Steam curing of concrete is the method of curing the concrete elements in water vapor. This curing is performed either under atmospheric pressure or high-pressure steam. The steam curing method is preferred where there is a need for accelerated strength gain and the concrete requires additional heat to perform hydration. This is especially performed in regions where the temperature is low. Steam curing can be used to advantage where early strength gain in concrete is important or where additional heat is required to accomplish hydration, as in cold-weather concreting.
Need for Steam Curing:
The main reason to opt steam curing is to obtain high early strength. High early strength is very much desirable for the manufacture of precast and prestressed concrete units. These units demand forms and stress beds which is very costly.
Fast removal of concrete forms and moving the finished units to the storage yards is only possible by early strength gain of concrete units. The proper use of steam curing meets this purpose as it accelerates the early gain of strength.
ADVANTAGES:
- It can be used in cold weather conditions for Rapid hardening of concrete
- By this method high early age strength is achieved in concrete
- Speedy construction can be achieved
- Concrete curing time is less than the other methods of curing
- It is mainly used for curing of precast members
DISADVANTAGES:
- Steam curing method cannot will not be efficient for large surface.
- Skilled labours are needed & special materials are required.
- Initial cost of this curing method is high.
METHOD OF CURING:
There are two methods of steam curing
(1) Curing in live steam at atmospheric pressure (for enclosed cast in place structures and manufactured precast units)
(2) Curing in high pressure steam autoclaves (for small manufactured units)
A steam curing cycle consists of:
- An initial delay prior to steaming
- A period for increasing temperature
- A period for holding the maximum temperature constant
- A period for decreasing temperature.
