Self-compacting lightweight concrete

Abstract

The present invention relates to a self-compacting lightweight concrete based on Portland cement, comprising Portland cement, aggregate and at least one chemical concrete additive, wherein - the lightweight concrete is free of sand and gravel and - the concrete additive comprises at least one shrinkage reducing agent, at least one flow agent and at least one stabilizer, characterized in that - the lightweight concrete has a dry bulk density of < 1000 kg / m3 and - the aggregate consists exclusively of expanded glass or exclusively of a mixture of expanded glass and hollow glass spheres, and wherein the lightweight concrete comprises: (a) 40-65 wt.% expanded glass or a mixture of expanded glass and hollow glass spheres, based on the weight of the dry mixture of cement and expanded glass or based on the weight of the dry mixture of cement, expanded glass and hollow glass spheres; (b) 35-60 wt.% cement, based on the weight of the dry mixture of cement and expanded glass or based on the weight of the dry mixture of cement, expanded glass and hollow glass spheres; (c) 0.4-1.5 wt.% shrinkage reducing agent, based on the weight of the cement, (d) 1.0-5.0 wt.% plasticizer, based on the weight of the cement, and (e) 0.5-2.0 wt.% stabilizer, based on the weight of the cement.

Description

[0001] Self-compacting lightweight concrete

[0002] Technical area

[0003] The invention relates to a self-compacting lightweight concrete and a method for producing a self-compacting lightweight concrete.

[0004] State of the art

[0005] Self-compacting lightweight concrete is well-known and represents a new development in the field of high-performance concrete, as it combines the good flow properties of self-compacting concrete with the good deaeration properties of lightweight concrete. This concrete is self-compacting in its fresh state and has a maximum dry bulk density of 2000 kg / m³. 3 .

[0006] Since the weight, the driving force of the flow and compaction process, is lower in lightweight concrete due to its lower bulk density than in normal concrete, the flow and compaction processes are slower than in normal self-compacting concrete. In addition, the lightweight aggregate, i.e. aggregates with high porosity or low density, such as expanded clay, expanded glass, expanded slate or pumice, tends to float due to the sometimes considerable difference between the grain density of the lightweight aggregate and the bulk density of the mortar, if the viscosity is insufficient and the yield point of the mortar is too low. The mostly open-pored lightweight aggregates also extract some of the added water from the fresh mix, which can lead to premature stiffening of the fresh concrete and thus to a loss of the self-compacting properties of the self-compacting lightweight concrete. WO03097553A1 describes a foam glass concrete, i.e.a lightweight concrete in which all or a substantial portion of the aggregate consists of crushed foam glass, i.e., expanded glass, preferably made from recycled glass. However, the use of glass-containing concrete is not without its problems. A particular problem with glass-containing concrete is the presence of alkali in the concrete and the associated problems. Glass is alkali-reactive and reacts with water-soluble alkalis in the concrete, which, in combination with foam glass, leads to the formation of a voluminous gel. In contrast to angular and broken foam glass, expanded glass consists of spheres / round grains that are very lightweight yet compressive, thermally insulating, alkali-resistant, and highly resilient. This type of concrete is not self-compacting.

[0007] US 2016 / 060169A1 describes a lightweight concrete composition comprising one or more cementitious materials and an aggregate mixture consisting of individual particles that are substantially volumetrically stable and non-absorbent. The aggregate mixture comprises hollow glass microspheres, and a deaerating agent, a shrinkage reducing agent, and a viscosity modifier are added. The lightweight concrete composition has a compressive strength, measured according to ASTM C39, of at least about 1750 psi after 28 days. This composition is also not self-compacting.

[0008] AT 406864 B describes a process for producing a lightweight concrete element, wherein a hydraulic binder, e.g. cement, and a low-density aggregate, e.g. expanded clay, expanded glass, pumice, polystyrene or perlite, are mixed under water and a stabilizer made of cellulose ether is added.

