RU2739979C1 - Dry mixture for preparation of composition for strengthening of soil mass by compensation injection method - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to reconstruct building structures, namely, to eliminate their common deformations. Dry mixture for preparation of composition for preliminary consolidation of soil mass by method of compensating injection contains, wt%: microcement 15-45, fluidized metakaolin 5-40, finely dispersed mineral filler from 15-X to 80-X, at least one target additive X, where X is from 0 to 5 wt%.

EFFECT: technical result consists in improvement of strength of soil mass, sedimentation stability, reliability of works on elimination of deformations of buildings and structures due to exclusion of cracking and hydraulic fractures of soil mass, reduction of viscosity.

10 cl, 2 tbl

Description

FIELD OF TECHNOLOGY

The invention relates to the field of reconstruction of building structures, namely the elimination of their general deformations.

LEVEL OF TECHNOLOGY

A known composition for an injection solution for fixing soils in the base of existing and newly constructed buildings and structures, containing a binder component of OTDV "Microdur" and a filler - carbonate rock with the following ratio of components, wt%: OTDV "Microdur" 20-59, carbonate rock 50 -80 (Injection consolidation of loess soils in Grozny with very finely dispersed substances such as "Microdur" / S.-A. Yu. Murtazaev [et al.] // Bulletin of DSTU. Technical sciences. - 2014. - No. 4 (35). - С . 114-120).

The disadvantage of this composition is its limited application mainly for loess soils.

A known solution for preliminary injection into the soils of bases when eliminating deformations of buildings and structures, containing a mixture of water and dry ingredients on a mineral basis, including cement additives, while the solution contains the following composition: bentonite powder 25%, Portland cement - 50%, fly ash - 23%, plasticizer 2% (M. R. Moseley, K. Kirsch, E. Falk. Soil fracturing // Ground Improvement (second Edition). 2004. Pp. 220-251).

The disadvantage of the composition of this solution is the instability of the results achieved when using it, as a result of which cracks of indefinite length and opening appear. These cracks require an increased consumption of the solution, they can remain partially unfilled with the solution, which in the future can lead to suffosion processes and reverse deformations of the structure.

The closest to the proposed solution is a solution for preliminary injection into the soils of bases when eliminating deformations of buildings and structures containing the following components, wt%:

microcement (type microdur) 20-50,

colloidal silica 5-15,

hydrated lime, for example, Ca (OH) ₂ 10-25,

finely dispersed mineral filler,

for example, carbonate flour 20-50,

suspension viscosity regulator, for example, superplasticizer C-3 to 2 by weight of the binder,

water-retaining additive, for example, methylcellulose up to 5% by weight of the binder (RF patent No. 2603786 C1).

The disadvantage of this solution is its low penetrating ability, which requires the use of high pressure when injected into the soil and can provoke hydraulic fracturing of the soil massif.

SUMMARY OF THE INVENTION

The objective of the present invention is to create a composition for preliminary strengthening of a soil mass by the method of compensation injection, which has a set of properties:

- high penetrating power for all types of soils,

- high sedimentation stability,

- high strength and deformation characteristics of the fortified soil massif.

The technical result is that the above problem was solved, while it was possible to improve the reliability of work to eliminate deformations of buildings and structures by eliminating cracking and hydraulic fracturing of the soil mass.

The above technical result was achieved due to the fact that the dry mixture for the preparation of a composition for preliminary strengthening of the soil mass by the method of compensation injection contains, wt%:

(a) microcement 15-45,

(b) fluidized metakaolin 5-40,

(c) finely dispersed mineral filler from 15-X to 80-X,

(d) at least one targeted additive X,

where X is from 0 to 5 wt%.

Microcements suitable for the purposes of the present invention are suitable microcements obtained by air separation of Portland cement with a normalized particle size distribution and a particle size of 5 to 15 μm, for example, microcements described in the monograph by A.I. Panchenko, I.Ya. Kharchenko, S. Alekseev. .IN. Microcements. Moscow: ASV Publishing House, 2014 .-- P. 4.

The microcement, in one preferred embodiment, can be a microcement of the Microbond MS brand.

Fluidized highly active metakaolin is a product of dehydroxylation of natural kaolin clay (natural hydroaluminosilicate) with a normalized particle size distribution and a particle size of less than 15 microns.

Dehydrated amorphous aluminosilicate is a highly active mineral additive capable of reacting with Ca (OH) ₂ hydroxide, which is a hydration product of Portland cement, to form low-basic calcium hydrosilicates.

Fluidized highly active metakaolin is obtained by treating the initial metakaolin with a polycarboxylate ether solution (Chemical and mineral additives / Edited by A.V. Usherov-Marshak. - Kharkov: Kolorit, 2005. - pp. 61-83).

Metakaolin, in one of the preferred forms of embodiment, can be a fluidized highly active metakaolin type FM-100 (see RF patent for invention No. 2690242).

Metakaolin, in one of the preferred forms of embodiment, may contain at least 95% of particles of a fraction less than 15 μm.

Metakaolin, in one of the preferred forms of embodiment, may contain at least 90% of the particles in the fraction less than 10 μm.

Metakaolin, in one of the preferred forms of embodiment, may contain at least 45% of particles of the fraction less than 5 μm.

