GENERAL ENGINEERINGYEAR: 1992

Explain :

[1] Anticorrosive treatment to mild steel:

Mild steel is a self carbon steel and may contain 0.2 to 0.5% of carbon. It is an elastic material and can be easily cut machined, punched or drilled, welded and rolled.

1. GALVANIZING: The surface of steel is coated with a thin layer of zinc to protect it against corrosion. There are two processes like hot deep galvanizing and electro galvanizing.

2. DRY GALVIZING: It is a process for coating articals with zinc by packing them in zinc dust and heating to 3000C to 4000C.

3. METAL SPRAYING: A coating of molten zinc, tin, lead and or aluminium etc. is given by means of spray gun under high pressure at ordinary temperature.

4. NICKLE PLATING: It is done by immersing the article in a solution of Nickle cynide and Sulphuric acid.

5. CHROMIUM PLATING: Chromium is used for coating the wearing part of pins, bushes etc…6. TIN PLATING: It is a process similar to hot galvanizing.7. ELECTRO PLATING: Here the coating is given on the principle of electrolysis.

[2] Heat Treatment of Steel:

Heat treatment is a factor which affects the mechanical characteristics of steel. The object of heat treatment is to develop in the steel a particular structure or condition which is required for the metal to be used for any particular purpose. Hardening, tempering, annealing and normalizing are the main heat treatment of steel.

1. HARDENING: It means heating the metal to 950 to 10000C temperature and then cooling it more or less rapidly in a suitable media like water, brine, oil etc…

2. TEMPERING: A hardened steel unless tempered is too hard and brittle for most of the practical use. Tempering of softening is reheating of hardened steel to a temperature of 600 to 6500C and subsequent cooling in air, water or oil. Tempering imparts ductility, improves toughness and reduces brittleness.

3. Annealing: It is the opposite of hardening i.e it is a softening or hardness removing process so that the article may be machined readily. The usual annealing and temperatures for high carbon steel are between 760 to 7800C. It reduces tensile strength but increase ductility and brings back the steel to the best physical state.

4. NORMALIZING: In this method the cooling is done in air and more rapidly. This method is used to give steel its normal tensile strength and higher yield point.

[3] Water Cement Ratio:

It is the ratio of weight of water in a mix to the weight of cement and is most important factor for the strength of concrete. Lower the water content the stronger the concrete. Concrete made with low w.c.ratio is unworkable. It stiff or dry concrete is used, honey combing will result decreasing density and strength. Also excess of water weakens the concrete, produces shrinkage-cracks and decreases density. The correct quantity of water required for a particular mix depends upon various factors such as mix proportion, type and grading of aggregates, method of compaction applied and weather condition too.

[4] Soil Stabilization:

The three main constituents of soil – Sand, silt and clay rarely occur in nature in a pure or stabilized form. Stabilized soil means that the different constituents of soil are mixed in such a proportion that the properties of the resultant soil produced are more resistant to weathering and the load carrying capacity is increased and the soil is maintained in high state of stability.

1. Arboricluture: It is the cultivation, management and study of individual trees and other perennial woody plants. This technique is used in japan.

2. Frog in Bricks: It is a trade mark of the producer which is beneficial for better bonding between two layers of bricks. The size of frog is 8 x 4 x2 cm.

3. Dado:4. Nahni Trap:5. Paints and Varnishes: It is a resin which is dissolved in oil, turpentine or alcohol and it is used

to give hard and tough coating.6. Paint: It is a base of solid matter comprising of white lead, red lead, zinc oxide and used to

protect the surface of wall and steel etc…7. Tor Steel: It is a torque operated reinforcing bar and is prepared by special heat treatment

process to give greater strength and much superior workability than mild steel. Grade FE-415-500.

8. Headers:9. Sectional Modulus: Z = I / Y

Where Z = Section Modulus, I = Moment of inertia and Y = Distance of outer most fibre from neutral axis d/2.

Give the characteristic of good timber and describe the various uses of timber.

1. It should be light in weight with adequate strength.2. It should be sound and strong and durable.3. It should have dark uniform colour.4. It should possess good fire resistance.5. It should resist weathering action.6. It should be free from knots, cracks and rapture etc…7. It should be workable and have good mach inability.