[0009] The problem with conventional lightweight concrete mixes is that they rarely produce a very lightweight yet compressive-resistant concrete. These lightweight concrete mixes are often not self-compacting during production, or excessive shrinkage is observed. Furthermore, the production of self-compacting lightweight concrete is complex, subject to many conditions, and the mix often fails, making it impossible to process. This also results in the final product having an aesthetically unappealing surface. Fair-faced concrete cannot be produced with this mix.

[0010] For all these reasons, it has not been possible to date to produce a lightweight concrete composition without the addition of sand and gravel, which meets all the requirements of a self-compacting lightweight concrete, such as high compressive strength, low weight, fair-faced concrete surface, no shrinkage during production, and homogeneous mixing, i.e. no demixing or floating of the lightweight aggregate during production.

[0011] Object of the invention

[0012] The object of the present invention is therefore to create a self-compacting lightweight concrete which eliminates all the disadvantages of the prior art, which has high compressive strengths and a low specific weight, ie a low dry bulk density, good flow properties and good ventilation behavior, which has an aesthetically pleasing exposed concrete surface, and which does not fail during production and does not exhibit shrinkage.

[0013] Description of the invention

[0014] This object is achieved with a self-compacting lightweight concrete based on Portland cement, which comprises Portland cement, aggregate and at least one chemical concrete admixture, wherein the lightweight concrete is free of sand and gravel and the concrete admixture comprises at least one shrinkage reducing agent, at least one superplasticizer and at least one stabilizer, and a dry bulk density of less than 1000 kg / m 3and wherein the aggregate consists exclusively of expanded glass or exclusively of a mixture of expanded glass and hollow glass spheres. The lightweight concrete according to the invention comprises (a) 40 - 65 wt.% expanded glass or a mixture of expanded glass and hollow glass spheres, based on the weight of the dry mix of cement and expanded glass or based on the weight of the dry mix of cement, expanded glass and hollow glass spheres, (b) 35 - 60 wt.% cement, based on the weight of the dry mix of cement and expanded glass or based on the weight of the dry mix of cement, expanded glass and hollow glass spheres, (c) 0.4 - 1.5 wt.% shrinkage reducing agent, based on the weight of the cement, (d) 1.0 - 5.0 wt.% superplasticizer, based on the weight of the cement, and (e) 0.5 - 2.0 wt.% stabilizer, based on the weight of the cement.

[0015] Lightweight concrete is a concrete with a dry bulk density, i.e. volume weight or specific weight, between 350 and 2000 kg / m3 , whereas "normal" concrete has a dry bulk density of 2000 to 2600 kg / m 3 The low density is due to the addition of high-porosity, low-density aggregates. Each grain contains a high proportion of up to 85% by volume of extremely fine air pores. These air pores make the lightweight concrete thermally insulating (low thermal conductivity). Self-compacting lightweight concrete is a lightweight concrete that flows and deaerates solely due to its own weight.

[0016] Any type of Portland cement is suitable, for example, cement defined as CEM I or CEM II according to EN 197-1. CEM I is particularly preferred.

[0017] The lightweight concrete according to the invention contains exclusively expanded glass or a mixture of expanded glass and hollow glass spheres as aggregate and has a dry bulk density of less than 1000 kg / m 3 , particularly preferably from 700 to 990 kg / m3 The specific self-compacting lightweight concrete composition according to the invention enables lightweight concrete with all desired properties. It has a high compressive strength of 11 to 18 MPa / mm 2 , as well as a low specific weight, ie a low dry bulk density of less than 1000 kg / m 3 , particularly preferably from 700 to 990 kg / m 3 In addition, the lightweight concrete exhibits good flow properties and good ventilation behavior, has an aesthetically pleasing exposed concrete surface, and does not shrink during production. Furthermore, virtually no shrinkage of the lightweight concrete is observed during production. Until now, it has not been possible to produce a satisfactory self-compacting lightweight concrete with a dry bulk density of less than 1000 kg / m³. 3Conventional lightweight concrete mixtures that do not contain the proportions of ingredients according to the invention do not provide satisfactory results, as they have a higher dry bulk density than 1000 kg / m 3 or fail during production, meaning the aggregate floats. Furthermore, they do not achieve high compressive strengths with low specific gravity and are not suitable for exposed concrete. Conventional lightweight concrete mixes are also not satisfactorily self-compacting at a dry bulk density of less than 1000 kg / m³. 3 .

