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Abstract:This project comprises of strengthening the compressed fly ash bricks by addition of Ironite
powder.The green movement has greatly influenced the design and construction of the built infrastructure
across the globe. There is a growing interest in delivering high performance building systems. A highperformance
building is as defined in the Energy Policy Act of 2005 [1]:a building that integrates and optimizes
all major high performance building attributes, including energy efficiency, durability, life cycle performance,
and occupant productivity.
This view was echoed by the US building enclosure community in 2008 when they launched a formal
initiative which underscored the linkages between energy efficiency, durability and the quality of the indoor
environment. The discussion in this paper focuses on the realization of high performance buildings through
developing more ecological and durable walling elements based on the use of compressed fly ash bricks by
adding the admixture named Ironite materials to the compressed fly ash bricks at certain ratio. In this we are
going to show the improvement of strength in fly ash bricks through a comparative study.
Introduction
Fly Ash bricks are made of fly ash, lime, gypsum and sand. These can be extensively used in all
building constructional activities similar to that of common burnt clay bricks. The fly ash bricks are
comparatively lighter in weight and stronger than common clay bricks. Since fly ash is being accumulated as
waste material in large quantity near thermal power plants and creating serious environmental pollution
problems, its utilization as main raw material in the manufacture of bricks will not only create sample
opportunities for its proper and useful disposal but also help in environmental pollution control to a greater
extent in the surrounding areas of power plants. In view of superior quality and eco-friendly nature and
government support the demand for Fly Ash Bricks About 150 million ash bricks have been manufactured and
used in house consumption. All the plant use similar processes called FAL-G Technology by using fly ash,
cement/lime and gypsum to manufacture fly ash bricks. These bricks are water cured, thus avoiding the need of
firing or stream curing of the bricks. These Guidelines have been prepared based on inputs provided by various
NTPC plants .These guideline are uniformly followed by manufacturing unit which are conformed through
IS:12894.
Fly Ash
Fly ash is finely divided residue resulting from the combustion of powdered coal transported by the
flue gases and collected by electrostatic precipitator. In UK it is referred as pulverized fuel ash .fly ash is the
most widely used pozzalanic material all over the world. Fly Ash is the inorganic mineral residue obtained after
burning of coal/lignite in the boilers. Fly Ash is the portion of ash which is collected from the hoppers of ESP’s
and pond ash is collected from the ash ponds. Bottom ash is the portion of ash which can be collected from the
bottom portion of the boilers. The characteristics of fly ash depens upon the quality of lignite/coal and the
efficiency of boilers. In general fly ash collected from 1st or 2nd fields of ESP’s as per IS: 3812.
Sand/Stone Dust
All plants use locally available sand/stone dust which is used for collecting works. The following
practice generally followed by most of the plants is recommended. Deleterious material such as clay and silt in
sand /stone dust shall not be more than 5%
Lime
Quick Lime or hydrated lime or both can be mixed in the composition. Lime should have minimum
40% CaO content. Most of the plants use sludge lime, available as waste from acctelyne industries since
hydrated lime confirming much costlier than sludge lime. Use of sludge lime also gives good quality bricks.
However following problems have been noticed while using sludge lime
i. The sludge lime contains extraneous material
ii. It is generally wet
iii. It contain lumps
iv. It is difficult to know the % of available lime (CaO)
Based on the experience of sites the following is recommended for use of good quality sludge lime
i. Sludge lime/hydrated lime proposed to be used during the week should be tested for calcium oxide
content as per clause-9(determination of available lime as CaO) of IS- 1514
ii. Sludge lime shall be free of extraneous material , lumps etc. to the extent possible
Gypsum
Hydrated calcium sulphates are called gypsum. (CaSo4 2H2O). Gypsum should have minimum 35% of
purity and 5 to 15% may be used. The following recommendation is made for the use of gypsum in ash
brick making
i. Gypsum should be free of lumps .Lumps, if any should be screened and remainder over the screen
should be crushed and re-crushed before use.
Gypsum should be tested for its purity as per IS 1288-1982. Its purity should be above 80%. However , in case
of variation in purity percentage of gypsum in the mix it should be adjusted to obtain desired quality of finished
bricks
Cement
Cement is generally defined as binding material .Many of the manufacturing plans has replaced sludge
lime to cement because of the difficulty in the supply of quality sludge lime regularly. Ordinary
Portland cement conforming to IS-269, IS-8112 or IS-12269
Ironite
Ironite is an ore taken from the iron ore .It was used in flooring so that it can withstand heavy vehicles.
