DE19537246C1 - Cupola furnace slag - Google Patents

Abstract

Cupola furnace slag is used as hardening material in the skim surface layer of concrete flooring. The grain size of the slag is: 0-0.5 mm 14-39%; 0.5-2 mm 22-32%; 2-8 mm 29-64%. Also claimed is a process for laying the skim layer.

Description

The invention relates to a cupola slag as a hard material for cement-bound Hard floor screeds and methods for using them in the wear layer of the Screed can be used as an additive, with the cupola slag as Slag is not technologically treated during the liquid phase and as a solidified mass into a crystalline, low-pored rock, which is machined.

The recycling of smelting slag from the state of the art is Smelting process has long been known. These slags fall into considerable Quantities in the iron and steel works. The metallic ones (e.g. iron, copper, lead, zinc) or non-metallic materials (e.g. sulfur, glass, brick) Application mainly thermal processes from ores or minerals as well their concentrates won. The processing of slag is in many patents have been recognized.

A significant disadvantage of all recycling areas is the very fluctuating chemical composition of the slag. This technical disadvantage cannot be fixed because the smelting ores (even from a deposit) have different mineral components. So are the substantial ones Explain fluctuations in basic chemical components, which too lead to changed mechanical properties.

According to the publication DE 37 01 856 A1, the use of blast furnace slag is the a non-machined, uncrushed cupola slag is in place of freshly extracted sand as a cheap raw material for the production of Lime sandstone recorded. The use of non-machined, Uncrushed cupola slag instead of fresh sand is also used for Slimming clay in brick making, in the production of  cement-bound stones, in the manufacture of expanded clay articles or in Given asphalt mixing plants.

One goes in this patent u. a. also assume that the cupola slag springs and can be compressed so that it then expands again or formed into the initial size. Because of these properties, this Technically, cupola slag during the liquid phase have been pretreated that the liquid rock with a water jet was granulated because cupola slag is one to a little crystalline porous rock solidified mass or is present as cupola furnace slag, the does not have these special properties.

The disadvantage of using this blast furnace slag, which is not mechanical Machined, uncrushed cupola slag is that it does not have the required compressive strength and the required bending tensile strength that they for the use of this as an aggregate for hard material in the wear layer of cement-bound hard layers cannot be used.

To eliminate these disadvantages, a high level of technological and technical effort so that it is not mechanically processed, unreduced Cupola slag as granules the necessary usable printing and Bending tensile strength reached.

Furthermore, according to DE-PS 13 02 315 is a glassy solidified, granular Slag is known as a sandy aggregate that works in mortar and concrete with a Binder (lime or cement) and possibly as a coarse aggregate is used, which has thermal insulation and to increase the pressure resistance contributes. This glassy solidified, granulated slag is one Melting boiler slag.

The disadvantage is that this boiler melt slag is a "real" Water granulation to achieve a higher degree of glazing  must be subjected before it is in the corresponding roller mill Grain size is brought. Thus, the boiler melt slag is before it solidifies Technologically pretreated or liquefied again after it has solidified and then treated technologically, so that they can then have a mechanical processing can be used as an additive and / or additive.

According to the document DE 37 26 903 A1 is a self-leveling, hydraulic hardening liquid screed using a hydraulic binder known by quenching and crushing the hydraulic binder granulated blast furnace slag.

The disadvantage here is that the blast furnace slag in the metallurgical plant is technological must be pretreated, then mechanically treated, ground here, to be operational. Another disadvantage of blast furnace slag is that too indicative non-room resistance.

The prior art thus shows aggregates and additives that are made from Boiler smelting slag and blast furnace slag are produced, the Slag before their mechanical treatment and before their solidification subject to technological pretreatment and shows cupola slag that as an additive or additive, before they are used and before they solidify technological pretreatment, but not mechanical is processed.

The use of smelting chamber power plant slags in layers wherever are exposed to increased wear, is from the document DE 36 08 831 A1 known.

Since it is a glassy slag melt, this slag has, in In contrast to cupola furnace slag, there is no sufficient impact smash values. From the above Reasons can be seen that the individual grain of the  Melting chamber slag, as it occurs, is easily divisible. That is the reason for insufficient impact strength and low compressive strength.

