KR930010927B1 - Process for producing a filling intended to be injected into porous or fissured materials - Google Patents

Abstract

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Description

Method for preparing filling for injection into porous or cracked material

The present invention relates to a process for preparing a liquid powder suspension having a specific purpose of injecting into porous or cracked material or fine or very fine soil to change their robustness.

It is well known from the prior art that there are several materials which inevitably involve treatment by injection of cement filling. Examples are porous reinforced concrete, reinforced concrete damaged by corrosive liquids or cracked concrete. In this case, the penetration of cement filling into this kind of object is limited by the particle size of the unit cement particles and at the same time by the coagulation of these same particles.

Likewise, alumina is generally known to be classified into two major forms, bold alumina.

Coarse alumina can be easily injected with cement filling or bentonite cement filling (the cement particles are present as a suspension in aqueous solution, with bentonite added to increase the stability of the suspension).

However, this kind of filling cannot be injected into the fine alumina because the soil pores therein are so small that they do not allow the penetration and circulation of conventional cement particles. For this reason it can be possible to inject into this kind of fine alumina only when using a solution containing silicate or silica which is solidified by reagents without suspended particles.

This latter method has the disadvantage of causing soil contamination, remarkably high pollution to groundwater, and short lifespan in view of the fact that the gel structure obtained by the silicate solution is not stable over time. This phenomenon, known as syneresis, has a very bad effect on the gel obtained by the silicate solution.

For this reason, cement filling using conventionally finely crushed cement, i.e. cement having a particle size of less than about 15 microns (typically cement particle size is 0 to 100 microns), is injected into porous or cracked material or fine alumina Attempts have been made.

However, finely ground cement is difficult to obtain and is very expensive, costing about 20 times that of conventional cement.

Attempts have also been made to obtain the required cement from aerodynamically conveyed conventional cements by using centrifugal effects to separate fine particles from fairly large particles.

However, this method is expensive in its application, and the products obtained by this method are also very irregular and unreliable for injection into this kind of filling-containing cement, which is not satisfactory.

The present invention relates to a process for the preparation of a filling consisting of a suspension in a liquid of particles such as sufficiently fine cement particles whose particle diameter is smaller than the particle space in the soil to be injected to the extent that it can be injected into fine alumina.

It is an object of the present invention to provide a method for preparing a filling which can be injected into a fine alumina or porous or cracked material, the characteristic of which is to separate the suspended particles from a liquid such as water and suspended particles. Mixing in the presence of a dispersant and leaving the suspension dispersed in this manner in a container for a time sufficient for partial precipitation thereof to occur, and then recovering the volume of the suspension above a predetermined level in this container.

According to the invention 0.5 to 5% by weight of dispersant is used relative to the weight of the particles in the suspension. Thus, by selecting not only the height of the vessel serving as the decantation tank, but also the decantation time and the level of recovery of the suspension, the maximum diameter of the particles contained in the recovery suspension, depending on the geometry of the cavity to be injected, is determined. Can be.

According to the invention, the suspension obtained by the above-mentioned method is used to prepare fillings which can be infused into fine alumina or cracks or porous material.

The bottom layer of the remaining suspension is used for other purposes or discarded.

In a preferred embodiment of the invention, the solid material in the form of particles is made of cement and the liquid which acts to form the suspension is water.

According to the invention, instead of cement, ashes of silica and pulverized calcium carbonate can be used, which are treated separately according to the process of the invention and then mixed or used immediately before injection. There is also a method of injecting each into the media so that they can contact each other in situ.

According to the invention, silicate solutions or silica solutions may be used as suspensions, or other liquids are possible so long as they can react with the solid product present in the form of particles after injection.

As the dispersant added to the suspension of the solid particles, for example, melamine resin, naphthalene sulfonate, sodium polyphosphate, sodium alkyl sulfonate or ammonium polyacrylate can be mentioned.

It is an object of the present invention to obtain a suspension of solid particles obtained by the above method.

Some applications have been described below as examples to better understand the present invention, which are intended to illustrate, but not to limit the invention.

Example 1

The following method was adopted to produce a peeling consisting of an aqueous solution of cement to be injected into fine sand with a particle diameter of 0 to 0.3 mm.

500 kg of CLK 45 cement are dispersed in 830 l of water in a high-turbulance cement-mixer. After mixing for about 3 minutes, 2.5 to 7.5 kg of melamine resin serving as a dispersant is added and stirring is continued for about 2 minutes.

The mixture thus prepared is allowed to settle for one hour in a tank having a cross-sectional area of 2 m ³ having a cocock attached below 25 cm from the liquid level.

The coke is opened and 500 l of peeling is recovered, which contains 30 to 35% of 500 kg of cement at initial use.

The size of the cement particles contained in this peel is 0-10 microns, whereas the initial size of the cement particles is 0-100 microns.

