NO323108B1 - Process for preparing a dry mixture for preparing a cement suspension - Google Patents

Abstract

A dry mix, for producing a cement suspension for filling and/or injecting pore spaces and cavities in loose rock or cavities and/or cracks in rock or in concrete components, is in the form of a ready mix containing (a) sulphate additive-free finely ground clinker and/or smelter sand powder; (b) additives; and (c) an ettringite-forming swelling component which produces swelling during strength development of the fine cement-binder mixture while the matrix is still soft after the filling and/or injection operation. The entire homogeneous dry mix has a continuous graduated particle distribution with sieve pass values of d95 = ≤ 24 (preferably ≤ 16) microns and d50 = ≤ 7 (preferably ≤ 5) microns, the d50/d95 ratio preferably being 0.33 plus or minus 0.04. Preferably, the mix contains a naphthalene sulphonate-formaldehyde condensate as plasticiser. Also claimed are: (a) preparation of the above dry mix, in which all the components have the above defined fineness and particle distribution and are stored separately in storage silos, certain components being dosed from the corresponding silos for delivery to a mixer and the components being homogenised and mixed in the mixer to form the ready mix; and (b) apparatus for carrying out the above process, in which a storage silo (7-12) is provided for each component and is combined with a dosing device, the silos being followed by a mixer (14).

Description

The invention relates to a method for the production of a dry mixture for the production of a cement suspension for filling and/or pressing into, for example, pore spaces and cavities in loose stones or cracks and cavities in rocks or in concrete structures. The dry mixture contains so-called fine cements.

Fine cements are very fine-grained hydraulic binders with constant and narrowly graded grain distributions and with a limitation for the largest grains. The properties and use of fine cements are regulated, for example in a preliminary notice for injection work with fine binders in loose stones (Bautechnik 70, [1993], booklet 9, Ernst & Sohn, Pages 550 to 560, and ZTV-RISS 93, Verkehrsblatt-Dokument B 5237 , Verkehrsblatt-Verlag).

The terminology in the two aforementioned regulations is not uniform. In the report, the term "fine binder" is used, and in ZTV-RISS the term "fine cement". The American literature speaks of microfine portland cements (US-PS 5,106,423). Below, mainly the term "fine cement" is used, which is also used in relevant professional reports (Beton 1/94, pages 12 to 16, Fels-bau 11 [1993], number 6, special edition, Bauingenieur 67,

[1992], pages 499 to 504).

According to the regulations in the regulations, the fine cement for the production of cement suspensions must have a sieve pass of > 95% at a mesh size of 16 nm (0.016 mm) and be produced with suitable additives and additives. The terms and the content of the terms additive and additive are defined in cement notice no. B 3, BBD/KA 1.93/20.

A cement suspension is used as filler for filling and/or pressing in (injection), which is in principle produced on the construction site. It is composed of at least two mixture components, namely of one containing fine cement and additive, and the other containing additive (Gyorgy Ivånyi, Walter Rosa: "Fli lien von Riss en und Hohlråumen im Konstruktionsbau mit Zementsuspensionen"/Filling of cracks and cavities in structural buildings with cement suspensions. Beton- und Stahlbetonbau 87 [1992], booklet 9, pages 224 to 229? Helmut Sager and Holger Graeve: "Ein-satzmoglichkeiten zementgebundener Injektionssyster-rne" / Application possibilities for injection systems related to cement. Beton 1 /94, pages 12 to 16).

Whether an injection with the filler will be successful depends on, for example, the rheological properties of the cement suspension and the mechanical-technological properties of the hydrated material in voids or cracks. It is necessary to effectively dissolve the fine cement through intensive mixing and with the correct mixing of the necessary additives in the order and in the working method prescribed by the manufacturer of the fine cement. The solid and liquid mixture components for the production of the filling mass are supplied by the manufacturer as individual components and must be stored in mixtures on the construction site in accordance with the regulations, whereby great accuracy must be shown at considerable cost regarding the storage conditions and compliance with the mixing conditions and the mixing order for the Professional completion of the cement suspension.

In DE 40 13 871 Al, according to claim 1, the mixing sequence for the production of the cement suspension of fine cement and additive, such as plasticizer, expansion agent, hardening retarder and water-repellent agent, is precisely prescribed, and according to claim 2 it is required that it be used demineralized water. Aluminates and bentonites must be included as expansion agents.

