SCIENCE TRIBUNE Thursday, December 14, 2000, Chandigarh, India

Promoting clay flyash bricks
by Jagvir Goyal
N order to meet ever rising demand for electricity, installed power generation capacity of India was increased by 67 times from 1947 to 1998. In 1947, we had just 1331 MW of power. In 1998, it become 89167 MW.

Jack Kilby: The inventor of microchip
by D.P. Singh
ITH five dozen patents in his name, with his picture hanging next to Edison’s in the National Inventors Hall of Fame and with virtually every engineering prize in the world on his shelves, Jack Kilby is a world renowned inventor. 

New products & discoveries

  • A computer on hand

  • Cool a flaming situation

  • “Green” process for artificial leather

Science Quiz
by J.P. Garg



Promoting clay flyash bricks
by Jagvir Goyal

IN order to meet ever rising demand for electricity, installed power generation capacity of India was increased by 67 times from 1947 to 1998. In 1947, we had just 1331 MW of power. In 1998, it become 89167 MW. Yet there is no respite. Demand continues to outstrip supply. And most part of this generation capacity is thermal based. Taking example of North India alone, 12977 MW of total 24782 MW capacity is thermal power. Further, out it, 9937 MW is based. In North India alone, we are producing 60,000 MT of ash everyday. Under the circumstances, it become essential to convert their residue i.e. flyash — into resource. The necessity of effective utilisation of flyash, has therefore, gained extreme importance.

Best utilisation of flyash has been found to be in manufacture of cement, bricks and in embankments. Bricks are the most common building material used by the man since ancient times. Ever rising demand for dwelling units is directly resulting into an increase in demand of bricks. Use of flyash in bricks can therefore dilute the problem of disposal of this hazardous material to a large extent. In addition, the depletion of fertile crest of earth, now underway to fulfill the demand of clay for manufacture of bricks, can also be slowed down. Flyash can be used in combination with clay or with lime and sand to produce clay-flyash bricks and flyash-sand-lime bricks respectively.

Production of clay flyash bricks was taken up by setting up a bricks kiln at Lehra Mohabat with the objective to produce 2 crore such bricks of first-class quality apart of the second-class and third-class bricks. The kiln has produced more than 1.8 core of first class clay-flyash bricks of which about 1.5 crore stand consumed by now.

The cost of conventional bricks varies from place to place. The variation is quite large and ranges from Rs 12000 to Rs 2200 per 1000 bricks. Machine moulded terracotta colour bricks cost Rs 2200 per 1000 no while hand moulded clay bricks cost between Rs 1200 to Rs 1700 no bricks. at Lehra Mohabat or in Bathinda region, conventional clay bricks of first class quality are available at Rs 1300 per 1000 bricks.

Taking into account the extra labour cost, power consumption, depreciation of machinery and interest charge on capital investment, the cost of clay flyash bricks being produced at Lehra Mohabat works out to be about Rs 1475 per 1000 no bricks. The cost of clay flyash bricks is thus higher by Rs 175 per 1000 no. The difference in cost of clay flyash bricks and conventional bricks will, however, vary from place to place.

It has been noted that hand-mixing, hand-moulding of clay flaysh bricks is not possible. Proper mixing and blending of soil and flyash do not take place in hand mixing. However machine-mixing, hand-moulding is possible in these bricks.

Clay-flyash bricks, when tested for various physical requirements laid in IS 13757-1993, give satisfactory results. These bricks need to be tested for compressive strength, water absorption and efflorescence. Actual results received on testing of these bricks show that compressive strength of these bricks is very high in comparison to the minimum strength requirement of 105 kg/sq cm prescribed for conventional burnt clay bricks. The water absorption and efflorescence results are also significantly better than those noted for the conventional bricks. Overall, the test results strongly plead for addition of flyash to clay for the manufacture of bricks.

It has been observed that the buildings where clay flyash bricks have been used show lesser signs of dampness in comparison to those using conventional bricks. This is because of low porosity of these bricks.

Comparison of machine-mixed, machine-moulding bricks with and without use of flyash was also made at the kiln site, keeping all other conditions same, to determine the effect of flyash on the strength of bricks. It was found that that average compressive strength of clay flyash brick was 300 kg/cm while that of bricks without flyash was 190 kg/cm. This shows that addition of flyash to soil has a positive effect on the strength of bricks.