[0018] Chemical concrete admixtures can be used as concrete admixtures. In addition to the shrinkage reducer, superplasticizer, and stabilizer, the concrete admixture preferably contains at least one accelerator. The advantage of a composition with an accelerator is that it accelerates the early strength of the concrete mix, i.e., the hardening process.

[0019] In a preferred embodiment, the self-compacting lightweight concrete comprises (a) 45 - 60 wt.% expanded glass or a mixture of expanded glass and hollow glass spheres, based on the weight of the dry mix of cement and expanded glass or based on the weight of the dry mix of cement, expanded glass and hollow glass spheres, (b) 40 - 55 wt.% cement, based on the weight of the dry mix of cement and expanded glass or based on the weight of the dry mix of cement, expanded glass and hollow glass spheres, (c) 0.5 - 1.0 wt.% shrinkage reducing agent, based on the weight of the cement, (d) 1.0 - 4.0 wt.% accelerator, based on the weight of the cement, (e) 2.5 - 3.5 wt.% superplasticizer, based on the weight of the cement, and (f) 0.7 - 1.2 wt.% stabilizer, based on the weight of the cement. Particularly good results are achieved in these quantity ranges and a lightweight concrete with compressive strengths of 11 to 18 MPa / mm 2and a dry bulk density of 700 to 990 kg / m 3 obtained with a homogeneous mix and no shrinkage during production. Furthermore, early demolding is possible, especially at ambient temperatures above 28°C. Demolding is then possible in less than 9 hours.

[0020] The quantity ranges of cement and expanded glass are each calculated as a percentage by weight (wt.%) based on the total weight of the dry mix of cement and expanded glass, or, if hollow glass spheres are used as aggregate in addition to expanded glass, based on the weight of the dry mix of cement, expanded glass, and hollow glass spheres. The quantity ranges of concrete admixtures and water are calculated as wt.% based on the weight of the cement.

[0021] The special thing about the self-compacting lightweight concrete according to the invention is that the aggregate consists exclusively of expanded glass or a mixture of expanded glass and hollow glass spheres, and therefore no other aggregate such as sand, gravel or other lightweight aggregate is added. The special composition of the ingredients enables lightweight concrete with the desired properties to be produced. Until now, it was not possible to produce lightweight concrete with satisfactory properties using only expanded glass or expanded glass and hollow glass spheres as aggregate, because expanded glass and also the hollow glass spheres tend to float on top of the mixture due to their very low specific gravity. Expanded glass as an aggregate has the advantage of being very light and insulating, having a high compressive strength for its specific gravity, being dimensionally stable yet slightly elastic, being fireproof, and having lower expansion and contraction rates.It has a lower shrinkage than other aggregates. The same applies to hollow glass spheres.

