteristics of concrete and mortar.

Attempts to use isomers of diatomic phenol as plasticizing additives for concrete mixtures have already been known.

In the invention according to the author's certificate SU 309924, 03/02/1979 for the concrete mixture was proposed the addition of a high molecular weight compound in the form of monomers of resorcinol and formaldehyde in order to increase the water resistance of concrete. Also known is the technical solution according to the invention (SU 1689328, 01/30/1989), in the description of which is given a plasticizer for concrete and mortar, including an organic component represented by a mixture of alkylresorcinol and urotropine, and an additive based on diatomic phenol in the form of oxidized wastes from the production of resorcinol. These additives to concrete do not provide satisfactory performance on the ductility of concrete and compressive strength. It was also proposed to use resinous waste of indeterminate composition as a plasticizer and strength modifier for concrete, obtained by the joint production of catechol and hydroquinone by hydroxylation of phenol with an aqueous solution of hydrogen peroxide. This technology is described in the description of patent RU 2028288, 02/09/1995.

Known additives to concrete containing a single isomer of dihydric phenol (resorcinol) or a combination of isomers (catechol and hydroquinone) and used individually, did not receive practical use and were not included in the range of recommended additives for use in concrete, since their technological effects were reduced to the average the value of plasticizing ability (OK = 14-18 cm), a slight increase in the strength of concrete at 28 days of age (320-340 kg / cm ² ) and a moderate increase in water resistance of concrete. In addition to the lack of effectiveness as plasticizers, these additives are poorly compatible with slag Portland cement compared to non-additive Portland cement.

In the present invention, the oligomer chain of polymethylene naphthalenesulfonates was modified by the combined complex action of a mixture of sodium salts of thiosulfuric and thiocyanic acids and a mixture of the above isomers of diatomic phenol and the creation of a new generation concrete modifier on this basis.

Resorcinol, pyrocatechol and hydroquinone each have two hydroxyl groups in their molecules and their properties are associated with the presence in the structure of isomers of mobile hydrogen atoms in hydroxyl groups, which easily give off this hydrogen atom when interacting with free radicals and functional groups of oligomers, exhibiting antioxidant properties. In this case, diatomic phenols act as reducing agents, turning themselves into low-active phenoxyl radicals, while the mechanism of action of the mixture of isomers on the organic component of the complex plasticizer is different from the interaction of individual isomers of diatomic phenols. In the latter case, resorcinol is a reducing agent, but weaker than pyrocatechol and hydroquinone, and can act as a weak plasticizer and stabilizer of high molecular weight compounds. Hydroquinone from these isomers is the most active substance with a pronounced manifestation of a synergistic effect, which as a part of a mixture in a solution with resorcinol and pyrocatechol significantly enhances their individual properties, including the anticorrosive properties of resorcinol and pyrocatechol when protecting steel reinforcement in concrete, as well as the effect PNS and SAW on the formation of the spatial structure of cement stone. In addition, hydroquinone has very pronounced antiseptic and antioxidant properties, which, suppressing the development of the bacterial environment in the lignosulfonate component and the oxidative processes of the salts contained, especially thiosulfates, allows the product to be preserved for a long time.

The combined effect of the mixture of sodium thiosulfate and sodium thiocyanate and isomers of the diatomic phenol on the organic component of this complex plasticizer - a block copolymer - is an increase in the plasticizing ability and acceleration of concrete strength gain to calculated values - in comparison with each of its components, it is determined by the induction effect in the organic material matrix, causing an increased electron density on each functional group of a given complex as compared to each of its constituent components comrade individually, thereby affecting the features of the formation and AFm AFt phases during cement hydration and their stable equilibrium (Concrete admixtures. Reference Manual. Ed. V.Ramachandrana, M .: Stroyizdat 1988 s.382-434). This contributes to a competitive decrease in the adsorption of superplasticizer on hydrated cement and, as a result, an increase in the effectiveness of the multifunctional plasticizer. This can explain both the increased plasticizing ability of the latter and the ability to accelerate the set of strength and increase it in the early stages of hardening of cement systems, while the possibility of false setting in cement systems is practically eliminated especially if cements of unstable quality can be found in concrete and mortar technologies.

For the preparation of a multifunctional superplasticizer, the SUPRANAFT superplasticizer obtained according to TU 5745-333-05800142-2008 is used; technical resorcinol. Technical conditions Interstate standard GOST 9970-74; catechol (technical) TU 6-09-4025-75; hydroquinone GOST 9627-74; thiosulfate GOST 244-76; thiocyanate (thiocyanate) CAS - number 540-72-7.

Alternatively, the source of additional components in a multifunctional superplasticizer - isomers of diatomic phenol, thiosulfate and sodium thiocyanate can be man-made phenols of tar pitch water from coke production, as well as an spent solution of wet coke oven gas desulfurization, and this solution should be purified from arsenic-antimony compounds, since these compounds act as a catalyst for the oxidation of sodium thiosulfate by atmospheric oxygen with crystallization of sodium sulfate itself from aqueous solutions of a multifunctional plasticizer, and for reasons of environmental safety, and from salts of heavy metals, salts of cadmium and zinc. If necessary, tar water from coke production and the spent solution of wet desulfurization of coke oven gas or a mixture thereof can be adjusted for the mass content of both isomers of diatomic phenol and sodium thiosulfate and thiocyanate.

