Method and device for the production of concrete

Abstract

The water necessary for the production of concrete is replaced by a super-cooled, cooling transfer agent, comprising snow crystals. The cooling transfer agent is produced by mixing water with air and a cooling medium, such as liquid nitrogen, to give a cold gas mixture. The cold gas mixture is sprayed in the form of a cold gas stream. The snow crystals thus formed from the water are brought to a low temperature, of, for example, below minus 30° C. and added to the mixture of binding agents.

1 . A method to produce concrete, in which a binder, such as cement, is mixed together with aggregates to form a binder mixture (Z) and then fresh concrete is made by adding water to the binder mixture (Z),  
       characterized in that 
 the water that is added to the binder mixture (Z) is at least in part in the form of a cold transfer agent (S) consisting of snow crystals.  
 
     
     
         2 . The method according to  claim 1 , characterized in that, in order to prepare the cold transfer agent (S), 
 water is mixed together with a propellant and a coolant to form a cold gas mixture,    the cold gas mixture is then sprayed in the form of a cold gas stream into a spraying chamber ( 9 ), a process in which the water freezes to form snow crystals.    
     
     
         3 . The method according to  claim 2 , characterized in that the cold gas stream is made to rotate when it is sprayed into the spraying chamber ( 9 ).  
     
     
         4 . The method according to  claim 2  or  3 , characterized in that, prior to being added to the binder mixture (Z), the cold transfer agent (S) is brought to a specified temperature of less than −30° C. [−22° F.] in an after-cooling process.  
     
     
         5 . The method according to one of  claims 2  to  4 , characterized in that a cryogenic gas, for instance liquid nitrogen or liquid carbon dioxide, is employed as the coolant for the cold gas mixture and/or for the after-cooling of the cold transfer agent (S).  
     
     
         6 . The method according to one of the preceding claims, characterized in that nitrogen and/or air is employed as the propellant for the cold gas mixture.  
     
     
         7 . The method according to one of  claims 2  to  6 , characterized in that the coolant is employed to transport the generated cold transfer agent (S) to the binder mixture (Z).  
     
     
         8 . A device to prepare concrete, comprising 
 a mixing device ( 7 ) to mix the water, the propellant and a coolant to form a cold gas mixture,    a spray nozzle ( 8 ) that is housed in a spraying chamber ( 9 ) and that is flow-connected to the mixing device ( 7 ), said spray nozzle ( 8 ) being used to spray the cold gas mixture so as to form a cold transfer agent (S) that at least largely consists of snow crystals, and    a mixing chamber ( 2 ) in which the cold transfer agent (S) generated in the spraying chamber ( 9 ) can be mixed together with a binder mixture (Z).    
     
     
         9 . The device according to  claim 8 , characterized in that the spraying chamber ( 9 ) is linked to a cooling unit ( 11 ) for the after-cooling of the cold transfer agent (S) generated in the spraying chamber ( 9 ).  
     
     
         10 . The device according to one of claims  8  or  9 , characterized by a control unit ( 12 ) that is effectively connected to the mixing device ( 7 ) and/or to the mixing chamber ( 9 ), by means of which control unit ( 12 ) the temperature and/or the composition of the cold gas mixture and/or of the fresh concrete can be set.