According to US-PS 5,106,423, a specific mixing order is also prescribed (column 2, lines 37 to 56). According to this printed document, mixtures of separately ground fine slag and separately ground fine cement can also be put together if the fineness of the substances is to be varied for special requirements (column 7, lines 8 to 26). It is also conceivable to use slow additives of the same grain size (column 7, lines 38 to 46).

US 5026215 relates to pressing in a cement mixture which, among other things, comprises slag particles with a relatively large size (over 7.8 micrometres) and has completely different properties than the suspension which is provided by means of the dry mixture which is provided by means of the method according to the present invention .

EF Al 0455940 shows the production of a cement suspension for pressing into cracks in a water-absorbing material, the cement suspension consisting of fine cement mixtures with additives. However, EP Al 0455940 does not provide any guidance on a dry mixture exhibiting constant and graded grain distribution with sieve pass values as in the present invention.

Delivery and storage of mixture components as well as the removal of mixtures are measures that significantly increase the cost of filler production. Moreover, the prescribed handling and mixing of the mixture components on the construction site cannot be ensured in many cases, and requires very expensive and strict monitoring conditions. In addition, it can be determined that even when the known methods for dissolving the fine cement are followed, the quality of the cement suspension and in particular of the hydrated material resulting from the cement suspension, can fluctuate significantly from mixture to mixture. The reasons for this have so far been unknown.

The task of the invention is to provide a method for the production of a finished factory dry mixture which will simplify the production of filler on the construction site and thereby ensure the prescribed properties of the filler and the hydrated material without special additional costs.

The task is solved by the method in claim 1. Advantageous further developments of the invention are characterized in the subclaims.

The fine cement-binder mixture produced from the factory dry mixture produced using the method according to the present invention consists of a mixture adapted to the particular use, which exhibits all the necessary additives and additives for the particular use in each case, preferably with equal or greater paint fineness as well such as balanced grain distribution, good dispersibility in water and high reactivity. The dry mixture must only be mixed with water in the prescribed amount on the construction site. The invention thus relates to a method for producing an industrial dry mixture which can be easily mixed under construction site conditions. The risk of possible mixing errors due to gravimetric and/or volumetric matching of mix components on the construction site is ruled out. In addition, compliance with the hitherto required order in the mixing of the mixture components, which, when it has not been followed, has hitherto led to significant quality changes, no longer applies. A production method according to the invention, coordinated according to the formulation of the industrial dry mixture with predetermined paint fineness and grain distribution, enables the precise dosing of all components such as clinker fine flour and/or slag fine flour as well as the dry additives such as additive and additive. The industrial dry mixture according to the invention does not require demineralized water. It can also be mixed with residual water with a chloride content according to table 1 in the "Restwasser-RichtlinieVRestvans guidelines from DAfStb (Deutscher Ausschup f tir Stahl beton/German Committee for Steel Concrete, "Richtlinie fiir Herstellung von Beton unter Verwendung von Restwasser, Restbeton und RestmSrtel"/ Guidelines for the production of concrete using residual water, residual concrete and residual mortar [September number 1991]).According to the agreed recipe, the processing technical properties of the suspensions as well as the mechanical-technological properties of the hydrated material are largely independent of the water quality.

The elimination of processing technical errors during the mixing of the suspensions according to the present invention is of decisive importance, for example, to the implementation and success of injection measures with fine binders, as a repetition of injection measures as a replacement for previously injected, incorrectly mixed fillers with insufficient properties usually does not is possible with economically justifiable costs. In addition, the use of industrial dry mixtures according to the invention provides economic advantages during bottling, storage and transport as well as when removing any transport containers.

The fine cement binder mixture contains the fine flour/ . the fine flours, the dry additive(s) and possibly the dry additive(s). The fine flour consists of a Portland cement clinker fine flour {this is simply finely ground Portland cement clinker) or of a mixture of a Portland cement clinker fine flour and a slag fine flour (this is a straight fine ground slag) or only of a fine slag flour plus activator. Bentonite is preferably used as an additive. Additives are essentially plasticizers or dispersants, solidification retarders, water repellants, solidification accelerators and expansion components.

