 |
|
| SCIENCE TRIBUNE | Thursday, February 21, 2002, Chandigarh, India |
|
Foamed bitumen: a breakthrough NEW PRODUCTS & DISCOVERIES
Non-lethal “odour bomb” |
|
|
Foamed bitumen: a breakthrough What could a road-builder dream of? Some process that may allow him to save bitumen, lay strong and durable roads at a lesser cost, re-use the aggregate scrapped off the worn out road, open the road built by him to traffic immediately on its laying and continue laying of a road even if a sudden downpour begins! This certainly seems to be a figment of imagination, a far-fetched idea but has become possible with the advent of a new technique: foamed bitumen. Many countries around the world, including Australia, Brazil, Canada, Finland, Mexico, Norway, South Africa, UK and the USA, are trying the technique in an enthusiastic manner and the results are encouraging. Foamed bitumen has been successfully used in new road construction, in strengthening of existing roads, as a base course material and to correct the subsidence caused in roads due to heavy traffic. Its area of application may further widen as it is showing full stability even under extreme climatic conditions. Foamed bitumen it is produced when cold water is added to the hot bitumen thus raising a lot of foam. As the bitumen is hot, water coming in contact with it evaporates causing foaming of bitumen along with. The bitumen expands up to 15 to 20 times its original volume, its extent depending upon the quantity of water added and the temperature of hot bitumen. The water is added by the method of injection by use of a specially designed spray-bar and under controlled conditions. The foamed is then mixed with the cold and moist aggregate to produce the ready-mix for laying on roads. The aggregate used for mixing with foamed bitumen may be the worn out material milled off the already laid road. In the conventional road building process, this aggregate is removed and disposed off and new aggregate is used. But while using foamed bitumen, this aggregate can be put to re-use as there is no reduction in strength or durability of roads on this account. Thus a lot of saving on account of cost of aggregate can be made. Another highly interesting aspect of foamed bitumen road construction is that the mix of aggregate and foamed bitumen need not be heated in a hot mix plant but can be laid in the cold condition itself. Not only this, if the produced mix does not get laid by the closure of working hours in a day, it may continue to lie on the road side and can be laid in position next day. The mixed material can even be stockpiled on the roadside and remains soft till the time it is laid and compacted. After compaction, the road can immediately be opened to traffic. Thus the road-closing hours due to road work in progress get minimised when foamed bitumen is used. And what may come as a big relief to a road builder, the laying of foamed bitumen mix can continue even if it starts raining. Moreover, the cold process also helps in lesser consumption of fuel thus bringing savings. As the volume of foamed bitumen increases to many times the original volume of bitumen, its viscosity decreases. This enables a much less quantity of foamed bitumen to coat the aggregate. The foamed bitumen coats only the finer particles of the aggregate and not the large particles thus producing a mastic to bind the material. As a result, the consumption of bitumen decreases thus bringing savings in cost on this front also. However, there is no loss on strength front as a foamed bitumen road gives stiffness values equal or greater than those of a hot mix bitumen road. With so many advantages in view, including savings in bitumen, fuel and aggregate; recycling of aggregate; cold processing; working in extreme climatic conditions and quicker opening of roads, engineers are working out complete design process of foamed-bitumen-pavements by studying the test results and analysing the behaviour of such laid roads. Germany has developed advanced equipment that mills out old and worn out roads, adds milled aggregate to the mixer drum, adds micro-processor controlled bitumen to the drum, injects micro-processor controlled water to the drum for the foaming of bitumen, mixes all the ingredients and then lays the mixed material along the road — all in one go. The quantities of various ingredients can be controlled with respect to the thickness of layer to be laid and the speed of construction of a road. There has been an unprecedented growth in road traffic in India. Cargo transport has grown by 60 times during the last 50 years. Passenger traffic has risen by 65 times and the number of vehicles by 80 times. The vehicular and passenger traffic is bound to rise further. Under the circumstances, making use of cost effective techniques such as foamed bitumen construction may prove quite useful for the country.