The description of the invention contains only a general technical teaching. Because of the lack of exact recipe descriptions and the chemical Composition of the smelting chamber slag is reproducible not given, why the functionality or industrial applicability is not guaranteed regularly.

One method is to manufacture heavy-duty concrete floors Subject of the document DE 37 07 613 A1. Thereafter, a hard material to Use come from quartz sand, corundum or slag from metallurgical Processes.

The invention leaves open what slag from metallurgical processes it is about. The description of the invention contains only a general one technical teaching. However, the feature that a slag as a hard material is sufficient can be used from metallurgical processes, not from to the to show immediate technical effect of the invention proposal. It is lacking here due to the lack of chemical compositions used metallurgical slags on the understandable revelation. The Functionality or industrial applicability is therefore not regular guaranteed.

According to DE-GM 92 04 857, blast furnace slag concrete is used or granulate screed in the floor covering. The disadvantage here is that very high technical and technological effort, as well as the occurring Stress cracks in the granulate screed layer from blast furnace slag. The additional reinforcement mesh can only partially overcome these disadvantages. It is also not understandable that all blast furnace slags have the same results can achieve because the chemical composition is missing.  

As already shown, blast furnace slags or the like have from the Metallurgical slag has the disadvantage that the chemical Composition of the resulting slags a significant mineralogical subject to change.

The object of the invention is to overcome the disadvantages of the prior art eliminate and cupola slag as hard material for cement-bound Use hard screeds, the cupola slag during their liquid phase does not have to be pretreated technologically until it solidifies and preferably from landfills or from foundries directly to one Aggregate to be processed and technologically pretreated Cupola slag present as granules, used mechanically processed shall be.

According to the invention lie in the use of cupola slag in their chemical constant composition compared to the smelter, power plant and steel works slags are justified, considerable advantages.

The foundry slags, which also include the cupola slag, arise in the manufacture of molten metal for casting in corresponding molds. Through the always chemically constant Feed materials (pig iron, cast iron, scrap, coke and aggregates) a slag always forms when melting cast iron in the cupola furnace approximately the same compositions, which are achieved by changing the target Supplements can be changed.

These technological requirements lie with the known ones Areas of application of the slag, power plant and steel works slag are not available.  

The building materials produced according to the invention from cupola slag and its Properties are dependent on the different variations the cooling conditions.

• 1. Cupola slag granules:
  arises from rapid cooling with water, water vapor or air. The result is a glassy raw material with amorphous properties and favorable thermal insulation properties. The granulate has latent hydraulic properties that can be seen in direct dependence on the grain size. The finely ground granulate has the favorable latent hydraulic properties.
• 2. Cupola slag pumice:
  arises from slow cooling with additional blowing agents. The resulting raw material has a glassy-crystalline-porous structure with latent hydraulic properties and favorable thermal insulation values.
• 3. Cupola slag:
  arises from slow cooling with or without vaccination. The properties of this slag are crystalline with low latent hydraulic properties and low thermal conductivities.

The lime-rich cupola slag as a concrete aggregate with the high Hydration factor pH = 10.2 is characterized by considerably higher Compressive strength results, compared to known reference tests technical slags, from.

According to the invention the object according to the in claim 1 specified feature solved.

Preferred developments of the invention result from the respective Subclaims.  

The advantages of the invention are that cupola slag before it Processing into an aggregate with no technological pretreatment must be suspended and after processing into an aggregate that Has property as a hard material in the wear layer of cement-bound Hard screeds to be used, in which

• - no hardening substances are present,
• - there is a higher compressive strength,
• - the room is stable and no lime and iron breakdown can be determined,
• - The levels of sulfur compounds and steel attacking substances clearly are below the limit values according to DIN 4226 T. 1, thus the use in steel and Given prestressed concrete,
• - Use as an artificial hard material for cement-bound hard screeds given is,
• - the frost resistance of the screed is increased,
• - the surface gains quality and there is a higher level of tightness,
• - improved post-curing occurs,
• the cupola furnace slag has a particular hardness,
• - the screed has a high resistance to wear,
• - it is environmentally compatible.

The invention is based on a cupola slag with the following chemical components shown, with slight deviations in the Ca, Mg and Mn content in comparison with cupola slag from different Iron foundries can exist:

The slag consists of glassy solidified calcium-iron-aluminum silicates are water-insoluble and purely mineral.