Uses: 1. Timber is used in preparing various tools and kits.2. Timber is used in furniture.3. It is used in cremation. (સ્મશાન)

4. Village people use for cooking by burning wood.5. Environment is preserved by trees plantation.

What are common defects found in teak wood?

Timber is a natural product and therefore it is hardly free from some or other defects. The defects may be of two types.

1. Developed during the natural growth of trees:

A. Natural Defect:

(I) Shakes: Complete or partial separation between adjoining layers is termed as shake. The shakes are caused due to shrinkage of wood when the logs stand even after maturity.

B. Defects due to seasoning:

1. Honey combing is separation of fibers in interior due to drying stresses.2. Collapse is the corrugated appearance of timber caused due to uneven shrinkage during

drying.3. Split is due to separation of fiber along the grain extending from one end of the plank to

the other while working on timber some defects also develop such as chipped or torn grain.

C. Describe various uses of [1] plywood [2] figurewood [3] laminated sheet.

1. Plywood: It is a commercial timber based product. The board formed by gluing together veneers is termed as plywood. There are multiple uses of plywood in building construction for making of partitions, ceilings, doors, windows, furnitures etc…

2. Figurewood: 3. Laminated Sheet:

Why seasoning is done to timber? Describe in brief various methods of seasoning.

Seasoning of Timber: The process of drying timber to remove moisture or sap present in the felled trees under controlled conditions is called seasoning of timber.

Seasoning is necessary for the reasons given below.1. To minimize the tendency to shrink or warp.2. To increase strength and durability.3. To improve wood working including painting, polishing etc…4. To prevent possibility of insect and fungal attacks.

Various methods of seasoning: Methods of seasoning can be divided into two categories. [1] Natural Seasoning and [2] Artificial Seasoning.

[1] Natural Seasoning: In this method of seasoning of timber is done by natural air. This method of seasoning of timber is very cheap and simple. It does not require skilled supervision.

[2] Artificial Seasoning: Methods of artificial seasoning are as follow: [1] Boiling [2] Chemical seasoning [3] electrical seasoning [4] Kiln seasoning [5] Water seasoning.

In Artificial seasoning defects such as shrinkage, cracking and warping are minimized. Wood becomes more suitable for painting, gluing etc.. and It reduces the period of seasoning.

What are the characteristics of 1st class bricks? Describe in brief the various test performed on bricks.

Characteristics of Bricks:1. The brick should be well burnt, copper coloured and free from cracks.2. The edges should be sharp.3. The colour of brick should be red or copper and uniform.4. The bricks should be uniform in shape and with standard size.5. While strucking, the bricks should give clear metallic ringing sound.6. When the burnt clay brick dropped flat on hard ground from a height of about 1.0 m, it

should not break.7. First class bricks should have compressive strength not less than 105 kg/cm2.8. They should be sound proof and should have low thermal conductivity.

Various Tests performed on bricks:

[a] Absorption: While immersed in water for 24 hours it should not absorb water more than 20% of weight of dry brick.[b] Crushing Strength: Crushing Strength of a brick is found by placing it in a compression testing machine. M in crushing strength of brick is 35 kg/cm2 and for superior bricks it may vary from 70 to 140 kg/cm2

[c] Hardness: In this test a scratch is made on brick surface with the help of a finger nail. If no impression is left on the surface, brick is treated as hard brick.[d] Soundness: In this test, two bricks are taken and they are struck with each other. Bricks should not break and a clear ringing sound should be produced.[e] Presence of soluble salts: Soluble salts if present in bricks will cause efflorescence on the surface of bricks for finding out the presence of soluble salts in a brick. It is immersed in water for 24 hours. It is than put and allowed to dry in shade absence of grey or white deposit on its surface indicates absence of soluble salts.