[0022] Expanded glass or expanded glass granules is a building material made from recycled waste glass. Expanded glass is foamed glass with small, gas-filled pores and is preferably used in grain sizes of 0.04–8 mm. The granules have a closed lattice structure. In contrast to angular, broken foam glass, which is produced using a similar process but compressed under pressure, expanded glass or expanded glass granules consists of spheres / round grains. The expanded glass or the mixture of expanded glass and hollow glass spheres preferably comprises a mixture of expanded glass particles in each grain size diameter range from 0.04–0.125 mm, 0.1–0.3 mm, 0.25–0.5 mm, 0.5–1.0 mm, 1.0–2.0 mm, 2.0–4.0 mm, and 3.0–8 mm. This means that the expanded glass mixture preferably contains particles with a grain size distribution across the entire sieve curve of 0.04 to 8 mm. The small particles of the sieve curve with a grain size of 0.04 to 0.5 mm can be made of expanded glass or hollow glass spheres, or a mixture of expanded glass and hollow glass spheres. This means that the small grains with a grain size diameter of 0.04 to 0.5 mm can be made exclusively of expanded glass, exclusively of hollow glass spheres, or a mixture of expanded glass and hollow glass spheres. The larger grains with a grain size diameter of 0.5 mm to 8 mm are made exclusively of expanded glass.

[0023] Hollow glass spheres are thin-walled micro-borosilicate glass spheres. They are chemically very stable, have a very low density, high compressive strength, and a grain size of 0.04-0.5 mm. The hollow glass spheres are preferably made from recycled glass, a binder, and a blowing agent and are available, for example, under the name poraSpheres®.

[0024] In a preferred embodiment, the lightweight concrete comprises (a) 9.0 - 17.0 wt.% expanded glass and / or hollow glass spheres with 0.04-0.125 mm grain size diameter, (b) 6.0 - 12.0 wt.% expanded glass and / or hollow glass spheres with 0.1 - 0.3 mm grain size diameter, (c) 6.0 - 11.0 wt.% expanded glass and / or hollow glass spheres with 0.25 - 0.5 mm grain size diameter, (d) 3.0 - 8.5 wt.% expanded glass with 0.5 - 1.0 mm grain size diameter, (e) 2.5 - 9.5 wt.% expanded glass with 1.0 - 2.0 mm grain size diameter, (f) 1.5 - 7.0 wt.% expanded glass with 2.0 - 4.0 mm Grain size diameter, and (g) 1 .25 - 5.5 wt.% expanded glass with 3.0 - 8 mm grain size diameter, based on the total weight of the lightweight concrete dry mix of cement and expanded glass or cement, expanded glass and hollow glass spheres.

[0025] To achieve self-compacting lightweight concrete with the desired properties, the selection of chemical concrete admixtures in a specific amount is crucial. The lightweight concrete according to the invention comprises at least one shrinkage reducing agent, at least one superplasticizer, and at least one stabilizer.

[0026] A shrinkage reducer is a concrete admixture that reduces the drying shrinkage of concrete or mortar. Preferably, a shrinkage reducer is selected that also reduces the pores and blowholes on the concrete surface and expels air. The correct dosage is important, as too high a dosage reduces the concrete strength. The shrinkage reducer preferably comprises at least one polyol, preferably a modified polyol. The shrinkage reducer particularly preferably comprises 2-methyl-2,4-pentanediol and / or 2,2-dimethylpropane-1,3-diol. Such shrinkage reducers are available, for example, under the name SikaControl®. The shrinkage reducer is preferably added in liquid form. The advantage of adding the shrinkage reducer, in addition to minimizing drying shrinkage, is that it enables the production of high-quality exposed concrete.Particularly good results are achieved when the dosage of the shrinkage reducing agent is 0.4 - 1.5 wt.%, preferably 0.5 - 1 wt.%, even more preferably 0.7 - 0.8 wt.%, based on the weight of the cement.

[0027] A superplasticizer, also called a plasticizer, is a concrete admixture that improves the workability of fresh concrete without adding additional water, or that improves the hardened concrete properties by reducing the amount of water added. This means that the superplasticizer increases the water reduction and flowability of concrete mixes, leads to higher densities and strengths, and improves the creep and shrinkage behavior of the concrete. Depending on the dosage and choice of superplasticizer during production, this results in very soft and flowable concrete and thus in self-compacting concrete. The superplasticizer preferably comprises at least one polycarboxylate, more preferably a polycarboxylate ether, a so-called PCE superplasticizer. Such superplasticizers are available, for example, under the name Sika® Viscocrete®. The superplasticizer is preferably added in a dosage of 1.0 - 5.0 wt.%, preferably 2.5 - 4.0 wt.%, even more preferably 2.5 - 3.0 wt.%.5 wt%, based on the weight of the cement.

