RU1801960C - Method of light-concrete mixture making - Google Patents

Abstract

The invention relates to the building materials industry, to methods for producing concrete mixtures and can be used in monolithic construction. SUMMARY OF THE INVENTION: The fly ash of TPPs, fine aggregate, mixing water and an aqueous solution of a complex additive are mixed in an amount of 2.5. 10% by weight of ash of a concentration of 1.008 ... 1.015 g / 100 ml with a strain rate gradient of 600. ..700 for 1.5 ... 2 minutes, after which the remaining components are added and mixed for 2 ... 2.5 minutes. 4 tab.

Description

The invention relates to the building materials industry, to methods for producing concrete mixtures used in the manufacture of precast concrete products and the construction of monolithic structures.

The aim of the invention is to increase air entrainment, reduce stratification and the rate of loss of concrete mix of its initial mobility, as well as increase uniformity and decrease density while maintaining strength.

This goal is achieved by the fact that according to the proposed method for preparing lightweight concrete with a mixture by mixing the components, the fly ash of thermal power plants, fine filling, mixing water and an aqueous solution of a complex additive are mixed in an amount of 2.5 ... 10% by weight of ash concentration 1.008 ... 1.015 g / 100 mg with a strain rate gradient of 600 ... 700 for 1.5 ... 2 minutes, after which the remaining components are added and mixed for 2 ... 2.5 minutes.

The introduction of an aqueous solution of a complex chemical additive and ash while mixing the mixing water with a fine aggregate contributes to the creation of a layering homogeneous aqueous mixture of fine aggregate with continuous granulometry due to the interaction of the ash with the plasticizing component of the complex additive. This contributes to deflocculation, dispersion, increasing uniformity and improving the granulometry of ash. As a result, the immiscibility of the concrete mixture and the uniformity of the products increase. An increase in the mixing time of the components of the concrete mixture with the complex additive up to 3.5 ... 4.5 minutes helps to increase the air entrainment into the concrete mixture during mixing and uniformity. An increase in the effective specific surface area of ash particles due to interaction with the complex

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additive increases the role of ash as a filler with concrete, which leads to the creation of additional centers of crystallization and intensification of the reaction of ash with calcium hydroxide, an increase in the degree of hydration of cement, and thus contributes to the preservation of concrete strength, despite the increase in its degree of porosity. The introduction of cement at the final stage of mixing, as well as the presence of a surface-active plasticizer SDB in the complex additive, slows down the setting of the cement-ash test and reduces the rate of loss of the concrete mix of its initial workability.

In the experiments we used Portland cement grade 400, which meets the requirements of GOST 19178-85, expanded clay, gravel FR. 10 ... 20 mm with a bulk density of 605 kg / m3, meeting the requirements of GOST 98759-83, expanded clay sand fr. 0.1 ... 5 mm in the form of screening from expanded clay with a bulk density of 710 kg / m, meeting the requirements of GOST 9759-83, river sand with a modulus of particle size 1.4, meeting the requirements of GOST 8736-85, ash -unos of Ladyzhinsky state district power station with a specific surface of 300 m2 / kg, meeting the requirements of GOST 158-18-83 and a complex additive rosin soap VVD (TU 14-0281078-79-90, a.s. N 1135731) of the following composition, May. %: sulphate-yeast mash - 6, sodium hydroxide -3, saponification product of water-grout sludge of rosin-turpentine production - 82, sodium phosphate - 9.

The concrete mixture was prepared in the following ways:

I - First, ash, expanded clay sand, river sand and mixing water were mixed. Then cement, expanded clay gravel and an aqueous solution of a complex additive were added.

II - First, ash, expanded clay sand, river sand, aqueous solution, complex additive and mixing water were mixed. Cement and expanded clay gravel are then added.

III - Concrete mixture was prepared according to the prototype.

In addition, the content of the aqueous solution of the complex additive, its concentration, the mixing time of fine aggregates, ash, mixing water and the aqueous solution of the complex additive, the gradient of the strain rate and the mixing time of the concrete mixture were varied.

Concrete mixtures with mobility on draft of cone 6, .. 8 cm are received.

Samples were taken from the prepared concrete mixtures after they were unloaded from the laboratory concrete mixer and the workability was determined by

mobility by. cone settlement immediately after unloading and every 30 minutes for 2 hours according to GOST 10181.1-81, separation by solution separation according to GOST 10181.4-81, as well as experimental air extraction according to GOST 10181.3-81. Cube samples of 15 x 15 x 15 cm were made from the concrete mixture, which were used to determine the density, strength and uniformity of concrete, determined by uniformity in density and uniformity of concrete, determined by uniformity in density and uniformity in strength, which are characterized by in-series coefficients of variation in density and

0 concrete strength.

