SK279377B6 - Product for making impervious barrier mass suspension - Google Patents

Abstract

A product for making an impervious barrier mass suspension, especially for the erection of slotted impervious barriers by the single-phase process, consists of a dry mixture. The dry mix is stable during storing thereof and is based on bentonite, ground blast-furnace slag and an activator for the blast-furnace slag in an amount and type necessary for a particular use, as a part of the whole package being kept separate from the dry mix.

Description

Technical field

The invention relates to a composition for the production of sealants in a single-phase manner, in particular for use in the sealed walls of excavations.

BACKGROUND OF THE INVENTION

When forming the sealing walls in the excavations built in the ground, the material from which the sealing walls are made is introduced into such excavations, these sealing walls, which are vertical elements, are intended to prevent the spreading of any soil contaminants by ground water or used in construction or for surface mining as a wall to prevent a large reduction in groundwater levels and to reduce the amount of groundwater drained. In experiments carried out by drilling techniques, such as drainage layers with additional horizontal sealing of deposits and old deposits, special requirements are placed on the properties of single-phase sealing wall materials, such as a small change in their theological properties, preferably as long as possible, high limits. creep, low sedimentation, slight loss of filtrate water and later solidification, which should start as soon as possible at a certain point in time, and in particular a low water permeability coefficient at low compressive strength.

While in the two-stage process, the ground trench works first with pure bentonite slurry as the carrier liquid, and only in the second step by contracting the self-sealing material, such as concrete or bentonite-containing concrete, in a contracting manner, the single-phase bentonite-cement slurry solving this problem in vertical sealing walls in a particularly economical manner, while ensuring that the bentonite and the blast furnace slag, which later forms the calcium silicate hydration phases, are optimally evenly distributed.

In horizontal sealing, the two-phase process cannot be used due to the problematic complete penetration of the bentonite carrier suspension by the later introduced sealing suspension. DE-PS 36 33 736 discloses pre-made dry mixtures based on relatively expensive cement-stable bentonites - ground blast furnace slag (HOS) - and a few Portland cement (or other hydroxyl-ion-exciter) - and optionally inert additives. to increase bulk density. These preformed dry mixtures, preferably containing Portland cement, CaO or Ca (OH) ₂ as the hydroxyl ion-forming exciter for the blast furnace slag, are prepared by vigorous stirring with a consumed amount of water and introduced into the excavation in a known manner.

It has also been found that, for example, when using Na-bentonites or cheaper activated Ca-bentonites, and also using relatively more expensive cement-stable Nabentonites and activated Ca-bentonites and cement excitation, suspension properties such as viscosity, loss of filtrate water, solidification , strength and water permeability from the time of production of the dry mixture to the start of consumption (slurry mixing with water) at the same level.

In addition, the development of hardened suspension properties, such as the rate of hardening of known suspensions, is difficult to adapt to the various requirements of the installation sites (temperature, processing time required).

SUMMARY OF THE INVENTION It is an object of the present invention to provide a composition for the production of a sealing wall composition, the desired properties of which remain unchanged indefinitely until its use, and which need not include cement stable Na-bentonite or activated Ca-bentonite. does not change the properties of the sealing wall in its hardened state.

SUMMARY OF THE INVENTION

This is accomplished by a sealant suspension composition, in particular in the sealing walls of excavations made by the single-phase process of the present invention, which consists in that the composition is a dry, storage-stable mixture consisting essentially of bentonite, ground blast furnace slag and blast furnace slag exciter. in an amount and a kind intended for a particular use, which is part of the whole package, separated from the blast furnace slag.

According to a preferred embodiment, the dry mixture comprises unactivated bentonite. However, the dry mixture may advantageously also contain activated Ca-bentonite.

La Ca-bentonite can be added already in the treatment of a chelating agent for the Ca2 ⁺ ions and optionally other polyvalent cations and / or the precipitating agent of ^Ca2 + ions in place of the excitation of known agents or additives thereto.

The dry mixture may contain additives known per se to improve processability. To increase the bulk density, the dry mixture may contain known inert additives.

