EP0124724A1 - Method of cooling unset concrete - Google Patents

Method of cooling unset concrete Download PDF

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Publication number
EP0124724A1
EP0124724A1 EP19840102729 EP84102729A EP0124724A1 EP 0124724 A1 EP0124724 A1 EP 0124724A1 EP 19840102729 EP19840102729 EP 19840102729 EP 84102729 A EP84102729 A EP 84102729A EP 0124724 A1 EP0124724 A1 EP 0124724A1
Authority
EP
European Patent Office
Prior art keywords
cooling
flake ice
concrete
liquid nitrogen
fresh concrete
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP19840102729
Other languages
German (de)
French (fr)
Inventor
Wilfried Duesberg
Wolfgang Trappmann
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Messer Griesheim GmbH
Original Assignee
Messer Griesheim GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Messer Griesheim GmbH filed Critical Messer Griesheim GmbH
Publication of EP0124724A1 publication Critical patent/EP0124724A1/en
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28C—PREPARING CLAY; PRODUCING MIXTURES CONTAINING CLAY OR CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28C5/00—Apparatus or methods for producing mixtures of cement with other substances, e.g. slurries, mortars, porous or fibrous compositions
    • B28C5/46—Arrangements for applying super- or sub-atmospheric pressure during mixing; Arrangements for cooling or heating during mixing, e.g. by introducing vapour
    • B28C5/468—Cooling, e.g. using ice

Definitions

  • the invention relates to a method for cooling fresh concrete.
  • the temperature of the fresh concrete must be limited in order to avoid tension and cracks in the structure. In many cases, this cannot be achieved without additional cooling, since not only the supply of heat from the environment has to be taken into account, but also the heat setting process itself, which leads to an increase in temperature in the fresh concrete.
  • cooling the fresh concrete such as. B. cooling with fresh water, which is led through pipes in the building through the fresh concrete becomes.
  • Other methods include cooling the mixing water using chillers, adding flake ice during the mixing process and adding liquid nitrogen during the mixing process.
  • DE-OS 2 438 969 also mentions the possibility of cooling the aggregates or the cement before mixing with liquid nitrogen.
  • the known methods have various disadvantages.
  • the cooling effect of flake ice even if it comes from the cooling machine undercooled, is limited because the water content in the fresh concrete is predetermined. Any desired cooling effect can be achieved by using liquid nitrogen, but large quantities of gaseous nitrogen escape when the liquid nitrogen is sprayed into the mixing plant. Since only the heat of vaporization and not the sensitive heat of liquid nitrogen can be used due to the short batch times, the escaping gaseous nitrogen can lead to icing and malfunctions of the mixing plant.
  • the invention has for its object to provide a method for cooling fresh concrete, which on the one hand allows any cooling effect, on the other hand avoids the risk of icing and malfunctions of the mixing plant.
  • a method for cooling fresh concrete in which part of the water required for the concrete mixture is added to the mixture in the form of disc ice, in which, according to the invention, the flake ice is previously subcooled to low temperatures using a cryogenic refrigerant.
  • the preferred cryogenic refrigerant for the process according to the invention is liquid nitrogen, but in principle other low-boiling liquefied gases or their mixtures, for example liquid argon or liquid air, can also be used.
  • carbon dioxide can serve as a cryogenic refrigerant in liquid form or as dry ice. It is important to ensure that no carbon dioxide can get into the concrete.
  • the subcooling of the flake ice can be accomplished with known devices, for example rotary tube coolers, continuous freezers, cold chambers or continuous freezers.
  • the flake ice is expediently cooled in such a way that the flake ice passes through a bath of liquid nitrogen.
  • a particular advantage of the method according to the invention is that any desired temperature reduction can be achieved by setting the supercooling temperature of the flake ice. Additional cooling measures, such as there is no need to spray the additives with cold water or to cool down the mixing water.
  • the flake ice is additionally supercooled by 100 ° C., for example using liquid nitrogen, an additional 200 kJ / kg of cold are available. If the flake ice temperature is reduced to the temperature of the liquid nitrogen, almost 400 kJ / kg of cold are additionally available. As a result, the temperature reduction of the fresh concrete can be approximately doubled.

