The curing process is keeping the
concrete moist awaiting the safe hydration of concrete is complete and strength
is accomplished. Curing of concrete should start on soon after
initial setting time of concrete and should be continued up to 28 days to
attain maximum strength of concrete.
Good Curing of concrete results in
the following strength.
|
Comparative
Strength of Ordinary (Portable) Cement concrete at various ages |
|
|
Curing Time |
Compressive Strength |
|
3-Days |
40% |
|
7-Days |
65% |
|
14-Days |
90% |
|
28-Days |
99% |
|
3-Months |
115% |
|
6-Months |
120% |
|
1-Year |
130% |
Why Curing is Important.
1-Curing is required to avoid dryness
of concrete during setting and hardening of cement that is only possible with
effective hydration of cement, Now how hydration of cement will be effective,
it's only possible when mixing water will remain in concrete during
setting time period of concrete which is 28-days.
If curing is not started after
placing the concrete it will produce only 50% of the total designed compressive
strength in concrete.
2-Curing ensures the safe processing
for the attainment of strength in concrete structures and also helps in speedy construction
practices.
For Example, Concrete Structure avails
90 % strength in 14-Days and mostly engineers remove formworks after 14-days
because structures can afford to hold their self loads after 14-days. The self-load of structures remains around 50% of the total designed load so when concrete
avails its 90 % strength it provides easy and safe decision to remove the formwork
without any hesitation.
3-Curing can raise the strength of
concrete up to 130% which is the guarantee of long life and durability of concrete
in less budgeting, so it is easy to design the structures for 100 years with
effective curing of concretes.
4- Curing helps to attain high and
required strength in concrete which helps to avoid faulty constructions and
also finally provides a safe and
reliable structures.
Curing Methods
1- Shading.
In this method, concrete is covered to
avoid evaporation from sun rays.
2-Ponding.
This method is used only for
horizontal surfaces of slabs and concrete roads but require a lot of water.
3-Spraying of
Water.
This method involves the sprinkling of water on concrete surfaces to keep moist surfaces but this is difficult as requires periodic showering of water.
4-Membrane Curing.
In this method of curing a chemical
coating /Using some membrane is provided on the surface of the concrete to avoid
evaporation of concrete water.
5-Steam Curing/
Hot water Curing.
Curing with Steam and hot water is
sometimes adopted to gain rapid development
in the strength of concrete. This process of curing is best for the construction of
Pre-Cast Structures.
6-Covering.
This is a broadly used technique of curing, mainly for structural concrete. The uncovered surface of the concrete is prohibited from drying out by casing it with a hessian cloth or canvas cloth.
