Who invented fly ash bricks

You can further help us by making a donation. This will mean a lot for our ability to bring you news, perspectives and analysis from the ground so that we can make change together. Please use a genuine email ID and provide your name. Pollution Why are fly ash brick manufacturers in a tough spot? Though the government has stressed on increasing fly ash utilisation in the country, manufacturers allege that a situation of scarcity is being created by thermal power plants By Shagun Kapil Published: Monday 01 April Subscribe to Weekly Newsletter :.

The tests showed that within this range, durable fly ash masonry units can be produced without having to use any air-entrainment agent. Mixing fly ash with the water that contains air-entrainment agent —. Mixing the fly ash with the water that contains the air-entrainment agent can be done in batches by using an appropriate mixer, such as a rotary concrete mixer when the volume is large, or a kitchen mixer when the volume is small.

In continuous operation, a pugmill may also be used. The selection of the appropriate mixer for a given project is an engineering decision that must consider many factors including but not limited to the volume of materials to be mixed in each batch for batch operation , the volumetric flow rate of the mixture to be supplied to a unit operation for continuous operation , and cost.

Depending on the mixer selected, some testing is required in the beginning of any project to establish the appropriate rotational speed of the mixer and the corresponding mixing time in order to achieve thorough mixing of the fly ash for making bricks. The mixing time should be sufficiently long to achieve thorough mixing, but not excessively long to prevent the fly ash mixture to set or harden in the mixer. Usually, this means a few minutes.

After the fly ash mixture is adequately mixed, the mixture must be placed into a mold to produce the brick, block or other product shapes. While in laboratory tests this step is usually done manually by hand-feeding the mixed material into the mold, in commercial operation it must be automated in ways similar to conventional factories that manufacture concrete bricks pavers and blocks.

Depending on the type of mixer used in a project, placing the fly ash mixture into molds can be done by different means such as direct pouring by gravity , feeding by a screw conveyor, or injection molding.

Vibrating the mold —. Due to the use of relatively small amount of water in the mixture as described in step 2 of the process, upon mixing with water the fly ash is still relatively dry and forms innumerous small clumps that are not readily flowable by gravitational force alone. Thus, the mixture fed into the mold has large and non-uniform voids between the clumps, and the surface of the mixture is not leveled. Mold vibration causes the mixture to settle in the mold, producing a more uniform and denser mixture with a more leveled surface.

This helps to improve the quality control of the brick produced. Note that this step vibration is desirable but not necessary. It may not be needed in situations where the required quality of the masonry unit is not high, or the pouring of the fly ash mixture into the mold is sufficiently uniform to produce an acceptable product. The next step is to compact the fly ash in the mold die by using a piston or plunger. The mold is a cylindrical object with a bore of uniform cross-section to allow the entrance and penetration of the mold through the bore by a piston.

The piston should have a head i. The clearance between the mold and the remaining body of the piston i. An alternative is to use a piston of uniform diameter or cross section i. However, in doing so, the risk of piston jamming in the mold is increased. The piston and the mold may or may not be made of the same material. An appropriate material for making the piston and mold is steel, including stainless steel, although other metallic or non-metallic materials that have sufficient strength, hardness and workability can be used.

It is desirable to have the mold's inner surface be a material harder than the piston-head material. To do so will allow the piston head rather than the mold to wear. Wearing of the piston head is of a lesser concern than mold wear, as the piston head can be replaced more easily at less cost than replacing a damaged mold. The mold may be made of either a single material such as stainless steel or heat-treated annealed steel, or two or more materials, such as having the main body outside layer of the mold made of wrought steel but the inside layer made of tungsten carbide, which can form a harder surface subject to less wear.

Another alternative is to chrome-plate the inside of the mold. No matter what the material used, the inner surface of the mold should be smooth to minimize contact friction between the mold and the piston.

The piston should be made of a non-corroding material, such as stainless steel or aluminum, which is not as hard as the material that makes up the inner surface of the mold, but sufficiently hard to minimize abrasion caused by contact with fly ash. The outer surface of the piston - the part in contact with the mold— should be smooth. The shape and size of the piston and the mold depend on the shape and size of the brick. For ordinary bricks, both the mold and piston head may have rectangular cross section.

For brick with holes "cores" or surface indentations "frogs" , if the brick is compacted flatwise the piston head must have teeth or protrusions of appropriate shape and size. If the brick is compacted sidewise, retrievable bars protruding into the mold may be used, etc. The piston must be connected to a machine or device that can produce large linear force thrusts , such as a hydraulic or a pneumatic press, to provide the force and pressure needed to compact the fly ash in the mold.

Depending on the desired production capacity, each press system may be used to drive either a single piston and mold, or a multiple of parallel pistons and molds.

The compaction pressure needed to produce durable fly ash masonry units depends on the type of the fly ash used, the CaO content, the LOI 1 the curing time, the type and amount of the air-entrainment agent used, and other factors. It is usually in the range of 1 , to 4, psi 6. Even though pressures higher than 4, psi Dislodging the compacted green masonry unit from the mold — Upon compaction of fly ash in the mold, dislodging the compacted masonry unit namely, the "green masonry unit" from the mold can be done either by opening up the mold using a split mold design, or by pushing out the brick from inside a rigid single-piece mold by using either the same piston that compacted the brick or a different piston.