[0028] Concrete admixtures can be used as stabilizers; they increase the cohesion of fresh concrete, improve its workability, modify its viscosity, and reduce water separation (bleeding) or segregation. The fresh concrete becomes more slippery and easier to work. Stabilizers improve the quality of exposed concrete, particularly lightweight concrete. With appropriate dosage, the stabilizer can reduce the tendency to segregate during the production of self-compacting concrete. Overdosing can lead to the introduction of air voids and sticking of the fine mortar, which impairs workability. The stabilizer preferably comprises modified starch, for example distarch phosphate, acetylated starch or phosphate thereof, hydroxypropyl starch or phosphate thereof. Such stabilizers are available, for example, under the name Sika® Stabilizer. The stabilizer is preferably added in an amount of 0.5 - 2.0 wt.- %, preferably 0.7 - 1.2 wt.%, more preferably 0.8 - 1.2 wt.%, based on the weight of the cement, is added to the lightweight concrete mixture.

[0029] Accelerators are concrete admixtures that reduce the time until the mixture begins to transition from the plastic to the solid state (setting) or that accelerate the initial strength (hardening) with or without affecting the setting time. Hardening accelerators, available, for example, under the name SikaRapid®, are particularly preferred. The accelerator preferably comprises a nitrate-containing calcium silicate. The accelerator is preferably added to the lightweight concrete mix in an amount of 1.0-4.0 wt.%, preferably 2.0-4.0 wt.%, based on the weight of the cement.

[0030] The quantities specified above refer to the total weight of the dry mix. To produce the self-compacting lightweight concrete, the ingredients are mixed with water in the specified quantities. The amount of water is calculated as a percentage by weight based on the amount of cement. Preferably, the water is added in an amount of 50-100% by weight, particularly preferably 70-90% by weight, based on the total weight of the cement.

[0031] A further object of the present invention is a process for producing the self-compacting lightweight concrete according to the invention, comprising the steps:

[0032] (A) Mixing cement and expanded glass or a mixture of cement, expanded glass and hollow glass spheres;

[0033] (B) adding water and mixing with the cement / expanded glass or cement / expanded glass / hollow glass spheres mixture;

[0034] (C) adding the flow agent;

[0035] (D) Addition of the shrinkage reducing agent, the stabilizer and, if appropriate, the accelerator;

[0036] (E) adding additional water if necessary; and

[0037] (F) Pouring and processing the lightweight concrete.

[0038] A preferred method comprises the following steps:

[0039] (A) Mixing cement and expanded glass or cement, expanded glass and hollow glass spheres for 5 to 15 seconds;

[0040] (B) Adding water and mixing with the cement / expanded glass or cement / expanded glass / hollow glass spheres mixture for 30 to 40 seconds;

[0041] (C) Add the flow agent and mix for 40 to 50 seconds;

[0042] (D) adding the shrinkage reducing agent, the stabilizer and, if appropriate, the accelerator and mixing for 35 to 45 seconds; (E) if appropriate, adding additional water and mixing for a further 50 to 70 seconds; and

[0043] (F) Pouring and processing the lightweight concrete.

[0044] Preferably, in step (B) the water is added in an amount of 70 - 100 wt.% based on the cement.