YEAR: 2004/2005

Give the full name of followings;

Sr.No Short form Full form1 R.P.M Revolution Per Minute2 R.W.S Rotational Water Supply3 S.B.C Soil Bearing Capacity4 M.D.R Major District Road5 I.C.A Irrigable Command Area6 C.B.R California Bearing Ratio7 CBR1 Central Building Research Institute (Roorkee)8 C.P.M9 O.M.C Optimum Moisture Content

10 R.C.C Reinforced Cement Concrete11 C.D.O Central Design Organization12 S.W.F Standing Wave Flume13 S.G.R.Y Sampurn Gramin Rojgar Yojna14 WALMI Water And Land Management Institute15 C.O.T Cut Off Trench16 C.W.C Central Water Commission17 GWRDC Gujarat Water Resources Development Corporation18 S.O.R Schedule Of Rates19 F.R.L Full Reservoir Level20 PCC Plain Cement Concrete21 GERI Gujarat Engineering Research Institute22 SSNNL Sardar Sarovar Narmada Nigam Limited23 PIM Participated Irrigation Management24 BIS25 ISD Indian Standard Organization26 PERT27 LAQ Land Acquisition28 C.R Cross Regulator29 H.R Head Regulator30 CBI&P Central Board of Irrigation and Power31 NWR Narmada Water Resources32 NCA Narmada Contact Authority33 PIM Participatory Irrigation Method34 PFD Proportionate Flow Distribution35 SWF Standing Wave Flume36 CIR Consumptive Irrigation Requirement37 CNS Cohesive Non Swelling Soil38 NBC National Building Code39 UVRB Urban Village Road Bridge40 NHRB National Highway Road Bridge41 ASTM American Society for Testing of Materials

I.S.Code for Aggregate – IS 383, Brick – IS 1077, Sand – IS 1542, Steel – IS 1761, Cement – IS 1489.

Define Cement. What are its constituents? List various tests that are performed on cement.

Cement : Natural cement is obtained by burning and crushing the stones containing clay, carbonate of lime and some amount of carbonate of magnesia. Natural cement is brown in colour and known as Roman cement. It sets very quickly after addition of water. It is not so strong as artificial cement and hence it has limited use in practice.

Artificial cement is obtained by burning a mixture of calcareous and argillaceous material at a very high teprature. Calcined product is known as clinker. A small quantity of gypsum is added to clinker and it is then pulverized into very fine powder which is known as cement. This cement is also known as Portland cement.

Constituents of Ordinary Cement:It contains two basic ingradients namely argillaceous and calcareous. A typical chemical analysis of a good ordinary cement is as follows.

Sr.No

Ingradient Percentage Function

1 Lime (CaO) 62 It imparts strength.2 Silica (SiO2) 22 It imparts strength.3 Alumina (Al2O3) 5 It imparts quick settings.4 Calcium Sulphate (CaSO4) 4 It increase initial setting time.5 Iron Oxide (Fe2O3) 3 It imparts colour hardness of strength.6 Magnesia (MgO) 2 It imparts hardness of colour.7 Sulphar (S) 1 It makes cement sound.8 Alkalies 1 In excess, causes efflorscene.

Total 100

Various Tests for Cement:[A] Field Test: (1) Colour: It should be uniform. (2) Physical Properties: It should feel smooth when touched or rubbed between fingures.(3) Presence of lumps: It should be free from any hard lumps.(4) Strength: It can roughly be ascertained by making brequettes with mortar. The proportion of mortar may be 1:6. The size of briquettes may be 75 x 25 x 12 mm. [B] Laboratory Test: (1) Chemical Composition: Ratio of percentage of alumina to that of iron oxide should not be less than 0.66.(2) Fineness: This test is carried out to check proper grinding of cement.(3) Compressive Strength: Here the mortar of cement and sand is prepared in proportion 1:3 and then after pouring in cubes they are tested in compression testing machine at the end of 3 and 7 days. Compressive strength at the end of 3 day is not less than 115 kg/cm2 and for 7 days it should not less than 175 kg/cm2

(4) Tensile Strength: Generally used for rapid hardening cement tensile stress at the end of 3 days it is not less than 20 kg/cm2 and for 7 days it is not less than 25 kg/cm2.(5) Consistency: To determine the percentage of water required for preparing cement paste for other tests.(6) Setting Time: This test is used to detect deterioration of cement due to storage. This test is carried out to find out Initial setting time and final setting time.

