|SCIENCE TRIBUNE||Thursday, March 28, 2002, Chandigarh, India|
to bad construction practices
IN order to live in this age of increased specialisation, it becomes necessary to have a critical examination of various techniques and materials under use, at periodical intervals, so as to discard bad practices or materials and adopt newer technologies and alternatives wherever possible. Economy, Quality, Progress and Safety remain the four prime factors that need to be kept in mind and weighed accurately while taking decision over the specifications for each component of a structure. A close look at the construction practices being adopted by the individuals in the construction of their houses as well as by the government departments who execute the major chunk of development works, brings the following limitations to surface :
1. Quality and Safety are the two areas often relegated to the bottom rung of priorities.
2. There is a lot of hesitation in switching over to new materials as the engineers lack faith in them.
3. New techniques, if adopted, can lead to sound and economical structures but do not become popular as the engineers lack initiative to study and try them.
4. Many times, the tendency to earn profits by compromising over the soundness of structural components that get hidden under attractive finishes prevails among builders.
Mason's dictum still prevails in the present era when the construction industry has entered a revolutionary phase. Computer-aided-design, efficient and versatile machinery, highly sophisticated equipment, tens of kinds of concrete, amazing grades of cement and steel and eco-friendly substitutes to the conventional materials are fast playing a pivotal role in changing the construction scene around the world. Yet, in India, the old and traditional line is being toed. Result : wastage, leakage, cracks, dampness, efflorescence and termite attacks. There is an urgent need of reviewing various practices in vogue and finding right alternatives to them.
Higher cement content
Better strength of higher grades of cement coupled with remarkable improvement in the technique of production of cement necessitates a review of minimum cement contents prescribed by various consultants and government departments in the concrete specifications laid down by them. It further asks to define new grades of concrete with respect to the grade of cement being used. Such a review may result in achieving great economy. It is assessed that if concrete grades are re-defined and minimum cement contents are reviewed and revised, an annual saving of Rs 2500 crore can be effected in India alone.
RMC and hand mixing
Indian specifications laid and followed by government departments allow even "hand mixing" of concrete. Hand mixing does not produce desirable blending of concrete ingredients; consumption of cement is more and water-cement ratio does not remain under control. Uniform mixing of ingredients is just not possible in hand mixed concrete and this means lack of workability, strength and density of concrete.
In sharp contrast to hand-mixed concrete, RMC, a house-hold term abroad and fast making its mark in India, is prepared and supplied to construction sites in a plastic, unhardened and ready to use state. The consumer avoids all sorts of burden of procurement of various aggregates, cement, plant and machinery. Above all, a strict quality control can be ensured at the RMC station.
RMC needs to be given a careful thought by the Government who should offer concessions, excise and sales tax holidays to RMC-industrialists. It being a sure route to quality and economy should be promoted on a large scale and hand-mixing of concrete-a really bad practice in vogue -- should be wiped off the Indian construction scene.
A major practice being followed in India is provision of Reinforced Brick (RB) roofing in houses. This type of roofing has been more common than the strong, impervious and economical RCC. A survey in this direction reveals two main reasons for adopting such type of roofing. First is that the people follow whatever the mason suggests. Second is that there prevails a general belief that a RCC roofing develops cracks while a RB roofing does not. A comparison of both types of roofing however brings about a total change in general belief.
A RB roofing proves costlier than RCC slab, has lesser strength and durability and is prone to appearance of ugly patches on the ceiling due to soakage of water by the bricks which usually possess high porosity. The practice of using RB roofing should therefore be stopped altogether and only RCC roofing should be used.
Use of bricks
Bricks are the most common building material used by the man since ancient times. Bricks produced in the country suffer from the drawbacks of high porosity and low strength. Use of flyash in bricks can not only dilute the problem of disposal of this hazardous material to a large extent but may also avoid the depletion of fertile crest of earth. Flyash can be used in combination with clay or with lime and sand to produce clay-flyash bricks and flyash-sand-lime bricks respectively.
Keeping in view better test results of clay flyash bricks, their comparable cost with that of conventional bricks and their role in utilisation of flyash, a switchover to clay flyash bricks should be brought in by revising the work specifications and adding the items of brickwork in clay flyash bricks to the tender documents. Government departments should declare it compulsory to use only flyash bricks in all public works to achieve the aim.
Concrete can be singled out as one construction material that has been most used as well as abused by the construction industry. However, a major handicap during its use has been our inability to test it to be as per specified parameters without destroying it and some builders have been taking maximum benefit of this handicap. An engineer may long for such testing methods that may indicate the strength and soundness of a structure without destroying or harming it. It is due to this reason that the focus has been on non-destructive testing for the past few years and significant breakthrough has been made in this direction.
Many tests and instruments are now available which can check the strength, soundness or say, full anatomy of a structure without disintegrating it. What needs to be practised by the engineers is that they should become fully conversant with these instruments and should avail of them whenever in doubt.
Flooring eats up a major percentage of total cost of construction of a building. The latest trend is to provide marble flooring in buildings and every individual tries to have such a flooring in his house. For such a flooring of good quality, the cost factor is too heavy to bear.
A fine and traditional alternative to marble flooring, equally good and having better appearance is to provide pure white terrazzo flooring in white cement with 4 mm to 7 mm size white marble chips, rubbed and finished with granite polish. The strips to be provided in the floor are also to be of white colour and in plastic. This flooring gives a wonderful appearance and may put even white marble flooring to shade if skilled masons are engaged and good quality white cement and marble chips are used.