Abstract

A part of the mixing water is admixed in the form of crushed ice. To enhance the cooling effect, the crushed ice is subcooled to low temperatures, preferably by means of liquid nitrogen.

Description

Die Erfindung betrifft ein Verfahren zur Kühlung von Frischbeton.The invention relates to a method for cooling fresh concrete.

Bei der Betonierung großvolumiger Bauwerke, beispielsweise von Staumauern, muß die Temperatur des Frischbetons begrenzt werden, um Spannungen und Risse im Bauwerk zu vermeiden. Ohne eine zusätzliche Kühlung läßt sich dies vielfach nicht erreichen, da nicht nur die Wärmezufuhr aus der Umgebung berücksichtigt werden muß, sondern auch durch den Abbindeprozess selbst Wärme entsteht, die zu einem Temperaturanstieg im Frischbeton führt.When concreting large-volume structures, such as dams, the temperature of the fresh concrete must be limited in order to avoid tension and cracks in the structure. In many cases, this cannot be achieved without additional cooling, since not only the supply of heat from the environment has to be taken into account, but also the heat setting process itself, which leads to an increase in temperature in the fresh concrete.

Zur Kühlung des Frischbetons gibt es verschiedene Methoden, wie z. B. das Kühlen mit Frischwasser, welches durch im Bauwerk eingelassene Rohre durch den Frischbeton geführt wird. Weitere Methoden sind die Kühlung des Anmachwassers mittels Kältemaschinen, die Zugabe von Scherbeneis während des Mischprozesses und die Zugabe von flüssigem Stickstoff während des Mischprozesses.There are various methods for cooling the fresh concrete, such as. B. cooling with fresh water, which is led through pipes in the building through the fresh concrete becomes. Other methods include cooling the mixing water using chillers, adding flake ice during the mixing process and adding liquid nitrogen during the mixing process.

Solche Methoden sind beschrieben worden in der US-PS 3,583,172 und der DE-OS 2 438 969. In der DE-OS 2 438 969 wird auch die Möglichkeit erwähnt, die Zuschlagstoffe oder den Zement vor dem Mischen mit flüssigem Stickstoff zu kühlen.Such methods have been described in US Pat. No. 3,583,172 and DE-OS 2 438 969. DE-OS 2 438 969 also mentions the possibility of cooling the aggregates or the cement before mixing with liquid nitrogen.

Den bekannten Methoden haften verschiedene Nachteile an. Die Kühlwirkung von Scherbeneis, selbst wenn dieses unterkühlt aus der Kühlmaschine kommt, ist begrenzt, weil der Wasseranteil im Frischbeton vorbestimmt ist. Durch Verwendung von flüssigem Stickstoff läßt sich zwar eine beliebige Kühlwirkung erzielen, beim Einsprühen des flüssigen Stickstoffs in die Mischanlage entweichen jedoch große Mengen gasförmigen Stickstoffs. Da wegen der kurzen Chargenzeiten nur die Verdampfungswärme und nicht die sensitive Wärme des flüssigen Stickstoffs ausgenutzt werden kann, kann der entweichende gasförmige Stickstoff zu Vereisungen und Funktionsstörungen der Mischanlage führen.The known methods have various disadvantages. The cooling effect of flake ice, even if it comes from the cooling machine undercooled, is limited because the water content in the fresh concrete is predetermined. Any desired cooling effect can be achieved by using liquid nitrogen, but large quantities of gaseous nitrogen escape when the liquid nitrogen is sprayed into the mixing plant. Since only the heat of vaporization and not the sensitive heat of liquid nitrogen can be used due to the short batch times, the escaping gaseous nitrogen can lead to icing and malfunctions of the mixing plant.

Der Erfindung liegt die Aufgabe zugrunde, ein Verfahren zur Kühlung von Frischbeton zu schaffen, welches einerseits eine beliebige Kühlwirkung gestattet, andererseits die Gefahr von Vereisungen und Funktionsstörungen der Mischanlage vermeidet.The invention has for its object to provide a method for cooling fresh concrete, which on the one hand allows any cooling effect, on the other hand avoids the risk of icing and malfunctions of the mixing plant.