A saving in fuel consumption has been noted while manufacturing clay flyash bricks. A flue consumption of 11 to 12 tonne of coal for production of one lakh clay-flyash bricks has been noted. This is 3 to 4 tonne lesser than the normal corresponding consumption of coal. This awing occurs due to presence of unburnt carbon in the flyash. Percentage of unburnt carbon in flyash may vary from place to place depending upon the efficiency of boilers of the thermal plant. In general, percentage of 6-12% unburnt carbon in flyash has been noted. The above saving, however, is for an unburnt carbon content of 3-6% only.

The quality and calorific value of coal also determines its consumption. If good quality coal is used, the consumption may be further reduced. The rates of coal vary from Rs 3000/- to Rs 500/- per metric tonne. When Assam coal of medium variety, costing around Rs 4000/- MT was used, its consumption per lakh of bricks was found to be 10 to 11 tonnes only.

More than 12000 cubic metre flyash has been consumed in the manufacture of bricks at Lehra Mohabat kiln site. This makes little percentage of total flyash generated by the unit in a year. Significant percentage can be achieved if the Gazette notification is followed and all the kilns within 50 km radius begin to use flyash in the manufacture of bricks. In addition to consumption of flyash, there is an equal saving of soil also.

Keeping in view the above observations made during the manufacture of clay-flyash bricks, the following steps if taken will help in large scale promotion of clay flyash bricks:

Incentives to be given to brick kiln owners: A few benefits are already available to the brick kiln owners choosing to produce clay flyash bricks. These include a) sales tax exemption by the government, b) excise duty exemption on ash based products and c) A category incentives by the industry department such as 30% subsidy on building and fixed machinery. In addition, there are saving in fuel and clay. Yet the brick manufacturers are reluctant to switch over to clay flyash bricks. The following incentives need to be given further to the brick kiln owners to promote clay flyash bricks:

1. Low interest loans should be given to meet the higher initial investment. The machinery purchased by the manufacturer should be hypothecated to the department extending the loan till its full recovery.

2. Easy availability of flyash to the kiln owners should be ensured. It should be the responsibility of the thermal plant authorities to supply free-of-cost flyash to the brick kiln owners. In the initial years — till the time clay flyash bricks become popular — cost free flyash should be provided by the thermal plants at all kiln sites falling within 50 km radius of them.

3. Power connection should be given to clay-flyash brick manufacturers on a priority basis.

4. Kilns producing clay flyash bricks should be declared seasonal industry. On average basis, kilns remain closed for 4 months in a year due to rains or extreme weather. During these months, they have to deposit the minimum electricity charges to the SEBs. If declared as seasonal industry, they will be exempted of depositing these charges.

5. Industry department should maintain a separate list of these kilns for A-category incentives. Now, coupled with other industries having similar benefits, it takes a long time to pay the subsidy to the brick manufacturers.

Steps to be taken by PWDs and SEBs:

Items of brick-work in clay flyash bricks should be added to the common schedule of rates. A higher rate in comparison to that for brickwork with conventional bricks should be allowed to accommodate higher cost of clay flyash bricks, however, after making fresh analysis with respect to the reduction in their cost that might arise due to the benefits given to the industry.

The work-specifications should be revised and items with clay flyash bricks should be added to the new tender documents in place of normal brickwork items. Government departments should declare it compulsory to use only clay flyash bricks in all public works. If this is done, major purpose will be achieved.

3. State Electricity Boards should pass a regulation to give power connection to brick manufacturers producing clay flyash bricks on priority basis.

4. Thermal plant authorities should resolve to supply flyash free of cost at kiln sites within 50 km radius and the cost of transportation should be borne by the thermal plant authorities. This will help them in disposal of flyash as well as in meeting with environment-protection regulations.

Amend Gazette Notification no 563: The gazette notification of September 14, 1999, issued by Ministry of Environment and Forests Government of India binds the brick manufacturers to use atleast 25% ash on weight to weight basis in the manufacturer of bricks. As per notification, this stipulation can be relaxed or waived by the State/Union Territory Government only in case of non-availability of ash from thermal power plants. The notification needs to the further amended to the effect that the percentage of ash to be used in bricks can be reduced if the local soil does not contain sufficient percentage of clay in it. The authority under para 1 (2) of the notification should be empowered to decide the percentage of ash to be used in the local soil for production of best quality bricks.