Now a day’s Strength Increasing Admixture for Concrete, also known as Ironite-R, is used to enhance the
working of concrete. The plasticizing action of Strength Increasing Admixture for Concrete helps to improve the
appearance mobility and strength of the products. It can also be used for the reduction in cement without loss of
strength. Further, these also have cement dispersing properties that helps in the greater utilization and hydration
of cement. Also, Ironite is an acid-soluble metallic salt, which means that when it comes in contact with water
or acid, it creates a liquid that imparts a permanent stain. Although this stain will not color everything and is not
uniform in shade or transparency, it does provide a lovely mottled earthy brown stain to concrete. It is advisable
that to perform a trial in an inconspicuous area to ensure that, the color it yields. Their current application and
details are as follows.
Objective
The main objective of this project is to increase the strength of the compressed earth bricks which has
been provided through modified spray testing for the assessment of erosion resistance by adding the
admixture Ironite.
The main objective of manufacturing fly ash bricks is to promote ash utilization in thermal power plant
through FAL-G technologies
It has an advantage of reusable property that is, when the brick gets broken it can be used for
construction as there will be no level change in the strength.
The Bricks manufactured through this project will be of cost economical when compared to that of the
Earthen Clay Bricks.
It has also an advantage that there is no occurrence of environmental problems due to the burning of the bricks
as it doesn’t involve any burning process
II. Literature Review
Esther Obonyo, Joseph Exelbirt and Malarvizhi Baskaran. Are the authors of the paper “durability of compressed earth bricks: assessing erosion resistance
using modified spray testing.
The discussion in this paper is part of research directed at establishing optimal stabilization strategy for
compressed bricks. The deployment context for the use of the compressed bricks was Dar es Salaam (Tanzania)
where manually fabricated bricks are increasingly being used in low cost housing units. This discussion
specifically focuses on strategies that can be used to counter deterioration due to wind-driven rain erosion. The
impact of using cement, lime, fibre and a commercial stabilizing fluid was assessed. Factory-produced bricks
were used for benchmarking. The durability of the bricks was assessed using the ―modified Bulletin 5 Spray
Test. The different brick specimens were sprayed with water at 2.07 MPa and 4.14 MPa over one-hour time
period while measuring the depth of erosion every 15 minutes. Factory-produced bricks hardly eroded at both
2.07 MPa and 4.14 MPa pressure levels. The maximum depth of erosion for Soil-Cement bricks ranged from a
maximum of 0.5 mm at 2.07 MPa water pressure to 0.8 mm at 4.14 MPa. The maximum and minimum depths
of erosion for Soil-Cement-Lime bricks were 25mm and 17 mm respectively. The inclusion of natural fibre in
the bricks resulted in a sharp increase of the erosion depth to a maximum of 40 mm at 2.07 MPa and 55 mm at
4.14 Mpa. As the use of natural fibres and lime enhances some physical-mechanical properties, further research
is necessary to determine the ways for achieving this goal while maintaining acceptable levels of erosion
resistance.
Manufacturing Process
The manufacturing process of brick requires fly ash, sand/stone dust, lime and gypsum to be mixed in a
suitable proportion.
Lime and gypsum are first added to the hydraulic mixer machine where it is ground finely as a dry
mixture.
While the mixture is mixed finely and uniformly the grinding of the machine is stopped.
After the above process, the materials ash and the sand stone are of taken in the required quantity.
Ash and sand /stone dust are then added into the pan –mixture to form uniform mixture.
When cement is used in place of lime, first fly ash and sand/stone dust is mixed in pan- mixture and
then cement is added into pan-mixture to have uniform dry mixture
Now the mixer machine is made in ON condition and the above mixture is ground uniformly in the dry
condition.
After this Water is added into the pan-mixture once the uniform dry mixture of fly ash, sand/stone dust and
cement is achieved.
The water content must be added in a required quantity as the mixture must be in a concentration that
they must be capable of molded into the brick.
It is to be carefully noted that the quantity of water must not be more and for per Kg of cement the
water content ratio must not exceed 0.6%.
After the above procedure, now the Ironite material is added in order to improve the strength of the
brick.
In this, ironite are added in an increasing ratio to the pan –mixture
When the quantity of the materials are less they are needed to be transferred through the workers.
When the quantity of the mixture is more, then the process of transferring to the mould could be done
by a belt conveyor.
Hydraulic machine consists of three pairs of brick mould.
After the quantity of the mixture content is transferred to the place of the location of brick mould, it is needed to
be filled into the holes provided in the machine which represents the brick mould.
The mould is usually provided at the circular table which is capable of rotating in clockwise direction.
Conclusion
We have completed our project “Strengthening of Fly ash Bricks by Ironite” successfully. The main
objective of our project is to manufacture the brick with erosion resistance. We also came to know about the
material used, manufacturing method and the strength of the bricks.
From the above we came to know about the realization of high performance buildings through developing more
ecological and durable walling elements based on the use of compressed fly ash bricks by adding the admixture
named Ironite materials to the compressed fly ash bricks at certain ratio.
We have shown the Results over the strengthening of fly ash bricks through a comparative study between the
normal Fly ash bricks and the bricks with the addition of the Admixture named Ironite. The project can be used
to construct structure with erosion resistance by using these bricks.