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.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Structural Engineering (AREA)
• Preparation Of Clay, And Manufacture Of Mixtures Containing Clay Or Cement (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6195934

Family Applications (1)

Country Status (3)

Cited By (3)

Families Citing this family (2)

Citations (1)

Family Cites Families (1)

• 1983
  • 1983-04-11 DE DE19833312900 patent/DE3312900A1/de not_active Withdrawn
• 1984
  • 1984-03-13 EP EP19840102729 patent/EP0124724A1/de not_active Ceased
  • 1984-04-09 DK DK183484A patent/DK183484A/da not_active Application Discontinuation

Patent Citations (1)

Also Published As

Similar Documents

Legal Events