SE2050089A1

SE2050089A1 - Concrete material

Info

Publication number: SE2050089A1
Application number: SE2050089A
Authority: SE
Inventors: Björn Almqvist; Kjell Svedman
Original assignee: Conpore Tech Ab
Priority date: 2020-01-30
Filing date: 2020-01-30
Publication date: 2021-07-31
Also published as: EP4097058A1; WO2021151747A1

Abstract

The present invention relates to a concrete material having a density of 800-2200 kg/m3 and an air pore volume of at least 10 %, the concrete material comprising fired ceramic particles as aggregate material. This provides a fire resistant and relatively light concrete material, able to withstand high temperatures without deteriorating.

Description

CONCRETE MATERIAL FIELD OF THE INVENTIONThe present invention relates to a concrete material, a method ofproducing such a concrete material and uses thereof.

BACKGROUND OF THE INVENTION Concrete is extensively used worldwide for building durable structures.lt is further commonly used in industrial applications in rather harshconditions, such as for industry flooring, and in furnaces where it is exposedto high temperatures. A problem with concrete materials used for hightemperature applications, such as in furnaces, incinerators or chimneys, isthat they are often cumbersome to install and require long downtimes formaintenance in case replacements are needed due to for example cracking,or loss of mechanical properties of the material over time.

A problem with concrete materials used in industrial environmentshandling combustible liquids is that is that, although concrete per se might befire-resistant, extinguishing a fire due to ignited combustible liquids spilledthereon is difficult. This since the lighter density and different polarity of suchliquids with respect to water causes the ignited liquid to flow on top of thesurface of water which might be applied thereto to extinguish the fire, whereat it continues to burn.

SUMMARY OF THE INVENTIONlt is an object of the present invention to overcome or at least alleviatesome of the above mentioned drawbacks. A particular object is to provide aconcrete material with improved fire resistance and reduced weight. lt is afurther object of the invention to provide a method of producing such aconcrete material.To better address this concern, in a first aspect of the inventionthere is presented a concrete material having a density of 800-2200 kg/m3 and an air pore volume of at least 10 %, which Concrete material comprisesfired ceramic particles as aggregate material.

This provides a fire resistant and relatively light concrete material, withthe density of 800 to 2200 kg/m3, which is able to withstand hightemperatures without deteriorating. The structure of the concrete material,having an air pore volume of at least 10 %, allows liquids applied thereto, orspilled thereon, to be absorbed in the material, i.e. to enter the air pores andtravel there through. The fired ceramic particles of the concrete material canfurther absorb liquids with which it comes into contact. Thus, if aninflammable liquid, such as for example gasoline, diesel or other chemicals, isspilled on the concrete material, for example when used as industrial flooring,such liquid is absorbed by the air pores and the aggregate material of theconcrete material. Should the inflammable liquid ignite and a fire break out,the fire could easily be extinguished with water when sprayed in such anamount that a layer of water covers the fire affected area. As water covers theconcrete material, air pores are obstructed whereby no air enters the interiorstructure and reaches the ignited liquid, thus eliminating air supply to the fire.When the air supply to the fire is eliminated, the fire is extinguished. Should afire break out at the concrete material due to a combustible liquid spilledthereon, it can thus easily and efficiently be extinguished with water. lt isgenerally hard to extinguish a fire caused by an ignited combustible liquid withwater, as such liquids tend to flow on top of the water and remain on fire. Theinventors surprisingly found that this behavior of combustible liquid can beprevented with a concrete material as disclosed herein, providing a greatadvantage in terms of fire resistance thereof.

A further advantage of the concrete material having an air pore volumeof at least 10 %, is that it provides an insulating material considering that theair pores do not conduct heat.

Yet another advantage of the concrete material is its resistance to hightemperatures, provided by the fired ceramic particles. This allows theconcrete material to withstand high temperatures, such as from 1100 to1500 °C, without deteriorating in terms of, for example, cracking, chipping,exploding, or suffering major losses of mechanical properties following exposure to high temperatures. Using fired ceramic particles as aggregatematerial provides stability to the material when heated, since fired ceramicparticles present little to no expansion upon exposure to high temperature. ltfurther allows using recycled material, considering that used fired ceramicobjects may be crushed into particles and thereafter reused as fired ceramicparticles. Undoubtedly, this presents a benefit for the environment.

