WO1994014720A1

WO1994014720A1 - Process and device for producing concrete building components and concrete building components

Info

Publication number: WO1994014720A1
Application number: PCT/DE1993/001239
Authority: WO
Inventors: Stephan Huber; Erich Huber
Original assignee: Gebr. Huber Gesellschaft Für Versorgungs- Und Geotechnik Mbh
Priority date: 1992-12-26
Filing date: 1993-12-23
Publication date: 1994-07-07
Also published as: EP0675859A1; DE4244249C1

Abstract

A process and device are disclosed for producing concrete building components, in which crushed soil from a soil decontamination plant is used as aggregate besides a binder. Also disclosed is a concrete building component in which crushed soil from a soil decontamination plant is at least partially used as aggregate.

Description

METHOD AND DEVICE FOR PRODUCING CONCRETE COMPONENTS AND CONCRETE COMPONENTS

The present invention relates to a method and a device for the production of concrete components and a concrete component.

Technologies have now been developed for cleaning contaminated floors which permit extensive cleaning of the contaminated floors, so that they can be reused after cleaning. However, considerable costs are associated with the cleaning itself and with the disposal of the contaminants removed from the soil. In particular, the tediousness of the known cleaning methods and the associated relatively low effectiveness and the costs caused by the final storage of the contaminants in landfills intended for this purpose have proven to be considerable in practice.

The present invention is therefore based on the object, on the one hand, of enabling a faster cleaning of contaminated soils and, on the other hand, of reducing the proportion of contaminants to be disposed of in a landfill or of making contaminant storage unnecessary.

This object is solved by the features of claims 1, 5 or 7. The method according to the invention has the features of claim 1.

According to the invention, floor fractions of floor material fractionated in a floor cleaning installation are used as additives in the production of concrete components.

This invention is based on the idea of incorporating soil fractions of contaminated soils to provide a way of safely disposing of the residual contaminants still present in the soil fractions after a cleaning treatment, without requiring a landfill storage that is useless beyond the storage effect. Rather, the method according to the invention enables the residual contaminants to be safely reused as a component of concrete components.

In addition to the landfill substitution, the method according to the invention makes it possible to align the floor cleaning method to a higher permissible residual contamination value because of the safe incorporation of the residual contaminants into the concrete component, as a result of which the floor cleaning is shorter and thus more effective with regard to the duration of the method.

The fractionation of the contaminated soils in the floor cleaning system makes it possible to classify the floor particles during the cleaning process, so that defined floor fractions as additives can be selected with regard to their particle diameter. With appropriate selection of soil fractions, it is thus possible to generate such a grain spectrum in the aggregates as it does is prescribed by the sieve lines according to DIN 1045 for the production of standard concrete.

The amount of the permissible residual contamination value mentioned depends on various parameters in the method according to the invention. In addition to the type of contaminant, the quantity and type of binder used as well as the quantity and type of concrete additives used have a decisive effect on this. Accordingly, the residual contamination value is set variably. It is assumed here that, in order to prevent contamination of the surroundings of concrete components produced by the method according to the invention, the pollutant quantities measured in the eluate must not exceed a certain value.

If the contaminant is, for example, mineral oil hydrocarbon, the hydrocarbon content in the eluate determined in eluate tests on concrete parts provided with conventional additives can be used as a yardstick for the level of the permissible residual contamination value. As was found in tests, this value is particularly sensitive to the proportion of the binder contained in the concrete. When using cement as a binder, it was found that less hydrocarbon is eluted at lower cement contents than at higher cement contents. This fact, which initially appears to be absurd to the person skilled in the art, is based on the fact that the cement itself has a considerable pollutant load, in particular due to hydrocarbon, due to its production process and the raw materials used. Therefore, it is generally important to determine the proportion of binder, in particular the cement content, within the scope of the To keep the use of specified concrete pressure resistance as low as possible. In addition, it proves to be advantageous to add additives to the concrete that have a sealing effect and reduce the water flow through the manufactured concrete components. Examples of these are epoxy resins or acrylic resins. Such concrete additives make it possible to increase the cement content without simultaneously increasing the eluate values.

Therefore, with a low binder content, in particular a low cement content, a relatively high hydrocarbon value of the soil fractions can be permitted, whereas a relatively low value should be selected for a high binder content. When appropriate concrete additives are added, a higher hydrocarbon value can also be selected.

