RU2535321C1 - Method of preparing construction mixture - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to preparation of construction mixtures, primarily fine-grained concrete mixtures and mortars which harden in natural conditions or under steam curing. Disclosed is a two-step method of preparing a construction mixture using mineral filler, a plasticising additive, sand and binder. The first step comprises mixing the binder - portland cement M500 D20, mineral filler - silicon carbonate gaize, 55-65% sand and 60-70% hardening water to obtain a homogeneous mixture, and the second step comprises adding to the obtained mixture the remaining sand, plasticising additive - superplasticiser SP-1 and the remaining water, and finally mixing to obtain a homogeneous mixture of given workability.

EFFECT: reducing consumption of expensive materials without reducing strength of the obtained material.

1 tbl

Description

The invention relates to a technology for the preparation of building mixtures, mainly fine-grained concrete mixtures and mortars, hardening in natural conditions or during heat and moisture treatment.

The main disadvantage of the traditional method of preparing fine-grained mixtures is the increased consumption of cement.

A widely known method of preparing fine-grained mixtures using mineral fillers, such as ash, limestone flour, ground sand, introduced into the mixture to save cement (Bazhenov Yu.M. Concrete technology. - M .: Higher school, 2003, p. 287).

The disadvantage of this method of preparing fine-grained mixtures is their increased water demand, associated with a high dispersion of mineral fillers and causing an increased consumption of cement.

To reduce the water demand of fine-grained mixtures with dispersed fillers, plasticizing additives are used.

A known method of preparing a concrete mixture (patent RU 1760981 A3, С04В 40/00, 09/07/1992, Bull. No. 33), according to which the process of preparing a concrete mixture involves mixing in a high-speed turbulent mixer of cement, filler, water and a complex chemical additive, containing MF-AR superplasticizer and sodium or calcium nitrate, mixing the resulting mixture with fractionated quartz sand in a low-speed mixer until smooth. First, part of the water with a filler — highly active silica fume with specific surface area (20–40) · 10 ³ cm ² / g — is mixed in a high-speed turbulent mixer, then three fractions of quartz sand with particle size 2.2–2.5 are introduced; 1.0-1.5 and 0.05-0.5 and mixed with water and a filler, after which a complex additive with an electrolyte is introduced into the resulting mixture and final mixing is carried out in a low-speed mixer.

The method provides high strength characteristics of fine-grained concrete, but is difficult to perform, which inhibits its widespread use.

Closest to the claimed technical essence is a method of preparing a mortar (see patent RU No. 2373171 C2, C04B 40/00, published November 20, 2009).

This method includes two stages of preparing a fine-grained mixture: in the first stage, a mixture is obtained consisting of a mineral filler, plasticizing agent, sand and water, and in the second stage, a binder is added to the resulting mixture and final mixing is carried out.

The disadvantage of this method is the increased consumption of cement and plasticizing additives.

The objective of the invention is to reduce the consumption of expensive materials.

The essence of the invention lies in the fact that in the method of preparing a building mixture, comprising two stages, using a mineral filler, plasticizing agent, sand and a binder, the binder is mixed in the first stage - Portland cement M500 D20, the mineral filler is carbonate-silica flask, 55-65 % of sand and 60-70% of mixing water until a homogeneous mixture is obtained, and in the second stage, the rest of the sand is added to the resulting mixture, the plasticizing additive - superplasticizer SP-1 and the rest of the water, and finally eshivayut them until a homogeneous mixture given workability.

As a mineral filler, crushed carbonate-siliceous flask is used.

As a plasticizing additive, the superplasticizer POLYPLAST SP-1 is used.

The technical result will be - a decrease of 15% in cement consumption and 25% plasticizing additives without reducing the strength of the material obtained.

The result is achieved in that in the method of preparing the building mixture, which includes two stages of mixing the components, the binder (Portland cement M500 D20 (GOST 10178-85 *) of the Circassian cement plant), mineral filler (carbonate-silica flask) are mixed in the first stage, 55-65 % of sand and 60-70% of mixing water, and in the second stage, the rest of the sand, the POLYPLAST SP-1 superplasticizer and the rest of the water are added to the resulting mixture, after which they are finally mixed until a homogeneous mixture of the desired workability is obtained .