Es wurde nun ein Verfahren zur Kühlung von Frischbeton, bei dem ein Teil des für die Betonmischung nötigen Wassers in Form von Scheibeneis in die Mischung gegeben wird gefunden, bei dem gemäß der Erfindung das Scherbeneis zuvor mittels eines cryogenen Kältemittels auf tiefe Temperaturen unterkühlt wird.A method has now been found for cooling fresh concrete, in which part of the water required for the concrete mixture is added to the mixture in the form of disc ice, in which, according to the invention, the flake ice is previously subcooled to low temperatures using a cryogenic refrigerant.

Bevorzugtes cryogenes Kältemittel für das erfindungsgemäße Verfahren ist flüssiger Stickstoff, jedoch lassen sich im Prinzip auch andere tiefsiedende verflüssigte Gase oder deren Mischungen, beispielsweise flüssiges Argon oder flüssige Luft, verwenden. Desgleichen kann Kohlendioxid in flüssiger Form oder als Trockeneis als cryogenes Kältemittel dienen. Hierbei ist aber darauf zu achten, daß kein Kohlendioxid in den Beton gelangen kann. Die Unterkühlung des Scherbeneises kann mit bekannten Einrichtungen, beispielsweise Drehrohrkühlern, Durchlaufgefriergeräten, Kältekammern oder Durchlaufgefrierkammern bewerkstelligt werden.The preferred cryogenic refrigerant for the process according to the invention is liquid nitrogen, but in principle other low-boiling liquefied gases or their mixtures, for example liquid argon or liquid air, can also be used. Likewise, carbon dioxide can serve as a cryogenic refrigerant in liquid form or as dry ice. It is important to ensure that no carbon dioxide can get into the concrete. The subcooling of the flake ice can be accomplished with known devices, for example rotary tube coolers, continuous freezers, cold chambers or continuous freezers.

Bei Verwendung von flüssigem Stickstoff als Kältemittel erfolgt die Unterkühlung des Scherbeneises zweckmäßigerweise derart, daß das Scherbeneis ein Bad aus flüssigem Stickstoff durchläuft.If liquid nitrogen is used as the refrigerant, the flake ice is expediently cooled in such a way that the flake ice passes through a bath of liquid nitrogen.

Ein besonderer Vorteil des erfindungsgemäßen Verfahrens besteht darin, daß durch die Einstellung der Unterkühlungstemperatur des Scherbeneises jede gewünschte Temperaturabsenkung erreicht werden kann. Zusätzliche Kühlmaßnahmen, wie z.-B. das Besprühen der Zuschlagstoffe mit kaltem Wasser oder das Herabkühlen des Anmachwassers erübrigen sich.A particular advantage of the method according to the invention is that any desired temperature reduction can be achieved by setting the supercooling temperature of the flake ice. Additional cooling measures, such as there is no need to spray the additives with cold water or to cool down the mixing water.

Die Verbesserung der Kühlwirkung durch das erfindungsgemäße Verfahren wird aus folgendem Beispiel ersichtlich:

  • Ein typischer Beton, wie er beispielsweise für den Bau von Talsperren verwendet wird, besteht aus 2 100 kg Zuschlagstoffen/m3 110 kg Wasser/m3 und 170 kg Zement/m3. Da durch die Zuschlagstoffe Wasser in Form von Eigenfeuchte in den Beton eingebracht wird, können nur maximal 30 - 40 kg Scherbeneis/m' zur Absenkung der Frischbetontemperatur zugesetzt werden. Dies bedeutet, daß nur etwa 350 kJ/kg Scherbeneis dem Beton entzogen werden können. Es ist damit höchstens eine Temperaturabsenkung von etwa 3 - 4 °C erreichbar.
The improvement in the cooling effect by the method according to the invention can be seen from the following example:
  • A typical concrete, such as that used for the construction of dams, consists of 2 100 kg aggregates / m3 110 kg water / m 3 and 170 kg cement / m 3 . Since water is introduced into the concrete in the form of its own moisture through the additives, only a maximum of 30 - 40 kg of flake ice / m 'can be used to lower the Fresh concrete temperature can be added. This means that only about 350 kJ / kg of flake ice can be extracted from the concrete. A temperature reduction of about 3 - 4 ° C can be achieved.