The method according to the invention proves to be particularly effective if, according to the production of standard concrete, floor fractions to be used with fixed particle diameters are fed from the floor cleaning installation to a downstream concrete mixer and mixed with binder and any concrete additives in the latter.

It is particularly advantageous if the water required for the production of concrete is removed from the cleaning water circuit of the floor cleaning system and fed to the concrete mixer.

The device according to the invention for producing concrete components has the features of claim 5. This device consists, so to speak, of a coupling of a cleaning system which carries out a fractionation with a concrete mixer.

It proves to be particularly advantageous if the floor cleaning installation is designed as a mechanical floor washing installation and the concrete mixing unit is connected to a cleaning water circuit of the washing installation. In this way, depending on the degree of contamination, the cleaning water in the concrete that cannot be readily discharged into the environment can be set.

The concrete component according to the invention has the features of claim 7.

According to the invention, in addition to the binding agent, the concrete component has additives which are formed at least partially from soil fractions fractionated in a floor cleaning installation. Components of this type enable contaminated soil materials to be returned as a building material without the need for a largely complete decontamination of the soil materials.

In this context, it proves to be advantageous if cement, bitumen or plastic is used as the binder. By choosing a binder that is matched to the pollutant, it is possible to set the pollutant particularly effectively without increased pollutant values in the eluate compared to the binder in the concrete component. Therefore, it proves to be advantageous to use bitumen for setting polycyclic aromatics (PAHs) or cement to set mineral oil hydrocarbons (MKW). If the elutable pollutant content is to be kept as low as possible, it is advantageous, particularly in the case of contamination with mineral oil hydrocarbons, because of the mineral oil carbon materials usually contained in the cement anyway, to choose the cement portion of the concrete part as low as possible. Whereas, in the case of contamination with polycyclic aromatics and the use of bitumen as a binder, it is advantageous to choose as little as possible the proportion of bitumen due to the polycyclic aromatics usually contained in the bitumen. The same can also apply with regard to mineral oil hydrocarbons.

In order to reduce the elutability of the pollutants contained in the concrete component due to the residual contaminations contained in the aggregates and - particularly in the case of cement and bitumen - in the binder of house made from harmful substances, the concrete can be reduced by concrete additives which reduce the water flow. about alkali silicates, mineral additives based on cement, polymer resins, etc. are added.

The method according to the invention and the device are to be explained in more detail below with reference to the drawings.

Fig.l shows an embodiment of the method according to the invention in a schematic representation;

Fig. 2 Results of eluate experiments in a tabular overview.

1 shows a method for the production of concrete components, in which soil fractions 1-5 of in one mechanically cleaned floor contaminated soil material can be used as additives. The contaminated material introduced into the floor washing system is first subjected to a pre-fractionation, in which floor particles with a particle diameter> 100 mm are first crushed in a crusher and finally combined with the rest of the contaminated material are fed to a first washing / fractionation station . This is followed by a first classification into cleaned material with a particle diameter> 32 mm, which forms the bottom fraction 1, which comprises coarse gravel or gravel.

In the following, further washing / fractionation stations are run through, in order to form gravel fractions one after the other into the bottom fractions 2, 3 and 4. These each have soil particles with a particle diameter of 16 to 32 mm (soil fraction 2), 8 to 16 mm (soil fraction 3) and 4 to 8 mm (soil fraction 4). Finally, in accordance with the fractionation process shown as an example, there is a further washing / fractionation station for cleaning the residual contaminated material with a particle diameter of 0 to 4 mm, ie sand, which forms the bottom fraction 5.

Depending on the type of concrete to be produced, all or part of the soil fractions are fed to a further station, in which a sieve line comparison is carried out in order to compose a grain spectrum for the concrete manufacture from the classified soil fractions, which corresponds to a sieve line area according to DIN 1045. This sieve line adjustment now enables the production of a standard concrete with the appropriate addition of cement in a concrete mixing plant following the sieve line adjustment station. By adding water In accordance with a predetermined water / cement value and any concrete additives that are intended to reduce the water flow rate or the depth of water penetration into the concrete, a concrete is finally produced that can be reworked or further processed.

By pouring the concrete into the provided molds, prefabricated concrete parts can be produced, which are particularly suitable, particularly with a large weight / surface area quotient, for reducing the elutability of residual contaminants that have entered the concrete. The smallest possible addition of cement leads to a further reduction in the elutability of mineral oil hydrocarbons.