[0045] In both of these aforementioned processes, the cement is first mixed with the expanded glass or with the expanded glass / hollow glass sphere mixture and mixed preferably for 10 to 15 seconds. Then, a large portion of the total water used, also called mixed water, is added to the cement / expanded glass or cement / expanded glass / hollow glass sphere mixture in step (B) and mixed preferably for 30 to 40 seconds. Preferably, 70-90% of the required water is added in step (B). The superplasticizer is then added in the preferred amount and mixed preferably for a further 40 to 50 seconds. Subsequently, the shrinkage reducing agent, the stabilizer, and, if applicable, the accelerator are added in the preferred amount and mixed for a further 35 to 45 seconds. Depending on the consistency of the fresh lightweight concrete mix and as required, additional water can be added as a fine water dosage and mixed again if necessary.As soon as the fresh concrete mix has the desired consistency, it is poured and processed.

[0046] A further embodiment relates to a method comprising the steps:

[0047] (A) Mixing cement and expanded glass or cement, expanded glass and hollow glass spheres;

[0048] (B) Addition of water and simultaneous addition of a mixture of the concrete admixtures superplasticizer, shrinkage reducer and, if necessary, accelerator, but without stabilizer, and mixing with the cement / expanded glass or cement / expanded glass / hollow glass spheres mixture for 70 to 100 seconds;

[0049] (C) Add the stabilizer and mix for 25 to 35 seconds;

[0050] (D) Allowing the concrete to stand (mature) before processing; (E) Pouring and processing the lightweight concrete.

[0051] In this process, the entire required amount of water is added in step (B) along with the superplasticizer, shrinkage reducer, and any accelerator, but without stabilizer, and mixed with the cement / expanded glass or cement / expanded glass / hollow glass sphere mixture, preferably for 70 to 100 seconds. Only then is the stabilizer added and mixed, preferably for another 25 to 35 seconds. The mixture is then allowed to mature, i.e., stand, for preferably about 20 minutes before further processing and pouring.

[0052] A further object of the present invention relates to the use of a bound expanded glass fill for producing a self-compacting lightweight concrete according to the invention.

[0053] The specific composition and the method according to the invention result in a self-compacting lightweight concrete which has a high compressive strength of 11 to 18 MPa / mm 2and a low specific weight, ie a low dry bulk density of less than 1000 kg / m 3 , particularly preferably from 700 to 990 kg / m 3 In addition, the lightweight concrete exhibits good flow properties and good ventilation characteristics, has an aesthetically pleasing exposed concrete surface, and does not collapse during production. Furthermore, virtually no shrinkage of the lightweight concrete is observed during production.

[0054] Embodiments of the invention

[0055] The present invention is described in more detail below by means of exemplary embodiments, which, however, do not limit the scope of the inventive objects. Various mixtures of the inventive lightweight concrete, as well as a mixture containing ingredients outside the inventive amounts, were prepared, and the specific gravity, i.e., the dry bulk density, and the compressive strength were measured. The appearance and shrinkage behavior were also observed.

[0056] For each example, a 1000-liter mixture was prepared. 360 kg of cement and 302.4 liters of water were used. 360 kg of cement was mixed with the amount of expanded glass specified in the tables and mixed for 10 seconds. 270 liters of water were added to this cement / expanded glass mixture and mixed for 35 seconds. The superplasticizer was then added in the preferred amount, specified as a weight percent based on the cement, and mixed for a further 42 seconds. The shrinkage reducing agent, stabilizer, and accelerator were then added in the specified amounts, specified as a weight percent based on the cement, and mixed for a further 41 seconds. Another 32.4 liters of water were added to adjust the fine water dosage, and the mixture was mixed for another 60 seconds. The fresh concrete mix was then poured into 15x15 cm cubes and allowed to harden. The compressive strength and dry bulk density were determined after 7 days and 28 days. The compressive strength and dry bulk density were determined.The dry bulk density was determined according to the test standards SN EN 12350-1,-2,-4, -5, -6, -7, -8, or SN EN 12390-1, -5, or SIA 262 / 1.