Wird dagegen gemäß der Erfindung das Scherbeneis beispielsweise durch flüssigen Stickstoff um 100 °C zusätzlich unterkühlt, so stehen zusätzlich 200 kJ/kg Kälte zur Verfügung. Erfolgt die Temperaturabsenkung des Scherbeneises auf die Temperatur des flüssigen Stickstoffes, so stehen nahezu 400 kJ/kg Kälte zusätzlich zur Verfügung. Dadurch kann die Temperaturabsenkung des Frischbetons in etwa verdoppelt werden.If, on the other hand, the flake ice is additionally supercooled by 100 ° C., for example using liquid nitrogen, an additional 200 kJ / kg of cold are available. If the flake ice temperature is reduced to the temperature of the liquid nitrogen, almost 400 kJ / kg of cold are additionally available. As a result, the temperature reduction of the fresh concrete can be approximately doubled.

Claims (2)

1. Verfahren zur Kühlung von Frischbeton, bei dem ein Teil des für die Betonmischung nötigen Wassers in Form von Scherbeneis in die Mischung gegeben wird,
dadurch gekennzeichnet,
daß das Scherbeneis zuvor mittels eines cryogenen Kältemittels auf tiefe Temperaturen unterkühlt wird.1. Method for cooling fresh concrete, in which part of the water required for the concrete mixture is added to the mixture in the form of flake ice,
characterized,
that the flake ice is previously subcooled to low temperatures using a cryogenic refrigerant. 2. Verfahren nach Anspruch 1,
dadurch gekennzeichnet,
daß die Unterkühlung des Scherbeneises mit flüssigem Stickstoff erfolgt.2. The method according to claim 1,
characterized,
that the undercooling of the flake ice takes place with liquid nitrogen.
EP19840102729 1983-04-11 1984-03-13 Method of cooling unset concrete Ceased EP0124724A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3312900 1983-04-11
DE19833312900 DE3312900A1 (en) 1983-04-11 1983-04-11 METHOD FOR COOLING FRESH CONCRETE

Publications (1)

Publication Number Publication Date
EP0124724A1 true EP0124724A1 (en) 1984-11-14

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EP19840102729 Ceased EP0124724A1 (en) 1983-04-11 1984-03-13 Method of cooling unset concrete

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EP (1) EP0124724A1 (en)
DE (1) DE3312900A1 (en)
DK (1) DK183484A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2300631A (en) * 1995-05-10 1996-11-13 David Michael Beaumont Lightweight product; concrete
DE10131838A1 (en) * 2001-06-30 2003-01-16 Messer Griesheim Gmbh Method and device for cooling mixtures of substances by means of supercooled water ice

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004010129B3 (en) * 2004-03-02 2005-09-01 GÖTZ, Werner Device for producing pre-cooled concrete used in civil engineering comprises a unit for producing refrigerated artificial snow, a metering scale arranged in a refrigerated environment, and a feeding system
DE202009005112U1 (en) 2009-08-06 2009-10-22 Hemack Gmbh Device for cooling gravel

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3583172A (en) * 1969-06-30 1971-06-08 Union Carbide Corp Cryogenic cooling of concrete

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2438969A1 (en) * 1974-08-14 1976-02-26 Messer Griesheim Gmbh METHOD FOR COOLING CONCRETE

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3583172A (en) * 1969-06-30 1971-06-08 Union Carbide Corp Cryogenic cooling of concrete

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2300631A (en) * 1995-05-10 1996-11-13 David Michael Beaumont Lightweight product; concrete
DE10131838A1 (en) * 2001-06-30 2003-01-16 Messer Griesheim Gmbh Method and device for cooling mixtures of substances by means of supercooled water ice

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Publication number Publication date
DK183484A (en) 1984-10-12
DE3312900A1 (en) 1984-10-11
DK183484D0 (en) 1984-04-09

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Inventor name: DUESBERG, WILFRIED

Inventor name: TRAPPMANN, WOLFGANG