1. Error in a single horizontal distance in stadia surveying must be?
a) Less than 1 in 1000. b) Less than 1 in 500. c) Less than 1 in 100. d) None of these.
View Answer
a) Less than 1 in 1000.
Error in a single horizontal distance in stadia surveying must be less than 1 in 1000.
2. The spectral range of ‘ChlorophyII Absorption Band’ is?
a) 1.9 μm – 2.7 μm. b) 1.4 μm – 1.9 μm. c) 0.45 μm – 0.67 μm. d) 0.29 μm – 0.38 μm.
View Answer
c) 0.45 μm – 0.67 μm
The spectral range of ‘ChlorophyII Absorption Band’ is 0.45 μm – 0.67 μm (or, 450 nm -670 nm).
3. The spatial resolution of Landsat 8 OLI(Operational Land Imager) sensor is?
a) 1 m. b) 5 m. c) 30 m. d) 60 m.
View Answer
c) 30 m.
The spatial resolution of Landsat 8 OLI(Operational Land Imager) sensor is 30 m.
4. In standard FCC image urbun area appear as
a) Red. b) Steel grey. c) Blue. d) Brown.
View Answer
b) Steel grey.
In standard FCC image urbun area appear as steel grey.
5. The sum of the three sides in a spherical triangle is less than?
a) π b) 2π c) 3π d) 4π
View Answer
a) π.
The sum of the three sides in a spherical triangle is less than π.
6. The instruments which provide electromagnetic radiation of specified wave length or a band of wave lengths to illuminate the earth surface, are called
a) Active sensors. b) Passive sensors. c) Latent sensors. d) None of these.
View Answer
a) Active sensors.
7. The refractive index of the water
a) Increases with pressure. b) Increase with salinity. c) Increase with temperature. d) Increase with pressure and temperature.
Rockfill cofferdams are similar in construction to earth cofferdams. They can be used for comparatively large depths say about 3m depth of water.
They can withstand the effect of swift water currents more successfully. They are economical at places where rock is available easily. The side slope, in this case, maybe as steep as 1:1. The biggest drawback of this cofferdam is its poor imperviousness. In case of small heights, a clay puddle larger in required thickness may be laid in the central part of the cofferdam.
For comparatively large or deep cofferdams puddle concrete or steel sheet pile core walls may be constructed. These cofferdams if properly constructed, can withstand the effect of over-topping of water without any serious danger.
Cofferdam is a temporary structure that helps to carry out the construction work under reasonable dry conditions. Now, what is the sandbag? A sandbag is nothing but a bag filled with sand and clay. When these sandbags are used to make a cofferdam, it is known as a sandbag cofferdam.
In this system, at first, empty bags or empty cement bags are collected as required. Then they are partially filled with a mixture of clay and sand. Next, partially filled bags are laid in courses just like masonry work and at last empty space between bags is filled with puddles to make them water-tight.
It has been observed that sandbag cofferdam can withstand the swift of water currents successfully. The side slope of this cofferdam is very steep as sandbags can even maintain the verticle face.
The terrace, porch, balcony, or similar like that shall not be permitted to be erected or rebuilt, or any extension or improvement made to a building beyond the distance referred to below, as provided for in the current Indian Electricity rules and its modifications from time to time between the building and any overhead electrical supply line:
Distance of Building From Electric Lines
Types of Overhead Line
Horizontally
Vertically
1. For low and medium voltage lines and also for service line
1.22 m
2.4 m
2. For high voltage lines up to 33000 volts
1.83 m
3.66 m
3. For extra high voltage lines, above 33000 volts.
3.66 m + 0.3 m for every additional 33000 volts or part thereof
3.66 m + 0.3 m for every additional 33000 volt or part thereof
Asphalt flooring is water-proof, dustless, jointless, acid-proof, and attractive in appearance and as such becoming popular these days. Asphalt flooring is also non-slippery and noiseless.
Construction Method
Construction of asphalt flooring consists of the following two operations.
Preparation of Mastic Asphalt
Asphalt which is generally available in drums is broken into pieces and put in an iron pot known as ‘cauldron’. The iron pot is heated by lighting fire under it. Due to heating, asphalt starts melting.
