The process consists in controlling the rate of dispersion of moisture in the fresh concrete in the phase just after the casting, guaranteeing the time for the reaction of hydration of the cement. Accelerated curing systems control the temperature, since this parameter influences the speed with which the cement is hydrated and consequently the final properties that the concrete can reach.
Accelerated curing can take place using steam, hot water, hot air and diathermic oil as a thermal fluid to accelerate the cement setting reaction.
Traditional but always very effective method of low pressure steam is among the most used techniques in prefabrication. The process takes place placing the products with their molds in aging rooms, or in tunnel providing coverage of the same with appropriate sheets.
Direct steam ensures both the increase in temperature and the increase in relative humidity. These combined effects promote the achievement of high strength values in a short time.
An alternative to the use of direct steam is the use of radiant batteries for condensate recovery heating systems.
For both solutions, low pressure steam is the thermal vector which has the highest latent heat. This, combined with the fact that the concrete curing processes do not require particularly high temperatures, makes the low pressure steam very effective and suitable for this type of application.
The high density polyethylene sheets are used to cover the items after casting, in order to reduce the loss of moisture. They are part of the technique of seasoning with steam to create a saturated atmosphere of moisture and accelerate the hydration of cement. The prefabrication plant must be equipped with wrapping machines to reduce preparation times.