SCIENCE TRIBUNE Thursday, December 21, 2000, Chandigarh, India
  Fighting the menace of dampness
by Ved Parkash Takyar
HE dampness not only become an eyesore but is also unhygienic and reduces the life span of the buildings. Dampness mainly occurs in toilets due to the following reasons.

Computer simulation of rivers
by Deepak Bagai
IMULATION is an effective way of pretesting proposed systems, plans, and policies before developing expensive prototypes, field testing, or actual implementations. In simulation analysis, the computer describes in detail the implications and consequences of a proposed course of action.

New products & discoveries
  • You have e-mail on TV!
  • Measure roughness of fabrics

Science Quiz
by J.P. Garg



Fighting the menace of dampness
by Ved Parkash Takyar

THE dampness not only become an eyesore but is also unhygienic and reduces the life span of the buildings. Dampness mainly occurs in toilets due to the following reasons.

1. When the RCC slab under the floor has not been laid monolithic by using vibrator and fixing water-cement ratio and effective waterproof treatment (which become part of the RCC slab) is not provided.

2. When sanitary pipes, bends and traps conforming to ISI specifications are not used and are not checked before use. The stem should have a uniform thickness and without flaws and cracks.

3. When floor traps and bends etc. are embedded in RCC slab to maintain level of toilet floors with the level of other floors. Due to thermoexpansion of these traps and bends etc., either these are fractured or create cracks surrounding them in the RCC slab which result in leakage and dampness. The HDPE and PVC pipes have high thermo-expansion and not recommended for concealed piping in this region specifically.

4. When the laying, embedding and jointing of pipes and traps is not carefully done and filling of molten lead in joints is not done to the specification. Some plumbers are of the habit to steal the lead and do the filling just as an eye-wash.

5. When floor main trap is overcrowded with connections and their bends are not forming an obtuse angle and proper slope is not given for smooth flow of water.

6. When GI pipes are over threaded shile making screws. All the part of thread should be inserted in the socket with cotton thread smeared with good quality of white lead. The erosion of pipes always starts through these exposed threads of G.I. pipes where galvanisation is lost. It is advisable that the joint of pipes should be further covered with M. Seal. The pipes running in walls and floors should be covered with Teflon tape painting with anti-corrosive paint.

7. Dampness also occurs through the joint between the wall and projected skirting stone tiles. A crack is developed between the mortar and stone tiles due to shrinkage or thermoexpansion. When any water is dropped on the skirting some of its part seeps through the crack which results in dampness in walls. Similar is the case surrounding the kitchen washbasin.

8. When slow setting cement is not used in fixing water supply and sanitary fixtures and rapid hardening cement i.e. 53 grade is used which results in shrinkage craks in concrete and mortar due to carelessness of curing by plumbers who never bother about it.

9. Whenever during fixing and laying of pipes and bends, the dismantled portion of concrete or bricks is not properly repaired or cured by the plumbers.

10. When the floor traps and gully traps are not regularly cleaned so that the clogging is bare minimum.

11. When the upper ring of floor trap is not coinciding with the top of floors (which is practically not possible) around such floor traps, brick-blast concrete of 1:4:8 is required to be laid and compacted solidly by placing a vertical pipe in the hole of trap which is later on removed. ‘This brick concrete is more dependable than 1:2:4 concrete of bajri/shingle which is more prone to shrinkage and cracks. The inner round area of concrete inside trap is required to be given a coat of mulmi plaster prepared with waterproof chemical that will eliminate any chance of leakage. To keep the inside hole free from any injury, a piece of PVC pipe equal to the inner dia of floor trap may be placed from the upper ring of the cast iron trap upto the floor level.

Precautions & treatment
i) The RCC slab of toilets should be laid sunken from 9” to 15” depth in case of European and English seat respectively. This will reduce the unnecessary load of brick concrete filling on whole other part of the roof slab to match the floor levels in addition to the cost-factor. The vertical and plain area of sunken floor should be coated with neat cement paint prepared with waterproof chemical having PH-6-7 value. A drawing of sunken floor showing the waterproof treatment surrounding fixtures is enclosed for ready reference.