Bulk density d = 2.6 kg / dm³ / color: gray-green.

The position HCl insoluble shown in the table represents extremely glazed Silicates that are insoluble by hydrochloric acid and essentially contain SiO₂, Al₂O₃ and CaO.

When calculating the reactivity of the slag, the comparison is done by formula below

known to the expert, z. B. the value greater than 1 to 1.9 an increasing Shows reactivity of the slag. The cupola slag shows on average Values from 1.3 to 1.8. Because of this chemical composition of the slag, the with exciter, e.g. B. cement, have good latent hydraulic properties achieved by grinding fineness or by increasing the glass content will.

In foundries, the slag is produced as piece slag or as granules, whereby The granulate is formed when the liquid slag is passed over a water jet becomes. The granulate can be regulated by changing the water jet will. Granulation in the dry process is also possible.

According to the invention, the cupola slag, which is in the form of slag, is also used an impact mill crusher broken, the slag during this mechanical processing behaves very well and it can do any desired Grain groups are produced.

In contrast, the cupola slag, which is present as granules, is used in roller crushers or ball mills ground to a fine aggregate.

Thus, a comprehensive utilization of all emerging and already on Landfill existing cupola slag given. A recovery of the Cupola slag as mechanically processed cupola slag is one of the Surprisingly, experts have not yet been considered, though recycling of blast furnace slag and boiler melt slag is present.

Because of the fact that the German foundry industry according to the new regulations no longer dispose of the cupola slag via environmental protection new fields of application must be opened up. With the recovery Possibilities of this invention can be a valuable one from the residue Starting material for the most diverse areas of application can be created.  

So far, the professional world has not yet tried the area of application as a hard material in screed with mechanically processed cupola slag as an additive carried out.

The invention takes a completely new path. Neither the use of Cupola slag as a glassy solidified, non-granulated aggregate and / or Additive still breaking this and breaking granular Cupola slag using a roller mill is known from the prior art.

The cupola slag comminuted by means of a roller mill shows that in the specified grain size, the slag is particularly well surrounded by the binder. These very good properties of the cupola slag are crucial for that Performance of concrete and screed and thus also for the Performance of cement in concrete. Through the interface, which at the Cupola slag as reaction zone (quasi-continuous transitions, comparable to a weld seam, between the cement stone matrix and the Cupola slag grains) is formed, the strength properties of the material concrete. The chemical inventory of the reaction zone represents a transition mechanism between cupola slag grain and the cement stone matrix. The main elements are aluminum and potassium.

The glassy material is high in energy and thus contributes to increasing the latent hydraulic properties.

This improves the hydration conditions in the screed. It will achieved significantly higher compressive strength and wear values compared to Screed without the use of cupola slag as an additive.

It is significant whether it is broken slag or a Slag granules act because the granules have only the required basic hardness brings. The broken piece slag reaches a hardness of 7 to 7.5 after  10-part Mohs hardness scale and is therefore very suitable for increasing resistance to abrasive wear.

The test grain size was 8 mm to 16 mm Impact destruction values reached. The frost resistance test according to DIN 52104 part 1, method N with the required frost-thaw changes with the test grit 8/16 (chipping <5 mm) gave an average of 0.1 to 0.2 percent by weight in the test.

According to DIN 1100, the addition of cupola furnace slag can be used as hard material in the wear layer of cement-bound hard screeds. The cupola furnace slag is in hard material group A and / or in a mixture with substances from hard material group M (metal) and hard material group KS (Electrical corundum and silicon carbide) can be used. The necessary Grinding wear values (DIN 52108) according to Böhme in hard material group A of max. 5.5 cm³ per 50 cm² is achieved. The bending tensile strength size 10 N / mm² and Compressive strength above 80 N / mm² has been proven.

The use of finely ground cupola slag 0 mm to 2 mm and broken as a supplement of 0 mm to 4 mm is special when used in hard screed advantageous. The grain range between 0.001 and 0.2 mm plays a role special role. One speaks of a mineral grain of flour, the one Has a filling effect in the screed mixture. This grain area has at the same time a latent hydraulic effect.

The latent hydraulic effect of the cupola slag is based on the position in the Three-substance system (SiO₂-Al₂O₃-CaO). The fine-grained cupola slag forms how calcium hydroxide, calcium silicate released during the hardening of the cement and aluminate hydrates.