Based on actual experience in production of clay flyash bricks, it is concluded that steps elaborated above need to be taken to promote the production and use of clay flyash bricks. These steps will help brick manufacturers in shedding unfounded fears and adopt use of flyash in bricks thus contributing towards utilsation of flyash and save environment. These steps will also help in reduction in cost of production of clay-flyash bricks, further helping the consumer to switch over to clay-flyash bricks as he will get machine moulded and stronger bricks at a cost comparable to that of conventional bricks.


Jack Kilby: The inventor of microchip
by D.P. Singh

WITH five dozen patents in his name, with his picture hanging next to Edison’s in the National Inventors Hall of Fame and with virtually every engineering prize in the world on his shelves, Jack Kilby is a world renowned inventor. This year’s Nobel Prize in Physics has been awarded to Kilby for his revolutionising invention of microchip.

The invention of microchip has changed the daily life of the people as fundamentally as did the light bulb and the telephone. Jack St. Clair Kilby’s idea has laid the foundation to launch the Information Age. He has come up with the most valuable invention of our times: the semiconductor integrated circuit, better known as the microchip.

The tiny silicon chip is at the heart of all digital devices. Just think of the life without personal computer, without mobile phone, without Internet, without space programme and without play stations. Such a life is as good a life in medieval times. Today microelectronics is a $ 300 billion global industry and the microchip is ubiquitous.

Kilby was born in 1923 at Great Bend, Kansas (USA). His father ran the local electric utility. He received his education at the Great Bend High School. Here he dreamed of joining the Massachusetts Institute of Technology (MIT) to obtain his graduation in Electrical Engineering. So in June, 1941, the young Kilby boarded a train to Cambridge (a suburb of Boston) in Massachusetts, to appear in the entrance examination for MIT, but flunked. The minimum passing grade was 500 and he got just 497. With a heavy heart to took the long, unhappy train trip back to Kansas.

A few months later World War II began. Young Kilby joined the Army. He was assigned to the radio repair shop at a US Army outpost on a tea plantation in the northeast India. After V-J Day, Kilby joined the University of Illinois on the GI Bill. By 1947 he obtained the bachelor degree in electrical engineering. After graduation Kilby joined Centralab-a small electronic component maker firm.

A few years later, at the age of 34, he got the first lucky break of his career. In 1958 he joined his new job at the semiconductor research lab at Texas Instruments’ (TI) headquarters in Dallas. In the 1950s, electric circuit designs were growing so complex that they called for miles and miles of wire and millions and millions of soldered connections. All over the world, engineers were searching for a solution. TI put Kilby to work on this most important problem in electronics — “the interconnections problem”.

Working at the semiconductor lab, Kilby came up with an answer to the interconnection problem. It was to eliminate the wires connecting the various elements of electric circuits. To implement his idea, he thought that if all the elements of a circuit could be made of the same material (i.e. silicon) then all these can be carved into a single slice of that material. Then the interconnections could be laid down or even printed, right on a little chip of silicon. Thus no wires are required and no soldering is needed for making electrical connections. In this way, a huge number of components could be compressed into a tiny space. Even a whole computer circuit can be constructed on a chip of the size of a baby’s fingernail by using this technique.

On July 24, 1958, he scrawled the idea in his lab notebook: “The following circuit elements could be made on a single slice: resistors, capacitors, distributed capacitor, transistor.” Time has proved the validity of his ideas. New electronic devices such as high speed computers powerful enough to run worldwide communication networks or steer rockets to the moon have already been fabricated using Kilby’s ideas.

Now, at 77, Jack Kilby has been awarded this year’s Nobel Prize in Physics (of course, jointly with Z. I. Alpherov of Russia and Horbert Croemore of USA). They have jointly laid the foundations for the occurrence of the modern day communication revolution in the world. Jack St. Clair Kilby deserves the recognition he is showered with for his pioneering work in the field of information/communication technology.


New products & discoveries
A computer on hand

THE CS21 is a hand-held microcomputer specially designed and fully certified for use in hazardous conditions in mines, paint stores, petro-chemical installations and oil rigs.

Developed in Scotland, the CS21acts as a notepad, portable data capture unit, work study terminal, calculator, calendar, stopwatch and electronic tape recorder.

As versatile as a desk-top computer, the CS21 measures 9x4ins (229x102mm), weighs less than two pounds (one kg) and will withstand the rigorous environment of coalface conditions.

A keyboard with “click effect” keys and two liquid crystal displays are housed in a plastic case sealed from moisture and dirt. The keyboard has 31 keys providing 61 functions via a full set of alphanumeric keys and additional symbol/function keys.