ii) The laying of pipes and floor traps should be done at obtuse angle and with proper slope. The jointing of floor traps and pipes should be done with molten lead after inserting spun yarn up to the half depth of joint. All the dismantled RCC and brick portion during laying of pipes and traps should be repaired properly. It is desirable that before laying of concrete around the traps and filling of cinder, the vertical and horizontal surface of sunken slab may again be coated with cement paint prepared with water-proof chemical i.e. after cleaning the surface so that the repaired portion and injury to the already done treatment while laying of pipes and traps is sealed.

iii) No dividing strip for paneling should be laid in toilet floors. Before laying the flooring with stone or ceramic tiles, the bed of concrete should be roughened with steel wire brush and cleaned. The tiles and stones etc. should be laid over a bed of 3/4” thick cement sand mortar 1:3 prepared with water-proof chemical having P.H. value7.

iv) Cast iron floor traps having deep water seal depth should be used for flow of waste water.

iv) If building has more than one storey, the toilets should be planned one on the other having atleast on wall outer side i.e. preferably on South,West or East directions to have the sun rays.

The above precautions and methods of treatment eliminate any chance of dampness.

Open system of pipes is easily manageable. If aesthetic can be given the go by, then a duct for pipe should be preferred than embedding in the walls. Moreover, open duct serve as chimney for cross ventilation. The surface of the duct wall and floors should be given waterproof treatment because the duct becomes a well and its walls remain in shadow, which can give dampness in walls of adjoining rooms especially in rainy season.

Now a days professionals are more dependable than the masons and plumbers or the contractors. These problematic and unsolvable items of dampness/leakage should be checked during execution of work. Before covering the joints of pipes and traps, the plumbers and contractors should get it checked by the engineer in charge.


Computer simulation of rivers
by Deepak Bagai

SIMULATION is an effective way of pretesting proposed systems, plans, and policies before developing expensive prototypes, field testing, or actual implementations. In simulation analysis, the computer describes in detail the implications and consequences of a proposed course of action. Compared with other forms of analysis, simulation can be more realistic, more easily understood, and hence more persuasive. Simulation is the most practical way to ensure safe planning for projects on a changing river. It can predict the impact of mining a river’s bed or determine the safety of building on its bank.

HEC is an existing computer model for rivers but it is not accurate for all rivers because it assumes a fixed riverbed. It is accurate for channelised beds, where the bedrock is close to the surface, or the bottom is natural stone or gravel. The model works poorly for alluvial rivers (with earthen beds) or ephemeral rivers (that flow only for part of the year) with highly concentrated flooding.

Chang’s model called FLUVIAL, is based on several principles of river dynamics. In its virgin state a river balances the power it expends along its length to find a state of equilibrium. Human activities, such as mining or bridge building, distort the natural balance and cause the river to seek a new equilibrium. According to the theory of minimum power, a river adjusts its width to minimise power expenditure. The current moulds the channel so that each segment does equal work. When a river expends power equally along its channel, it uses the minimum power over its length. Chang has used this principle to simulate river changes.

FLUVIAL is a simulation programme that calculates three kinds of river changes: bed elevation, channel width, and lateral migration. The measurements required in FLUVIAL simulation are:

Water routing which is the volume of flow, water surface elevation, energy gradient, and gravitational acceleration.

Sediment routing which calculates the change in channel boundary at the bed or bank, sediment movement, and the volume and porosity of bed material.

Stream width and profile is the formula for calculating stream width to determine total stream power in energy per unit of time. It considers the reach of the river, the specific weight of the flow, the discharge in cubic feet per second, and the energy gradient.

Cross-section data profiles are made of the river every few hundred feet and new measurements are taken at fixed time intervals. For practical use, a time period may be set to study such things as channel changes caused by new construction. For comprehensive analysis of how the river changes, the following are computed at each cross-section.

Water surface elevations and sediment loads.

Changes in channel cross-section area.

Changes in channel width.

Lateral migration of sections in the channel bends.

FLUVIAL can be used on any river anywhere, but it is especially valuable on ephemeral streams with seasonal flooding. After being mined or developed, the river can regain its equilibrium only when it flows. But changes occur quickly during a flood. Constantly flowing rivers repair themselves continuously.

Using FLUVIAL in a practical application requires the use of a high range Pentium machine. Such things as flood discharge, velocity, sediment rate, and river channel configuration change constantly. Hundreds of calculations have to be made at regular intervals of time. A purely theoretical problem might use only a few data points, but such models are too risky for applications involving human safety and large investments of money. Dependable models require precise input. River simulation can benefit civil engineers. Government agencies still use very old standards derived from trial and error. River modeling and simulation will soon occupy an important place in the planning and decision-making processes involved in civil engineering design work.