These hydrate products are largely identical to those of the cements. The Filling effect is based on the fact that the gusset between the grains of the concrete  and screed aggregate are filled by the particles of the cupola slag. The The structure becomes denser. The geometric relationships in a grain mixture depend essentially on the relation between the grain sizes. Normally in the concrete there is only the grain structure for the aggregate over 0.25 mm known. However, this only accounts for 60% of the volume of the concrete. The remaining Fine mortar accounts for 40% of the concrete volume.

The properties of this fine mortar are decisive for its workability of the total mixture. The crystals of the hydrated Ca silicates adhere firmly to the Cupola slag or are firmly connected to each other in the reaction zones and thus achieve increased abrasion resistance.

The filler effect of the cupola slag reduces the Water requirement of a mixture if the additives are adjusted accordingly are. The mix design is in accordance with the technological requirements with the help of the material space calculation. It can be done with a grain density from 2.6 to 2.7 kg / dm³ can be expected.

With the application in hard screed with the addition of cupola slag achieve the following economic effects:

• - The screed has a high resistance to wear, i.e. H. the unwanted Separation of small particles due to mechanical causes becomes essential improved,
• - The mixed batch dry or as a supplement in the factory-made screed of unbroken and broken grains of certain size distributions according to the sieving line with a maximum grain of 8 mm made of cupola furnace slag, as shown below,
• - Can be used economically in all high traffic areas become,
• - The hard material mixture has good processability.

The use of cupola slag as a hard material for cement-bound Hard screeds in the grain size 0 mm to 8 mm as a mixture of different Grain groups are usually made in the top screed layer as factory prefabricated screed or in connection with cement fresh on fresh on the Supporting concrete by incorporation with trowel or with hand rubbing boards.

The process is characterized in that the cupola slag as Aggregate in the above-mentioned grain sizes of the previously mentioned sieve line 0 mm to 8 mm, preferably 0 mm to 4 mm, in different grain sizes 1: 0.4 to 1: 0.8 parts of cement, dry mixed, the not yet set but walkable screed and / or concrete is sprinkled on and then on the Surface is rubbed.

A mixture of cupola furnace slags is used to increase grinding wear. Hard material and known hard material supplements, such as metals or electro-corundum or silicon carbide in a ratio of 1: 04 to 1: 0.8 is advantageously possible.

The dry total mixture of the various hard aggregate supplements is a Add dry cement from 1: 0.5 to 1: 0.9. The further processing is then carried out according to the procedure already mentioned.

The production of a hard screed after a factory mixed Mortar process is also advantageously possible. The aggregate is made Cupola slag produced in compliance with the ideal screening line A8 / B8. The Mixing takes place with a minimum cement content of 350 kg to 450 kg cement each m³ of finished hard screed with a water cement factor of 0.5.  

The fresh hard screed produced in the factory is used on the construction site in two different procedures, installed according to local conditions.

1. An already set concrete surface with a quality of at least B25 is to prepare according to the generally recognized rule of the specialist, d. H. clean, Remove loose parts, dust, cement slurry, oil and grease. Then thoroughly Pre-water, but puddles should be avoided. On the matt damp The surface is an adhesive bridge - preferably consisting of a dispersion of Cement and styrene acrylate - brushed in with a hard broom.

The factory-made hard material screed is then on the Adhesive bridge "fresh in fresh" in a layer thickness of at least 20 mm in To be applied indoors and at least 30 mm outdoors. Of the Hard screed is to be divided between gauges and with a vibrating plank or pull off by hand. After the material has stiffened, the surface is rubbed and smoothable.

For this purpose, trowels or hand rubbing boards are used. In the underground Existing joints must also be congruent in the new coating to be ordered. The after-treatment of the hard screed is carried out according to the Rules of technology (e.g. by covering with foil in front of faster To protect dehydration). Different temperatures influence the Solidification and hardening process.

2. On a freshly installed concrete surface that has not yet set (at least one Concrete quality B25) is after the hard screed has been stiffened in "fresh in fresh" - Procedure applied immediately. This has several advantages. The in the above-mentioned adhesive bond absolutely necessary can be omitted. A monolithic is created between the sub-concrete and the hard screed Connection. It is therefore a shell formation between the sub-concrete and screed locked out. The minimum layer thickness of the hard screed is inside  of 15 mm and 20 mm outdoors. The further processing and aftertreatment is carried out analogously to the procedure mentioned under 1.