It is further preferred that the exciter is in the form of a powder. The exciter may be cement, at least one alkaline earth metal hydroxide, which may have bivalent or polyvalent ions. The driver may preferably be Ca (OH) 2. Other preferred embodiments of the invention are described in the dependent claims.

Within the scope of the invention, it has been found that the preset properties of known preformed dry mixes deteriorate with increasing storage time and temperature, as well as the reaction ability of the blast furnace slag. An uncomplicated process has been found within the scope of the invention which, on the basis of the mixing ratios, guarantees unchanged, predetermined properties over time and thus prevents deterioration of properties (hereinafter referred to as "improper fit" or "improper storage"). According to the invention, this misalignment is counteracted by the fact that the dry mixtures are produced on a base

- bentonite,

- milled blast furnace slag,

- any additives for alteration of processability,

any inert ingredients to increase the bulk density without the exciter, wherein the exciter is added at the earliest when the suspension of the condensed substances is stirred or at any time after the suspension of said substances is stirred and the bentonite is swollen. The exciter is then preferably added in the form of an aqueous solution, for example in the form of an alkali metal hydroxide solution, in particular NaOH, and contains at least one further alkali compound, which may be in particular alkali metal sulfate, alkali metal chloride and / or alkali metal carbonate. . Therefore, according to a preferred embodiment, the solution has an exciter in liquid form. A particularly suitable solution comprises NaOH, Na 2 SO 4. The effect of this solution is relatively independent of temperature, i.e. it acts uncritically in the mass intended to form the sealing walls over a wider temperature range, for example from 10 to 30 ° C. The action of other solutions may be temperature dependent, for example depending on the ratio of mixing of NaOH with other alkaline compounds. The dependence can be empirically detected and adapted to the suspension temperatures in a simple manner.

In the case of the use of alkaline exciters, almost any type of bentonite can be used according to the invention.

The development of the strength properties of the sealing wall mass can be controlled in a simple manner by adding the exciter at a certain point in time and / or adjusting the amount of the exciter to the evolution of the strength properties of the sealing wall mass.

It is known to excite the blast furnace slag, inter alia, with a solution of NaOH, Na ₂ CO ₃ or water glass. It was not possible to recognize from the prior art and probably not even expect that the storage of the exciters selected according to the invention prior to their use separately from the other pre-mixed reactants, as well as the use of exciters mainly in the form of solutions and their preferred addition to the already mixed suspension consisting In addition, bentonite and blast furnace slag, or additives, provide particularly suitable sealant properties which, at the time of addition, depend not only on the reaction of the blast furnace slag exciter, but also on the physico-chemical properties of the premixed slurry.

At sludge temperatures up to 20 ° C, the addition of the exciter solution after a certain period of standstill until a well-miscible suspension with a high liquidity limit up to that time is achieved, results in the same solidification and hardening development achieved by adding the same solution immediately after sludge production. respectively. suspension. At temperatures of about 20 ° C, the hydraulics of a certain ground blast furnace slag can in itself give rise to an uncontrolled start of solidification even after a few days without chemical excitation. In order to prevent this, and to achieve the same properties as at temperatures below about 20 ° C, a particular embodiment of the invention uses bentonite to which a chelating agent or Ca ^{2 I} precipitant has been added directly during its manufacture or treatment. In this way, the start of solidification of the suspension can be postponed until the exciter is added.

It is known that the development of the properties of the sealing wall mass in its hardened state, in particular water permeability, is time-dependent. Surprisingly, this dependence is positively influenced by the process of the invention.

According to the invention, therefore, packaged or bulk (unpackaged) dry mixtures are produced, each consisting of a certain content of bentonite and blast furnace slag, composed according to the desired properties of the sealing wall mass, and possibly of known additives for improving workability and possibly of known inert additives. For example, reactive silicic acid according to, for example, DE-OS 38 00 776. These dry mixtures can be stored in a dry environment. indefinitely, without changing, respectively. without the mass produced therefrom having other than predetermined properties.

