WO2013004853A2

WO2013004853A2 - Process for producing concrete

Info

Publication number: WO2013004853A2
Application number: PCT/EP2012/063441
Authority: WO
Inventors: Andreas NEBE; Martin SPINDLER; Michael Stehle
Original assignee: Neoton Betonsysteme Gmbh
Priority date: 2011-07-07
Filing date: 2012-07-09
Publication date: 2013-01-10
Also published as: WO2013004853A3; EP2729429A2; DE102011051630A1

Abstract

In a process for producing concrete from water, binder and at least one aggregate, the water for wetting the binder is treated in a first stage, a water/binder suspension is produced in a second stage and the at least one aggregate is added in a third stage.

Description

Process for producing concrete

TECHNICAL AREA

The invention relates to a method for producing concrete from water, binder and at least one aggregate, and a plant for this purpose.

STATE OF THE ART

Concrete plays an important role in the construction industry, especially since the beginning of the last century. Here, concrete is synonymous with a building material that consists of matrix and filler. The matrix, made from cement paste that solidifies into cement stone, runs through the building material continuously. Sand and gravel are only stored as fillers in the matrix and more or less firmly connected to the cement stone. In the past, concrete was basically considered a ternary system, namely cement-water aggregates. For a long time it has been known that simply mixing together cement-water aggregates in conventional mixers (usually compulsory mixers) does not guarantee that, in particular, the ingredients, cement, water and aggregates, must react chemically with one another actually be able to fully interact with each other. Since the 1970s, efforts have been made to complete the concrete production process in two steps. The first step was to produce cement suspensions in high-performance mixers by producing water-cement mixtures. The corresponding additives (condenser, air entraining agent, accelerator, etc.) are then added in this first stage of the process in the liquid cement suspension also still in the high-performance mixer. The production of colloidal cement suspensions in high-performance mixers was already preferred at that time in order to achieve the maximum hydration of cements (encapsulation of the cement crystals with water molecules). Only in a second step should the chemically-physically treated colloidal cement suspension be brought together with the corresponding inert additives, such as sand and gravel etc. in forced or free-fall mixers. Sands and gravels are therefore inert additives for the hydraulic setting process because they themselves do not participate in the hydration and only serve as fillers to increase the volume of the total mixture. However, the concrete manufacturing industry has not responded to these findings for decades, so that it remained with the relative "primitive" technology: In a compulsory mixer sand / gravel, then cement, finally water and additives are added.

In the last decade, since about 1997, concrete is experiencing an innovation boom. High-tech concrete is developing more and more into a multi-substance system cement-aggregate-water-additive-additive-air. Producing high-performance concrete (HPC) for high-rise buildings, offshore structures, bridges and highways, places high and specific demands on the concrete industry. It is not just a question of producing concrete with certain strength properties, but also of greater importance must be given to the durability or durability of the structures made of concrete. Changing environmental conditions are also having an increasing impact on the destruction of concrete structures. Since the mid-1990s, Japanese scientists have begun a new era in concrete production by producing "self-compacting concretes." The vision of producing a concrete that flows without external force has been based on the development of new additives However, with the development of high-performance plasticizers (superplasticizers) and the study of their liquefying effect in the cement-water aggregate mixture on the hydraulic setting process, only a first step was taken, as it increasingly turns out that that the sole addition of high-performance liquefiers to existing blends while maintaining the commonly used concrete-making technology does not produce the desired and possible results. "It has been shown that the use of high-performance liquefiers calls for concrete producers to break new ground to use the concrete production and processing in order to be able to fully exploit all the opportunities offered by the new generation of concrete admixtures.

With the use of high-performance liquefiers not only the production of the concrete reaches a maximum of precision, but also the processing of the concrete itself places high and new demands on the construction industry. Since the efficiency of the high-performance liquefiers is limited in time and since even within a short time after the addition of the liquefier, the still liquid concrete undergoes changes which are negative On the workability of the still liquid concrete and finally also on the quality of the then hardened concrete impact, in addition to the demands on the manufacturing technology also demands on logistics in the time window between production and processing. In this time window, in which the filling of the transport vehicles, then the transport itself, the emptying of the vehicles and the introduction of the concrete are to be considered, there are a variety of factors that can not be ignored due to the sensitivity of the total mixture. Not only are the internal chemical-physical conditions prevalent in liquid concrete, but also external environmental factors such as humidity and temperature have a considerable influence on the overall reactions of the hydraulic setting process. A method for producing concrete is known, for example, from DE 10 2005 014 704. There is a colloidal mixture of the substances entered in a reactor. The suspension formed therefrom is placed in a downstream mixer and mixed intensively with additives. TASK

The object of the present invention is to develop a method by which concrete of a quality can be produced, as required today by the construction industry. SOLUTION OF THE TASK