The cupola furnace slag is shown below in three specific individual cases Hard material for cement-bound hard screeds shown, the hard material consists of cupola furnace slag as crystalline slag and / or granulate and is used in the dry process. The starting material is in the Screen line (A8 / B8) manufactured.

In the first exemplary embodiment according to FIG. 1, the cupola furnace slag hard material is made from crystalline piece furnace slag with the grain sizes

• - 0 mm to 0.5 mm with 26 percent by weight,
• - 0.5 mm to 2 mm with 31 percent by weight,
• - 2 mm to 8 mm with 43 percent by weight

manufactured.

50 kg of cement are mixed homogeneously in the dry state on 100 kg of the said hard cupola slag. This dry hard material-cement mixture 1 is sprinkled on the sub-concrete / screed fresh 2 , after which these can be walked on, fresh on fresh on the base concrete and / or screed in approx. 1 cm thickness and as an abrasion-resistant wear layer with wing blades or with hand-rubbing boards worked into the fresh concrete and / or screed. (Compressive strength after 28 days 55 N / mm², grinding wear according to Böhme: at least 4 cm³ / 50 cm²).

The water required for the hydration of the hard cement mixture 1 is taken up from the excess water (bleeding) of the concrete and / or screed. A monolithic connection 3 is thus formed as a sub-concrete / screed fresh after incorporation 4 between the hard-cement mixture 1 applied in this way and the sub-concrete and / or screed 2 . Shell formation or crack formation which often occurs with hard materials therefore does not occur.

The cement content of the hard material mixture of 100 kg can vary depending on the requirements fluctuate between 40 kg and 80 kg.

The grain mixture can be used to further increase the wear properties from cupola slag hard material and other hard materials, such as hard metals, or Electro corundum or silicon carbide, with a grain size of 0 mm to 4 mm, be mixed.

The mixing ratio consists of:

• - 100 kg cupola slag hard material
• - 40-80 kg hard materials (hard metal, aluminum oxide, silicon carbide).

Further processing takes place with the addition of cement 50 kg to 90 kg Cement per 100 kg of the hard material mixture in the dry state.

After applying the cupola slag-hard material-cement mixture to the fresh concrete and / or screed, this mixture is described as before incorporated. (Compressive strength after 28 days 55 N / mm², grinding wear after Böhme: at least 4 cm³ / 50 cm²).

Another application of the cupola slag hard material as an additive in Screed in the mortar process should be explained in the application example. With a planned W / Z value = 0.5 a mixture of:

• - Cupola slag according to the A8 / B8 sieve line (see previous Example in the text) 1786 kg / m³ screed,
• - cement 380 kg / m³ screed,
• - Water 190 kg / m³ screed

manufactured.

The screed mixture with hard material properties produced in this way is divided into two different procedures.  

The first method is now explained as an exemplary embodiment in FIG. 2. Thus, an adhesive bridge 6 - known from the prior art - is applied to already set sub-concrete 5 in order to achieve good adhesion to the fresh screed with hard material properties.

The adhesive bridge 6 is preferably a mineral adhesive bridge, consisting of cement and styrene acrylates in dispersion, for the non-positive connections of cement-bound coatings. The subsequent coating is applied to the still soft adhesive bridge "fresh in fresh". After installing a 2 cm to 8 cm thick screed layer as a hard material-screed mixture (liquid / plastic) 7, processing with a hand-held trowel or with a trowel is required.

In the second preferred method according to FIG. 3, the "fresh in fresh" building sub-concrete and screed is represented in layers of 1.5 cm to 5 cm. The hard screed mixture 8 (liquid / plastic) before incorporation, the sub-concrete 9 (liquid / plastic) before incorporation and the hard screed mixture 10 after incorporation into the set sub-concrete 11 are shown. This results in a monolithic structure of the concrete floor 12 . Finally, as in the previously described methods, the compaction should be carried out with a hand-held rubbing board or trowel.

The aftertreatment of all of the methods mentioned is Hard material screed coatings according to the recognized rules of the subject To comply with the standards.

Environmental impact studies of cupola slag manufactured aggregate showed that according to test tables for the assessment of Concentration levels of various contaminated substances in concrete aggregate are not consist.  