For the specified consumption, a slurry of dry blend and exciter is made when alkaline exciters are used. Preferably, a suspension is first prepared in a conventional manner by premixing the dry mixture by adding a given amount of water, for example by thorough mixing. An alkaline exciter in a given amount is then added to the suspension immediately after mixing or swelling of the bentonite, so that the excitation occurs immediately and after some time the desired properties of the sealing wall mass develop. The same amount of alkaline exciter can be added to the same suspension by admixing at any later time, whereby at the time of later addition the exciter action begins and the development of the desired mass properties takes place over a period of time from the time of addition.

Alkaline exciters are admixed at the time of use, for example in powder form, into a dry mixture, but admixture in slurry or rinsing water is preferred.

However, it is much more preferred to admix the slurry water or suspension in the form of an aqueous solution from at least one alkaline exciter, with NaOH solution being particularly preferred. Also suitable are solutions of alkali salts such as Na ₂ SO 4 and solutions of two or more alkali salts. With a solution of NaOH and a single alkali salt, especially Na ₂ SO 4, it can be particularly well controllable to set the start and the course of the alarm, and the development of the desired properties of the material of the sealing wall.

Within the scope of the invention, it is also possible to excite the blast furnace slag with cement clinker components, alkaline earth metal hydroxides, in particular Ca (OH) ₂ . It has been found that the use of cement-stable bentonites gradually increases the loss of filtrate water as the suspension is stirred until solidification begins. This is prevented according to the invention by first preparing a suspension without an exciter and adding the exciter only after the bentonite is swollen. Another possibility is the use of alkaline exciters according to the invention.

The amount of exciters to be added depends in particular on the type, fineness and quantity of the blast furnace slag and on the type and quantity of bentonite, and possibly also on the type and quantity of other substances to be added, and is determined essentially empirically.

The invention overcomes the above-mentioned disadvantages that the exciters can cause when present in a dry premix (incorrect placement). However, the invention can also be used if the components of the mixture are added to the mass of the sealing walls only at the construction site and where they are mixed with water to form a suspension. The use of alkaline exciters prevents higher losses of filtrate water and allows the use of almost all types of bentonites. When using alkaline earth metal ion exciters, a cement-stable bentonite or bentonite containing a chelating agent for Ca 2+ ions or a precipitating agent for Ca 2+ ions is preferably used. In this case, the exciter is added after the bentonite has been swollen.

In many cases, especially at normal residual moisture of activated bentonites, it is advantageous to achieve maximum swelling of the bentonite by chelating the bentonite with a chelating agent to retain the C < + > + ions and other polyvalent cations for

SK 279377 Β6

Ca ²⁺ ions and optionally for other polyvalent cations and / or a precipitant for Ca ²⁺ ions.

DETAILED DESCRIPTION OF THE INVENTION

The precipitation of Ca ² ions with alkali salts, whose anions form insoluble compounds with Ca, is known from the patent DR-PS 613 037.

The following Tables 1 and 2 show the results of the experiments which show that the addition of the exciter only after the suspension has been prepared from the other components of the sealing wall mass has the surprising effect of guaranteeing the desired properties of the sealing wall mass. Table values were determined as follows:

The slurry mixing procedure according to DIN 4127 (August 1986) - data in para. 6.1.1. Were used 2-liter mixer with turbomiešačkou revolutions of 3000 min ^- '. Reagent mixing time 10 minutes. The geometry of the mixer and container was DIN-compliant.

Marsh time = time of Marsh funnel discharge according to API RP 13 B (1982), para. 2.2 to 2.4. for discharge 1.00 dm ² .

Loss of filtrate water when tested on a filter press according to DIN 4127 (August 1986) sec. 4.6

Sedimentation in a 250 ml cylinder (as defined in API 10 (1990) 6.1.).

Beginning and end of "solidification" according to the patented method developed by the patent owner: penetration of a 9.7 g steel ball or wire penetration.

Compressive strengths = uniaxial compressive strength according to DIN 18130, determined on solids up to the test permanently stored in water and at a temperature corresponding to the required test temperature.

Water permeability coefficient according to DIN 18139 (November 1983) with modification according to Mesecka, described in the Mitteilungen des Instituts für Grundbau und Dodenmechanik TU-Braunschweig, journal issue 25 (1987), p. 109, determined after a three-day water race and subsequent water storage of test specimens.