Samples were tested according to GOST 10180-78 and GOST 12730.1-78 after 28 days. Storage of samples in a chamber of normal hardening ...

5 Example. To prepare a light concrete mixture with a sediment mobility of 6 .., 8 cm cone, ash was first mixed in the amount of 16 kg of expanded clay sand, 5 kg of river sand, 10.5

0 kg of mixing and an aqueous solution of a complex additive of VVD 1.0 kg / 100 ml concentration in an amount of 7.5% by weight of ash for 1.75 min with a strain rate gradient. Then the resulting mixture was fed into

5 a concrete mixer at the same time as previously dosed materials: cement -11.25 kg and expanded clay gravel - 25.75 kg. After this, the concrete mixture was mixed for 2-, 25 minutes.

0 PRI me R 2. For the preparation of lightweight concrete mix with a sediment mobility of 6 ... 8 cm cone, ash was first mixed in an amount of 10 kg from 16 kg of perlite sand, 5 kg of river sand, 10.5

5 kg of mixing water and an aqueous solution of a complex additive of VVD 1.015 g / 100 ml concentration in an amount of 2.5% by weight of ash for 1.5 minutes with a strain rate gradient of 650. Then, the resulting mixture was fed into a concrete mixer simultaneously with preliminarily dosed materials: cement 11.25 kg and expanded clay gravel 25.75 kg. After this, the concrete was mixed.

5 mixtures for 2.25 minutes

Example 3, In order to prepare a light-concrete mixture with a sediment mobility of a cone of 6 ... 8 cm, the ash was first mixed in an amount of 10 kg with t6 kg of expanded clay sand, 5 kg of river sand,

10.5 kg of mixing water and an aqueous solution of the complex additive VVD 1.008 g / 100 ml concentration in the amount of 10% by weight of ash for 2 minutes with a strain rate gradient of 650. Then, the resulting mixture was fed into the concrete mixer simultaneously with previously dosed materials: cement 11.25 kg and expanded clay gravel 25.75 kg. Thereafter, the concrete was mixed for 2.25 ml.

Received concrete mixtures of the following composition, May. %: cement 12.36, ash 11, expanded clay gravel 28.3, expanded clay sand 17.58, river sand 5.49, rosin soap VVD 0.82, water 24.45.

Dependence of technological character. tristik of the concrete mix and physico-mechanical characteristics of concrete on the concentration of an aqueous solution of a complex additive VVD, its content on the mass of ash, grad. The rates of deformation rate and mixing time of ash, expanded clay sand, river sand, an aqueous solution of a complex additive and mixing water, as well as the mixing time of the concrete mixture are given in the tables.

In the table. 1 shows the performance of an aqueous solution of a complex additive VVD, air entrainment into the concrete mixture and uniformity of concrete when introducing a complex additive in an amount of 7.5% by weight of ash, the first stage of mixing for 1.75 minutes with a gradient of the strain rate of 650 and the second stage of mixing with the rest of the components for 2.25 minutes

. As follows from the table, the proposed parameters for the preparation of concrete mixture (concentration of an aqueous solution of a complex additive of VVD) are selected from the condition of obtaining concrete with high rates of air entrainment and uniformity.

In the table. 2, it is shown that a decrease in the declared parameters of the aqueous solution of a complex additive of VVD leads to a decrease in the homogeneity of concrete, a deterioration in workability and an increase in delamination of the concrete mixture, and an increase in deterioration in homogeneity, an increase in delamination and the absence of an additional effect in determining the workability. The experiments were carried out at a time of the first mixing step of 1.75 minutes with a strain rate gradient of 650 s and a time of the second mixing step with the remaining components for 2.25 minutes.

In the table. 3 shows the dependence of the mobility of the concrete mixture, the intensity

loss of the mixture of its initial mobility, density, strength and uniformity of concrete, as well as delamination and air entrainment of the concrete mixture from the method of preparing 5 concrete mixture (I, II, III), the strain rate gradient and the time of the first stage of mixing, the time of the second stage of mixing with other components , the content of an aqueous solution of complex

0 additives VVD and its concentration.

In the preparation of the concrete mixture according to method 1, the air entrainment is reduced, the stratification and the rate of loss of the concrete mixture of its initial mobility are increased, the density is increased and the uniformity of the concrete is deteriorated.