The relationship between the cement content and the determined eluate values is to be explained in more detail below with reference to the table shown in FIG. 2. The table shows results of a series of tests in which various blocks of DIN concrete of strength classes B 10, B 15 and B 25 with a weight of about 2 kg were examined. In a mechanical soil washing plant (BWA), contaminated soil material cleaned to a residual contamination of <300 mg mineral oil coal hydrocarbons per kg dry matter was used as the concrete additive. This additive was used in samples BWA B 10, BWA B 15 and BWA B 25.

For comparison, concrete samples were examined in which commercial concrete gravel was used as the additive. These samples are designated B 10, B 15 and B 25.

The elution test was carried out with a water / sample ratio of 1: 1, the The sample was hung in a suitable vessel and washed with distilled water. The trial lasted 24 hours. The eluted hydrogen content was determined according to DIN 38409 part 18 by means of infrared spectroscopy. The measurement results were finally evaluated according to equation 1 of DIN 38141 part 4.

The test results clearly show that, compared to the samples with conventional additive (B 10, B 15, B 25), the samples with re-contaminated additive (BWA B 10, BWA B 15, BWA B 25) did not contain any increased amounts of coal Show eluate. Furthermore, it can be seen that as the cement content of the concrete increases, an increase in the carbon dioxide content in the eluate can be observed. This applies both to the samples with conventional aggregate and to the samples with residual contaminated aggregate. The conclusion drawn from this that the cement already contains parts of hydrocarbons could be confirmed by tests on pure cement.

Because of the incorporation of the contaminated aggregates in the cement matrix, the content of carbohydrates that can be measured in the eluate is essentially determined by the hydrocarbons contained in the cement. In general, it can therefore be concluded that, depending on the binder used and the pollutants contained therein - in the case of bitumen, for example, primarily polycyclic aromatics - additives may be contaminated to the extent that this is caused by the "contamination background noise" caused by the binder-inherent degree of contamination is not exceeded. With regard to the use of cement as a binder, it can be stated that ready-made inferior concrete of quality class B 10, that is to say with a relatively low cement content, is completely sufficient to withstand the residual contamination with mineral oil coal contained in the aggregate in an amount of <300 mg per kg dry matter ¬ to stabilize oleic acids sufficiently so that washing out of the concrete and escaping into the environment can be largely prevented.

In addition to the production of precast concrete parts, the concrete provided with residual contaminated aggregates can of course also be used for the production of concrete components which, like foundation parts, are poured in place. For this purpose, the concrete can be transferred to the construction site as ready-mixed concrete or can also be produced at the construction site itself. The floor cleaning system for the fractional cleaning of the contaminated soil particles can be associated with the concrete mill necessary for the production of concrete or separately installed locally from the concrete mill.

Claims

PATENT CLAIMS

1. A process for the production of concrete components, characterized in that, in addition to a binder, soil fractions of soil material fractionated in a floor cleaning installation are used as additives.

2. The method according to claim 1, characterized in that depending on the amount and type of binder used and any concrete additives, the residual contamination to be achieved with the floor cleaning in the floor cleaning system is variably determined.

3. The method according to claim 1 or 2, characterized in that according to the manufacture of DIN concrete floor fractions to be used with fixed particle feeders from the floor cleaning system are fed to a concrete mixing plant and mixed in this with binder and any concrete additives.

4. The method according to Anεpruch 3, characterized in that the mixture formed in the concrete mixer water is fed from a cleaning water cycle of the floor cleaning system.

5. Device for the production of concrete components, characterized by a floor material during the cleaning fractionating floor cleaning system and a concrete mixing unit arranged downstream of the floor cleaning system.

6. The device according to claim 5, characterized in that the floor cleaning system is a mechanical floor washing system, and the concrete machine is connected to a cleaning cycle of the floor washing system iεt.

7. Concrete component, characterized in that the concrete has aggregates which are at least partially formed from soil fractions from fractionated soil material in a floor cleaning system.

8. Concrete component according to claim 7, characterized by the use of cement as a binder, wherein the cement content is preferably chosen to be as low as possible.

9. Concrete component according to claim 7, characterized by the use of bitumen as a binder, the bitumen content preferably being selected to be as low as possible.

10. Concrete component according to claim 7, characterized by the use of synthetic material as a binding agent, wherein the synthetic material content is preferably chosen to be as low as possible.

11. Concrete component according to one of claims 7 to 10, characterized by the use of concrete additives which reduce the water flow through the component.