The amounts added to the clinker fine flour or to the mixture of clinker fine flour and slag fine flour or to the slag fine flour are very precisely and reproducibly matched to each other, whereby preferably all essential components exhibit a grain distribution d95 £ 24 pm, preferably d95 £ 16 Jim, and d50 < 7 um, preferably d50 £ 5 pm and preferably a ratio d50 to d95 = 0.33 ± 0.04 (d95 = grain diameter for 95% by weight of the filtrate; d50 = grain diameter for 50% by weight of the filtrate). Especially when these conditions are met, it is possible to optimize the impact of an additive. For example, shown in fig. 2 below, the effect of the amount of addition, for example of a plasticizer, on the processing technical properties of a cement suspension consisting of a fine cement-binder mixture with a water-binder ratio of 0.7. The course of the curves makes it clear without further ado that even small deviations in the proportion of plasticizer from a predetermined mixing ratio affect the suspension's rheological properties, which are of decisive importance for the success of the injection. Thereby, by increasing the proportion of plasticizer from 2 to 4% by weight, the initial viscosity of the suspension, in fig. 2 indicated by the flow-through time in the marshcone at time t = 0, comparatively little affected; nevertheless, the subsequent viscosity development during the processing time of the fresh mixture is subject to a marked dependence on the dosage of the plasticizing agent. A professional application of the cement suspension can therefore only be expected if both the initial viscosity and the viscosity after the end of the processing time are optimized through the selection of a suitable plasticizing agent with coordinated weighing.

When optimizing the dosage of additive, account must also be taken of the additive's impact on the firmness of the hydrated suspensions, so that the material requirements included in statically effective restoration measures can be met. The results of compressive strength tests on prismatic specimens compiled in table 1 below show that even an overdose of plasticizer of 5% by weight leads to a loss of early strength. At a proportion of plasticizer of 6% by weight, no compressive strengths can be measured in the completely insufficiently fixed suspensions.

It has surprisingly been shown that quality assurance and processing technical problems when using a multi-component system on the construction site can be eliminated by simultaneously meeting high requirements for the filling mass if a prefabricated dry mix with a specific paint fineness and grain distribution of fine flour, additive is used in the production of a cement suspension and additive. This is achieved by the fact that the base materials for the production of the fine cement-binder mixture according to the invention, depending on the use case, are mixed with the necessary additives and additives already at the factory after the separate grinding of a clinker or a slag, so that this dry mixture for processing on the construction site only water must be added according to the pre-given water-binder value for preparation of the ready-to-work cement suspension. This is possible through the use of additive and additive in powder form with a grinding fineness and grain distribution that corresponds, for example, to fine flour, whereby these additive and additive acquire a very good dispersibility and reactivity when the dry mixture is mixed with water. The coordinated dispersibility and water solubility and reactivity of these redispersible dry components ensure immediate effectiveness in the contained substances after mixing with the mixing water. It is therefore surprising that not only different amounts of addition, but especially different paint fineness and grain distributions, especially within the framework of the specified d95 and d50 limits and ratios respectively, produce correspondingly different effects, which had been attempted previously through the preparation of separate mixing components and prescribed mixing sequence as well as the use of demineralized water. The additives react unexpectedly sensitively in the specified fineness range, so that the paint fineness and grain distribution can be used as parameters for predefined properties.

For the formulation of the dry mixing according to the invention, a grinding, sifting, dosing and mixing plant is required which enables the accurate production of a fine cement-binder mixture of uniform quality. The method according to the invention includes the individual components being processed completely separately to a predetermined paint fineness and grain distribution. Using precisely controllable dosing and mixing systems, the dry mixture is then produced in accordance with the predetermined chemical-mineralogical composition through homogenization.

The prefabricated dry mixes (industrial dry mixes) which are produced by means of the method according to the invention are distinguished by the fact that, through mixing with water, they produce mixing-stable low- to medium-viscous cement suspensions which, due to the dry mix's chemical-mineralogical and physical specification and the consistency after mixture with water, as well as due to low reactivity during the processing period, are characterized by particularly good workability, so that they are suitable as mineral systems for impregnations and injections of all kinds. Furthermore, due to the composition of the dry mixture, after the processing period has elapsed, comparatively high early strengths can be achieved in the hydrated mixture, so that such cement suspensions are also suitable for statically active (properly dimensioned) measures, and that regardless of the state of moisture in the elements in which the injection

must be carried out.

