The concrete accellerated curing technique, by transfer heat to the concrete, allows to increase the productivity throught a more rational use of plant and work and a reduction of the storage time. Tecnositer s.r.l. propouse principally three methods to transfer heat at concrete by fixed or mobil (in container) thermic plants as follows:

We would make a clear point on the fact that the hot water , flowing inside finned tubes embedded into the casting platforms or into the nelle cassaforme to heat the concrete after the casting, is clearly a possible method but it don't risult more efficient. An example about this statment could be the following: starting from a water temperatur of 95°C we can't give to the concrete a temperature higher than 35°C . Using the hot water as thermic carrier we can take, a quantity of heat, less than the same we could take from the steam. It happens because the only usable heat from the hot water is provided from the "sensitive heat".

The use of the steam, instead of the hot water, permits us to take more heat and therefore a process with a best control about the termperature gradient necessary in the concrete's curing.

To take a decisions between the method of concrete curing with loss of steam or the other with flowing steam into finned tubes we must look upon various things belonging to the technician and economic fields. At the start of the finned solution we will spend a lot (because we must consider the linear cost of the finned tubes) but during the exercising phase we will have clearly, as result, a big energy and money economize. During it's passage into the tubes the steam transmits heat, releasing latent heat, to the concrete and reduce it's temperature and pressure until the condensation. If this condensate drains to the atmospheric pressure it will have a temperature lower than the evaporation's temperature. The last statement imply that the condensate steam (85°C) could be used again in the water's circle saving energy instead of the well's water (15 ÷ 20°C). Using the method with loss of steam we will burn combustible to carry the well's water first from 15°C to 85°C and after from 85°C to evaporation. It means more use of combustible and money.

From a practical point of view, if we must curing concrete items with remarkable dimensions, and especially if it is the thickness, is better use the method with lose of steam because it provides a directly heating to the item with the maximum heat quantity that the steam has at the exit from the distribution system: this situation permits a more effectiveness heating of the item's center.

Curing items with remarkable dimensions by finned tubes method lost something in efficiency. It happens because the steam exchanges heat to the external first by convection, after by conduction and radiation through the tube's wall, and at last by conduction through the concrete; this type of process adds thermic resistens against the heat's passage. The resistens depend on the material's thermic exchange coefficient and on the steam. It's clear that those additioned resistens go to make worse, in it's globality, the thermic exchange between steam and concrete.

Diathermic oil boilers work at temperature lower than the oil's evaporatin temperature and they aren't under pressure. Don't work under pressure guarantees an advantage about the safe plant management. Most of the diathermic oils in commerce today can reach temperatures like 280 ÷ 300°C staing to be liquid at atmospheric pressure.

Diathermic oil presents:

•  very low steam's tens (it permits to work at very low pressure and reduce at minimum the canche of cavitation in the circulation pumps);

•  very low freezing point (it permits to work at extreme ambiental conditions);

•  very good themic stability al high temperature;

•  high heat's transmission coefficient.

Those positive characteristics can be translate into better facility and rapidity about the temperature's control. At last they compete to create a very good heating unit.

The plant's cost is fixed as 100 for the solution with "steam to lose" like indication to be able to compare the other proposed solutions of concrete curing.

Note. Good norm, to choose which solution assume, is consider carefully the real needs during tha concrete curing phase and make attention to the main advantages and disadvantages proposed. We invite you to contact us for a more detailed and personalized research about your plant solution needs.