Creep and shrinkage in concrete structures
Shrinkage in concrete means decrease in concrete volume because of loss of water.
Coefficient of shrinkage differs with due course of time. Coefficient of shortening is given as follow :-
- 0.00025 at 28 days
- 0.00035 at 3 months
- 0.0005 at 12 months
Shrinkage = Shrinkage coefficient x Length
By undertaking exact curing method, additional shrinkage can be controlled throughout initial 28 days since half of the entire shrinkage occurs throughout this period.
Also read : PROPERTIES OF CONCRETE IN CIVIL ENGINEERING
Workout shortenings owing to creep
Select a column of 3m that is susceptible to sustained load for a long period of time.
Compressive Strength, fc´ = 30 MPa
Sustained stress because of load = 10 MPa
Specific creep for 28 MPa fc´ = 116 x 10-6 per MPa
Creep strain = 10 x 116 x 10-6 = 116 x 10-5
Shortening because of creep = 3000 x 116 x 10-5 = 3.48 mm