To achieve this object, that in a first stage, the water is prepared for a wetting of the binder, in a second stage, a water - binder suspension produced and in a third stage the at least one additive is added. With the separation of the concrete production process into these three process steps, the conditions are created for the first time that with the activation of the water, the cement and the additives in a mixture can optimally react with one another. The new technology assumes that water plays an important role, if not the decisive role, even in the hydraulic reaction with cement. This consideration is new and has thus far not been put in the foreground in the scientific discussion on the hydraulic reaction with cements. The necessity of this consideration is connected not least with the demand of the new concrete production process for the upstream colloidal digestion of cements for the production of cement suspensions as starting material for the concrete mixture in the second process step. The treatment of water happens in suitable facilities. For the treatment of water a variety of ways are conceivable. The simplest case is that distilled water is used. This distilled water has the advantage that it has a low surface tension, so that it can penetrate deep into the binder and there can coat the individual components of the binder. The aim of the present invention is to wet the individual components of the binder, if possible, 100% with water while at the same time as little as possible to require water.

It is also thought to break up the clusters of water, for example to shorten the molecular chains. Furthermore, it is thought, by chemical or mechanical means, the binding forces between the Reduced water molecules. Ionization or deionization of the water can also be envisaged as a possibility.

Another possibility, however, which can be combined with the mentioned, is that the water is activated chemically, mechanically, physically, electrically and / or magnetically. Preferably, it should be polarized.

In addition or alone, the water can be vortexed before and / or when feeding to the second stage. This is also to be included in a treatment of the water in the context of the present invention.

Furthermore, it is envisaged to supply the water of the second stage with an increased pressure. For this purpose, for example, be provided in the supply line, a booster pump. If the water pressure is normally 6 bar, e.g. the water pressure can be increased to 15 bar via the booster pump. It has been found that, depending on the required type of concrete and the quality of the water, pumping pressures in the range of 1 to 25 bar are optimal. On average, the required pressure is between 6 and 15 bar. The aim is to introduce the water into the second process stage as quickly as possible, which at the same time also leads to a turbulence there.

In a secondary step, especially the binder, in particular the cement, colloid-digested. An enlargement of the surface of the cement crystals preferably also takes place here. The increase in the surface area of the cement crystals ultimately results in a substantial increase in the energy content of the solid components, which leads to a very great tendency of these particles to unite, so as to assume a lower-energy state. If water is added here in particular, this colloidal solution should actually become unstable and tend to flocculate. However, this is within the scope of the present invention not the case, which has to do with counter-forces, which prevents the union of small, high-energy particles to larger, lower-energy parts. The counterforces can act by enveloping the solid particles and / or by electrically charging the surfaces.

However, before the pretreated binder is brought into contact with the water, it should be fluidized before and / or during introduction into the second stage. In particular, the binder can be aerated here, so that it floats on an air cushion in the second process stage quasi. As a result, lumps are avoided, which in turn facilitates wetting. Furthermore, there is a continuous flow of solids.

In a particular embodiment of the invention, the binder is still passed through an (ultrasonic) sieve before it enters the second process stage, whereby it is further refined.

It is also thought to reduce the binder in the suspension again, so that the water wetting is further improved. Here it is thought to push the binder in the suspension through at least one perforated plate, whereby the granule size of the binder can be reduced and the reactive surface is increased.

Hydraulic binders are typically referred to as hydration when they come into contact with water, i.e., a coating of water molecules (hydrophilic colloids) rather than electrical charges. In the case of a colloidally digested binder, the energy or the reactivity of the surface on the solid is so great that the absorption of water molecules also takes place in accordance with the electrical charge ratios on the surfaces.

The more surfaces of the surface created by colloidal digestion Binders are, the stronger the electrical charge conditions come to the fore. The stability of the suspension thus depends essentially on how the type and size of the charge distributions between the reactants are adjusted. In the context of the present invention, it has been possible to pretreat the water so that the charge conditions in the water can be influenced at least for a decisive time. On the one hand, the colloidal digestion of the binder achieves high reactivity of the crystals and, on the other hand, structures ordered by the polarization of the water for distributing or attaching water molecules to the highly reactive surfaces. It is understandable that these enormous forces only work over a certain period of time, ie that the stability of the suspensions prepared in this way can only be maintained for a short time. However, the time is sufficient in any case to mix the binder suspensions prepared in this way with other materials such as sand, gravel, polystyrene, perlite, pumice, Liapor, straw, rubber, glass, cork, etc. The stability of the suspension is in this Time, however, so great that the water of absorbent additives, such as Liapor from the suspension is not or only in a very small mass is released and thus a water / binder mixture can initially attach as a stable gel to eg the Liapor. This enormous advantage of using only the amount of water required for the hydraulic setting process and thus eliminating any "excess" water from the finished product, is essential for the quality of the highly fluid concrete and, ultimately, for the quality of the hardened concrete responsible.