(7) Soundness: This test is used to detect the presence of uncombined lime in cement.

YEAR : 2003

Enlist various types of cement mentioning their utility in brief.[1] Blast furnace cement: Here slag is used which is a waste product hence it is economical.[2] Coloured cement: Here chromium oxide, cobalt, Iron oxide, Manganese dioxide etc.. are used to give different colours. Coloured cement is used for finishing of floors external surface.[3] Expanding cement: This cements us produced by adding expanding medium like sulpho aluminate to ordinary cement. It is used for construction of water retaining structure.[4] High alumina cement: It is produced by grinding clinkers formed by calcining bauxite and lime. It sets quickly and attains higher ultimate strength in short period.[5] Low heat cement: In order to reduce the amount of heat, this type of cement is used. It contains lower percentage of tricalcium aluminate and higher percentage of dicalcium silicate. It is mainly used for mass concrete work.[6] Pozzuolana cement: Pozzuolana is a volcanic powder. It resembles surkhi which is prepared by burning bricks. It is used to prepare mass concrete of lean mix and for marine structures. It is also used in sewage works and for laying concrete under water.[7] Quick setting cement: This cement is produced by adding a small percentage of aluminium sulphate and by finely grinding the cement. This cement is used to lay concrete under static water or running water.[8] Rapid hardening cement: This cement attains high strength due to increased lime content in cement composition and very fine grinding. Here the initial setting time and final setting time are same. Use of this cement allows higher permissible stresses in the design it therefore, results in economic design.[9] Sulphate resistives cement: In this cement percentage of tricalcium aluminate is kept below 5 to 6 % and it results in increase in resisting power against sulphate. This cement is used for structures against sulphate. This cement is used for structures which are likely to be damaged by severe alkaline. Conditions such as canal lining, culverts, syphon etc…[10] White cement: It is a variety of ordinary cement and is prepared in such a way that it is free from iron oxide. It is used for floor finish, plaster work etc…

Explain in brief importance of any three of the following with respect to cement concrete.[1] Proportioning and Mixing: The process of selection of relative proportions of cement, sand, coarse aggregates and water so as to obtain a concrete of desired quality is known as proportioning of concrete. The proportion of coarse aggregate, fine aggregate, cement and water should be such that resulting concrete is fresh. It should have enough workability so that it can be placed in the formwork economically. It should be strongest and watertight.[2] Mixing of concrete: The material of concrete should be mixed thoroughly so that there is a uniform distribution of materials in the mass of concrete. The thorough mixing also ensures that cement water paste completely covers the surface of aggregates. Mixing of materials of concrete can be done either with hand or with the help of machine.[3] Transportation: The concrete, as it is comes out of the mixer, it is to be transported and placed on the formwork for ordinary building works human ladder is used and concrete is conveyed in pans. For important works various mechanical devices like dumpers, trucks, buckets, belt conveyor etc may be used. The concrete should be transported in such a way that there is no segregation of aggregates. Under no circumstances, water should be added to the concrete during its passage from the mixer to the formwork.[4] Compaction: The main aim of consolidation of concrete is to eliminate air bubbles and thus to give maximum density to the concrete. The process of consolidation of concrete can be carried out either with hand or with the help of vibrator.

[5] Curing of concrete: Concrete surface are kept wet for a certain period after placing of concrete. This is called curing of concrete. Curing protects concrete surfaces from sun and wind. By proper curing, durability and impermeability of concrete is increased and shrinkage is reduced also resistance of concrete to abrasion is increased.Period of curing: This depends on type of cement and nature of work. For OPC, the curing period is about 7 to 14 days.

What is sand? What role it plays in imparting the strength to concrete. What are the tests that are performed on sand? Describe any one in detail.

Sand: Sand is a material which passes through 4.75mm I.S.Sieve. It is used as an ingradient of concrete that fills the voids in coarse aggregates to produce dense concrete and to reduce the quantity of cement. Sand is usually obtained from the following sources. [1] Sea sand: Particle size are often to fine and too uniform for good class work.[2] Pit sand: Sand obtained from old abandoned beds of rivers. It has sharp angular grains while river sand is fine with rounded grains.[3] River sand: It is usually quite good but may be mixed with clay, silt and mica.