[0057] The following tables contain the quantities of the ingredients used to produce the lightweight concrete mix. The quantities of cement and various grain sizes of expanded glass are given in wt.% based on the total dry mix of cement and expanded glass. The quantities of concrete admixtures and water are given in wt.% based on the weight of the cement. Example 1 - Inventive Example The lightweight concrete mix was prepared as described above using the quantities of the ingredients specified here. The fresh concrete mix was poured into 15x15 cm cubes and allowed to harden. The compressive strength and dry bulk density were determined according to the test standards SN EN 12350-1, -2, -4, -5, -6, -7, -8, SN EN 12390-1, -5, and SIA 262 / 1, respectively.

[0058] With this composition, a lightweight concrete with a dry bulk density of 931 kg / m 2 and a compressive strength after 7 days of 9.7 N / mm 2 or after 28 days of 11 N / mm 2 . In addition, the cast concrete had a homogeneous surface and showed no shrinkage. Example 2 - Inventive Example With this composition, a lightweight concrete with a dry bulk density of 990 kg / m 3 and a compressive strength after 28 days of 16 N / mm 2 . In addition, the cast concrete had a homogeneous surface and showed no shrinkage.

[0059] Comparative Example 3 - outside the scope of the invention This lightweight concrete mix was also prepared as described above, using the quantities of the ingredients specified here. The fresh concrete mix was poured into 15x15 cm cubes and allowed to harden. The compressive strength and dry bulk density were determined according to the test standards SN EN 12350-1, -2, -4, -5, -6, -7, -8, SN EN 12390-1, -5, and SIA 262 / 1, respectively.

[0060] This composition resulted in an unworkable concrete mix which segregated and had a high number of voids, i.e. cavities in the mix.

Claims

Patent claims 1. Self-compacting lightweight concrete based on Portland cement, comprising Portland cement, aggregate and at least one chemical concrete admixture, wherein the lightweight concrete is free of sand and gravel and the concrete admixture comprises at least one shrinkage reducing agent, at least one superplasticizer and at least one stabilizer, characterized in that the lightweight concrete has a dry bulk density of less than 1000 kg / m 3 and the aggregate consists exclusively of expanded glass or exclusively of a mixture of expanded glass and hollow glass spheres, and wherein the lightweight concrete comprises: (a) 40-65% by weight of expanded glass or a mixture of expanded glass and hollow glass spheres, based on the weight of the dry mix of cement and expanded glass or based on the weight of the dry mix of cement, expanded glass and hollow glass spheres, (b) 35 - 60 wt.% cement, based on the weight of the dry mix of cement and expanded glass or based on the weight of the dry mix of cement, expanded glass and hollow glass spheres, (c) 0.4 - 1.5 wt% shrinkage reducing agent, based on the weight of the cement, (d) 1.0 - 5.0 wt% superplasticizer, based on the weight of the cement, and (e) 0.5 - 2.0 wt% stabilizer, based on the weight of the cement.

2. Lightweight concrete according to claim 1, characterized in that the concrete admixture additionally comprises an accelerator.

3. Lightweight concrete according to one of the preceding claims, characterized in that the lightweight concrete has a dry bulk density of 700 to 990 kg / m 3 has.

4. Lightweight concrete according to one of the preceding claims, characterized in that the lightweight concrete comprises: (a) 45-60% by weight of expanded glass or a mixture of expanded glass and hollow glass spheres, based on the weight of the dry mix of cement and expanded glass or based on the weight of the dry mix of cement, expanded glass and hollow glass spheres, (b) 40 - 55 wt.% cement, based on the weight of the dry mix of cement and expanded glass or based on the weight of the dry mix of cement, expanded glass and hollow glass spheres, (c) 0.5 - 1 .0 wt.% shrinkage reducing agent, based on the weight of the cement, (d) 1.0 - 4.0 wt% accelerator, based on the weight of the cement, (e) 2.5 - 4.0 wt% superplasticizer, based on the weight of the cement, and (f) 0.7 - 1.2 wt% stabilizer, based on the weight of the cement.