When preparing the concrete mixture according to method II:

Reducing the time of the first stage of mixing leads to a decrease in the volume of entrained air, an increase in the solution separation of the concrete mixture, an increase in the density and deterioration of the uniformity of the concrete, and there is no additional

5 effect in determining the intensity of loss of a mixture of its initial mobility. With increasing time of the first stage of mixing, an increase in the intensity of loss of concrete mix is observed

0 initial mobility, solution separation, there is no additional effect when determining the volume of air involved, the density and uniformity of concrete. A decrease in the velocity gradient of the first stage of mixing compared with the claimed leads to a decrease in air entrainment and an increase in the density of concrete, and there are no additional effects in determining the intensity

0 loss of concrete mixture of its original. mobility, density of concrete.

Exceeding the declared time of the second stage of mixing with the other components leads to an increase in the rate of loss of concrete mixture of its initial mobility, delamination, in addition, there are no additional effects in determining the air entrainment, uniformity and density of concrete. With a reduction in the declared time of the second stage of mixing with the remaining components, a decrease in the air entrainment and an increase in the solution separation are observed; concrete mixture, concrete density and its uniformity deterioration, and there is no additional effect in determining the intensity of loss of concrete mixture to its initial mobility.

When preparing a concrete mixture according to method III.

Air entrainment is reduced, and stratification is increased, the rate of loss of concrete mixture of its initial mobility is increased; uniformity deteriorates and concrete density increases.

In the table. Figure 4 shows comparative indicators of air entrainment into concrete mix, delamination (determined by solubility), workability (determined by mobility by cone draft) and change in the intensity of loss of concrete mix of its initial mobility, concrete homogeneity (determined by uniformity in strength and uniformity in density, which are characterized by an in-series coefficient of variation in strength and density of concrete, respectively), compressive strength and density of concrete.

As can be seen from the tables, the claimed method has mainly before the known part: increase in air entrainment, decrease in delamination and intensity of loss of concrete mix, its initial mobility, increase in uniformity and decrease in density while maintaining concrete strength.

In addition, the use of the claimed method improves the mobility and strength of lightweight concrete.

The technical solution is recommended to

Claims (1)

use on existing and planned concrete mixing units for the preparation of lightweight concrete mixtures for the manufacture of building envelopes. The claims A method of preparing a light-concrete mixture by mixing cement, fly ash of TPPs, coarse and fine porous aggregates, an aqueous solution of an air-entraining additive and water, which consists in that, in order to increase air entrainment, reduce delamination and the intensity of loss of initial mobility of the concrete mixture , reducing the density while maintaining strength and increasing uniformity, first mix the ashes. entrainment of thermal power plants, fine porous aggregate, mixing water and an aqueous solution of air-entraining additives in an amount of 2.5% by weight of ash, concentration of 1.008-1.015 g / 100 ml with a strain rate gradient of 600-700 s for 1.5-2 minutes, then the remaining components are introduced and finally mixed for 2-2.5 minutes. Table 1 table 2 Beyond Values - ..; - g. ; The prototype of a. with. IT I20626T with the introduction of water mixing cement and ash at 0.75%, a strain rate gradient of 550 s, stirring time of the suspension 45 minutes, mixing the dispersion 0.35 minutes and mixing the concrete mixture 0.45 minutes 0.43 .0.39 Indicators Relative indicator of air entrainment in concrete mix,% / air entrainment in concrete mix,% / Relative indicator of air entrainment in concrete mix,% / mobility of concrete mix, cm /, through 5 minutes. 30 minutes. 60 min 90 min 120 minutes Relative rate of solution separation of concrete mix,% / solution separation of concrete mix,% / Relative index of the intra-series coefficient of variation of concrete strength,% / int-series coefficient of variation of concrete strength,% / Relative indicator of the in-series coefficient of variation in the density of concrete,% / in-series coefficient of variation in the density of concrete,% / Relative indicator of concrete compressive strength,% / concrete compressive strength, MPa / Relative concrete density index% / density, kg / m3 / Table 4 Claimed Famous 138 .... 150 / 11-12 100/8 / 100/5/100/3 / LLP / 2/100/2/100/1 / 67 ... S6 /3,1...3,6/ 100 / 4,2 / 63 ... 67 / 2.9..D1 / 100 / 4.6 / 64 ... 70 /0.39...0.43/ 103 ... 111 /12.5...13.4/ 88 ... 89 / 1162...1186