High Density Concrete

The density of normal concrete is in the order of 2400 kg. per cubic meter. To call the concrete as high-density concrete, it must have a unit weight of around 3360 kg to 3840 kg per cubic meter. However, they can be produced with the densities up to about 5280 kg per cubic meter using iron as both fine and coarse aggregate.


The scope of High-Density concrete. 

The high-density concrete is mainly used in the construction of radiation shields.


            The advent of the nuclear energy industry presents a considerable demand for the concrete technologists. Large scale production of penetrating radiation and radioactive rays as a result of the use of nuclear reactors, industrial radiography, X-ray therapy etc. require the need of shielding material for the protection against any radiation.


 Concrete for Radiation Shielding:


Concrete is an excellent shielding material that possesses the needed characteristics for radiation and has satisfactory mechanical properties and has a relatively low maintenance cost. Also, the ease of construction makes concrete more suitable. Its only disadvantage is  space and weight.

The effectiveness of radiation shielding quality of concrete can be increased by increasing the density. Another important requirement of shielding concrete is its structural strength even at high temperature. To produce high density and high strength concrete, it is necessary to control the water cement ratio very strictly.
There are many aggregates whose specific density is more than 3.5 for making a heavy weight concrete. Out of these, commercially employed aggregates are barite, magnetite, ilmenite, limonite hematite etc. are used.
Physical Properties of high-density concrete


High modulus of elasticity, low thermal expansion and low elastic and creep deformations are ideal properties of high-density concrete.
Concreting practices with respect to mixing, transporting, placing as adopted for normal concrete may also be adopted for high-density concrete but extra care must be taken with respect to segregation of heavy aggregates from rest of the ingredients. 
The formwork is required to be made stronger to withstand higher load.