Due to fine cement's relatively large water requirements, a pronounced loss occurs during the hardening process, which has so far only been able to be partially and uncontrollably compensated by the use of additives known in this context (bentonite) or additives (expansion components). In the case of the above-described industrial dry mixtures according to the invention, the shrinkage is indeed controllable, as the fine cement binder contains the additives and the additives are controllable in their effect, but the disadvantages of the shrinkage, namely in particular loss in adhesion strength, cannot be compensated. With the known mixtures according to the state of the art, it has been shown that in particular the degree of shrinkage also fluctuates, and - as a result of this

- no uniform quality of the hardened filler compound's mechanical-technological properties can be ensured. Through a special additional measure, with the fine cement binder mixtures according to the invention, it is possible to produce a predetermined expansion with respect to shrinkage or shrinkage, and to adjust a specific degree of expansion according to the particular use. Through the expansion effect, respectively the increase in volume, adhesion becomes phase the ts losses in a compound system consisting of

stone (e.g. rock) or concrete and injected filling mass controllable or predefinable avoided. At the same time, the complete filling of a cavity or a crack, due to the expansion, improves the tightness of the compound system.

There are known numerous so-called expansion cements based exclusively on cements of ordinary composition and paint fineness as well as ordinary expansion component. The many years of practical experience with these expansion cements have shown that a certain guarantee can be achieved for the properties of expansion cements with ettringite-forming expansion components, whereby the known expansion cements consist of mixtures of ordinary portland cements with an aluminate sulfate-containing component. The properties of these known expansion cements depend on the chemical-mineralogical composition and the quantity ratio of the components as well as on technological factors such as consistency and storage conditions or the like. Despite extensive experience from the practical use of these known expansion cements, there are significant problems with accurate control during the hardening of the structure formation process which is decisive for the properties of the solid material. With the known expansion cements, the weight ratio between the portland cement proportion and the expansion components as well as the chemical activity of the expansion components mainly serve as controllable influencing factors.

Within the framework of the invention, it was found that with the industrial dry mixes that are produced using the method according to the invention, the expansion can be purposefully controlled not only through different amounts of addition, but also with a specific reactive ettringite-forming expansion component, as the reactivity of the expansion component is changed at a predetermined mixing ratio or at a predetermined amount of addition on the basis of different grain distribution and fineness. Thereby, the fixing rate of the binder mixture matrix and the ettringite formation rate of the expansion components are matched to each other. For example, an expansion component on an aluminate-sulphate basis is used, in particular consisting of calcium aluminate and calcium sulphate, whose grain distribution and fineness of paint are within the scope of the above-mentioned grain distribution and fineness of paint of the fine cement-binder mixture. With the parameters of paint fineness and grain distribution, the expansion can be controlled reproducibly, so that the fine cement-binder mixture can meet the applicable technical material requirements.

It is surprising that an ettringite-forming expansion component causes a synergistic effect, as the deposit stability of the cement suspension is increased.

The expansion control according to the invention is particularly effective when using calcium aluminate- and calcium-ferrite-poor clinker fine flour.

In the industrial dry mixture which is produced using the method according to the invention, the expansion component is matched to the expansion component-free fine cement binder mixture. Thereby, the expansion component-free fine cement-binder mixture with a proportion of 50 to 95% by weight, preferably of 70 to 90% by weight, and a grain distribution of d95 ^ 24 pm, preferably of d95 £ 16 pm, and d50 < 7 pm, preferably d50 < 5 pm, and preferably a ratio of d50 to d95 = 0.33 ± 0.04 mixed with the expansion component for example on an aluminate-sulphate basis, preferably of calcium aluminate and calcium sulphate, with a proportion of 5 to 50% by weight, preferably of 10 to 30% by weight, of preferably lower or equal fineness and grain distribution, whereby the homogenized total mixture exhibits a grain distribution of d95 < 24 pm, preferably of d95 < 16 pm, and d50 ≤ 7 pm, preferably d50 < 5 pm, and a ratio of d50 to d95 = 0.33 ± 0.04.

In order to determine predefinable different expansion effects for fine cement-binder mixtures that are produced using the method according to the invention, the binder mixture is first prepared in charges with predetermined different paint fineness and grain size distributions, and then the setting speed of the charge is determined. Also, the expansion components are prepared in charges with predetermined different finenesses and grain size distributions, and then the ettringite formation rates of the charges are determined. On the basis of the fixed fixation and ettringite formation rates, the mixtures with predefinable degree of expansion are then determined and then the production is adjusted.

The invention is explained in more detail in the example below with the help of the drawings. Fig. 1 schematically shows a plant for producing the industrial dry mixture according to the invention. Fig. 2 shows a diagram of the effect of the amount of addition of a plasticizing agent.

