Steam curing is one of concrete curing method especially used in prefabricated industries. It is preferable where early strength gain in concrete and early removal of formwork is desired or in cold weather condition. When concrete is cured by steam at atmospheric pressure, the temperature of the steam is below 100°C. In this curing method, steam will get converted into water, thus it can be called as hot water curing.
This method is something different from ordinary steam curing. In this method, curing is carried out in a closed chamber and superheated steam at high temperature and high pressure is applied on the concrete. This process is also known as “Autoclaving”. The autoclaving process is practiced in curing precast concrete products in the factory such as lightweight concrete products.
This method of curing is practiced in the manufacture of cellular concrete products, such as Cellular block, precast panel, autoclaved aerated concrete (AAC) blocks etc.
For this curing, concrete is subjected to maximum a temperature of about 175°C which corresponds to a steam pressure of about 8.5 kg/Sq.cm. The curing temperature in the enclosure should not be changed until the concrete has reached the desired strength.
Advantages of high-pressure steam curing
The following are the advantages of high-pressure steam curing process:
(i) High-pressure steam cured concrete develops in one day or less the strength as much as the 28 days’ strength of normally cured concrete. The strength developed does not show retrogression.
(ii) High-pressure steam cured concrete exhibits higher resistance to sulphate attack, chemical action and freezing and thawing action. It also shows less efflorescence.
(iii) High pressure steam cured concrete exhibits lower drying shrinkage, and moisture