The building mixture according to the invention is prepared as follows. In accordance with the recipe, dosed by weight and loaded into the mixer Portland cement, mineral filler (carbonate-siliceous flask), 55-65% of sand and 60-70% of mixing water. These components are mixed until a homogeneous mixture. In the second stage, the rest of the sand, superplasticizer and the rest of the water are dosed and added to the mixer, after which all components are finally mixed until a homogeneous mixture of the desired workability is obtained.

The introduction of the POLYPLAST SP-1 superplasticizer into the mixture with part of the mixing water in the second stage allows, without compromising the workability of the mixture, to reduce the consumption of the superplasticizing additive and to reduce the consumption of binder (Portland cement) without reducing the strength of the material obtained.

The invention is illustrated by the following example.

To implement the method using the following materials:

1. Portland cement M500 D20 (GOST 10178-85 *) of the Circassian cement plant.

2. River sand for construction work (GOST 8736-93) of the Liventsovskoye field with a particle size modulus of 1.32.

3. Superplasticizer - POLYPLAST SP-1 (TU 5870-005-58042865-2005).

4. Mineral filler - the carbonate-siliceous flask of the Maslovsky field, crushed to a full passage through a No. 008 sieve. The specified flask has a light yellow color. The breed is dense, with signs of stratification, microporous. With a slight impact, it collapses along the bedding planes. The average density of 1.35-1.55 g / cm ³ , the true 2.45-2.55 g / cm ³ . When wetted, the strength properties of the rock are greatly reduced. The fracture is semi-clumsy. Reacts with 10% hydrochloric acid. It does not soak in water. The bulk of the rock is composed of opals of colloidal micrograin structure. Terrigenous fine-medium-aleurite material is represented by grains of acute-angled and slightly rounded quartz with a size of 0.01-0.05 mm in an amount of about 10%. The carbonate component is represented mainly by organogenic and pelitomorphic calcite. Pyrite grains (0.04–0.07 mm) are present as a small impurity; scapiform aggregates and lamellar crystals with a pearly tint, similar to zeolite minerals, are also observed.

To prepare the building mixture by the proposed method, 55-65% of sand, Portland cement, the mineral filler — carbonate-siliceous flask and 60-70% of mixing water are dosed in the mixer according to the recipe and then mixed until a homogeneous mixture is obtained. The rest of the sand, the POLYPLAST SP-1 superplasticizer and the rest of the water are introduced into the mixture, and then the final mixing is carried out until a homogeneous mixture of the desired workability is obtained.

To obtain comparative data, a building mixture is also prepared according to the prototype method: in the first stage, a mixture of filler, plasticizing agent, sand and water is obtained, and in the second stage, cement is added to the resulting mixture and finally mixed.

From prepared equal-moving mixtures (with a cone spread on a standard shaking table of 110 mm), beam samples 40 × 40 × 160 mm in size are manufactured, hardening for 28 days under normal conditions and during heat and moisture treatment (TWT) after two hours preliminary exposure according to the 2 + 6 + mode 2 at an isothermal exposure temperature of 85 ° C. Hardened samples are subjected to strength tests by conventional methods.

The compositions of the mixtures prepared by the comparative methods, and the test results are shown in the table.

Analyzing the test results presented in the table, we can conclude that the boundary limits of sand consumption in the first stage of mixing the mixture are 55-65% of its total consumption in the mixture, and the limits of mixing water consumption in the first stage are within 60-70 % of its total consumption for the preparation of the mixture (compounds No. 3, 4, 5). Going beyond the specified limits both to the greater (composition No. 2) and to the smaller side (composition No. 5) reduces the strength characteristics of the material obtained.

The test results shown in the table indicate that the proposed method provides the possibility of reducing the consumption of Portland cement by 15% and the POLYPLAST SP-1 superplasticizer by 25% without reducing the strength compared to the known method.

Claims (1)

A method of preparing a building mixture, comprising two stages, using a mineral filler, plasticizing agent, sand and a binder, characterized in that at the first stage the binder is mixed - Portland cement M500 D20, the mineral filler is carbonate-silica flask, 55-65% sand and 60 -70% mixing water until a homogeneous mixture is obtained, and in the second stage, the rest of the sand is added to the resulting mixture, the plasticizing additive is the superplasticizer SP-1 and the rest of the water and they are finally mixed until dnorodnoy mixture given workability.