Since Mortar & concrete have no elastic limit the modulus of elasticity for them must be the slope of stress strain curve at zero stress. However as per IS Code it can be calculated as Ec = 5000 sqrt(fck)
Where, fck = Characteristics Compressive Strength, Ec =14×103 – 40×103 N/mm2
Under unit compression, lateral expansion of concrete about (1/6-1/12) times of unit strain in the direction of applied forces for the ordinary stress. The ratio increases with richness of mix. The value of Poisson’s ratio varies in the range of 0.15-0.2.
The continued deformation with time under applied load is called creep. It may be defined as increase in strain in concrete with time under sustained stress. This is also termed as Plastic Flow/Time yield. The rate of creep decreases with the time & the creep strain at “5 years” are taken as terminal creep. Creep may be due to loss of internal voids, viscous flow of cement paste, flow of water out of cement gel. In RCC structure it is of advantage, as it helps in better distribution of stresses. Creep causes large deformation and deflection that is undesirable.
Shrinkage is contraction concrete in absence of load is known as shrinkage. It may be the following types:
Plastic Shrinkage : It occurs very soon after poring the concrete. The hydration of cement results in reduction in volume of cement due to evaporation of water from the surface.
Drying Shrinkage : It appears after the setting & hardening of concrete due to loss of capillary water.
Carbonation Shrinkage : It occurs due to reaction of carbon dioxide with hydrated cement minerals & carbonating Ca(OH)2 to CaCO3.
Autogenous Shrinkage : It occurs due to no moisture movement from concrete paste under constant temperature.
2. Ultrasonic Pulse Velocity Test
3. Maturity Test
4. Concrete Core Test
5. Pull Out Test
6. Penetration Test
7. Radio Active Test