There are two liquid crystal displays, one with two lines of 24 characters, the other with two lines of 16 characters enabling the top display to be used for giving the operator instructions and the bottom display for showing the information as it is entered.

The unit can be supplied with a maximum of 128K of memory and can be programmed in computer assembly language to suit a particular application; it can also be equipped with basic language to allow programmes to be written by the user.

The unit is fitted with a socket that allows connection to a desk top computer via a suitable interface while a small auxiliary battery maintains the contents of the memory when the CS21 is switched off or when the mains battery pack runs down or is removed.

Cool a flaming situation

Scientists in United Kingdom have developed a technology to insulate gas cylinders from the effects of fire for more than 30 minutes, thus delaying their explosion.

At higher temperatures, the pressure in an unprotected canister increase, forcing the safety valve to fail. The new technology increases the time for safe evacuation and moving dangerous cylinder from a heat source or extinguishing fire.

The new technology, developed by a company called Nullifire and scientists at Warwick University, involves fitting gas cylinders with a fire resistant jacket-Gas-Safe. The fire-resistant jacket reduces the risk of ignition or explosion.

The gas cylinder, covered by its insulating skin, withstands temperatures of 600 degrees celsius for more than 40 minutes without exploding.

“Green” process for artificial leather

Researchers in Japan have developed a new environmentally friendly process for making artificial leather which does not involve the use of organic solvents.

The new leather has a composite fiber and polyurethane structure that comes much closer than previous materials to the structure of natural leather. It achieves this by employing a manufacturing method the impregnates a specially fine-structured, high-density nonwoven fabric with a unique moisture-dispersing polyurethane that solidifies quickly. The resulting material has outstanding processing ability and wearability and is moisture repellant.

The use of moisture-dispersing polyurethane creates a product that is much kinder of the environment than previous artificial leathers where organic solvents such as DMF (dimethylformamide) were required during manufacture. It also has a soft feel.

The use of leather sheet materials is growing worldwide. It is used in a variety of fields including shoes, apparel, furnishings and automobiles. The amount of natural, artificial and composite leather used annually is estimated to total 1.6 billion square meters.


Science Quiz
by J.P. Garg

1. This Indian astro-physicist had about 20 years back predicted theoretically the existence of more moons orbiting around Saturn and with the recent discovery of four such moons, his theory has been corroborated. Name this astro-physicist.

2. Marriage between biology and information technology? Using computer techniques, we may soon be able to extract useful information from huge biological data available from different sources and then deduce the structure and function of complex biological molecules. What name would you give to this marriage?

3. There is a controversy going on among world astronomers whether Pluto is a planet, a TNO, or both a planet and a TNO. What is a TNO?

4. This dinosaur lived 200 million years ago, was 26.4 feet long, had a long neck and weighed over a ton. What tentative name has been given to this dinosaur identified recently by Italian scientists, which is considered the world’s oldest three-fingered dinosaur, and one of the oldest overall?

5. It has been observed that when one species population is split up and inducted into two different environments, then the two new populations of this species are less likely to breed with each other. Thus they become reproductively isolated from each other and two species are formed from one. What is this process called?

6. This chemical compound is released by some nerve cells and serves as a transmitter in the nervous system. Its function is to transmit impulses between nerve cells or across the junction between nerve and muscle cells which initiate the contraction of muscles. Which is this compound?

7. What is the study of processes called which are activated when a body dies?

8. What does the term “terraflop” generally mean?

9. Suppose we tie one end of a string to a small hooked metallic sphere and tie the other end to our finger by making a loop of the string. Now if the string is continuously wound by rotating the finger in a horizontal plane, it is observed that the speed of rotation of the sphere goes on increasing. Which law of physics explains this observation?

10. Electronic Voting Machines are in hot news these days. The first Electric Vote Recording Machine was patented in 1868 in the U.S.A. Who patented it? 


1. Dr. J. J. Rawal, Director, Nehru Planetarium, Mumbai 
2. Bioinformatics 
3. Trans-Neptunian Objects (these are objects with orbits close to Neptune’s orbit, but are much lighter than even Pluto) 
4. Saltriosaur 
5. Ecological speciation 
6. Acetylcholine 
7. Tophonomy 
8. A unit of performance of a computer equal to one trillion operations per second 
9. Law of conservation of angular momentum 
10. Thomas Alva Edison.