The mobility, stiffness and bulk density of the concrete mixture, strength and frost resistance of concrete were determined in accordance with the requirements of GOST 10181-81 “Concrete mixtures. Test methods ”, GOST R 53231-2008“ Concretes. Strength control rules ”, GOST 1860-76“ Concretes, Methods for determination of frost resistance ”.

For the preparation of concrete mixtures were taken: medium-aluminate cement grade M 500 with NG = 26.5%, quartz sand with a particle size modulus of 2.30 mm and granite crushed stone containing 40% grains of a fraction of 5-10 mm and 60% of grains of a fraction of 10- 20 mm. For the preparation of mortar used the same cement and sand. The composition of the concrete mixture is C: P: SC: B = 1: 2.34: 2.94: 1.94; the composition of the mortar is C: P = 1: 2, B / C = 0.45, Pc3 (8-12 cm).

The method of preparing the concrete mixture or mortar was as follows: cement and aggregates were loaded into a forced-action mixer followed by intensive mixing until a dry, homogeneous mixture was obtained, then water was fed into the mixture and a complex superplasticizer was introduced in amounts from 0.45 to 1.0 by weight cement and mixed until a homogeneous mass. Then, according to the standard method, samples were prepared for laboratory tests.

Tables 1 and 2 present test data that allow us to conclude that the technical result achieved using complex superplasticizer in concrete and mortar is to realize the objective of the invention - both increasing the ductility of the concrete mixture and strength in the early and late stages of hardening. The use of a multifunctional superplasticizer also provides the opportunity to work with concrete and mortar at low outside temperatures. At the same time, an increase in the protective properties of concrete to steel reinforcement was noted, no traces of corrosion were found on the latter.

Table 1 The composition of the multifunctional superplasticizer No. p / p Dosage of multifunctional superplasticizer, wt.% Organic component - SUPRANAFT * superplasticizer *, wt.% A mixture of sodium thiosulfate and sodium thiocyanate, wt.% A mixture of resorcinol, pyrocatechol and hydroquinone, wt.% Water, wt.% one 0.45 45.5 13.48 6.79 31.23 2 0.6 50,0 14.29 7.24 28.47 3 0.75 55.5 14.71 8.67 21.12 four 1,0 65.0 15.0 8.35 11.05 5 prototype 0.7 31,0 - - Note: 1. Examples No. 1-4 correspond to the invention. 2. In examples 1, 2, the ratio of thiosulfate and thiocyanate is 2: 1, in example 3 - 1: 1, in example 4 - 1: 4 3. In examples 1, 2, the ratio of resorcinol, pyrokakhetin and hydroquinone 0.3: 6.45: 0.04, in examples 3, 4, 0.5-8.01: 0.07 * Supranaft - a block copolymer of polymethyleneaphthalenesulfonates with fractionated lignosulfonates, contains an antifoam

table 2 The effectiveness of the multifunctional superplasticizer in concrete and mortar No. p / p Dosage of multifunctional superplasticizer,% by weight of cement The density of the concrete mixture, kg / m Cone draft, CM W / C Compressive strength, in MPa Frost resistance cycles Water
department, P _in ,% 3 days 28 days Concretes (composition of the multifunctional superplasticizer No. 3 from table 1) one 0.45 2380 16,0 0.45 30.1 59.0 370 0.37 2 0.60 2395 17.6 0.45 48.8 63.5 370 0.22 3 0.75 2395 18.0 0.45 45,2 62.3 380 0.23 four 1,0 2390 22.0 0.45 32.9 61.0 370 0.25 5 prototype 0.7 2360 16.5 0.45 29.0 39.5 350 0.70

Mortar Pk3 (8-12 cm) (composition of polyfunctional supeoplastificatoa No. 4 from table 1) one 0.45 2060 10 0.45 14.2 29.1 2 0.60 2120 eleven 0.45 17.3 32,0 3 0.75 2100 10 0.45 18.1 31.6 four 1,0 2080 eleven 0.45 16.3 28.3 5 prototype 0.7 2050 9 0.45 15.0 27,2

Claims (3)

1. A multifunctional superplasticizer for concrete and mortar, including a water-reducing organic component, a mixture of sodium thiosulfate and sodium thiocyanate and water, characterized in that it contains a superplasticizer SUPRANAFT and a mixture of resorcinol, pyrocatechol and hydroquinone in a ratio (0 in ratio) 3-0.5) :( 6.45-8.01) :( 0.04-0.07) in the following ratio of superplasticizer components, wt.%:
Superplasticizer SUPRANAFT 45.5-70.0 A mixture of thiosulfate and sodium thiocyanate 13.48-15.4 A mixture of resorcinol, catechol and hydroquinone 6.79-8.67 Water Rest 2. The multifunctional superplasticizer according to claim 1, characterized in that it contains the specified mixture of resorcinol, pyrocatechol and hydroquinone in the form of tar resin waters of coke production. 3. The multifunctional superplasticizer according to any one of claims 1 and 2, characterized in that it contains the indicated mixture of thiosulfate and sodium thiocyanate in the form of a solution of wet coke oven gas desulfurization after separation of arsenic-antimony compounds, heavy metal salts and cadmium and zinc salts from it.