What is mass concrete| where it is used| Problems

What is Mass concrete?

Any volume of concrete in which a combination of dimensions of the member being cast, the boundary conditions can lead to undesirable thermal stresses, cracking, deleterious chemical reactions, or reduction in the long-term strength as a result of elevated concrete temperature due to heat from hydration.

The one characteristic that distinguishes mass concrete from other concrete work is thermal behavior.
Where is is used?

The mass concrete placed in different massive structures such as dams, bridge piers, canal locks etc

Mass concrete may or may not be reinforced depending upon the intended purpose of the structure. Most of the mass concrete is generally placed in gravity dams which doesn’t require reinforcements but even in these gravity dams, piers for spillway gates and spillway chutes are also heavily reinforced mass concrete.

Problems

The cement-water reaction causes the temperature to rise within a large concrete mass, and where the heat is not quickly dissipated, can be quite high.
Significant tensile stresses and strains may result from the restrained volume change associated with a decline in temperature as heat of hydration is dissipated.
The high temperature due to the heat of hydration may result in an extensive and serious shrinkage in the mass concrete. The shrinkage cracks can be prevented by using low heat cement and by rapid curing of the concrete.

Mass concrete is any volume of concrete with dimensions large enough to require that measures be taken to cope with the generation of heat from hydration of the cement and attendant volume change to minimize cracking.

Grade & strength of mass concrete