Fig. 3 shows a diagram of the grain distributions.

Fig. 4 shows a diagram of the reaction rate for a fine cement-binder mixture and an expansion component. Fig. 5 shows the grain distribution for a fine cement-binder mixture and an expansion component.

The method according to the present invention produces for the first time an industrial dry mixture suitable for construction sites, and ready-made for construction sites, in the form of a single dry mixture which should only be mixed with the prescribed amount of water. Mixing errors in the dosage of the components for the production of the fine cement-binder mixture can no longer occur. The mixing with water takes place with a high-efficiency mixer. During mixing, the extremely fine, dry additives can unfold their effect immediately. The industrial dry mixture can be produced with the same composition and quality as often as desired. This is successful because of the knowledge that additives must not be ground together with the cement clinker, that the additives must preferably have equal or higher fineness and coordinated grain distribution, and that the additives in this fineness range work very intensively, as there are relatively small differences in the amount of addition (see Fig. 2 ) and in grain distribution and fineness show large differences in the intended effect. The addition amounts of additive are preferably 2 to 5% by weight (except for the expansion component).

Generally, fine cement is extracted by jointly grinding Portland cement clinker and at least one sulphate carrier, with the corresponding final part only being derived from a cement mill if there is an order for the delivery of fine cement. Thereby, the proportion is derived through <y>ind sieving, which proportion meets the requirements regarding the d95 value. Within the framework of the invention, it was known that this type of extraction is the principle reason why the cement suspensions do not exhibit constant quality from delivery to delivery. In ignorance of the cause, attempts have been made to meet the evil by providing mixtures and through regulations on special mixing orders, which, however, has not led to good enough results. The separate grinding of cement clinker into clinker fine flour and slag into slag fine flour, provided that slag fine flour can be included in the fine cement-binder mixture, as well as the use of additives and additives, in particular of at least equal fineness and grain distribution, and the separate storage of all components of the composition of fine cement-binder mixtures, enables the precise dosing of the components and, after homogenization, the guarantee for a specific quality of the filling mass, respectively the cement suspension and the hardened product. It is essential that the dry additives are used with at least the fineness and grain distribution of the fine cement-binder mixture, or that the fine cement-binder mixture exhibits the required fineness and grain distribution in total, whereby the additives can be coarser, but must align in the grain distribution so that the binder mixture's grain distribution shows the required values. If the market cannot offer the additives in the desired fineness and grain distribution, the additives are correspondingly produced separately. In other cases, the additives, provided they are available in different finenesses and grain distributions on the market, must be selected accordingly. It is surprising that the additives, especially in the finest grinding degree, have a special, previously unknown reaction method with the finest grinding of the binder mixture, and the desired injection quality can be ensured if it is ensured that the fine cement-binder mixture is also available in a defined quality - that is defined in terms of its constituents and its fineness and grain distribution. This was not possible with the usual extraction through "milking" when grinding normal cements, as "milk products" vary in composition, which can well be fed back to mixing during the "milking process". For example, the "milk products" are uncontrollably enriched with certain mineral phases, for example with sulphates.

With that in fig. 1 schematically produced plant allows fine cement-binder mixtures to be produced without further ado using the method according to the present invention. Thereby, pure portland cement clinker is delivered to a mill 1 via a transport route la, and ground in the mill 1 to a coarse clinker meal. The coarse clinker flour is transported via transport routes 18, 2a to a storage silo

2. With the same cleaned mill 1, which is supplied with slag in granule form via transport route la, the slag is ground into a coarse slag meal which is transported via transport routes 18, 3a to a storage silo 3. From transport route 18, part of the ground mass can is diverted via a transport road 18a to a cement plant for the production of, for example, normal portland cement. In a storage silo 4, a supply of finely ground bentonite is prepared, which is supplied to the silo 4 via a transport route 4a. From the silos 2, 3 and 4, mass is in each case separately extracted on transport routes 2b, 3b and 4b and sieved in a wind sieve 5, whereby the same wind sieve 5 - cleaned each time - is used for each case, or it is for each mass flow ready a separate wind screen (not shown). Similarly, for the slag, for example, a different mill can be used for the production of the slag coarse meal. The number of mills depends on the desired efficiency for the plant. During wind sifting in the wind sifter 5, the fines with the predetermined paint fineness and grain distribution are diverted and blown using a fan 6 via a transport path 5a into a respective transport path 7a, 8a, 9a and from there into a respective fines silo 7, 8 or 9. For example contains silo 7 clinker fine flour, silo 8 slag fine flour and silo 9 bentonite in the prescribed fineness and grain distribution.