The mass is continuously heated and stirred till the whole of the mass melts. Once the whole mass acquires uniform consistency (i.e., the whole mass has melted) clean sharp sand or grit is added in a proportion of two parts of sand or grit to one part of asphalt.
This mixture of sand and asphalt is continued to be heated till it starts emitting light brown-colored smoke. At this stage, the mixture which is also known as compost, acquires such a consistency that it can drop freely from the stirrer. At this temperature, the mix or compost is considered fit for use.
Compost should not be heated further as otherwise, it may get over-burnt and its properties undergo marked change which is unfavorable for a good floor finishing.
The hard and unsinkable base is prepared by a 10 cm to 15 cm thick layer of lean cement concrete or lime concrete. The surface is thoroughly cleaned and dried. The mastic asphalt prepared as above is poured on the prepared base with the help of iron ladles and spread evenly on the surface in thickness varying from 13 mm to 25 mm.
Before the mastic asphalt becomes hard on cooling, very fine sand is shifted on the surface. The surface is then rubbed with the help of a trowel or hand float. The asphalt floor is put to use after it has hardened.
In case mastic is to be laid in two layers instead of one, sand should not be shifted over the bottom layer. The second layer should be laid before the bottom layer solidifies. The second layer of mastic should be covered with fine sand and finished by trowelling before the mastic becomes hard.
In the old days, asphalt floors were not favored because of the bad smell and ugly color of the asphalt. Nowadays asphalt flooring can be made in a variety of colors. Floors may be made from asphalt tiles, which are manufactured from natural asphalt, asbestos fibers, and mineral pigments. Asphalt floors may also be formed from asphalt terrazzo which is manufactured by mixing marble, and chips into colored asphalt.
All the requirements of a good stair are given one by one as follows as per ISI recommendation.
1. Location
The stair should be located in such a place that it can be easily accessed. The stairs should be situated near the main entrance in the case of public buildings. And, in the case of residential buildings, it should be centrally placed and all rooms should have a simple, convenient approach to the stair. A good stair should be well-ventilated and lighted.
2. Width of the stair
The width of the stair is a very important point when considering a good stair. The width of the stair rely on the situation and the purpose. The minimum width of the stairs is fixed on the basis that two persons can cross each other on the stairs without any difficulties. The width of the stairs should be more in case the number of stair users is likely to be higher.
In public buildings where there is more daily traffic using stairs, the width of stairs should be more. And, in that case, the minimum width of the stair may be 1.37 m to 1.5 m. In the case of residential buildings, the width may be provided on a minimum basis. And, in that case, the minimum width of the stair may be 0.9 m.
3. Pitch of the Stair
The inclination of the stair should not be less than 25° and should not exceed 40°. Too much inclination requires the introduction of large risers which is dangerous for the users. Old and weak persons may feel it difficult to use such stairs. Too flat slope is also not considered desirable.
4. Head Room
The clear distance between the tread and the soffit of the flight, immediately above it, should not be less than 2.14 m.
5. Length of flight
The number of steps in a flight should be a minimum of 3 and a maximum preferably not more than 12. A flight of single-step should never be introduced, anywhere, under any circumstances.
6. Landing
The width of the landing should not be less than the width of the stair.
7. Winders
As far as possible, the introduction of winders should be avoided. Winders may prove dangerous and also involve extra expenditure in shaping them.
8. Balustrade
From a safety point of view, open well stairs should be provided with balustrade on the open side of the stair.
9. Hand Rail
When the flight of the stair consists of more than three steps, a handrail should be provided to give support to the users of the stair.
Mosaic flooring is very good in appearance, and best for all types of buildings. This flooring is used for both residential and commercial buildings. In mosaic flooring, the top surface exhibits different designs of marble pieces or broken tile pieces.
Pieces of marble and tiles used for this floor may be in different colors and sizes, depending on what type is required for a particular building. The process of cutting or breaking tiles or marble is very specialized work. The tiles should be broken to the shape of a wedge, with a polished or glazed side on the broad face.
In the case of mosaic flooring construction, at first, a hard sub-grade of lime concrete is prepared around 100 to 150 mm thick. Then, A layer of cement concrete is laid over the subgrade, and the thickness of this layer is kept around 25 mm to 40 mm. The surface of this layer is then cleaned properly and wetted by sprinkling water over it.
