SU1761729A1 - Lightweight concrete mixture and method for preparation of same - Google Patents

Abstract

Use: production of light cement concrete for road and industrial civil engineering. SUMMARY OF THE INVENTION: Light concrete mix, comprising, in wt%: Portland cement 9.6- 17.0, bauxite slurry 25.0-30.0. inert aggregate and water, additionally contains fly ash 3.0-4.5, and as an inert aggregate, expanded clay 37.0-41.4 with a ratio of the water content of bauxite slurry and expanded clay within 4.0-40.0 and water content bauxite slime exceeding its hygroscopic moisture. When preparing the mixture, first mix the bauxite slurry with fly ash and 55-65% of the mixing water, then add the clay, re-mix, inject the cement and the remaining part of the water and finally mix. 2 sp.f-ly, 1 tab.

Description

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WITH

The invention relates to the production of lightweight cement concrete used as thermal insulation, structural and structural material for road and industrial civil engineering.

Light concrete mixtures are known, which include cement, ash and fuel slag as cement.

The closest in technical essence and the achieved result to the invention is a light-weight concrete mixture including expanded clay, cement, fly ash and water.

However, concrete obtained from a known mixture is characterized by low strength with a significant consumption of cement.

The purpose of the invention is to increase the strength and reduce the consumption of cement.

This is achieved by the fact that the lightweight concrete mixture, including cement, fly ash, expanded clay and water, additionally contains toxic sludge in the following ratio of components, wt.%:

Cement9.6-17.0

Expanded clay37,0-41,4

Bauxite slime25.0-30.0

Fly ash3.0-4.5

WaterEverything

wherein the ratio of the water content of bauxite sludge and expanded clay is 4.0-40.0.

The method of preparing light-mix, including mixing Portland cement, aggregates and water, consists in mixing bauxite sludge first with fly ash and 55-65% of the required mixing water, then keXI is added

ABOUT

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Ramzit and mix the resulting mixture, after which Portland cement and the rest of the water are introduced and stirring is continued until a homogeneous mixture is obtained. A positive effect is achieved as follows. When introduced into a known light-weight mixture of fly ash and expanded clay with a water content of 4–40 times less than the water content of bauxite sludge, which, in turn, exceeds its hygroscopic moisture content, which potential of moisture content of claydite exceeds the potential of moisture conductivity of bauxite sludge. As a result of this, migration of dissolved hydrate cementing neoplasms from bauxite sludge into the pores of expanded clay occurs, which activates it, increasing the strength of the grains and the strength of adhesion to the cement stone and, consequently, increases the strength and frost resistance of lightweight concrete.

The use of bauxite sludge with a water content exceeding the value of its hygroscopic moisture ensures the presence of free water in it with cement substances dissolved in it, capable of moving in claydite.

The introduction of fly ash into the mixture, due to calcium oxide in it, speeds up the process of dissolving the hydrated neoplasms of the sludge and saturating the pores of the expanded clay gravel, i.e. also helps to increase the strength and frost resistance of lightweight concrete. Reduced cement consumption and a decrease in the density of concrete are due to the replacement of inert sand with activated clay.

Achieving this goal is ensured by purposeful creation of the potential difference in moisture conductivity between expanded clay and bauxite slurry, which ensures the redistribution of cementitious neoplasms between active and inert aggregate and thereby, by increasing the uniformity of the concrete structure, increases its strength and frost resistance.

Introduction to the mixture of water in the amount of 55-65% due to the fact. what in this case provides such a water content in the pores of the bauxite sludge, which creates, firstly, the maximum concentration in the solution of cementitious substances, and, secondly, the ability of this solution to move into the pores of the expanded clay upon its subsequent introduction,

Examples of specific compositions of light concrete mix.

To test the compositions, mixtures were prepared that differ in the percentage of cement components, dump bauxite slurry, fly ash, expanded clay, and water within the specified limits. In addition, a prototype mixture and mixtures are prepared in parallel, including fly ash and cement in quantities outside the specified limits,

For the manufacture of mixtures used:

Portland cement 400 Starooskolsky plant; dump bauxite sludge from the Boksitogorsky alumina refinery with a maximum grain size of 10 mm and a content of 40–45% dicalcium silicate (belite); French clay gravel 5-10 mm; fly ash Baltic Baltic TPP.

Light concrete mixtures were prepared both by a known method (prototype), i.e., by mixing the components, first in a dry state, and then with mixing water, and by the proposed method as follows. First, bauxite sludge was mixed with fly ash and 55-65% of mixing water, then expanded clay was injected and the resulting mixture was stirred, then cement and the rest of the water were injected and mixed again until a homogeneous mixture was obtained. From the mixtures prepared in this way 10 cm by vibration (vibration frequency 50 Hz, amplitude 0.3-0.6 mm) for 60-80 with a surface loading of 25 g / cm2.

Heat and moisture treatment of the formed samples was carried out in a steam chamber according to the regime of 3-8 + 3 hours at an isothermal heating temperature of 30-85 ° C,

The test results are shown in the table.

Thus, as can be seen from the table, the strength of concrete in the whole range of the claimed composition of the mixture with a reduced consumption of cement exceeds the maximum strength of the mixture according to the prototype.

Claims (2)

1. Light concrete mix, including cement, fly ash, expanded clay and water, characterized in that, in order to increase strength and reduce cement consumption, it additionally contains bauxite slurry with respect to the content of bauxite slime and expanded clay, 4.0-40.0 , in the following ratio of mixture components, wt.%: Cement9.6-17.0; Expanded clay37.0-41.4; 25.0-30.0: 3.0-4.5; Rest. 2. A method for preparing light concrete mix, which includes mixing cement, ash, expanded clay, additives and water, differing in the fact that first mixed bauxite sludge with fly ash and 55-65% of mixing water, then expanded clay is added and re-mixed, after which the cement and the remainder of the mixing water are introduced and the mixture is finally stirred.