Another positive characteristic of the highly stable binder suspensions prepared with "depolarized" water is the resulting excellent processability and pumpability of these products. Decisive for the stability of the colloidal system, however, is the coordination of the stabilized water with the additives in order to obtain other properties in addition to the stability of the system. Not only the size of the surface of the solid, but also the nature of the solvent, so the water and its interactions with the specially selected for each application additives are decisive factors for the overall chemical-physical behavior of the colloidal system. Since a not inconsiderable part of the energy remains in the system for some time and thus also represents a measure of the stability of the suspension, water and binder then form a stable system when the forces inherent in both components are coordinated. With this vote it is achieved that the bond between water and binder is maintained as long as possible and thus externally acting forces are weakened as far as possible.

Only after a certain time, an energy exchange takes place inside the gel and the forces polarize, so that only then the process of natural agglomeration of the particles can take place. Of course, it is important for the properties of the final products that all reactants could communicate with each other at least beforehand and that there is not an excess of binder or an excess of water. In both cases, this has devastating effects on the quality of the end products. With the new process technology you can exclude these things in principle as far as possible.

In the second stage of the process it is also important that the suspension does not heat above a certain temperature. It should not heat above 40 ° C, ideal is a temperature of 15 ° C to 25 ° C. This heat is developed by the reaction between water and cement. These Temperature control is controlled according to the invention and in particular the mixing water used is tested for its temperature. If possible, water is used at a temperature optimum between 5 ° C and 25 ° C. The second stage is carried out essentially in a colloidal mixer. In this particle sizes are finally of solid components of about 0.01 μιτι to about 0.1 μιτι produced during the mixing process or kept in dispersion, without too early agglomeration of these particles occurs.

It is important that a corresponding mixer for producing the suspension according to the invention operates at a relatively high speed. Preferred is a speed of 400 to 2,500 revolutions per minute and / or peripheral speeds between 3 m / s and 25 m / s.

After preparation of the suspension, the suspension should be left a little at rest to allow it to react sufficiently. Now, the additives can either be entered directly into the suspension, if the concrete is to be prepared immediately or the suspension is mixed in another mixer with the additive.

The third process step preferably takes place in stationary mixers or truck mixers.

DESCRIPTION OF THE FIGURES

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing; this shows in its single figure a block diagram representation of the inventive method for producing concrete.

In the method according to the invention for producing concrete, the water is prepared in a first method step. This is done in a suitable plant 1, in which the water is prepared for a wetting of the binder. It is e.g. thought to polarize the water in this plant. In a device 2, the binder is e.g. Preparing cement, e.g. is treated in a colloidal mixer so that its surface area is increased. This is done in particular by mechanical treatment, so that the particle size of solid components of the binder at about 0.01 μιτι to about 0.1 μιτι. It is then fed via, for example, a screw 3 to a mixer 4. In this case, this screw 3 is still assigned an ultrasonic sieve 6.

In the mixer 4, the treated water and the treated binder are brought together and mixed to form a stable suspension. Preferably, the pressure of the water is increased by a booster pump (8) and the water introduced via a nozzle 7 in this mixer 4, wherein the binder is injected as a solid mist directly into the water jet. However, only the amount of water necessary for the hydraulic setting process is used, so that no "excess" water is present in this suspension, the suspension is therefore gel-like Water and binder form a inherently stable system the inherent in both components forces are coordinated.

Only in a third process step, the necessary additives of this suspension are then preferably added in a stationary mixer 5 or a truck mixer, which then leads to the setting of the concrete. Since no excess water is present, neither evaporation channels nor bubbles or the like are formed in the concrete. In experiments with the process according to the invention, the following results were obtained:

Formulation of the comparison:

Strength class: C25 / 30 Cement uptake -10%, water -20%

Conventional NEOTON " ^l Mix Process Mix Flow

Cement swivel 32, 5R CEM II 340 kg 306 kg

Water (total size) 180 liters 144 liters

Gravel concrete 0/4 830 kg 830 kg

Gravel 4/8 280 kg 280 kg

Gravel concrete 8/16 760 kg 760 kg

Concrete liquefier FM6 0.8% 2.72 liters 2.50 liters

Concrete liquefier BV3 0.4% 1, 36 liters 1, 23 liters

Consistency: F3 F3

Full compressive strength after 28 days 35 N / mm '36.4 N / mm ²

W / Z value 0.53 0.47

Presentation class XC4, XF1, XC4, XF1,

XA1 / WA XA1 / WA

Mix time: (unadulterated mixing / total) 30s / 5 min. 30s / 2 min Formulation of the comparison:

Strength class: C25 / 30 cement uptake -10%, water -30%

Conventional NEOTON ^IM Mix Flow Mix Flow

Cement swivel 32, 5R CEM II 340 kg 306 kg

Water (total size) 180 liters 126 liters

Gravel concrete 0/4 830 kg 830 kg

Gravel 4/8 280 kg 280 kg

Gravel concrete 8/16 760 kg 760 kg

Concrete liquefier FM6 0.8% 2.72 liters 2.50 liters

Concrete liquefier BV3 0.4% 1, 36 liters 1, 23 liters

Consistency: F3 F3

Full compressive strength after 28 days 35 N / mm '40.9 N / mm ²

W / Z value 0.53 0.42

Presentation class XC4, XF1, XC4, XF1,

XA1 / WA XA1 / WA

Mix time: (unadulterated mixing / total) 30s / 5 min. 30s / 2 min

Claims

claims

Process for producing concrete from water, binder and at least one aggregate, wherein in a first stage the water is prepared for wetting the binder, in a second stage produces a water - binder - suspension and added in a third stage, the at least one additive becomes.

A method according to claim 1, characterized in that distilled the water is used.

A method according to claim 1 or 2, characterized in that clusters of the water are broken up.

A method according to claim 3, characterized in that the length of the clusters of the water is shortened.

Method according to at least one of claims 1 - 4, characterized in that a binding force between water molecules is reduced.

Method according to at least one of claims 1-5, characterized in that the water is ionized or deionized.

Method according to at least one of claims 1-6, characterized in that the water is activated chemically, mechanically, physically, electrically and / or magnetically.

A method according to claim 7, characterized in that the water is polarized.

Method according to at least one of claims 1-8, characterized in that the water is vortexed before and / or when feeding to the second stage.

Method according to at least one of claims 1 to 9, characterized in that a pressure of the water in the supply line to the second stage is increased.

1 1. A method according to claim 10, characterized in that a pressure of the water in the supply line to the second stage to 1 - 25 bar, preferably 9 - 15 bar is increased.

12. The method according to at least one of claims 1 to 1 1, characterized in that the reactive surface of the binder is increased (colloidal digestion).

13. The method according to claim 12, characterized in that the particle size of the binder at about 0.01 μιτι to about 0.1 μιτι is maintained.

14. The method according to at least one of the preceding claims, characterized in that the binder is fluidized before and / or during introduction into the second stage.

15. The method according to at least one of the preceding claims, characterized in that the binder is aerated during introduction into the second stage.

16. The method according to at least one of the preceding claims, characterized in that the binder is subjected to an ultrasound before and / or during introduction into the second stage.

17. The method according to at least one of claims 1 to 16, characterized in that the binder is injected directly into a water jet.

18. The method according to at least one of the preceding claims, characterized in that in the second process step, a suspension is prepared which is saturated so that it gives little or no water.

19. The method according to at least one of claims 1-18, characterized in that the suspension at high speed, preferably at a speed of 400-2,500 revolutions / min (3-

25m / s), mixed.

20. The method according to at least one of the preceding claims, characterized in that the binder is further split in the suspension.

21. The method according to claim 20, characterized in that the binder is pressed in the suspension by at least one perforated plate.

22. The method according to at least one of the preceding claims, characterized in that the temperature of the suspension is controlled

23. The method according to claim 22, characterized in that the temperature of the suspension below 40 ° C, preferably between 15 and 30 ° C, is maintained.

24. The method according to at least one of the preceding claims, characterized in that the suspension is moved between 15 s and 5 min.

25. The method according to at least one of the preceding claims, characterized in that the suspension is allowed to rest after its preparation.

26. The method according to at least one of the preceding claims, characterized in that the additive is entered directly into the suspension.

27. Plant for carrying out the method according to at least one of the preceding claims, characterized in that a device (1) for water treatment, a device (4) for mixing the treated water is connected downstream of the binder

28. Plant according to claim 27, characterized in that in a supply line of the water to the device (4) for mixing the treated water with the binder, a booster pump (8) is turned on.

29. Plant according to claim 27 or 28, characterized in that the means (4) for mixing the treated water with the binder is a colloidal mixer at high speed.

30. Plant according to claim 29, characterized in that the treated water passes through a nozzle (7) in the colloidal mixer (4).

31. Installation according to claim 29 or 30, characterized in that the colloidal mixer operates at peripheral speeds between 3 to 25 m per second.

32. Plant according to at least one of claims 27 - 31, characterized in that in the device (4) for mixing the treated water with the binder at least one perforated plate is arranged.

33. Plant according to at least one of claims 27 - 32, characterized in that the means (4) for mixing the treated water with the binder at least one ultrasonic sieve (6) is connected upstream of the binder.

34. Plant according to at least one of claims 27 - 33, characterized in that a mixer (5) in the third process stage is a conventional separate stationary mixer or truck mixer.