While laying absolutely white terrazzo flooring, care has to be taken that the cement, the chips and the strips have to be of white colour only and no pigment or coloured chips are to be used. Full attention has to be paid to rubbing and polishing of floor. White cement and chips are to be mixed as one part of cement with one and a half part of chips and laid in 9 mm thick layer. Sometimes, the mason insists for a one to one ratio of cement and chips. This has not to be allowed as it will not only cause wastage of cement but weaken the floor also. So only right proportions should be used.
It has often been experienced that safety in construction is paid little attention by the builders and the engineers. Irreparable loss of money, manpower and progress may occur whenever a scaffolding fails, a roof collapses or a fatal accident takes place at site of work. Many builders have experienced that once a worker loses his life in an accident at site, the morale of the working force sinks to a new low. The spirit to work is lost and the progress of work never remains the same as had been earlier. Despite this realisation, safety aspect is often ignored. Findings of International Labour Organisation reveal that the accident rate among industrial workers is highest in India, touching 4 per 1000 and a major share of it goes to the construction sector.
It is time that a "Construction
Safety Manual" is evolved, made a part of standard tender
document in every organisation and strictly enforced by the
supervising agency. Some teething troubles may arise in doing so but
gradually the safety aspect will become a part and parcel of every
site and the builders will not hesitate in making expenditure on this
NEW PRODUCTS & DISCOVERIES
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Neatly styled, it has a two-line display for time and date, plus a second time zone. There’s an eight minute snooze function, plus two independent crescendo alarms that can be set to wake you gently at different times for weekdays and weekends. A manual focusing knob ensures a crisp projected image, and a strong LED backlight shows the clock display in the dark. Sells for about 25 pounds.
Novel coatings for missiles, aircraft
Researchers in the country have successfully developed several novel "coatings" that find applications ranging from increasing the shelf life of missiles to making aircrafts stealth.
"We have provided the defence industry with certain coatings, developed indigenously, that have the potential of increasing the shelf life of the country’s missiles by preventing their corrosion," M. Raghavan, Director, Central Electrochemical Research Institute, told reporters.
Electromagnetic Interference Absorbing coatings have also been developed, which have the ability in making surveillance aircrafts stealth by absorbing the electromagnetic radiation directed towards it by a radar, Raghavan said.
He said the Institute, one of the R&D establishments under the CSIR (Council for Scientific and Industrial Research), was currently engaged in the development of "thin film corrosion-prevention coatings."
These thin-film coatings will provide the same level of corrosion protection as the conventional coating but with thinner and fewer coats. "Instead of the 100-200 micron thick coatings and four coats being resorted to currently, the new coating will reduce the job to 50 microns and two coats thereby proving to be cost-effective," he said.
Raghavan said a "smart paint" was also on the way, the action of which would change in accordance with the weather (less protection during dry weather and more during humid weather). PTI
Novel listening device
Scientists are developing a novel device, partly based on artificial intelligence, that records and recognises what people are discussing at meetings and alerts them if decisions are inadvertently being remade.
The aim of the three-year study, being done at Staffordshire University’s School of Computings Information Systems Group and Lancaster University, is to avoid the reworking of management decisions which is a common problem, particularly in big organisations, and that can lead to potential disaster.
"Often, in big projects, people make a decision and then they forget all about it so another decision is made about the very same issue," explained Professor Alderson who is leading the project for Staffordshire University.
"This is obviously counter-productive and very wasteful in time and other resources. It can even lead to fatal consequences, such as the launch of the space shuttle Challenger which exploded shortly after take-off," he said.
"This disaster is a prime example of one decision being make but at a later point a contradictory decision being agreed — with calamitous results. That is why this research project is potentially so important and will have a wideranging impact on any group which plans to make important decisions," Alderson said in a report in London Press Service.
He said that the project will be based
around a laptop computer which will be used by the person taking
minutes at any meeting. The computer will be fitted with the latest
technology, such as a graphics pad and software that can capture and
understand handwriting. PTI
SCIENCE & TECHNOLOGY CROSSWORD
1. Semiconductor device with three electrodes and same functions as thermionic valve.
9. Shadowing one heavenly by another.
10. A wing military intelligence doing photographic interpretation.
11. Creeping class of animals.
14. Very large period.
15. An element used in tinning utensils.
16. Symbol for zinc.
18. A telecommunication used in modern telephone exchanges. (abbr.)
19. To change magnification of an image while keeping it in focus.
22. A pulley-head or cross piece in a cased frame.
24. A spheroid flattened at poles.
25. Provided in concrete layers for better grip.
26. White blood-corpuscle.
27. Science of earth’s crust and strata.
1. Coloured stones laid in cement mortar in flooring.
2. Particle consisting of 2 neutrons and 2 protons and carrying 2 positive charges.
3. Another name for Potassium Nitrate.
4. An end of a pipe inserted into socket of next pipe.
5. Land surrounded by water.
6. Water that appears when water-proofing is not done.
7. Term used in medical science for pills to be taken orally.
8. A highly poisonous protein of albumin group.
12. A nail punch.
13. Disease caused by deficiency of vitamin D.
17. Inert gases having 8 electrons in outermost orbit.
20. Resin obtained by distilling dead pine wood.
21. A heavy beetle.
23. The faculty of sight.
Solution to last week’s Crossword: