Basics in Building Construction

Basics in Building Construction 4(2+2)

Lesson 14: Plan Cement Concrete

Curing Of Concrete

Curing of concrete is one of the essential requirements of the process of concreting. Curing is the process of keeping the set concrete continuously damp forsome days in order to enable the concrete gain more strength. It has been established that the strength of concrete increases with the age provided it is kept damp. During the process of curing the concrete absorbs the water necessary for its complete chemical action to reach its required strength. The strength of concrete increases more rapidly in the first few days after setting and afterwards the rate of increase in strength goes on retarding. The period for which curing should be continued depends upon atmospheric conditions such as temperature, humidity and wind velocity. In general the process -of curing should be continued for 7 to 10 days. In cold weather, the concrete- should be cured for at least 14 days, as the rate of hardening of cement is low in such conditions. Efficient curing increases both impermeability and the durability of concrete.

The concrete needs special attention when the concrete is exposed to water pressure or severe weather conditions. , Correct curing also increases resistance of concrete to abrasion and reduces shrinkage. Curing may be done in the following ways

1. by covering the exposed surface with moist. sand, earth, gunny bags etc. and sprinkling water at intervals to keep the
2. tofloors or other horizontal surfaces may be cured by impounding water in earthen or sandy bunds in squares over the entire area. The depth of water in the enclosed squares may be maintained as 5 to 8 cm.
3. columns, walls or other such vertical surfaces are usually cured by wrapping gunny bags or canvas over the surface and keeping the wrapped material continuously wet by sprinkling water or by some other means.
   During the process of curing, increase' in temperature' increases the rate of increase in strength of concrete. This property is made use of in curing small' precast members by steam. This enables the concrete to gain required strength in lesser time.