The normalization of the granulometric composition of metakaolin makes it possible to increase the penetrating ability of the composition during the preliminary strengthening of the soil mass by the compensatory injection method by reducing the viscosity.

In particular, compositions with a particle size of at least 95% fr <15 microns, at least 90% fr <10 microns, and at least 45% fr <5 microns and with the presence of particles on the surface have a particularly high penetrating ability.

The surface of the metakaolin particles, in one preferred embodiment, can be activated with polycarboxylate ethers.

The presence of a grafted layer of polycarboxylate ether on the surface of metakaolin particles makes it possible to further increase the strength of the soil mass by reducing the water-solid ratio in the composition for preliminary strengthening of the soil mass by the compensatory injection method due to the water-reducing action of the polycarboxylate ether.

Mineral filler - in one of the preferred forms of embodiment - may represent calcite, preferably marble dust (Korneev V.I., Zozulya P.V. Dictionary "What is what" in dry building mixtures. - SPb .: NP "Union manufacturers of dry building mixtures. ”2005. - pp. 110, 148-149), or colloidal silica.

The size of at least 75% of the filler particles, in one preferred embodiment, can be less than 5 microns.

Due to the normalized particle size distribution and the predominant particle size of less than 5 microns (more than 75%), the finely dispersed mineral filler ensures the regulation of rheological properties.

The target additive, in one preferred embodiment, can be a thickener or plasticizer.

CARRYING OUT THE INVENTION

6 compositions of a dry mixture were tested for the preparation of a composition for strengthening the soil mass by the method of compensation injection:

compositions No. 1-3 with the claimed content of components;

composition No. 4 with a content of components outside the minimum declared limits;

composition No. 5 with a content of components outside the maximum declared limits;

composition No. 6 was prepared according to the prototype.

For the manufacture of compositions 1-6 used the following raw materials:

- microcement obtained by separation of commercial Portland cement CEM I class 42.5 with a predominant particle size of less than 15 microns;

- fluidized highly active metakaolin with a surface treated with polycarboxylate ether, with a granulometric composition: fr. <15 microns not less than 95%, fr. <10 microns not less than 90%, fr. <5 microns not less than 45%;

- finely dispersed mineral filler of normalized granulometric composition with a predominant particle size of less than 5 microns (more than 75%);

- colloidal silica;

- hydrated lime, for example Ca (OH) ₂ ;

- slurry viscosity regulator, for example, superplasticizer C-3;

- a water-retaining additive, for example methylcellulose.

Compositions of compositions for preliminary strengthening

the soil massif by the compensatory injection method are given in Table 1.

Compositions for preliminary strengthening of the soil mass by the method of compensatory injection were prepared as follows.

A dry mixture is introduced into the volume of water required for the preparation of a composition for preliminary strengthening of the soil mass by the method of compensation injection. The mixture is stirred for 5-10 minutes at a stirrer rotation speed of 2500-3000 rpm. The water-solid ratio to obtain a solution is taken equal to 4.

To determine the strength of the soil mass, unidirectional linear models were made according to GOST 12248-2010 “Soils. Methods for determining the characteristics of strength and deformability ", which were tested at the age of 7 and 28 days.

The results of testing compositions for preliminary strengthening of the soil mass by the method of compensatory injection and soil massifs are shown in Table 2.

As can be seen from tables 1 and 2, the use of compositions No. 1 and 5 is impractical, since the composition obtained from the composition No. 1 has a low index of penetrating ability, and the composition obtained from the composition No. 5 has a low indicator of sedimentation stability.

Analysis of the remaining results shows that the compositions according to the invention, in comparison with the prototype composition, allow:

- to increase the strength of the soil massif by 50-180%;

- reduce the viscosity by 18%;

- to increase sedimentation stability by 4%.

The use of the compositions according to the invention makes it possible to reduce labor and material costs, to increase the reliability of the pre-strengthened soil massif by increasing its strength and eliminating hydraulic fracturing.

Claims (15)

1. Dry mixture for the preparation of a composition for preliminary strengthening of the soil mass by the method of compensatory injection, containing, wt%: (a) microcement 15-45, (b) fluidized metakaolin 5-40, (c) finely dispersed mineral filler from 15-X to 80-X, (d) at least one target additive X, where X is from 0 to 5 wt%. 2. A mixture according to claim 1, wherein the microcement is microcement of the Microbond MS brand. 3. A mixture according to claim 1, wherein the metakaolin is a fluidized high activity metakaolin of the FM-100 type. 4. A mixture according to claim 1, wherein the metakaolin contains at least 95% of particles of a fraction less than 15 microns. 5. A mixture according to claim 1, wherein the metakaolin contains at least 90% of particles of a fraction less than 10 microns. 6. A mixture according to claim 1, wherein the metakaolin contains at least 45% of particles of a fraction less than 5 microns. 7. A mixture according to claim 1, wherein the surface of the metakaolin particles is activated with polycarboxylate ethers. 8. A mixture according to claim 1, wherein said filler is calcite, preferably marble dust or colloidal silica. 9. A mixture according to claim 1, wherein the size of at least 75% of said filler particles is less than 5 microns. 10. A mixture according to claim 1, characterized in that the target additive is a thickener or plasticizer.