Herein, the term "fired ceramic particles" refers to materials of clayand/or ceramics which have been fired at high temperatures. The term isintended to denote all fired clay and ceramic wares, including but not limitedto pottery, technical, structural, and refractory products. The term alsodenotes volcanic rock or sand particles, which have effectively been fired athigh temperature when generated in a volcanic eruption. The particles mayhave a size which ranges from tenths of a millimeter to several centimeters.

The term "aggregate materials" as referred to herein refers to aparticulate material which may be added to the concrete mixture in order tocontrol the density of the concrete material. ln a preferred embodiment, the air pore volume is between 10 and60 %. This provides a good compromise between mechanical stability,absorption capacity and light weight of the concrete material. A density ofbetween 800 and 2200 kg/m3 provides a relatively light yet mechanicallystrong concrete material, which eases handling thereof. ln some examples,the concrete material has a density between 900 and 2000 kg/m3, preferablybetween 1000 and 1800 kg/m3. Densities closer to 800-1000 kg/m3 arepreferable when a higher air pore volume of the concrete material is desired,allowing the material to absorb a substantial amount of liquids. At the otherend, densities closer to 1800-2200 kg/m3 are preferable when highermechanical stability of the concrete material is desired. The fired ceramicparticles absorb liquids at all densities. The amount of liquid which can beabsorbed by the fired ceramic particles depend on the particle size.Generally, volcanic sand particles can absorb liquid up to around 30 % of itsown weight.

The concrete material is generally made from a cured concrete mixture comprising water, cement, an air pore forming agent and fired ceramic particles as aggregate material. This provides a fire-proof Concrete material.The cement of the Concrete material may be Portland cement or a mixture ofPortland cement and a refractory cement. The concrete material comprisingPortland cement as cement can generally withstand temperatures up toaround 700 °C. Portland cement is preferably used owing to its good all-roundproperties. Portland cement comprises tricalcium silicate, tricalcium aluminateand calcium aluminium ferrite. Other examples of suitable types of cement tobe used are Portland blast-furnace cement, white Portland cement, low-heatPortland cement and rapid-hardening Portland cement, which are all basedon Portland cement clinker.

The addition of a refractory cement, such as calcium aluminatecement, to the Portland cement allows accelerating the hardening process ofthe concrete mixture. the addition of a refractory cement also provides anincreased temperature resistance of the concrete material. ln an embodiment, the cement of the concrete material is a mixture ofPortland cement and at least 60 % by weight of a refractory cement withrespect to the total amount of cement in the concrete material. Providing amixture of Portland cement and the refractory cement increases thetemperature resistance of the concrete material. As an example, such aconcrete material, comprising a mixture of Portland cement and at least 60 %by weight of a refractory cement, can resist temperatures up to 1500 °C.

According to an embodiment of the concrete material, the refractorycement is a calcium aluminate cement. Such a calcium aluminate cementmay for example be known under the commercial names SECAR® andTERNAL®.

According to an embodiment of the concrete material, the cement ofthe concrete material comprises at least 80 % by weight of a refractorycement, with respect to the total amount of cement in the concrete material.This provides a higher resistance of the concrete material to hightemperatures, while maintaining a considerably low cost of the same.

According to an embodiment of the concrete material, the cement ofthe concrete material is a refractory cement. For producing such a concrete material, a starter is generally needed in order to initiate the chemicalreactions of the concrete mixture.

According to an embodiment, the concrete material has an air porevolume of at least 15 %, such as of at least 20 %, preferably of at least 25 %.lt is contemplated that the amount of liquid the concrete material can absorbrelates in part to the air pore volume, and in part to the amount of liquidabsorbable by the fired ceramic particles.