After properly completing the above processes, a layer of lime surkhi mortar or cement mortar is laid over the concrete base. And the thickness of this layer is around 40 mm to 60 mm. This mortar should be spread on a small area at a time so that it is possible to finish the flooring of this area before the mortar becomes dry and hard.
Now on this lime surkhi mortar layer, an another layer of paste or cementing material( 2 slaked lime :1 powdered marble: 1 pozzolana ) is laid, and the thickness of this layer is around 3 mm. After that, broken tiles or marble pieces are set in desired design and pattern.
When fragments of broken tiles or pieces of marble are set in the desired pattern, the dry cement is sprinkled over the top and the surface is then either gently rolled with a light roller or a large flat piece of wood, is placed on the surface and gently hammered on the top.
While rolling, water is sprinkled and cement works up between the pieces of tiles or marble. After rolling and when pieces are well set, the extra cement is wiped clean with sawdust.
The surface is left for a day to dry, and then it is polished by rubbing with a pumice stone to get a smooth and polished surface. At last, the finished surface is allowed to dry for one or two weeks before use.
Timber flooring is one of the most popular and attractive types of flooring. But, they are not good in fire resistance and damp resistance.
Timber flooring is a popular choice for adding warmth and natural character to homes and commercial spaces. It is a durable and long-lasting flooring option. Whether you are renovating your home or designing a new room, timber flooring can provide a beautiful solution for your flooring needs.
Although it is a good flooring option but cannot be used everywhere, as its price is much higher than other floorings, and is often not possible due to the lack of fair quality wood.
The timber floor is to be best suited for areas where the timber is easily available. This is why in our country this floor is mostly used in hilly areas.
They are also used for specific purposes made halls like dancing halls, auditoriums, etc. This floor, as far as possible, should not be used for ground floors but if they have to be, a cover of an impervious material should be provided throughout the area of the buildings below the ground floor in order to prevent dampness.
Timber flooring can be provided in the following methods:
Timber Flooring
Wooden block floors
Strip flooring
Wall plates and sleeper wall flooring
1. Wooden block floors
In this method of construction, at first, a layer of concrete around 15 mm thick is prepared. After the base concrete has fully set and hardened, it is left to dry completely.
Now the concrete base is covered with a layer of mastic asphalt or bitumen and then, the short wooden blocks somewhat thicker like brick are laid over this prepared base.
Generally, the size of the wooden blocks varying from 200 mm*80 mm to 300 mm*80 mm, and the thickness of these blocks are ranging between 20 mm to 40 mm.
In order to bind the wooden blocks together and also to impart resistance to the surface, hot bitumen is poured over the wooden block pavement. The hot bitumen will penetrate the wooden blocks and keep them bonded.
In this case, the base of cement concrete 15 cm thick is laid. While laying the concrete layer, wooden strips trapezoidal in section are embedded in it by maintaining the top level of the strip slightly above the surface of the concrete layer. While embedding, the wider face of the strips is kept embedded. This measure does not allow the strips to be dislodged. Once the cement concrete has fully set, timber planks are nailed straightway to the embedded strips.
While fixing the wooden planks some open space is left between the underside of the planks and the upper surface of the concrete layer. This open space should be ventilated properly either through the air bricks or in a different way.
3. Wall plates and sleeper wall flooring
This type of floor is provided where chances of the rise of dampness are very likely. Timber boards are supported on timber joists which in turn remain nailed to wall plates.
In case the room is very large, intermediate, dwarf walls are constructed to support the joists. Intermediate walls are termed dwarf walls or sleeper walls.
A longitudinal timber piece is fixed on the top of the sleeper walls and timber joists are nailed to this piece. The sleeper walls are generally 10 cm thick and are honey-combed.
In order to prevent the dampness from rising, a 15 cm layer of cement concrete is applied covering the whole area of the floor. D.P.C is applied throughout the width of the wall immediately below the wall plate.
The hollow space between the flooring and the concrete is kept properly ventilated by keeping openings in the main wall above ground level.
These openings are fitted with wire netting to prevent rats and vermins from getting access into the hollow space. Planks used for the boarding may be jointed to each other by tongued and grooved joints, rebated joints, or simple butt joints. Timber to be used for flooring should be of the best quality, well-seasoned, and free from cracks, knots, and other defects.