The coarse mass in the sifter 5 is transported via a transport route 5b and 18a, respectively 19a to a relevant intermediate storage silo 18, for example for clinker flour, and an intermediate storage silo 19 for slag flour, and from there via a transport route lb which opens into the transport route la, into in mill 1 again.

In the case of the bentonite, coarse components are discarded via a transport route 20 or supplied to other areas of use. Next to the fine mass silos 7, 8 and 9 there are further fine mass silos for additives, for example fine mass silos 10, 11 and 12, each of which contains an additive with the predetermined fineness and grain distribution.

From the silos 7 to 12, the fines are drawn with the help of dosing devices (not shown) dosed via transport ways 7b, 8b, 9b, 10b, 11b, 12b and delivered to a scale 13. From the scale 13 the fines are brought via a transport way 13b to a mixer 14, for example to a ploughshare mixer, where the fines are homogenized into the industrial dry mixture. The finished industrial dry mixture can then be immediately filled into sacks or transported via a transport route 14b to a storage silo 15 from where the finished mixture via a transport route 15b can be filled into a silo wagon 17.

The addition of additives can also be done in groups to simplify the homogenisation, since for example at least two additives, for example from silos 11 and 12, can be filled into a common pre-weight 16 and then delivered to the main weight 13. It may also be appropriate to assign each silo a preweight 16, which is produced in the area of silo 10.

According to the method according to the invention, the cement clinker is ground in the mill 1 without an additive, in particular without a sulphate carrier. The coarse flour and the fine flour thus contain no sulphate components in particular. For the production of fine cement-binder mixtures with or without expansion components, the grinding of the Portland cement clinker also takes place without the addition of sulphate, whereby an expansion component is stored in a silo, for example in silo 10, which is defined as supplied, or in silo 11 and in silo 12 in each case, a component is stored for the composition of an expansion component consisting of two substances, which is defined added.

In a silo, a sulphate carrier is also kept separately or stored for the influence of the clinker fine flour's reaction, which sulphate carrier is usually already added when the clinker is ground.

The plant used for the production of the industrial dry mixture which is produced by means of the method according to the invention naturally has as many silos as the number of components or components the industrial dry mixture can or must contain.

With the plant used, an industrial dry mixture can be put together with specific components in predetermined quantities with predetermined grain fineness and grain distribution, through which the effect of the components in the suspension can be purposefully controlled. Irregular qualities of the filler can thus be ruled out.

Figure 3 shows grain distribution curves. The curves KVI to KV3 show, for example, grain distributions in fine cement-binder mixtures which are produced using the method according to the invention. The curves KV4 to KV6 lie outside the required grain fineness and grain distribution for a fine cement-binder mixture which is produced using the method according to the invention. It is nevertheless within the scope of the invention to use additives, especially the expansion components, with grain distributions according to the curves KV4 to KV6 provided and to the extent that the final product, namely the finished industrial dry mixture, corresponds to the range of fineness and grain distributions according to the curves KVI to KV3. According to this, for example, a coarser additive according to curve KV6 can be added in an amount which displaces a fine cement-binder mixture with the grain distribution according to the curve KVI into the area of the grain distribution according to the curve KV3. This possibility can be used in particular when producing targeted and defined or reproducibly expanding binder mixtures, as the degree of expansion can thus be changed in a particularly effectively defined manner.

Fig. 4 exemplarily clarifies the adjustment of the ettringite formation, respectively the ettringite formation rate to the time period and the course of the firmness development in a fine cement-binder mixture with defined expansion which is produced using the method according to the invention. The ettringite formation due to the expansion component addition (curve 1) which

causes the expansion in the hardening suspension, is matched in such a way to the strength development of the fine cement-binder mixture that it coincides with the initial strength development {curve 2 at t0) and persists while the binder matrix is still shear-soft, i.e. is still elastically-plastically malleable fresh concrete.

According to the method, the degree of expansion can be purposefully controlled both through the amount of expansion component added and through the expansion component's fineness and grain distribution. These relationships are explained in more detail in the examples below.

Example 1

Fig. 5 shows a grain distribution in an expansion component-free fine cement-binder mixture as well as in an expansion component. Table 2 below contains reference values for the grain distribution in the expansion component-free fine cement-binder mixture chosen as an example and in the expansion component.