The filling thus obtained is placed in a tank with a stirrer. This peeling can be injected into soil consisting of sand having a particle diameter of 0 to 0.3 mm in the usual way.

As a variant, the precipitation time is limited to 30 minutes and the peeling of 500 L is recovered, which contains 50 to 55% of the initial weight of the cement having a particle diameter of 0 to 15 microns.

EXAMPLE 2

To prepare an aqueous silica suspension for injection into fine soils with a particle diameter of 0 to 0.3 mm, 300 kg of silica powder with a particle size of 0 to 50 microns are dispersed in 1 m ³ of water in a high-turbulence cement-mixer. The mixture is stirred for about 3 minutes and a dispersant such as 3 to 9 kg of naphthalene sulfonate is added.

This solution is placed in a tank with a surface area of 2 m ² provided with a cocock at a distance of 25 cm from the liquid level.

After 3 hours of precipitation, the suspension on the cock is recovered.

The density of the recovered suspension is 1.120-1.125, whereas the density of the initial suspension is 1.147. The suspension can be easily injected into the fine soil as in Example 1 and sealed.

In the control trial, the initial suspension was impossible to inject due to self filtration.

In contrast, the suspension obtained according to the invention can be injected very easily under low pressure, and the pores of the soil are filled by silica powder and sealed.

EXAMPLE 3

In order to inject a mixture of silica powder and calcium carbonate powder in the form of a suspension into the fine soil, the following operation was carried out.

에 현탁된 분쇄한 마블(CaCO₃) 300kg을 고-난류 시멘트-혼합기에 넣는다.A suspension of silica powder was first prepared as in Example 2, followed by 1000 water

300 kg of crushed marble (CaCO ₃ ) suspended in is placed in a high-turbulence cement-mixer.

6 kg of naphthalene, which acts as a dispersant, is added and the mixture is left to settle for about 45 minutes to 1 hour to settle and then a suspension of 25 cm or less of the initial liquid level is recovered.

The particle diameter of calcium carbonate initially used is 0 to 50 microns and the initial density of the suspension is 1.16 to 1.18.

In the suspension obtained according to the invention, the particle size of calcium carbonate is 0 to 20 microns and the density is about 1.14 to 1.16.

The two suspensions obtained as described above are mixed in equal volumes and the mixture is poured into soil consisting of fine sand with a particle diameter of 0 to 0.3 mm.

By such operation, a closed and stable sand is obtained. As a variant, two suspensions may be injected continuously into the soil.

EXAMPLE 4

The following operation was carried out to prepare a suspension of calcium carbonate powder in a solution of silica or sodium silicate that can be injected into the fine soil.

A suspension of calcium carbonate was first prepared as described in Example 3, and then the suspension was prepared from sodium silicate solution containing 10 to 25% by weight of silica SiO _{2 in a} ratio of 1 volume of calcium carbonate suspension to silica or 0.5 to 1.5 volumes of silica liquid. Or mixed with silica liquid.

Injecting the mixture thus obtained into a soil consisting of 0 to 0.3 mm particles yields a closed and stable soil.

It will be apparent that the above-described embodiments of the present invention are not limited, and any changes may be made without departing from the scope of the present invention.

Claims (9)

In the preparation method of injectable filling which can be injected into porous or cracked material or fine alumina, etc., a mixed dispersion suspension obtained by mixing a material material in the form of particles with a liquid such as water in the presence of a dispersant is contained in a container. A method of producing an injecting filling, characterized in that for recovering a supernatant suspension above a predetermined level in a vessel after leaving for a predetermined time to cause partial precipitation. The method of claim 1, wherein the particle material is in the form of cement, silica powder or calcium carbonate powder. The method of claim 1 or 2, wherein the liquid is water, a silica solution or a sodium silicate solution. The method of claim 1, wherein the dispersant is melamine resin, naphthalene sodium sulfonate, sodium polyphosphate, allylnaphthalene sodium sulfonate, sodium alkyl sulfonate or ammonium polyacrylate. 5. The method of claim 4, wherein the dispersant is used in a proportion of 0.5 to 5% by weight based on the particle material. The method of claim 1, wherein the length of time for the partial precipitation and the depth of the recovered suspension are determined so that the desired particle size is less than 15 microns. 2. The injection method according to claim 1, wherein two different suspensions, such as the suspension of silica powder or the suspension of calcium carbonate powder, are prepared separately, and then mixed with each other immediately before injection into the process layer. Method of manufacturing peeling. The method of claim 1, wherein after preparing two different suspensions, such as a suspension of silica powder or a suspension of calcium carbonate, these suspensions are combustively injected into the layer to be treated. Manufacturing method. A suspension for injection into a fine soil or a porous or cracked material and the like, wherein the suspension is prepared by the method of claim 1.