According to an embodiment, the air pore forming agent is a tenside. Asuitable tenside generates air pores of the concrete material which aresurrounded by the cement and wet the aggregate material, thereby creating abond between the cement and the aggregate material, here the fired ceramicparticles. The tenside may be of ionic or non-ionic type. Examples of tensidesof ionic type are anionic tensides and cationic tensides. Examples of tensidesof non-ionic type are ethylene oxide adducts, such as non-ionic tensidesobtained by adding ethylene oxide to linear secondary alcohols having alkylcarbon atoms ranging between 10 and 14. Such non-ionic tensides may beknown under the commercial names Softanol® (80, 90, 100 or 120) orSurfonyl® (500 or 600). Tensides with similar molecular chains and structureare also possible within the inventive concept. The air pore forming agentmay alternatively be a melamine resin or a protein-based air pore formingagent made up of protein and synthetic additives.

According to an embodiment of the concrete material, the fired ceramicparticles are selected from at least one of crushed bricks, tiles, clay products,pottery, earthenware, clinkers, light weight expanded clay aggregates andvolcanic rocks. This allows using recycled material in the production of theconcrete material, which is advantageous both from an environmental and aneconomic perspective. With respect to volcanic rocks, this is a material whichis naturally available in large quantities and for which no extensive use hasyet been found. As used herein, the terms "volcanic rock" and "volcanic sand"refers to sand and rock that has been formed from lava erupted from avolcano. ln an embodiment, the volcanic sand comprises grains of the glassyrock type obsidian comprising basalt. Particularly, particles of volcanic rockhave been considered unsuitable as aggregate material for forming a Concrete material due to the particles being porous and therefore having apoor mechanical strength per se. However, the inventors have surprisinglyfound that when provided as aggregate material in a concrete material asherein defined, these particles are wetted and adhere well to the cement,leading to a concrete material with high mechanical strength and temperatureresistance.

According to an embodiment of the concrete material, the fired ceramicparticles have a particle size which is less than 20 mm, preferably less than12 mm, more preferably less than 6 mm. The term "particle size" refers to thatthe particles are able to pass through a sieve having the corresponding meshsize. That is, particles having a particle size of less than 20 mm are able topass through a sieve having mesh size of 20 mm. Generally, the particledistribution curve of the aggregate material is chosen depending on theapplication of the concrete material. For a concrete material cast in thinlayers, a smaller particle size is desired. ln an embodiment of the concretematerial having a thickness of 10 mm, the maximum particle size is around3 mm. ln another embodiment, the concrete material having a thickness of3 mm comprises fired ceramic particles with a maximum particle size ofaround 1 mm. lt is generally preferable that the size of the fired ceramicparticles is three times less than the desired thickness of the concretematerial. Furthermore, in order to provide a good compromise betweenmechanical stability and absorption with respect to the density of the concretematerial, a maximum particle size of the fired ceramic particles of 20 mm ispreferred. Fired ceramic particles of this size provide a large surface forabsorbing liquid. For a concrete material of greater thickness, it is howeverpossible to use larger particles.

According to an embodiment of the concrete material, the fired ceramicparticles are fine grained, having a particle size of 0.05 to 2 mm. Providingfired ceramic particles in that particle size range, preferably with an evenparticle size distribution, allows providing the concrete material in a layer of athickness between 0.5 and 5 mm. Preferably, in order to provide mechanicalstrength and a smooth, thin layer, the thickness of the concrete material isthree times that of the particle size. Advantageously, such concrete material is applicable in thin layers to a surface before it hardens. Thus, the concretematerial can be provided in the form of a paste, such as e.g. a putty, which isspreadable onto a surface in thin layers whereat it is allowed to harden. Thespreadable concrete material can e.g. be applied to plaster or wooden wallsor surfaces to provide flame resistance of the same. This is a very efficientway of providing flame resistance of a surface, both in terms of cost and interms of handling and/or installation.

According to an embodiment of the concrete material, the concretematerial further comprises a hydrophobic agent. The hydrophobic agentcauses the concrete material to repel water rather than absorbing it. Thehydrophobic agent thus further enhances the ability of the concrete materialto be extinguished in case of a fire due to ignited combustible liquids spilledthereon, considering that water applied thereto will not be absorbed by theconcrete material.