The influence of the mixing ratio for expansion component free fine cement-binder mixture and expansion component on the expansion ability of the fine cement-binder mixture can be seen in table 3.

Component A: Expansion component-free fine cement-binder mixture (specific surface area 8,000 cm<2>/g)

Component B: Expansion component (specific surface area 10,000 cm<3>/g)

From table 3, it appears that with predetermined fineness for component A and component B, the expansion capacity of the filler can be controlled via the mixing ratio of the components.

Example 2

In this example, the effect of the fineness of the expansion component on the expansion capacity of a fine cement-binder mixture is made clear. To produce the effect of the fineness of the expansion component on the expansion capacity in a fine cement-binder mixture according to the invention, the fineness of the expansion component-free fine cement-binder mixture (component A) is given in advance and the fineness of the expansion component (component B) is varied. The mixing ratio of the two components is component A/component B = 70/30.

The two components' associated grain distributions are shown in fig. 3. The abbreviation given in table 4 below for the grain distributions (KV) for the two components refers to the preparation in fig. 3.

Table 5 below shows the effect of the fineness of the expansion component on the expansion capability.

It is clear from the example that through the adjustment of the fineness in the expansion component-free fine cement-binder mixture and in the expansion component, the expansion ability in the fine cement-binder mixture can be controlled. The expansion capacity of the fine cement-binder mixture decreases with increasing fineness of the expansion component. Thus, in particular, the expansion capacity of fine cement-binder mixtures can be controlled through the fineness of the components, so that expansion-capable and also expansion-free fine cement-binder mixtures, that is, in the latter case, binder lbl and ings without expansion, can be produced. The use of expansion-free mixtures is, for example, always necessary when structural damage can occur in the injected element through the expansion pressure that accompanies the expansion when an expansion-capable filler is used.

As already mentioned, the expansion component preferably consists of calcium aluminate and calcium sulphate. These constituents are separately ground to the predetermined different finenesses and grain distributions, and then the ettringite formation rates are determined. The weight ratio of calcium aluminate and calcium sulfate is determined with regard to the stoichiometric conditions for the complete ettringite formation. Likewise, fine cement-binder mixtures with predetermined different finenesses and grain size distributions are composed, and then the strength development is fixed. Based on the matching of the strength development and the rate of ettringite formation, the mixture of the components is then produced, which mixture ensures a certain degree of expansion. This mixture is then assembled as an industrial dry mixture in the device used in the method according to the invention and delivered to the construction site.

The determination of the reaction effect of fineness and grain distribution both in the clinker fines, the slag fines or in the mixture of these and in the additives, especially in the expansion components, makes it without further production technical and without great costs and immediately possible to respond to different use-specific requirements, since at the factory either several silos are kept for a component, where the component in each case is stored with different fineness and grain distribution, or the grinding aggregates and sieves are adjusted accordingly from charge to charge. Since the silos are combined with dosing facilities, the composition of industrial dry mixes for cement suspensions or for hardened products of the cement suspensions with differently defined and reproducible properties, particularly also regarding expansion, can be controlled not only through the dosage quantities, but especially also through defined fineness and grain distributions . The user side is thereby considerably relieved. The control of the mixtures is transferred to the production factory where a control can be carried out professionally and more easily.

Aluminum sulfate, alumina cement plus gypsum, calcium aluminate plus gypsum, aluminum powder plus alumina component as activator plus gypsum are also particularly useful as expansion components for the fine cement-binder mixture produced using the method according to the invention.

Claims (23)