Tests: [1] Test for presence of silt or clay in sand.[2] Test for organic impurities in sand.[3] Test for presence of sand in cement.

[1] Test for presence of silt or clay in sand: A rough field test may be carried out by rubbing a sample of sand between damp hands and noting the discolouration caused. Clean materials will leave the hands only slightly stained and such sand is good for ordinary purpose. Half fill a glass tumbler is three quarters full. Shake up vigorously and leave it to settle for about an hour. Clean sand will settle immediately and presence of clay will show the water muddy. Any clay or silt will settle slowly on the top of the sand. If salt is added in water, one tea spoonful to a pint it will quicken the process and silt will settle in a layer on the top of the sand. If the thickness of the silt layer is more, sand needs washing.The permissible limit for silt, clay and fine dust as given in B.SS 882 are Natural or crushed gravel sand – 4 %Crushed stone sand – 10 %Coarse aggregate of either type – 1 %

[2] Test for organic impurities in sand: A simple test for determining the presence of injurious organic matter in sand is made by shaking some of the sand in a plain glass bottle with an equal volume of a 3% solution (100 gm in 4 lit of water) of caustic soda and allowing the mixture to stand for 24 hours. The liquid above the sand should then not be darker than light straw (Pale yellow colour). If the colour is a marked yellow or brown the presence of an excessive amount of organic matter is indicated. Such impurities can be removed by washing sand.

[3] Test for presence of sand in cement: Dissolve the mixture in hydrochloric acid, sand remains undissolved.

YEAR 2002

Shortnote :[A] Line of Resistance: It is taken as the shortest distance from the centre of the charge to the nearest surface of the rock. If there is any fissure or weak point in the rock its distance from the explosive, if shorter than the above distance, is taken as the line of least resistance. The line of least resistance must never be in the direction of the hole bored.

[B] Coffer dam: It is a temporary structure built to excavate from the working area and to permit free access to the area within, during the construction of foundation or other structure that may be undertaken below water level. Cofferdams are usually made of steel, earth or timber piles. The coffer dams are usually made diameter of at least 10% more than the outside diameter of the wall to be sunk.

Requirement of coffer dam: [1] The cofferdam should be reasonably water tight.[2] The design and layout of the cofferdam should be such that the total cost of construction and maintenance and pumping is minimum.[3] It should be sufficiently stable against bursting, overturning and sliding under the floods, waves and anticipated loads.[4] It should be so planned as to facilitate easy dismantling and reuse of materials.

Types of coffer dam: [1] Earthfill coffer dam: This is the simplest form of coffer dam. Its use is limited in the vicinity where impervious earth is available and water depth is shallow with low velocity of flow. It should never be used where there is danger of over topping.

[figure]

[2] Rockfill coffer dam: They are constructed by placing rock material. They can be used for depths of water up to 20 m. and are suitable even in case of swift water. They are economical in places where rock is available in plenty. An impervious layer of earth is laid on the outer face of coffer dam which makes it impervious. They can with stand the over topping of water without any serious damage.

[figure]

[3] Rockfill crib coffer dam: It comprises of timber cribs. A crib is a frame work of wooden horizontal and cross beams laid in alternate courses. The cribs are open at the bottom and are filled with rock or gravel or earth. This gives stability to the crib against over topping or sliding.

[figure]

[4] Single wall coffer dam: This type of coffer dam is suitable when available working space is limited and area to be enclosed is small. It may be used up to the depth of water of 25m. The walls of a coffer dam are normally made up of steel sheet pile available to a maximum length of 22m. RCC and pre stressed concrete sheet piles have also been used.

[5] Double wall coffer dam: They are provided to enclose a larger area. The double wall gives stability to the coffer dam. This type of coffer dam is useful where scour problems and space limitations are prevalent.

[figure][6] Cellular coffer dam: They are made of steel sheet piles and are suitable for dewatering large areas. They are composed of diaphragm cells or circular cell. These type of coffer dams are used only in case of long span bridge piers across wide rivers.