The hydrophobic agent may be a synthetic or natural resin, orderivatives thereof, having molecular weights of usually below 10,000 and asaponification number of 100-250. Such a resin may be at least partiallysoluble in the concrete mixture, preferably substantially fully soluble in theconcrete mixture. The resin may have a viscosity (Brookfield, 25 degrees C,50 rpm, cps) in the range of 400-1200, such as 600. The resin may be addedas a dispersion having a pH in the range of 8.0-9.5, such as 8.5. The resinsand their derivatives may comprise one or more aromatic and/or aliphaticgroups having at least 10, preferably 16-35 carbon atoms. The groups maybe saturated or unsaturated. Preferred resins are such having an acid numberfrom 10-25, such as 20 and a saponification number from 150 to 175.Examples of suitable resins are various resin acids and mixtures thereof,such as colophonium, and their dimerised derivatives and wholly or partlyesterified and/or hydrated derivatives thereof. The resin may be a tall oil rosin.The resin may be a polymer.

According to an embodiment of the concrete material, the concretematerial has a thickness of at least 2 mm. This means that the concretematerial can be applied as thin blocks, for example as an outermostprotection or sacrificial layer within a furnace. The thickness of the concrete material can further be adapted to the requirements posed on its differentfields of application. The concrete material can be used as a fire delimitingelement, for example for flooring, furnaces, high temperature transportationcompartments, and buildings. More particularly, the concrete material can forexample be provided as panels used as fire delimiting wall elements inbuildings. The concrete material can also be used as sacrificial panels inincinerators to protect the masonry wall. Due to the light weight and cost ofthe concrete material, it can easily be replaced when needed, providingshortened down times of the incinerator for maintenance of this kind.Additionally, due to the high temperature resistance of the concrete material,the temperature of the incinerator using the concrete material as sacrificialpanels may operate at higher temperatures, such as at 1400 °C at which e.g.dioxins are dissolved, thereby preventing emissions of the same from theincinerator to the air.

According to an embodiment of the concrete material, the concretematerial comprises a reinforcing element, such as carbon fibres. Such areinforcing element provides increased mechanical strength of the concretematerial.

According to an embodiment of the concrete material the concretematerial can absorb at least 200 ml inflammable liquid per square meter,thereby allowing a fire in said inflammable liquid to be extinguished by waterbeing sprayed or poured on the concrete material. The inflammable liquidmay be gasoline, diesel or other inflammable chemicals, such as oils ofdifferent kinds. Preferably, the concrete material should be able to absorb atleast 250 ml, such as at least 300 ml, preferably at least 400 ml inflammableliquid per square meter, when the concrete material is used as e.g. a flooringmaterial. ln particular, it is capable of absorbing the above amount of liquidwhen said liquid is being spilled on the floor. Thus, should the inflammableliquid ignite and a fire breaks out in the spilled liquid, the fire could easily beextinguished with water when sprayed in such an amount that a layer of watercovers the fire affected area on the concrete floor. As water covers theconcrete material, air pores are obstructed whereby no air enters the interior structure and reaches the ignited liquid, thus eliminating air supply to the fire.When the air supply to the fire is eliminated, the fire is extinguished. ln accordance with a second aspect of the invention, there is provideda method of producing a concrete material having a density of 800-2200kg/m3 and an air pore volume of at least 10 %. The method comprises thesteps of providing water, an air pore forming agent, cement and aggregatematerial to a mixer; agitating the added ingredients while entraining air to forma homogeneous, stable, air-containing concrete mixture; and curing theconcrete mixture, thereby forming the concrete material having a density of800-2200 kg/m3 and an air pore volume of at least 10 %, wherein theaggregate material is composed of fired ceramic particles.

The method allows producing the concrete material with a density of800-2200 kg/m3 and an air pore volume of at least 10 % which is resistant tohigh temperatures. The method is further advantageous as it allowsproducing the concrete material on site or prefabricate the concrete materialfor posterior delivery to the installation site. The method allows casting theconcrete material vertically or horizontally.

The air pore forming agent may be a tenside of a non-ionic, cationic oran anionic type. The air pore forming agent may, in other embodiments, be amelamine resin or a protein-based air pore forming agent made up of proteinand synthetic additives, as discussed with regards to the first aspect of theinvenﬁon.

According to an embodiment, the fired ceramic particles areselected from at least one of crushed bricks, tiles, clay products, pottery,earthenware, clinkers, light weight expanded clay aggregates, and volcanicrocks. Such fired ceramic particles are inert during the curing of the cementmixture and has, thus, no accelerating effect on that stage of the productionmethod of the concrete material.