1. Method for the production of a dry mixture for the production of a cement suspension for filling and/or pressing into pores and cavities in loose stones, or cavities and/or cracks in rock or concrete components, in the form of a ready-made dry mixture that is adapted to the relevant application, and which must only be mixed with water, as the dry blending contains - clinker fine flour, which has been ground without a sulphate carrier, or slag fine flour or a mixture of these; - additives; and - possibly additives, where the homogeneous dry mixture in its entirety exhibits a constant and graded grain distribution with sieve pass values of d95 < 24 um and dso S 7 |i and all the components are kept separate in storage silos, characterized by al) Portland cement clinker being ground, without the addition of sulphate carrier, in a cement mill to a clinker coarse flour a2) the coarse clinker flour is stored in a storage silo, a3) the clinker coarse flour is intended for the production of a clinker fine flour which has a predetermined fineness and grain formation, a4) the fine clinker flour is stored in a storage silo, bl) if slag is used, slag granules are ground in a cement mill into a coarse slag flour, b2) the coarse slag meal is stored in a storage silo, b3) the coarse slag meal is sifted for the production of a fine slag meal that has a predetermined fineness and grain distribution, b4) the slag fines are stored in a storage silo, c) additives are stored in storage silos, d) any additives are stored in storage silos, e) predetermined components that are adapted to the application in question are taken out of the respective storage silos in predetermined, metered quantities, delivered to a mixer and mixed in the mixer to a homogeneous factory dry mixture with predetermined properties. 2. Method according to claim 1, characterized in that the relevant coarse material from the sieves is also stored. 3. Method according to claim 2, characterized in that the coarse mass is supplied in the relevant feed mill. 4. Method according to claim 2 or 3, characterized in that the additives are ground before pre-storage. 5. Method according to one or more of claims 1 to 4, characterized in that the additives are mixed in with somewhat coarser fineness and somewhat more graded grain distribution than stated in claims 1, 3 and 4. 6. Method according to one or more of claims 1 to 5, characterized in that at least one of the components in the factory dry mixture are stored separately in different finenesses and grain distributions. 7. Method according to one or more of claims 1 to 6, characterized in that each component of the factory dry mixture is stored in a storage silo (for example 7 to 12), each silo being combined with a dosing device, and a mixer (14) being arranged after the silos . 8. Method according to claim 7, characterized in that a weighing vessel (13) is used, the weighing vessel being arranged in front of the mixer (14). 9. Method according to claim 7 or 8, characterized in that a high-power mixer is used as the mixer (14). 10. Method according to one or more of claims 7 to 9, characterized in that at least two storage containers are used for the at least one component, in which containers the components are stored. 11. Method according to one or more of claims 7 to 10, characterized in that a storage silo (15) is used, the storage silo (15) being arranged after the mixer (14). 12. Method according to one or more of claims 7 to 11, characterized in that a plant is used, the plant having a cement mill (1), a storage silo (2) and a wind sifter (5) for the production of fine clinker flour, the cement mill- The outlet side of the funnel (1) is connected to the inlet side of the storage silo (2), and the outlet side of the storage silo (2) is connected to the inlet side of the wind sifter (5), likewise the outlet side of the wind sifter (5) is connected to the inlet side of a clinker fines silo (8) via associated transport routes. 13. Method according to claim 12, characterized in that a plant is used, the plant having a cement mill (1), a storage silo (3) and a wind sifter (5) for the production of fine slag flour, the outlet side of the cement mill (1) being connected to the storage silo (3) ) inlet side and the storage silo's (3) outlet side are connected to the wind screener's (5) inlet side, likewise the wind screener's (5) outlet side is connected to a slag fine meal silo's (7) inlet side via associated transport routes. 14. Method according to claim 12 or 13, characterized in that a plant is used, the plant at the outlet side of the wind sieve (5) being connected via transport routes to the inlet side of a silo (18c, 19), the silo and/or the silos (18c/ 19) outlet side is connected via a transport road with the cement mill (1). 15. Method according to claim 1, characterized in that sieve pass values of d9S < 16 µm and d50 £ 5 µm are set. 16. Method according to claim 15, characterized in that a ratio is set between the sieve review values of dso to d95 = 0.33 ± 0.04. 17. Method according to claim 15 or 16, characterized in that from 5 to 95% by weight of slag fine flour is used in relation to the clinker fine flour. 18. Method according to one or more of claims 15 to 17, characterized in that an activator is used for the fine slag flour with the same or finer grinding fineness and grain distribution than the fine slag flour. 19. Method according to one or more of claims 15 to 18, characterized in that a naphthalene sulfonate formaldehyde condensate in powder form is used as fluidizing agent. 20. Method according to one or more of claims 15 to 19, characterized in that the relevant additive is used in amounts of 2 to 5 percent by weight. 21. Method according to one or more of claims 15 to 20, characterized in that a swelling component is used as additive. 22. Method according to one or more of claims 15 to 21, characterized in that bentonite and/or tasse and/or high-dispersing silicic acid are used as additives. 23. Method according to one or more of claims 15 to 22, characterized in that an agent for fluidization and/or hardening retardation and/or hardening acceleration and/or water retention is used as an additive.