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Monday, 20 February 2012

FLY ASH BRICKS


With changing time and modes of construction and the type of form work which are taking place today has led to development of many new type of construction material which are now a days are widely used and also widely demanded. In this era the most important construction material which has change from time to time is the bricks. It is the foremost material for all type of construction without it the construction on any structure remains incomplete.


According to the construction work requirement of bricks also used to vary depending upon what type of construction work is to be done for example mud bricks were used to provide thermal comfort etc….. In the same era not new nor we can say that it is old also a new type of brick is emerging at a fast rate for the construction work and its name is “FLY ASH BRICKS” though it is not widely demanded but it has been introduce to some of the major projects. In this report it will show the process of manufacturing of fly ash bricks , its uses , and it is economical compared to the other bricks. All the detailing about “FLY ASH BRICKS” will be done in this report…..
                                                      
SCOPE

Since this bricks have not been used on large scale for the construction work. But it has good scope in future, because this brick is being manufactured from the waste material known as fly ash which generally comes from the industrials waste in mass, manufacturing of this bricks avoid the difficulty of dumping fly ash too….since the natural resources are becoming limit so what makes it availability and easy way to manufacture will increase its scope for the construction work.

Fly ash bricks also reduce the chances of pollution during its construction work which is not same in all the bricks manufacturing process. High compressive strength, better workability, fire resistance……..and all these quality of the bricks will increase its future scope of construction work. Soon we will find that in lots of construction work fly ash bricks are being widely used……….

TYPES OF BRICKS
THERE ARE DIFFERENT TYPES OF BRICKS AVAILABLE SOME OF THEM ARE AS FOLLOW :


·         MUD BRICKS

·         RAIL KLINS

·         BULL TRENCH KLINS

·         DRY PRESSED BRICKS

·         EXTRUDED BRICKS

·         CALCIUM SILICATE BRICKS

·         FLY ASH BRICKS

·         CEMENT CONCRETE BRICKS

·         BURNT CLAY HOLLOW BRICKS

·         STABILISED SOIL BRICKS

·         SAND LIME BRICKS

·         BURNT CLAY JALLIES BRICKS



DETAILS OF FLY ASH BRICK

Description:


Not too old but not too new also it is that type of brick which is composed of fly ash and water compressed 4,000 psi (27,939 kPa) for two weeks. Owing to the high concentration of calcium oxide in fly ash, the brick is considered "self-cementing". The brick is toughened using an air entrainment agent, which traps microscopic bubbles inside the brick so that it resists penetration by water, allowing it to withstand up to 100 freeze-thaw cycles. Since the manufacturing method uses a waste by-product rather than clay, and solidification takes place under pressure rather than heat, it has several important environmental benefits. It saves energy, reduces mercury pollution, alleviates the need for landfill disposal of fly ash, and costs 20% less than traditional clay brick manufacture.


MANUFACTURING PROCESS


Materials required:

§  Fly ash

§  Lime gypsum

§  Sand


Process involved:

§  Mixing the ingredients

§  Pressing the mix in machine

§  Curing the brick for stipulated period




Detail description of manufacturing process:


The process of manufacturing of fly ash bricks is based on the reaction of lime with silica of fly ash to form calcium silicate hydrate ( c-s-h ) which binds the ingredients to form brick. The quality of bricks obtained are highly dependant on the quality of fly ash. The manufacturing of LIME-FLY ASH bricks are generally designed such that they stand at par with burnt clay bricks used conventionally. 

FLYASH: (usage 60-70 %) Apart from conforming to IS requirement the minimum requirement for manufacturing of fly ash bricks are as follow :

                  Loss of ignition --- should not be more than 12 %
           
                  Availability of  Mgo ---should not be more than 5%

                  Availability of siO2 --- should not be more than 35 %

                 Availability of Al2O3 --- should not be more than 15 %
LIME: (usage 8-15%) Lime is very important ingredients used for manufacturing of bricks , hence it should satisfy following minimum requirement :

Lime , while slaking process should not attain less than 60 degree Celsius temperature and slaking time should not be more than 15 minutes .

Availability of Cao should be minimum 60% .

Mgo content should be maximum of 5% .

GYPSUM: (usage 2- 5%) It is added to mix in order to accelerate hardening process and acquiring the early strength . It should have minimum 35% of  purity .


SAND: (usage 0- 8%) Additional of sand is optional , but to enhance the gradation , of the mix , addition of coarse sand is quite preferable . Addition of sand also enchance the resitivity of mix to formation of laminar cracks caused due to entrapped air .


MIXING PROCESS


After all the materials are taken in the required proportion as mention above the first step involved is the mixing of the ingredients a fig below is shown how the mixing of these materials is done ……





                                              


                                      MIXING OF INGREDIENTS IS DONE



PRESSING THE MIX IN THE MACHINE

After the mixing process is over than the foremost steps comes in that is the pressing of the mix in the machine for getting the good shape of the bricks and good strength also. Fig below show the machine which is used for the pressing purpose….

                                              

                         BRICK PRESSED DEVELOPED BY CBRI, ROORKE



                                                                               

DOUBLE ACTING BRICK PRESS DEVELOPED BY CYBERTEK ENGINEERING, FARIDABAD

CURING OF THE BRICKS


After the mixing and pressing process is over curing is very important if it is not cured properly than the proper strength is not gained and as a result final bricks form cannot be used for the any type of the form work. Proper curing of bricks is very important for the bricks to regain its strength. It should be cured for a period of two weeks. Since it is prepared from the waste material so it regains a cementations property after proper curing is done.



After the curing process is over the brick is now ready for the use. Next we will see some advantages and disadvantages of fly ash bricks...


ADVANTAGES:

·         It is Durable.
·         It has low water absorption tendency.
·         It also consume low mortar.
·         It economical and ecofriendly.
·         Low energy consumption.
·         No emission of green house gases.


DISADVANTAGES:

·         Needs skill labors.
·         Needs lot of care while manufacturing.
·         Initial cost is more.

APPLICATION:

Since this type of bricks has not been used widely and on large scale but recommendation and projects are being passed to use this brick for the construction work. Till now this bricks has been used for the building construction purpose…..below we have a fig which the construction work being carried out using fly ash bricks….
CONCLUSION:

After doing the through study and knowing the way how the fly ash bricks are manufactured and its importance in the construction field we can say that in near future this brick is soon going to replace all the bricks and blocks which are now a days used for the construction purpose. With decreasing natural resources and boom in construction field will definitely increase the demand for fly ash brick as it has lots of quality and advantages than other bricks some quality are like high compressive strength, low resistance, low mortar consumption etc. Since it also accounts 20% less cost for its construction than the clay burnt bricks……..so all these and the present situation will make this brick as the most important material for the construction work…….