|
|
NEW PRODUCTS & DISCOVERIES The wind in your hair, the sun in your eyes, the smell of salt in the air—and then you get seasick. If you love boating but hate all that bouncing around, the OutRider may be for you. Mounted on a funny-looking ski and shock absorber, the flat-bottomed boat lightly skims the surface of the water for an ultra smooth ride. Side hulls and an aerodynamic design help keep the thing steady while you zip over waves at speeds of up to 80 m.p.h. It is available for $60,000.To learn more: www.klemflyingboats.com Solid stops light Researchers in the United States and Korea have brought light to a complete standstill in a crystal. The pulse is effectively held within the solid, ready to be released at a later stage, according to a report in Nature science update. "A crystal that holds light could facilitate quantum computing," said Philip Ball, author of the report. Normal computers store information in simple binary form (1’s and 0’s) in electronic and magnetic devices. Stationary light pulses can encode information in more sophisticated ways that use the laws of quantum mechanics, making information processing more powerful. Light moves at 186,000 miles per second through empty space, and was first stopped in its tracks at the beginning of last year. In that experiment, a vapour of metal atoms cooled close to absolute zero was shown to act like molasses on the passing light beam. Now, Philip Hemmer of the Air Force Research Laboratory at Hanscom Air Force Base in Massachusetts, and his colleagues have halted light in a crystal of Yttrium Silicate containing a few atoms of the element praseodymium. Light-stopping solids would be much easier to incorporate into faster, more powerful computers than extremely cold gases. PTI Electronic tongue has "good" taste A new hand-held electronic tongue promises to give accurate and reliable taste measurements for companies currently relying on human tasters for quality control of wine, tea, coffee, mineral water and other foods, according to a report. Human tasters are still irreplaceable for subtle products such as fine wines and whisky. But their sense of taste saturates after a while, losing its discriminating edge. The device made by Antonia Riul of EMBRAPA Instruments Agropeeuaria in Sao Carlos, Brazil, and his colleagues rivals human taste buds and never tires, says a report in international science journal Nature. The electronic tongue can sense low levels of impurities in water. It can discriminate between wines of the same year from two different wineries, and between those from the same winery but different years. It can also spot molecules such as sugar and salt at concentrations much low for human detection. The electronic tongue contains four different chemical sensors to detect four basic taste types: sweet, salty, sour and bitter. The sensors comprise very thin films of three polymers and a small molecules containing ruthenium ions. These materials are deposited onto gold electrodes hooked. Besides the telecom payload to demonstrate internet services and distance education, GSAT-2 will carry an X-ray telescope that will look at radiation coming from the sun and keep Indian astronomers busy. PTI New generation propellants Thiruvananthapuram-based Vikram Sarabhai Space Centre (VSSC) was working on new generation propellants for the country’s future space mission requirements, according to its senior scientist Dr K.N. Nainan. VSSC was currently making efforts to develop the next generation advanced solid propellant with improved performance, using novel high energy oxidisers and binders, he said, submitting a paper at national symposium on thermal analysis at Bhabha Atomic Research Centre. The Centre had earlier developed state-of-the-art HTPB (hydrozxyl terminated polybutadiene) propellant for Indian Space Research Organisation’s (ISRO) PSLV and GSLV launch vehicles, Nainan, senior scientist of Propellant and Special Chemicals Group of VSSC, said. Nianan, in his paper "Thermal Analysis in Development of Advanced Composite solid Propellant", said hydrochloric acid (HCL) free exhaust emanating from the formulations make them more eco-friendly in comparison to currently used ammonium perchloride (AP)-based propellants. PTI Comets brought nitrogen Scientists studying Jupiter’s atmosphere have concluded that nitrogen in the Earth’s atmosphere was carried here by comets thereby supporting the idea that other ingredients of life arrived in the same way. Researchers can trace the source of nitrogen by comparing the ratio of different isotopes. In Earth’s atmosphere, there are about three Nitrogen-15 atoms for every 1000 Nitrogen-14 atoms. But finding out the ratio elsewhere in the universe is difficult because light from distant nitrogen molecules is not greatly affected by their atomic mass, a report in New Scientist said. Thus, a team of researchers led by Tobias Owen of the University of Hawaii studied the data on nitrogen in Jupiter’s atmosphere from NASA’s Gahleo probe. They found the ratio of Nitrogen-15 to Nitrogen-14 to be about two out of every 1000, lower than on Earth. The isotopic composition of Jupiter’s atmosphere is thought to reflect that of the cloud of gas and dust from which the Sun and its planet formed. PTI
|
|
Non-lethal “odour bomb” A new non-lethal “odour bomb” that may not kill but make people flee in disgust is on the way. There is nothing nuclear about it, but the new stinking bomb may soon find its way into the army’s arsenal if chemical technologists have their way. The police too, could use it to disperse unruly mobs. The US Department of Defence Officials have asked researchers at the Monell Chemical Senses Centre in Philadelphia to create a universally offensive odour that can be used by the military for, among other things, crowd control, according to an article in the Chemical and Engineering News, the weekly news magazine of the American Chemical Society. The “odour bomb” is said to smell like rotting garbage, human waste and burning hair, according to the article’s author, senior editor Maureen Rouhi. Tests show the putrid odours “are potent in making people want to flee in disgust”, notes the article. The odours also cause shallow breathing, increased heart rate and can lead to nausea, it added. PTI
|
 |
Science & Technology crossword
Clues Across 1. Colloidal solution of a liquid in a liquid. 6. Full of pores. 8. A phosphate mineral. 11. Useful substances obtained by mining. 13. A seal certifying quality of products. 14. Relating to water. 18. One of biggest telescopes of world. (abbr.) 19. Term commonly used in printing as instruction to page-setter. (abbr.) 20. A dimensionless unit used to compare two currents. 21. Maximum distance of satellite from earth during its orbit around it. 22. A dull brown hardwood which warps badly if not seasoned. 25. Microscopic organisms used in fermentation or brewing. Down 1. A glassy coating fused to a metal at high temperature. 2. A metallic element having radioactive isotopes. 3. A liquid consisting mainly of Ethanol. 4. Smallest amount. 5. Black semi-solid sticky substance. 7. Device consisting of an electromagnet and an armature. 9. Abbr. for plasticity index. 10. Carry these out on materials to ensure their quality. 12. An equilateral rectangle. 15. An institute engaged in research in epilepsy. (abbr.) 16. Difference in level between two ends of a thing. 17. Tailless monkeys. 19. A narrow beam of light. 20. Largest scientific society in the world. 23. Long wave. (abbr.) 24. Symbol for Magnesium. Solution to last week’s crossword
|