5. Lightweight concrete according to one of the preceding claims, characterized in that the aggregate contains a mixture of expanded glass particles or a mixture of expanded glass particles and hollow glass spheres with a grain size diameter of 0.04 mm - 8 mm.

6. Lightweight concrete according to one of the preceding claims, characterized in that the lightweight concrete (a) 9.0 - 17.0 wt.% expanded glass and / or hollow glass spheres with 0.04-0.125 mm grain size diameter, (b) 6.0 - 12.0 wt.% expanded glass and / or hollow glass spheres with 0.1 - 0.3 mm grain size diameter, (c) 6.0 - 11.0 wt.% expanded glass and / or hollow glass spheres with 0.25 - 0.5 mm grain size diameter, (d) 3.0 - 8.5 wt.% expanded glass with 0.5 - 1 .0 mm grain size diameter, (e) 2.5 - 9.5 wt.% expanded glass with 1.0 - 2.0 mm grain size diameter, (f) 1.5 - 7.0 wt.% expanded glass with 2.0 - 4.0 mm grain size diameter, and (g) 1.25 - 5.5 wt.% expanded glass with 3.0 - 8 mm grain size diameter, based on the total weight of the lightweight concrete dry mix of cement and expanded glass or based on the weight of the dry mix of cement, expanded glass and hollow glass spheres.

7. Lightweight concrete according to one of the preceding claims, characterized in that the shrinkage reducing agent comprises a polyol.

8. Lightweight concrete according to one of the preceding claims, characterized in that the accelerator comprises a nitrate-containing calcium silicate.

9. Lightweight concrete according to one of the preceding claims, characterized in that the flow agent comprises a polycarboxylate, preferably a polycarboxylate ether.

10. Lightweight concrete according to one of the preceding claims, characterized in that the stabilizer comprises modified starch, preferably distarch phosphate, acetylated starch or hydroxypropyl starch.

11. A method for producing a self-compacting lightweight concrete according to any one of the preceding claims, comprising the steps: (A) Mixing cement and expanded glass or cement, expanded glass and hollow glass spheres; (B) adding water and mixing with the cement / expanded glass or cement / expanded glass / hollow glass spheres mixture; (C) adding the flow agent; (D) Addition of the shrinkage reducing agent, the stabilizer and, if appropriate, the accelerator; (E) adding additional water if necessary; and (F) Pouring and processing the lightweight concrete.

12. Method according to claim 11 comprising the steps: (A) Mixing cement and expanded glass or cement, expanded glass and hollow glass spheres; (B) adding water and mixing with the cement / expanded glass or the cement / expanded glass / hollow glass spheres mixture for 30 to 40 seconds; (C) Add the flow agent and mix for 40 to 50 seconds; (D) Add the shrinkage reducing agent, the stabilizer and, if applicable, the accelerator and mix for 35 to 45 seconds; (E) adding additional water if necessary and mixing for a further 50 to 70 seconds; and (F) Pouring and processing the lightweight concrete.

13. Method according to claim 11 comprising the steps: (A) Mixing cement and expanded glass or cement, expanded glass and hollow glass spheres for 5 to 15 seconds; (B) Addition of water and simultaneous addition of a mixture of the concrete admixtures superplasticizer, shrinkage reducing agent and, if appropriate, accelerator from steps (C) and (D), but without stabilizer, and mixing with the cement / expanded glass or cement / expanded glass / hollow glass spheres mixture for 70 to 100 seconds; (C) Add the stabilizer and mix for 25 to 35 seconds; (D) Allowing the concrete to stand (mature) before placing it; (E) Pouring and processing the lightweight concrete.

14. A process according to any one of claims 11 to 13, characterized in that in step (B) the water is added in an amount of 70 - 100 wt.% based on the cement.

15. Use of a bound expanded glass fill for producing a self-compacting lightweight concrete according to one of claims 1 to 10.