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Cooling Concrete |
| Concrete buildings like bridges, tunnels and e.g. sewage plants face extremely high quality requirements.
As tensions in the finished concrete building can cause cracks, it is necessary to control the temperature of the green concrete to avoid excessive internal heat-up
The solution
There are several methods :
- Cooling in the agitator truck
- Cooling the water before the mixing process
- Cooling the aggregates
We offer all these solutions.
Customer benefits
The use of liquid nitrogen (LIN) offers some technical and economical advantages:
- Cooling the green concrete in the truck with a cooling lance is the minimum effort solution. As the hardware is on stock, the lead-time can be as short as only one day. Also the investment costs are very low.
- The cooling of water is very efficient. Also the investment costs are quite low in comparison to a conventional water chiller.
- Venting them with cooled air can cool the aggregates stored in certain silos. This gives maximum flexibility to produce as well cooled as “normal” concrete.
- Those several cooling measures are quite low in invest costs compared to conventional cooling methods. Also cost for cooling only occur when there is a demand. LIN-cooling is a very efficient method for peak shaving when the cooling demand exceeds normal values.
Influencing parameters
The ideal cooling solution for the customer depends on individual project needs and circumstances like:
- Concrete production capacity [m³/h]
- Type of the production plant
- Required delivery temperature of the concrete
- Duration of the project
- Available space on the site
- Size of the agitator trucks
- Season of the year (ambient temperature)
Liquid Nitrogen
Concrete cooling with liquid nitrogen (LIN) uses cold, -196°C, liquefied nitrogen produced in air separation plants. LIN is stored in vacuum insulated vessels with some 10.000 litres volume.
A case study
On a construction site for a railway junction in Austria the maximum delivery temperature for some parts of the concrete works were 18°C. Therefore both “normal” and cooled concrete were demanded. To meet these requirements a flexible solution was chosen.
A containerised cooling unit which produce cold water and cold air was installed. To avoid freezing of the wet aggregates under the influence of the cold air a special designed hardware and operational mode is used. Cold water was used for mixing the concrete, the cold gas was blown in some aggregate bunkers. Then the unit was connected to the PLC of the production plant, which allowed an easy choice between several operational modes:
- Using normal water and not-cooled aggregates
- Using cooled water and not-cooled aggregates
- Using cooled water and cooled aggregates
As an additional option a lance cooling station was installed.
The average specific LIN consumption we achieved in 2001 was below 10 kg LIN per m³ concrete and 1 degree Kelvin temperature depression.
The cooling unit was developed in co-operation with the Swiss company Sauter AG, a well known leading manufacturer of heating units for concrete production plants.
1. Control room
2. Mixer
3. Inclined lift for the aggregates
4. Cooling container with cold air pipe
5. LIN storage tank
6. Lance cooling station
7. Aggregate silo
Our co-operation partner for concrete cooling units:  Sauter AG |
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| Dieter Rebhan |
| Telefon: | +49 89 31 001 652 |
| Fax: | +49 89 31 001 654 |
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