Novel Radiation Shielding Concrete Utilizing Industrial Waste for Gamma-Ray Shielding
Authors: Chouhan Er R.K. , Mudgal Manish 
Published: November 2022

For the first time, the capability of red mud waste has been explored for the
development of advanced synthetic radiation shielding aggregate and radiation
shielding concrete. Red mud, an aluminium industry waste, consists of multi.component and multi-elemental characteristics. Approximately two tons of red mud
are generated for every ton of aluminium production. There are about 85 alumina
plants all over the world, thus leading to the generation of about 77 million tons of
highly alkaline waste annually. The major mineral content of red mud waste includes
hematite, anatase, and cancrinite, thus making red mud waste the most suitable multi.component resource material for developing multi phases containing shielding
aggregate. Further, these multi-elements in the red mud are present in the form of
oxide, oxy-hydroxide, and hydroxides, having low as well as high atomic number
elements, namely sodium, iron, titanium compounds, respectively, and are non-toxic
in nature. The concrete possessing specific gravity higher than 2600 kg/m3
is known
as heavyweight concrete, and aggregate with specific gravities higher than 3000 kg/m3
is called heavyweight aggregate as per TS EN 206-1 (2002). The shielding aggregate
contains both naturally occurring as well as some of the artificial aggregate. The
natural aggregate includes hematite, magnetite, limonite barite, etc., which are non.replenishable and are useful for many other important applications, and the artificial
aggregate includes the use of iron shots and steel filing and in some cases, lead shots,
etc. The use of lead shots makes the material toxic in nature, therefore, there is a need
to avoid the use of lead-based materials for shielding applications, as it ranks second
in the list of hazardous materials. Apart from toxicity associated with lead, the low
melting point of lead is also prohibitive as the shielding concrete should be preferably
heat and fire-resistant. Further, all the natural minerals inherently contain only a single
shielding phase, therefore, conventionally shielding concretes are developed by a
combination of various natural minerals, which leads to an inhomogeneous radiation
shielding matrix in the developed conventional radiation shielding concrete. In view
of the above, there is an urgent need to develop advanced non-toxic synthetic
shielding aggregate capable of providing homogeneous radiation shielding matrix preferably obviating the use of toxic lead and conventional non-replenishable natural
minerals resources. In this chapter, aluminium industrial waste, i.e., red mud, has been
utilized. Chemical formulation and mineralogical designing of the red mud has been
done by ceramic processing using appropriate reducing agents and additives. The
chemical analysis, SEM microphotographs, and XRD analysis confirm the presence
of multi-component, multi shielding, and multi-layered phases in developed advanced
synthetic radiation shielding aggregate. The maximum density of developed synthetic
aggregate is found to be 4.16 g/cc. The mechanical properties, namely aggregate
impact value, aggregate crushing value, and aggregate abrasion value, have been
evaluated and was compared with hematite ore aggregate and found to be an excellent
material useful for making advanced radiation shielding concrete for the construction
of nuclear power plants and other radiation installations.
For the first time, the development and design mix of novel radiation shielding
concrete using innovative red mud-based synthetic shielding aggregates have been
carried out in which the heavy density shielding aggregates are developed using red
mud and are basically ceramic materials consisting of shielding phases, namely
barium silicate (san-bornite), barium iron titanium silicate (bafertisite), barium
aluminium silicate, iron titanium oxide (pseudorutile), barium titanate, barium iron
titanium oxide, barium aluminium oxide, and magnetite, which are multi-elemental,
multi phases, multi-layered crystal structures, therefore, they are excellent shielding
materials.
The radiation shielding concrete was made using developed synthetic shielding
aggregates adopting IS 10262-2009 standard for grade designation of M-30 concrete.
The reference hematite ore concrete and developed concrete tested for radiation
shielding attenuation properties for gamma rays using 137Cs (of photon energy 662
keV) and 241Am (of photon energy 60 keV) were found to possess highly effective
shielding properties. The developed novel design mix concrete achieved an
attenuation factor of 5.8 as compared to 5.1 attenuation factor for reference hematite
ore concrete. The developed radiation shielding concrete using red mud-based
synthetic shielding aggregates possess a broad application spectrum ranging from the
construction of diagnostic X-ray, CT scanner rooms, and storing radioactive waste to
nuclear power plants.