I.S.Code for Aggregate – IS 383, Brick – IS 1077, Sand – IS 1542, Steel – IS 1761, Cement – IS 1489.

What is SOR? What are the various sections appearing in the SOR booklet, explain the important parameters that are used to finalize the carting rates.

The rates of materials and labour vary from place to place and therefore rates of different items of work also vary from place to place for one given place or a district analysis of rates are finalized, standardized and scheduled and it is used by various offices that district/division.

The determination of rate per unit of a particular item of work, from the cost of quantities of materials, the cost of labourers, miscellaneous petty expenses required for its completion is known as Analysis of Rates.

Rates of materials are usually taken as the rates delivered at the site of work and includes basic cost (cost at origin), cost of transport, railway freight etc if any , taxes etc. if the materials are to be carried from a distant places more than 8 km, the cost of transport is also added.

In the SOR booklet, the analysis of rate is also work out for the unit payment of the particular item of work under two heads [a] materials and [b] labours.

Give technical specifications of

Brickwork masonry in CM 1:6:

All bricks shall be of first class of standard specification made of good earth thorough, burnt and shall be of deep cherry red of copper colour. Bricks should be in regular shape and their edges shall be sharp and square shall emit clear ringing sound on being struck, free from cracks, flows, shall not absorb water more than 1/6 + 20% of its weight after one hour of soaking. It shall have a minimum crushing strength of 105 kg/cm2.

For cement mortar, cement shall be fresh Portland cement. Sand shall be sharp and free of organic and foreign matters. Proportion of cement and sand shall be 1:6. Mortar shall have colour uniformity and it shall be dry prepared by using clean water. It shall be mixed thoroughly by at least three times.

Bricks shall be bounded and laid in English bond. Every course shall be truly horizontal and work shall be in plumb. Vertical joints of consecutive courses shall not come directly over one another, vertical joints in alternate course shall come over one another. No damaged or broken bricks shall be used. Clears bricks shall be laid with frog upward except in the top course where frogs shall be placed downward. Brickwork shall not be carried out at a straight 1.0m in height.

The brickwork shall be kept wet for a period of at least 10 days after laying.

Cement concrete M-15:

Materials: Aggregates shall be of inert materials and should be clean, dense, hard, sound, durable, non-absorbent and capable of developing good bond with mortar.

Coarse aggregate shall be of hard broken stone of granite or similar stone, free from dust, dirt and other foreign matters. The coarse aggregate from 4.75 mm to 20 mm shall be well granded such that voids do not exceed 42%.

Fine aggregate shall be hard, sharp and angular grains and shall pass through 4.75 mm sieve. Sand shall be of FM 2.6 to 2.8 sea sand shall not be used.

Cement shall be fresh Portland cement of standard IS specification and have required tensile and compressive strength.

Water shall be clean and free from alkaline and PH value of water generally be not less than 6.

Proportion: The proportion shall be 1 cement 2 sand and 4 coarse aggregate by volume unless otherwise specified. Minimum compressive strength shall be 140 kg/cm2 on 7 days.

Hand mixing: To give a plastic mix of required workability and water cement ratio, for machine mixing 1.5 to 2.0 minutes rotation is required.

A slump of 7.5 cm to 10 cm (3” to 4”) may be allowed for building work and 1.5” to 2.0” for road work.

Form work: Centering and shuttering shall be provided as required forms should not be removed before 14 days in general. Side forms may how ever be removed after 3 days.

Laying: Laying shall be gently and continuously in layers of 6” and compacted by pinning and tamping also.

Curing: After two hours laying when concrete has begun to harden, it shall be kept damp by covering with wet gunny bags. A wet sand for 24 hours and then cured by flooding with water making mud walls 3” high or by covering with wet sand on earth and kept damp for 15 days.

PCC in foundation 1:3:6: Materials, Laying and Compacting:

Bed of foundation trench shall be lightly sprinkled with water before concrete is laid. Concrete shall be laid slowly and gently (not thrown) in layers of not more than 8” and thoroughly consolidated to 6” with 6 kg iron rammers. Curing at least 7 days and no masonry shall be constructed.