According to an embodiment, the ratio, by weight, of cement toaggregate material is in the range of 0.8-1 .2 : 0.8-1.2. ln these proportions,the aggregate material and the generated air pores are surrounded bycement, providing mechanical strength to the concrete material, The air pores surrounded by cement further provides a good absorption capacity of theconcrete material.

According to an embodiment, the method comprises the step ofproviding a hydrophobic agent to the mixer to form part of the concretemixture. This provides hydrophobic properties to the produced concretematerial, enhancing the ability of the material to be extinguished with water incase of a fire due to ignited combustible liquids absorbed by the material.Examples of hydrophobic agents used are discussed with reference to thefirst aspect of the invention.

According to an embodiment, the concrete material obtained by themethod has a density of 1000-1800 kg/m3. The provision of differentconstituents of the concrete material, i.e. the amount of cement, aggregateparticles, air pore forming agent and eventual additives are adapted to thedesired density of the concrete material. A density of between 1000 and1800 kg/m3 is particularly preferred in view of the combination provided ofabsorption capacity, weight and mechanical strength of the concrete material.

According to an embodiment, the aggregate material is damp whenprovided in the mixer. According to another embodiment, the aggregatematerial is dry when provided in the mixer. That is, the aggregate material canbe provided either damp or dry. lt may be advantageous to provide theaggregate material damp in order to avoid particle contamination of the air inthe working environment.

According to an example, the method further comprises a step ofwetting the aggregate material before provision to the mixer. The wetting ispreferably performed by pouring water over the aggregate material understirring of the aggregate material.

According to an embodiment, the aggregate material, instead of beingprovided in the mixer together with water, the air pore forming agent andcement, is provided to the homogeneous, stable, air-containing concretemixture formed after agitating the aforementioned constituents. Also in thisexample, the aggregate material may be provided damp or dry to theconcrete mixture. ln accordance with a third aspect of the invention, there is provided ause of a concrete material as disclosed herein. According to an embodiment,there is provided a use of a concrete material as disclosed herein as a firedelimiting element, such as for flooring, walls, furnaces, high temperaturetransportation compartments, and buildings. The use of the concrete materialin such applications is advantageous due to its resistance to hightemperatures and capacity to be extinguished in case it is ignited asdiscussed herein. Further advantages with the use of the concrete material insuch applications are ascribed the light weight, low cost and convenientproduction method thereof.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail and with referenceto the appended drawings, in which: Figs. 1a-c show schematic illustrations of a floor of a standard concretematerial; and Figs. 2a-c is show schematic illustrations of a floor made of anembodiment of a concrete material according to an aspect of the invention.

DESCRIPTION OF EMBODIMENTS The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which exemplifying embodimentsof the invention are shown. The present invention may, however, beembodied in many different forms and should not be construed as limited tothe embodiments set forth herein; rather, these embodiments are provided forthoroughness and completeness, and to fully convey the scope of theinvention to the skilled addressee.

Referring to Figs. 1a-c, a scenario for an industry floor made of astandard concrete material 10 is illustrated. ln Fig. 1a, combustible liquid 2,such as for example gasoline or diesel, has been spilled onto the standardconcrete floor 10. lf the combustible liquid 2 ignites, a fire breaks out andwater 3 can be applied to the floor in an attempt to extinguish the fire, see Fig. 1b. Due to the nature of the combustible liquid 2, generally having a lowerdensity and different polarity with respect to water 3, the combustible liquid 2flows on the surface of the water 2 where it continues to burn. Therefore, thefire is difficult to extinguish.

Referring to Figs. 2a-c, a similar scenario for an industry floor isillustrated where the industry floor is made of a concrete material 1 having adensity of 800-2200 kg/m3 and an air pore volume of at least 10 %, theconcrete material comprising fired ceramic particles as aggregate materialand at least 60 % by weight of a refractory cement, with respect to the totalamount of cement in the concrete material. ln Fig. 2a, a combustible liquid 2is spilled onto the concrete material 1. ln case the combustible liquid 2 ignites,water 3 is applied to the floor of concrete material 1 in Fig. 2b. Due to thestructure of the concrete material 1, having an air pore volume of at least10 %, the combustible liquid is absorbed in the in the concrete material 1, seeFig. 2c. The water 3 applied to the surface of the concrete material 1 forms alayer on top of the same, obstructing the air pores, whereby no air enters thepores and to the ignited liquid 2. The fire is thereby efficiently extinguished.

