Temperature Regimes
Temperature Regimes
The temperature regime to be applied during the heating of the concrete should give the concrete its prescribed strength and other properties within a specified curing time.
The temperature regime to be selected;
massiveness of the structure,
type and activity of cement,
required concrete strength and
strength development during cooling time
determined by taking into account such matters.
In addition, the type and amount of available energy appears as a determining factor.
The temperature regimes in the heat cure applied to the concrete consist of the following stages:
Pre-wait until the main , when the concrete is placed in the mold, after the heating starts
temperature rise
Constant temperature heating (isothermal heating)
cooling down
Temperature rise and isothermal heating
Concrete reaches its calculation strength at the end of isothermal heating. This method is used in non-mass structural elements ( Mp > 10 ) where cooling is fast and the strength increase during this period is too small to be taken into account.
Temperature rise, isothermal heating and cooling
Concrete gains its strength at the end of the cooling period. It is applied on structural elements with surface modulus Mp = 4 - 10.
temperature rise and cooling; _cc781905-5cde-3194-bb3b-136bad5cf1365cd1363594-bb3b-136bad5cf5cf5cfc-136bad5cf1365cf5835941cf781905cf58d__cc781905-5cde-3194-bb3b-136bad-136bad5cf3b-136bad5cf136557835941
Without constant temperature curing (isothermal heating), only increasing the concrete temperature and at the end of the cooling period, the concrete gains its calculation strength. It is applied on structural elements with surface modulus Mp < 4 .
cooldown
Concrete placed in the mold as heated gains the required strength at the end of the cooling period.
Gradual temperature increase
Concrete is first heated to a certain temperature , cured at this temperature for 1 - 3 hours (isothermal heating), and then with a rapid temperature rise cured to the maximum allowable temperature, cured at this temperature . Depending on the surface modulus, the calculation strength is reached either at the end of curing or at the end of cooling. This method is generally used in prestressed structural elements.
Self-adjusting temperature regime
This method is only used for heating with electrodes. Concrete temperature varies inversely with the specific electrical resistance of concrete. Concrete temperature first increases, reaches a maximum value, then decreases.
All of the described temperature regimes are pre-dwelling.
The pre-wait time is limited to 2 - 6 hours. However, if there are regions in the building element that can cool down and freeze quickly, the preliminary determination period is determined by taking these regions into account, or heating is started as soon as possible.
In order to determine the isothermal heating time required to gain the desired concrete strength, the concrete temperature at the least heated point of the building element is taken as a basis.