Tests conducted in the NSF project that led to this invention found that there is little difference in the quality of the bricks produced by a split mold from that by a single-piece mold, though the latter method i. Note that ordinary commercial brick manufacturing use either compaction or extrusion to produce green bricks adobes. Though compaction and extrusion are very different processes, they achieve the same results: generating pressure to densify the raw material and to form green brick shapes.

Thus, steps 5 to 8 above can be replaced by extrusion using extruders that can produce the same minimum pressure of psi 6. Transporting the produced green bricks to curing room for curing —. As soon as a green fly ash brick is compacted and dislodged from the mold, or produced by extrusion and then cut into individual units, the brick should be transported to a curing room or curing chamber for curing.

Such transport over a short distance can be done by various means including but not limited to belt conveyors. Curing of green fly ash bricks is to be done in a manner similar to curing concrete products e. Curing is done by storing the green units in a moist room or chamber - called "curing room" or "curing chamber". The moisture can be supplied by spraying water to generate a mist in the room or chamber, or by supplying steam, in a manner similar to the curing of concrete products.

The water in the moist air reacts with the CaO calcium oxide and other ingredients in the fly ash, causing both cementitious and pozzolanic reactions, which in turn cause the fly ash bricks to harden and gain strength over time. Because fly ash reacts with water slower than cement does with water, the period needed for curing green fly ash bricks is normally longer than for curing concrete products.

With moist-air curing i. Strength growth becomes insignificant after 60 days of such curing. Curing can be sped up either by using warm steam to cure, or by immersing initially cured fly ash masonry units in water - called "water cure. The green fly ash bricks should first be cured in moist air for at least about 24 hours before subjecting them to water cure. Premature water curing can damage or melt dissolve the green bricks.

Upon leaving the curing room, bricks continue to cure for weeks in air until all the moisture in bricks is lost. Thus, fiyash bricks need not be cured to acceptable strength before leaving the curing room; continued air cure during storage and transportation may cause the bricks to gain further strength.

Once a fly ash brick has completed curing, the unit can either be shipped immediately to the marketplace or constructions site for use, or be stored temporarily either indoor or outdoor before shipment. Once cured, fly ash bricks can be store at practically any moisture and temperature - preferably in a moist place with air temperature above freezing, which will cause the bricks to gain strength continuously as time progresses.

Note that the foregoing 9-step method was sometime described for making fly ash bricks only. Because the same method described can also be used for making similarly manufactured fly ash units such as blocks, tiles, stepping stones, etc. It should also be mentioned that although a 9-step method process is described here, some of the steps may not be needed in special situations.

For instance, steps 1 and 2 can be omitted if through previous tests of the same kind of fly ash i. In such a case, just repeat the same method used before to produce the brick. A method to produce or manufacture durable, i. A method as set forth in claim 1 , wherein the mold or molds containing the mixture or the hopper feeding the extruder in step 4 are subjected to vibration or shaking in order to distribute the mixture uniformly in the molds or hoppers.

A method as set forth in claim 1 , wherein the air-entrainment agent is a material effective for introducing microscopic air bubbles into concrete, with the proper amount of said material needed for air-entrainment to be determined from test results in each case. A method as set forth in claim 2, wherein the air-entrainment agent is a material effective for introducing microscopic air bubbles into concrete, with the proper amount of said material needed for air-entrainment to be determined from test results in each case.

USP true USB2 en. EPA4 en. To encourage the widespread adoption of this environment-friendly technology, the inventors of FaL-G are providing their technology without invoking the patent. They filed a patent for FaL-G brick technology in They also provide microenterprises that opt for this technology with technical assistance on production techniques, skills training for workers, and advice on the marketing of bricks.

These revenues provide microenterprises with an additional incentive and enable them to offset some of their initial costs. This is because fly ash brick making, although a viable industry in urban areas, is often unable to compete with the low cost of clay bricks in the rural areas. In such instances, fly ash brick manufacturers often dilute the quality of their bricks by compromising on inputs to compete with the clay brick market.

Carbon credits help to overcome this problem in addition to supporting manufactures with their marketing expenses. Workers are covered by health and accident insurance and provided with protective gear for use at the workplace. In addition, HIV awareness programs are conducted. Toilets, showers, and drinking water facilities -- all of which are rarely found in rural India -- have also been installed at FaL-G production sites. Today, the manufacture of clay bricks is becoming increasingly unviable given the spiraling costs of the clay land and fuel.

However, proactive government policies are needed to help spread this new technology in order to reap its considerable environmental and social benefits. This is because unlike the informal sector clay brick industry, Fal-G bricks incur all the fiscal burdens of the organized sector such as sales tax, excise duty, and service tax, making it difficult for fly ash brick entrepreneurs to compete with their informal-sector counterparts.

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Thank you for agreeing to provide feedback on the new version of worldbank. Thank you for participating in this survey! Liu took the whitish powder, mixed it with water, and stamped it with 4, psi of pressure. Bricks are required to survive 50 cycles of freezing and thawing. He tried changing the shape, adding nylon fiber—nothing worked. Finally, he blended in a type of chemical known as an air-entrainment agent.