The Curing of Concrete. Curing has a strong influence on the properties of hardened concrete ; proper curing will increase, durability, strength, watertightness, abrasion resistance, volume stability, and resistance to freezing and thawing etc.
What is curing of concrete?
Curing is the maintenance of a satisfactory moisture content and temperature in concrete for a period of time immediately following placing and finishing so that the desired properties may develop.
Curing has a strong influence on the properties of hardened concrete ; proper curing will increase, durability, strength, watertightness, abrasion resistance, volume stability, and resistance to freezing and thawing etc.
Hydration of cement:
2C3S + 6H --------> C3S2H3 + 3 Ca(OH)2
100 + 24---------> 75 + 49
2C2S + 4H --------> C3S2H3 + Ca(OH)2
100 + 21 ---------> 99 + 22
C3S requires 24% and c2s requires 21% of water by weight of cement. It has been estimated that avg. 23% is required for complete chemical reaction.
It has been also estimated that about 15% water by wt. Of cement is requires to fill up the gel pores.
So total 38% of water is requires by wt. Of cement for complete hydration process.
In all this it is assumed that hydration is taking place in sealed container, where moisture evaporation does not take place.
Excess or lack of water
may cause undesirable
Capillary cavities.
DEFINATION OF CURING;
(as per ACI-308R)
The term "curing" is frequently used to describe the process by which hydraulic-cement concrete matures and develops hardened properties over time as a result of the continued hydration of the cement in the presence of sufficient water and heat.
(as per IS:456-2000 )
“ curing is the process of preventing the loss of moisture from the concrete.”
Types Of Curing
Water curing:
immersion
Ponding
Spraying
Wet covering