ExamplesExample 1. Production of a concrete material for ﬁre delimiting applications For producing a concrete material suitable for use in fire delimitingapplications, the following step-wise procedure took place. Into a laboratorymixer, 200 g of standard Portland cement, 800 g of refractory cement soldunder the trade name SECAR®71 and 1000 g of crushed brick particleshaving a particle size between 4 um - 3 mm was added. Thereafter, 700 g ofwater, 3.5 g of an air pore forming agent and 5 g of a hydrophobic agent,previously mixed, was added to the mixer. The mixture was agitated whileentraining air resulting in the formation of a homogeneous, stable, air-containing concrete mixture. The concrete mixture was casted in a mold toobtain a shape which is suitable for fire delimiting applications, and allowed toharden. The density of the produced concrete material was 1400 kg/m3.

Example 2. Production of a Concrete material for ﬁre delimiting applicationsFor producing a Concrete material suitable for use in fire delimiting applications, the following step-wise procedure took place. Into a laboratorymixer, 200 g of standard Portland cement, 800 g of refractory cement soldunder the trade name SECAR®71 and 1000 g of crushed brick particleshaving a particle size between 4 pm - 3mm was added. Thereafter, 640 g ofwater, 3.3 g of an air pore forming agent and 3.3 g of a hydrophobic agent,previously mixed, was added to the mixer. The mixture was agitated whileentraining air, resulting in the formation ofa homogeneous, stable, air-containing Concrete mixture. The Concrete mixture was Casted in a mold toobtain a shape which is suitable for fire delimiting applications, and allowed toharden. The density of the produced Concrete material was 1740 kg/m3.

Example 3. Fire extinguishing test The Concrete material produced according to Example 1 was used in afire extinguishing test. A block of the Concrete material having a size of 350 x350 x 50 mm with an edge around the periphery of the upper surface, referredto as block A, was arranged next to a block of a standard Portland cement ofgrade K400 having the same size and geometry, referred to as block B, with aspace there between. 100 ml of gasoline was poured onto each of the twoConcrete blocks. The edges around the periphery of the respective uppersurfaces assured that the gasoline did not flow along the outer sides of theblock. After 60 s, block A and block B were ignited by means of a lighter. Afteranother 60 s, during which both block A and block B were on fire, two bottleswith a volume of 330 ml containing water was used for pouring water ontoeach of the two blocks, i.e. one bottle was used for block A and one bottlewas used for block B. The fire of block A was extinguished immediately,before the content of the bottle was emptied. The fire of block B wasextinguished 60 s after the entire content of the bottle had been pouredthereon.

The test clearly shows that the Concrete material disclosed hereinpresents high fire delimiting capacity.

Example 4. Production of a flame proof Concrete material in form of a pasteFor producing a Concrete material suitable for being provided as a paste and spread onto a surface whereat it is allowed to harden for providingflame resistance of the surface, the following step-wise procedure took place.Into a laboratory mixer, 800 g of cement and 2000 g of fine grained volcanicrocks, having a particle size of 0.1-1 mm, was added and mixed to form a drymixture. Into a container, 875 g of water was added. Thereafter, 2.5 g of anair pore forming agent and 3.5 g of a hydrophobic agent was added to thewater, forming a liquid mixture. Subsequently, approximately 70 % of theliquid mixture was added to the dry mixture in the laboratory mixer forming aConcrete mixture. The Concrete mixture was agitated. More liquid mixture wasthereafter added until a desired density and consistency of the Concretemixture paste was obtained.

The skilled person realizes that a number of modifications of theembodiments described herein are possible without departing from the scopeof the invention, which is defined in the appended Claims. Other variations tothe disclosed embodiments can be understood and effected by those skilledin the art in practicing the Claimed invention, from a study of the drawings, thedisclosure, and the appended Claims. ln the Claims, the word "comprising"does not exclude other elements or steps, and the indefinite article "a" or "an"does not exclude a plurality. Any reference signs in the claims should not beconstrued as limiting the scope.

