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Posted by : Saurabh Gupta Saturday, February 28, 2015

Fly-ash Bricks & Pavement Tiles

INTRODUCTION :
Fly ash, Lime calcined gypsum and sand, with requisite quantity of water is mixed in proper proportions which produces slow setting cement, the resultant mass pressed is in to bricks of any desired strength. These bricks can be used in building constructional activities instead of common burnt clay bricks. These bricks are lighter in weight and stronger than common burnt clay bricks. The present generation or flyash in India by thermal power stations is more than 100 million tones per annum. One kilogram of coal of fired yields fly ash ranging from 200 to 500 grams. At present only 6% fly ash being utilized. Pavement Tiles are building components with an enhanced used
and adaptability at low cost. The pavement tiles are used for laying hard,durable and attractive flooring in the courtyards, pavements, walkways,car parking and similar locations. The paving stones are made by using fly ash and cement aggregates at very high pressure to give a hard faced,strong and durable stone like product with or without beveled edges.These stones do not require a sole concrete and needs just a consolidated sand bed for the support. No boding or pointing is necessary and does
not require any cement. Paving stones offer the advantage of removing from the position and replacing when ever needed for laying any pipelines etc. and hence eliminates any maintenance expenditure on the flooring. These stones can withstand the weight of a loaded truck and will last for a longtime. They are comparatively cheaper compared to concrete and other tiles.

MARKET :
180 billion tones of common burnt clay bricks are consumed annually approximately 340 billion tones of clay – about 5000 acres of top layer of soil dug out for bricks manufacture, soil erosion, emission from coal burning or fire woods which causes deforestation are the serious problems posed by brick industry. The above problems can be reduced some extent by using fly ash bricks in dwelling units. Demand for dwelling units likely to raise to 80 million units by year 2015 for lower middle and low income groups, involving an estimated investment of $670 billion, according to the Associated Chamber of Commerce and Industry (Assocha). Demand for dwelling units will further grow to 90 million by 2020, which would requires a minimum investment of $890 billion. The Indian housing sector at present faces a shortage of 20 million dwelling units for its lower middle and low income groups which will witness a spurt of about 22.5 million dwelling, units by the end of Tenth plan period. There is ample scope for fly ash brick and block units.

BASIS AND PRESUMPTION :
The process of manufacture is on the basis of single shift of eight hours per day with three hundred working days in a year.
I. To achieve full plant capacity it requires 1 year after trial production.
II. Labour and wages mentioned in profile are as per the prescribed minimum wages.
III. Interest rate at 14% considered in the project profile.
IV. Operative period of project is around 10 years considering technology obsolesce rate and period of repayment of loan.

IMPLEMENTATION SCHEDULE :
Project implementation will take a period of 8 months from the date of approval of the scheme. Break-up of activities with relative time for each activity is shown below :-

Nature of activities time period in months (Estimated)
I. Scheme preparation & approval : 0-1
II. SSI provisional registration : 1-2
III. Sanction of loan : 2-5
IV. Building construction, water, power arrangements : 3-4
V. Placement of order for M/c : 4-5
VI. Installation of machines : 6-7
VII. Power connection : 6-7
VIII. Trial run : 7-8
IX. Commencement of production : 9 onwards.

PROCESS OF MANUFACTURE :
Fly ash (70%) Lime (10%) Gypsum(5%) and sand (15%) are manually fed into a pan mixer where water is added in the required proportion for homogeneous mixing. The proportion of raw material may vary, depending upon quality of raw materials. After mixing, the mixture is shifted to press. The bricks are placed on wooden pallets and transported to open area where they are dried and water cured for 21 days. The bricks are tested and sorted before dispatch.

The manufacture of pavement tiles consists of following process :
• Grinding the fly ash/lime/gypsum compound in a pan-mixer to make a cementius compound.
• Grinding the necessary materials and pigments along with cement in a ball mill, which is used for the top-coat.
• Feeding the above materials into the machine and making the product by compressing the aggregates.
• Removing and staking the products for curing.
• Delivering the product.

INSPECTION AND QUALITY CONTROL :
The Bureau of Indian Standards has formulated and published the specifications for maintaining quality of product and testing purpose. IS : 12894 : 2002. Compressive strength achievable : 60-250 Kg/Cm.Sq. Water absorption : 5-12%; Density : 1.5 gm/cc Coefficient of softening (depending upon water consistency factor) Unlike conventional clay bricks fly ash bricks have high affinity to cement mortar though it has smooth surface, due to the crystal growth between brick and the cement
mortar the joint will become stronger and in due course of time it will become monolithic and the strength will be consistent.

PRODUCTION CAPACITY PER ANNUM :
Quantity : 24,00,000 nos of bricks Value Rs.37,20,000
MOTIVE POWER : 40 HP.
POLLUTION CONTROL :
The technology adopted for making fly ash bricks is eco-friendly. It does not require strength or auto-calving as the bricks are cured by water only. Since firing process is avoided. There are no emissions and no effluent is discharged. Facial masks and dust control equipment may bek provided.

ENERGY CONSERVATION :
General precautions for saving electricity are followed by the unit by providing energy meter. This products are low energy consumption since no need of fire operation in the production unlike conventional bricks. Thus considerable energy could be saved not only in manufacturing activities but also during the construction.


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