If the main column 1.1 is compared in column 1 with column 1.02, the effect of pre-storage (incorrect placement) is as follows: row a2 immediately liquid: 31 instead of 38 s / 1 a3 increased loss of filtrate water: 67 instead of ml a4 increased tendency to sedimentation: 1, 4 instead

0.7%, reduced compressive strength after 7 days: 0.6 instead

0.7 N / mm ² after 28 days: 1.0 instead

1.1 N / mm ² , increased permeability coefficient k: about 5x10'10 instead of 6, respectively. 2x10'11

To simplify the writing of the powers of the transmittance coefficients k in the tables, the generally used method has been chosen: 5x10'10 = 5xE-10.

In Table 1, PZ 45F means Portland cement according to DIN 1164.

The comparison of rows a3 with b3 in columns 1.01 shows that the loss of filtrate water of conventional preformed dry wall sealings, even when properly set, starts to deteriorate until the start of solidification; 1.02 as well as 1.1.

It can be seen from Table 2 that the exciter can be added at any time over a relatively wide time span without changing the set desired properties. This avoids the hitherto difficult adaptation of the standard mixtures to the different conditions of the installation sites, since the exciters are pre-added to them (for example, the addition of retarders).

A reduced dependence of strength properties on temperature results from a comparison of values in columns 1.01. and 1.02 in rows d3 and d6 with the values in columns 3.01 and 3.02, respectively. in columns 2.01 and 2.02 in Table 1.

Table 1 Effect of • type of ulfsnla dry neel * blast furnace boilers and temperature of sludge sludge not owned by haets tasnlaoaj walls

Paeept Production of sludge ihoaä after production of dry Mesl (DHN) Sludge production after storage (incorrect storage) * storage of dry iMii 1 village at tspLcte 4 «» C 1.0 2.0 3.0 4.0 1.1 2.1 3.1 4.1 beutonít each with 5 kg of the same dose of M-bentonite to »08 1 * 115.7 193.7 191.4 192.0 l «.l ! ·>.? 111.4 1 »2.0 kff from 45F ».7 9.7 dissolved in ka VaOB kg Ha ^ SOj 1.3 2.6 3.3 2.6 1.0 3.0 1.0 3.0 always 913 kg of water 1.1 1.2 1.2 2.2 1.3 3.13 1.4 2.4 1.1 2.1 3.1 4.1 atlp- 'XI' 10 ^e C 20 »C ÍC'C 20®C LC »C 30 ^and C 10 'C 20 »C 20®C H2O «C 20 »C 20 ^and C the D- ter.lvf k.1 al time Dorote t> m 37 3 ' 42 47 37 37 34 31 45 36 36 • 2

^ílUrl - 45 40 21 20 24 21 3S S7 20 27 - Ο.Ί 0.7 0.3 0 0.2 0.2 ⁰ 1.4 0.1 0.2 0.1 - '. point.... --- -.- bl time according to Natote tf / 11 42 57 40 51 36 42 37 35 49 31 b2 a.l.a. 7 125 ²⁶ 27 ³² 34 210 ^{32 32} B3 bteteteb r ·.! 0.6 0.1 0.4 0 0.6 0.2 0.2 1.0 0 0.2 b. ulntlv Ibod.l 14th 50 12 · · 13 - dl 44 14 40th • WITH 9 ' 35 200 32 .0 36 c2 0 0.1 0.1 0.05 0.2 0.1 dl .alpha.s 1.0 0.9 ... 1.1 1.1 1.4 0.6 1.4 1.1 1.3 · " po <dteob 1.2 1.1 1.5 1.9 1.4 1.1 of emulsifiers 0.7 2.0 1.9 1.0 44 __ «> O> «. d. te. »· ¹ ! 1.1 * 9 - 1.Β- ΙΟ 5.Β- ΙΟ 45 í.B- 6.1- 1. Β- ΙΟ 1.Β- ΙΟ S.B- 11 l.B- d « 20 First 10 10 First _ 3.2- 9 2.1- 11 1.Β- ΙΟ 1.Β- ΙΟ 5.3- 11 1.Β- ΙΟ 47 10 10 11 10 10