Claims

1. A Concrete material having a density of 800-2200 kg/m3 and an air pore volume of at least 10 %, wherein said concrete materialcomprises fired ceramic particles as aggregate material.

2. The concrete material according to claim 1, comprising at least 60 % by weight of a refractory cement, with respect to the total amount ofcement in said concrete material.

3. The concrete material according to claim 1 or 2, wherein said fired ceramic particles are selected from at least one of crushed bricks, tiles,clay products, pottery, earthenware, clinkers, light weight expandedclay aggregates, and volcanic rocks.

4. The concrete material according to any one of the preceding claims, wherein said fired ceramic particles have a particle size which is lessthan 20 mm, preferably less than 12 mm, more preferably less than 6mm.

5. The concrete material according to any one of the preceding claims, wherein said fired ceramic particles have a particle size of between0.05 and 2 mm.

6. The concrete material according to any one of the preceding claims, wherein the density of said concrete material is from 1000 to1800 kg/mß.

7. The concrete material according to any one of the preceding claims, wherein said concrete material comprises at least 80 % by weight ofsaid refractory cement, with respect to the total amount of cement insaid concrete material.

8. The Concrete material according to any one of claims 2-6, wherein saidrefractory cement is a calcium aluminate cement.

9. The concrete material according to any one of the preceding claims,wherein the ratio, by weight, of cement to aggregate material is in therange of 0.8-1 .2 : 0.8-1.2.

10.The concrete material according to any one of the preceding claims,wherein said concrete material further comprises a hydrophobic agent.

11.The concrete material according to any one of the preceding claims,wherein said concrete material has a thickness of at least 2 mm.

12.The concrete material according to any one of the preceding claims,wherein said concrete material comprises a reinforcing element, suchas carbon fibres.

13.The concrete material according to any one of the preceding claims,wherein the concrete material can absorb at least 200 ml inflammableliquid per square meter, thereby allowing a fire in said inflammableliquid to be extinguished by water being sprayed on the concretematerial.

14. A method for producing a concrete material having a density of 800-2200 kg/m3 and an air pore volume of at least 10 %, the methodcomprising the steps of: a) providing water, an air pore forming agent, cement andaggregate material to a mixer; b) agitating the added ingredients while entraining air to form ahomogeneous, stable, air-containing concrete mixture; and c) curing said concrete mixture, thereby forming said concretematerial having a density of 800-2200 kg/m3 and an air porevolume of at least 10 %, wherein said aggregate material is composed of fired ceramic particles.

15. The method according to claim 12, wherein said fired ceramicparticles are selected from at least one of crushed bricks, tiles, clayproducts, pottery, earthenware, clinkers, and light weight expandedclay aggregates.

16.The method according to any one of claims 12 and 13, wherein saidfired ceramic particles have a particle size which is less than 20 mm,preferably less than 12 mm, more preferably less than 6 mm.

17. The method according to any one of claims 12-14, wherein the ratio,by weight, of cement to aggregate material is in the range of0.8-1.2 : 0.8-1.2.

18. The method according to any one of claims 12-15, wherein at least80 % by weight of said cement is a refractory cement.

19.The method according to any one of claims 12-16, wherein said refractory cement is a calcium aluminate cement.

20.The method according to any one of claims 12-17, wherein step a)further comprises providing a hydrophobic agent.

21. .The method according to any one of claims 12-18, wherein theconcrete material formed in step c) has a density of 1000-1800 kg/m3.

22.The method according to any one of claims 12-19, wherein saidaggregate material is damp when provided in step a).

23.The method according to any one of claims 12-19, wherein saidaggregate material is dry when provided in step a).

24. The method according to any one of claims 12-21, wherein saidaggregate material, instead of being provided in step a), is provided to the homogeneous, stable, air-containing Concrete mixture formed instep b).

25. Use of a Concrete material according to any one of claims 1-11 as afire delimiting element, such as for flooring, furnaces, high temperaturetransportation compartments, and buiidings.