New products & discoveries

You have e-mail on TV!

WANT a shopping experience? Turn on your TV set and buy what you want sitting right inside your living room. No need to walk to your bank or doctor. Manage your on-line banking and get your health care advice from your family doctor, without once stepping out of your home. And it is friendly to the pocket as well.

It is a box that connects with your television and phone, requires no cable but promises to revolutionise your life. Accessing internet was never so easy. A wireless keyboard or a remote allows you to lean back against your sofa cushion and browse the World Wide Web.

A new interactive technology has opened up the world without the use of high-end computers. Optical fibres from your TV set now allow you to surf the internet and e-connect to the world.

Developed by Kris Narayan, a Hyderabad-born Indian settled in America, the attachment offers 21st century technology at costs you can afford. Many more families will now be able to log on to the new world of internet just by purchasing set-top boxes and keyboard or alternately buying a Net-ready TV set with an inbuilt chip or modem and pre-installed software.

Of all the technology options available to access internet, the Internet-on-TV is believed to be the cheapest, safest and most people-friendly. Even those who know little or nothing about computers can access the internet which is changing our world like never before.

Measure roughness of fabrics

SCIENTISTS in France have developed an optical multi-directional roughness meter, which measures roughness of textile fabrics through a non-contact method.

In the system, developed by M.A. Bueno, B. Durand and M. Renner from the University of Malhouse, a beam from a laser diode scans the fabric surface and the signal obtained by the reflected ray is studied. The calculated spectrum shows peaks which correspond to the structure and to the fabric density.

Ayarn is made up of fibres and several yarns make a woven or a knitted fabric. Some fibres are not entirely “contained” in the yarn and represent pile on its surface. The pile can also be found on the fabric surface and is therefore very important for the tactile feel and the look.

The most common mechanical finishing processes for the modification of the touch of fabrics are sanding and raising. During the sanding process, the fabric is worked mechanically on one or both sides with either rollers covered by energy slats or cylinders covered by an abrasive material (sand paper or diamond powder).


Science Quiz
by J.P. Garg

1. This thinker, philosopher and one of the greatest minds of the 20th century firmly believed in the scientific spirit of enquiry and wrote the masterpiece “Principia Mathematic”. Name this British writer who was awarded the Nobel Prize for literature.

2. This instrument, developed by a British doctor sometime back, can be used to diagnose eye glucoma, sleep disorders, certain cancers, addiction to drugs and diabetic neuropathy. Can you name this instrument the function of which is based on investigations of a part of human eye and employs a painless technique for diagnosis? Which part of the eye does it investigate?

3. This hardy plant can be called a shrub, a climber, a bonsai plant or a tree. Some of its popular varieties are Thimma, Partha, Golden Glow, Mary Palmer and Mahara. Can you name this plant which blooms with thick bunches of flowers of different colours in November and December?

4. What is common between Shovellers, Wigeons, Gadwals, Mallards and Pochards?

5. Cow-dung is rich in Vitamin B 12. “Chapatis” cooked by burning cow-dung cakes in a “chullah” get contaminated by the particles of cow-dung. It has been found that the intake of these particles is a blessing in disguise as it helps prevent a disease. Which disease?

6. It has been estimated that only about 3 per cent of the human genome is useful, the remainder does not apparently have any role in the functioning of human body. What is this apparently “useless” part of human genome called?

7. The Great Red Spot on the planet Jupiter is well-known. The planet Neptune also has a spot measuring about 12,000 by 8,000 km which is a region of high pressure in its atmosphere. Can you name this spot?

8. Bessemer process for the manufacture of steel invented by the British engineer and scientist Sir Henry Bessemer is well-known. Although patented by Bessemer, a US steelmaker had used a similar process earlier than Bessemer. Can you name him?

9. What is the number system in mathematics called on which the basic working of computers is based?

10. The polarity of the earth’s magnetic field has reversed at least 20 times since earth’s formation. What is the study of the changes in the direction and intensity of this magnetic field since ancient times called?


1. Bertrand Russel 2. Pupillometer, developed by Dr Dan Taylor; Pupil 3. Bougainvillaea 4. These are some exotic varieties of birds 5. Anaemia 6. Junk DNA 7. Great Dark Spot 8. William Kelly 9. Binary system 10. Palaeomag-netism.

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