• KOS 1

CaO · 41 · *

Slo ₂ > 17, á * * 1 ₂ O ₃ ».l *

400 and ² / kg

Table 3

Comparison of sewage sludge agility of the seal wall without exciter and the mass to which an alkaline exciter was added 5 days after the initial sludge spread

recipe Sludge production Immediately after the production of the mixture (DWM) bentonite always 55 kg of the same “dose of Ha-bentcnit” as in Table 1 Kg HOS 1 * kg PZ 45F (cement) dissolved in water kg NaOH kg NaaSOi water (kg) 900 1 5 + 6.7 + 3.0 + 13 Escape temperature 10'C 10 ° C

sludge after x days of rest: 5 minutes of time according to Narsha »/ l] loss of filtrate water 0,7 MPa / 7.5 '(mll 5 ca. * 70 30 4 days for 5 min. stirring was mixed into the unextruded sludge at inhomogeneity and time after uploads deposits (%) ca. 2.5 start of solidification ”(hours) ca. 280 (0} 15 end of solidification ”(hours) ca. 480 48 compressive strength 10x10 cm after 3 days [N / mm ² ] 0 after 7 days (N / tM ² ) 0 0.15 after 2Θ days (N / om *] 0.3 1.0 after 56 days (N / wa’i 1.1 1.3 water coefficient k at 20 ° C (i-30) after 3 days flow at 14 days (a.a ' ¹ ) at 20 days [not ~ l] at 56 days L.E.-9 L.E.-10 L.E.-10 L.E.-10

) See Table 1

Claims (22)

PATENT CLAIMS A composition for the production of sealant slurries, in particular for making sealing walls in trenches in a single-phase manner, characterized in that it consists of a storage-stable dry mixture consisting essentially of bentonite, ground blast furnace slag and a blast furnace slag activator in a quantity and type in advance for the respective use, which is part of the whole package, separated from the blast furnace slag. Composition according to claim 1, characterized in that the dry mixture comprises unactivated bentonite. A composition according to claim 1, wherein the dry mixture comprises activated Ca-bentonite. Composition according to claim 3, characterized in that the dry mixture contains activated Ca-bentonite, to which a chelating agent for Ca ²⁺ ions and optionally other polyvalent cations and / or a precipitator for Ca ² ions are already added during its treatment. ⁺ location or in addition to known activation means. Composition according to one or more of Claims 1 to 4, characterized in that the dry mixture contains additives for improving processability. Composition according to one or more of Claims 1 to 5, characterized in that the dry mixture contains additives of inert substances for increasing the bulk density. Composition according to one or more of Claims 1 to 6, characterized in that the dry mixture contains impermeability additives. Composition according to one or more of Claims 1 to 7, characterized in that the exciter is in the form of a powder. A composition according to claim 8, wherein the exciter is cement. 10. The composition of claim 8, wherein the exciter is at least one alkaline earth metal hydroxide. Composition according to claim 10, characterized in that the alkaline earth metal hydroxide contains divalent or polyvalent ions. The composition of claim 11, wherein the exciter is Ca (OH) 2 -. The composition of claim 8, wherein the exciter is an alkaline compound. 14. The composition of claim 13, wherein the alkaline compound is an alkaline salt. Composition according to one or more of Claims 8 to 14, characterized in that the exciter comprises at least two exciters. Composition according to one or more of Claims 1 to 6, characterized in that the exciter is an aqueous solution containing an alkali, preferably with a pH value greater than 11. The composition of claim 16, wherein the exciter is a solution containing an alkali hydroxide, preferably a NaOH solution. The composition of claim 16, wherein the solution is an alkali salt solution. The composition of claim 18, wherein the solution is a Na 2 SO 4 solution. The composition of claim 16, wherein the solution comprises two or more alkali salts. 21. The composition of claim 16, wherein the solution comprises NaOH and at least one alkaline salt. 22. The composition of claim 21, wherein the solution comprises NaOH and Na2SO4-.