Page 30 - GRIHA Manual Volume IV - Introduction to National Rating System
P. 30
Building planning and construction 21
CRIteRIon 15
utIlIzAtIon of fly AsH
In buIldInG stRuCtuRe
Introduction
The construction sector in India is growing at a fast pace, thus, resulting in an ever-increasing
demand of construction materials for the increasing number of buildings.
Conventional clay fired bricks are one of the most important building materials in India. Firing
of bricks is a highly energy-intensive process that utilizes very large quantities of coal and biomass
fuels. Conventional clay fired bricks also leads to depletion of fertile agricultural land, which affects
the quantity of agricultural produce. Thus, there is a need to identify alternatives to the conventional
clay bricks that can be used to replace clay fired bricks and have minimal impact on the environment.
Fly ash is produced as a result of the combustion of coal. It is a residue left at the end of the
combustion process. Coal-based thermal power plants produce thousands of tonnes of fly ash
annually. Fly ash contains various heavy metals and toxic elements like arsenic, cadmium, barium,
lead, mercury, and so on. Fly ash, which is generated as a result of coal combustion, is allowed to be
dispersed in the atmosphere or is usually dumped in landfill sites and ash ponds.
Fly ash consists of very fine particles, and these particles when air-borne are hazardous to both
flora and fauna. Fine fly ash particles stick to the surfaces of leaves reducing their evapo-transpiration
rate, thereby causing chemical as well as physical damage. Fly ash particles form a film on top of the
plants, reducing photosynthesis activity. Excess amount of fly ash in the soil also leads to a shift in
the chemical balance of the soil, causing damage to the plants.
Air-borne fly ash particles, when inhaled, lead to lung disorders in humans. Fly ash leaches
heavy metals into groundwater sources from ash ponds and landfills leading to contamination of
groundwater, making it unfit for consumption.
Blast furnace slag, produced as a by-product of smelting of metals, is another industrial waste
which has negative impacts on human health. Prolonged exposure to slag may cause inflammation
of the cornea, allergic dermatitis, asthma, and lung inflammation.
Solutions
Both fly ash and Blast Furnace Slag (BFS) have pozzolanic properties. This means that they can
be easily used in the construction industry as a substitute for cement. The Indian Standard (IS)
codes recommend certain percentages up to which Ordinary Portland Cement can be replaced by
pozzolana (fly ash or BFS) and converted to Portland Pozzolana Cement.
Using industrial wastes like fly ash and BFS also reduces the amount of virgin materials required
for production of high-embodied energy materials such as cement.
Various uses of fly ash and BFS are mentioned below.
CRIteRIon 15
utIlIzAtIon of fly AsH
In buIldInG stRuCtuRe
Introduction
The construction sector in India is growing at a fast pace, thus, resulting in an ever-increasing
demand of construction materials for the increasing number of buildings.
Conventional clay fired bricks are one of the most important building materials in India. Firing
of bricks is a highly energy-intensive process that utilizes very large quantities of coal and biomass
fuels. Conventional clay fired bricks also leads to depletion of fertile agricultural land, which affects
the quantity of agricultural produce. Thus, there is a need to identify alternatives to the conventional
clay bricks that can be used to replace clay fired bricks and have minimal impact on the environment.
Fly ash is produced as a result of the combustion of coal. It is a residue left at the end of the
combustion process. Coal-based thermal power plants produce thousands of tonnes of fly ash
annually. Fly ash contains various heavy metals and toxic elements like arsenic, cadmium, barium,
lead, mercury, and so on. Fly ash, which is generated as a result of coal combustion, is allowed to be
dispersed in the atmosphere or is usually dumped in landfill sites and ash ponds.
Fly ash consists of very fine particles, and these particles when air-borne are hazardous to both
flora and fauna. Fine fly ash particles stick to the surfaces of leaves reducing their evapo-transpiration
rate, thereby causing chemical as well as physical damage. Fly ash particles form a film on top of the
plants, reducing photosynthesis activity. Excess amount of fly ash in the soil also leads to a shift in
the chemical balance of the soil, causing damage to the plants.
Air-borne fly ash particles, when inhaled, lead to lung disorders in humans. Fly ash leaches
heavy metals into groundwater sources from ash ponds and landfills leading to contamination of
groundwater, making it unfit for consumption.
Blast furnace slag, produced as a by-product of smelting of metals, is another industrial waste
which has negative impacts on human health. Prolonged exposure to slag may cause inflammation
of the cornea, allergic dermatitis, asthma, and lung inflammation.
Solutions
Both fly ash and Blast Furnace Slag (BFS) have pozzolanic properties. This means that they can
be easily used in the construction industry as a substitute for cement. The Indian Standard (IS)
codes recommend certain percentages up to which Ordinary Portland Cement can be replaced by
pozzolana (fly ash or BFS) and converted to Portland Pozzolana Cement.
Using industrial wastes like fly ash and BFS also reduces the amount of virgin materials required
for production of high-embodied energy materials such as cement.
Various uses of fly ash and BFS are mentioned below.