Measured against the test table for assessing the concentration level contaminated substances in soils and groundwater ("Dutch list") are Heavy metals measured according to the DIBt test plan in significantly lower amounts Concentrations in the sample under investigation, than those for groundwater, Test values c, would be permissible.

Measured against the limit (or guideline) values that apply to RCL building materials DIN 38414 are the measured concentrations of heavy metals - as far as the Investigations were carried out - significantly lower. The possibly in The heavy metals that can be detected in the solid substance are therefore predominantly not in water-soluble form.

An impairment of the groundwater or soil with possible elution of the concrete made with prepared slag is therefore excluded.

Reference list

1 hard material-cement mixture with further hard materials before incorporation according to embodiment 1
2 sub-concrete / screed fresh before incorporation according to embodiment 1
3 monolithic connection
4 fresh concrete / screed fresh after incorporation according to embodiment 1
5 hard material-screed mixture (liquid / plastic) according to embodiment 2
6 adhesive bridge
7 Sub-concrete / screed set
8 hard material-screed mixture (liquid / plastic) before incorporation according to embodiment 2
9 sub-concrete (liquid / plastic) fresh before incorporation according to embodiment 3
10 hard material-screed mixture after incorporation according to embodiment 3
11 sub-concrete set after incorporation according to embodiment 3
12 monolithic structure of the concrete floor

Claims (9)

1. cupola slag as hard material for cement-bound hard screeds, characterized in that the cupola slag can be used as hard material in the wear layer in the grain size 0 mm to 8 mm, the hard material

• - with a grain size of 0 mm to 0.5 mm 14-39 percent by weight,
• - with a grain size of 0.5 mm to 2 mm 22-32 percent by weight,
• - with a grain size of 2 mm to 8 mm 29-64 percent by weight

has and from granulated cupola slag and / or cupola slag exists, which is in the finely ground and / or broken state. 2. Cupola slag as a hard material for cement-bound hard screeds after Claim 1, characterized in that the hard material preferably with the Grain size 0 mm to 4 mm can be used. 3. Cupola slag as a hard material for cement-bound hard screed after Claim 1 and claim 2, characterized in that the hard material with Cement in a ratio of 1: 0.4 to 1: 0.8 can be used as a mixture in the dry state is. 4. Cupola slag as hard material for cement-bound hard screed after Claim 1 and claim 2, characterized in that the hard material with other hard materials, such as hard metal or aluminum oxide or silicon carbide Cupola slag-hard material mixture forms, the cupola slag with 55 up to 71 percent by weight and the other hard materials with 29 to 45 Weight percentages in a mixture with a grain size of 0 mm to 4 mm are present by the cupola slag-hard material mixture with cement in the dry state in a ratio of 1: 0.5 to 1: 0.9 can be used.   5. Cupola slag as hard material for cement-bound hard screed after Claim 1 and claim 2, characterized in that the hard material with 82 - 87 percent by weight, the cement with 8-11 percent by weight and the water taking into account the water-cement factor with WZ 0.5 as Screed mixture with hard material properties can be used. 6. Process for the use of cupola slag as hard material for cement-bound screed according to claim 1 to claim 4, characterized characterized in that the hard cement mixture in the dry state on the fresh concrete or screed, after which they can be walked on, fresh on fresh the supporting concrete and / or screed as a 1 cm thick abrasion resistant Sealing layer with wing blades or hand rubbing boards in the fresh concrete and / or screed is incorporated, the water for the hydration of the Hard cement mixture from the excess water (bleeding) of the concrete or Screed is available. 7. Process for the use of cupola slag as hard material for cement-bound hard screed according to claim 5, characterized in that the screed mixture with hard material properties on already set Sub-concrete is applied in a thickness of 2 cm to 8 cm and by means of Wing smoothers or hand-rubbing boards this screed mixture is processed by beforehand, an adhesive bridge is applied to the set sub-concrete so that good adhesion to the fresh screed mixture is achieved. 8. Process for the use of cupola slag as hard material for cement-bound hard screed according to claim 5, characterized in that the screed mixture with hard material properties fresh in fresh as a build-up Base concrete and screed in layers from 1.5 cm to 5 cm as a monolithic structure of the concrete floor is applied and then the layers using Wing smoothers or hand rubbing boards are compressed.