Saturday, 29 July 2017

Highway Engineering MCQs





Question No. 01

Group index method of design of flexible pavement is

(A) A theoretical method

(B) An empirical method based on physical properties of sub-grade soil

(C) An empirical method based on strength characteristics of sub-grade soil

(D) A semi empirical method

Answer: Option B

Question No. 02

Which of the following is considered to be the highest quality construction in the group of black top pavements?

(A) Mastic asphalt

(B) Sheet asphalt

(C) Bituminous carpet

(D) Bituminous concrete

Answer: Option D

Question No. 03

Los Angeles testing machine is used to conduct

(A) Abrasion test

(B) Impact test

(C) Attrition test

(D) Crushing strength test

Answer: Option A

Question No. 04

When the width of car parking space and width of street are limited, generally preferred parking system is

(A) Parallel parking

(B) 45° angle parking

(C) 65° angle parking

(D) 90° angle parking

Answer: Option A

Question No. 05

When the bituminous surfacing is done on already existing black top road or over existing cement concrete road, the type of treatment given is

(A) Seal coat

(B) Tack coat

(C) Prime coat

(D) Spray of emulsion

Answer: Option B

Friday, 28 July 2017

UNIT WEIGHT


01. Concrete 25 kN/m3
02. Brick 19 kN/m3
03.  Steel 7850 Kg/m3
04. Water 1000 Lt/m3
05. Cement 1440 Kg/m3
06. 1Gallon  4.81 Litres
07. Link 8″ = 200mm
08. 1 Hectare 2.471 acr(10000m2)
09. 1  Acr 4046.82m2 = 100 cent

Unit conversation

CONCRETE GRADES:
M5 = 1:4:8
M10= 1:3:6
M15= 1:2:4
M20=  1:1.5:3
M25= 1:1:2

CLEAR COVER TO MAIN REINFORCEMENT:
1.FOOTINGS : 50 mm
2.RAFT  FOUNDATION.TOP : 50 mm
3.RAFT FOUNDATION.BOTTOM/SIDES : 75 mm
4.STRAP BEAM  : 50 mm
5.GRADE SLAB : 20 mm
6.COLUMN : 40 mm
7.SHEAR WALL : 25  mm
8.BEAMS : 25 mm
9.SLABS : 15 mm
10.FLAT SLAB : 20 mm
11.STAIRCASE  : 15 mm
12.RET. WALL : 20/ 25 mm on earth
13.WATER RETAINING STRUCTURES :  20/30 mm

WEIGHT OF ROD PER METER LENGTH:
DIA WEIGHT PER METER
6mm = 0.222Kg
8mm = 0.395 Kg
10mm = 0.616 Kg
12mm = 0.888  Kg
16mm = 1.578 Kg
20mm = 2.466 Kg
25mm = 3.853 Kg
32mm = 6.313  Kg
40mm = 9.865 Kg

1bag cement-50kg
1feet-0.3048m
1m-3.28ft
1sq.m-10.76sq.f t
1cu.m-35.28cu.ft
1acre-43560sq.ft
1hectare-2.47acre

DESIGN MIX:
M10 ( 1 : 3.92 : 5.62)
Cement : 210 Kg/ M 3
20  mm Jelly : 708 Kg/ M 3
12.5 mm Jelly : 472 Kg/ M 3
River sand : 823 Kg/ M  3
Total water : 185 Kg/ M 3
Fresh concrete density: 2398 Kg/M 3

M20 ( 1 : 2.48 :  3.55)
Cement : 320 Kg/ M 3
20 mm Jelly : 683 Kg/ M 3
12.5 mm Jelly :  455 Kg/ M 3
River sand : 794 Kg/ M 3
Total water : 176 Kg/ M  3
Admixture : 0.7%
Fresh concrete density: 2430 Kg/ M 3

M25 ( 1 : 2.28 :  3.27)
Cement : 340 Kg/ M 3
20 mm Jelly : 667 Kg/ M 3
12.5 mm Jelly :  445 Kg/ M 3
River sand : 775 Kg/ M 3
Total water : 185 Kg/ M  3
Admixture : 0.6%
Fresh concrete density: 2414 Kg/ M 3
Note: sand 775  + 2% moisture, Water185 -20.5 =
164 Liters,
Admixture = 0.5% is  100ml

M30 ( 1 : 2 : 2.87)
Cement : 380 Kg/ M 3
20 mm Jelly : 654 Kg/ M  3
12.5 mm Jelly : 436 Kg/ M 3
River sand : 760 Kg/ M 3
Total water :  187 Kg/ M 3
Admixture : 0.7%
Fresh concrete density: 2420 Kg/ M 3
Note:  Sand = 760 Kg with 2% moisture
(170.80+15.20)

STANDARD CONVERSION FACTORS
INCH = 25.4 MILLIMETRE
FOOT =  0.3048 METRE
YARD = 0.9144 METRE
MILE = 1.6093 KILOMETER
ACRE = 0.4047  HECTARE
POUND = 0.4536 KILOGRAM
DEGREE FARENHEIT X 5/9 – 32 =  DEGREE
CELSIUS
MILLIMETRE= 0.0394 INCH
METRE = 3.2808FOOT
METRE =  1.0936YARD

Physical test on cement.

(a) Soundness Test:

It is conducted by sieve analysis. 100 gms of cement is taken and sieved through IS sieve No. 9 for fifteen minutes. Residue on the sieve is weighed. This should not exceed 10 per cent by weight of sample taken.

(b) Setting Time:

Initial setting time and final setting time are the two important physical properties of cement. Initial setting time is the time taken by the cement from adding of water to the starting of losing its plasticity. Final setting time is the time lapsed from adding of the water to complete loss of plasticity.

Vicat apparatus is used for finding the setting times Vicat apparatus consists of a movable rod to which any one of the three needles shown in figure can be attached. An indicator is attached to the movable rod. A vicat mould is associated with this apparatus which is in the form of split cylinder.

 

Before finding initial and final setting time it is necessary to determine water to be added to get standard consistency. For this 300 gms of cement is mixed with about 30% water and cement paste prepared is filled in the mould which rests on non porous plate. The plunger is attached to the movable rod of vicat apparatus and gently lowered to touch the paste in the mould. Then the plunger is allowed to move freely. If the penetration is 5 mm to 7mm from the bottom of the mould, then cement is having standard consistency. If not, experiment is repeated with different proportion of water fill water required for standard consistency is found. Then the tests for initial and final setting times can be carried out as explained below:

 

Initial Setting Time: 300 gms of cement is thoroughly mixed with 0.85 times the water for standard consistency and vicat mould is completely filled and top surface is levelled. 1 mm square needle is fixed to the rod and gently placed over the paste. Then it is freely allowed to penetrate. In the beginning the needle penetrates the paste completely.

As time lapses the paste start losing its plasticity and offers resistance to penetration. When needle can penetrate up to 5 to 7 mm above bottom of the paste experiment is stopped and time lapsed between the addition of water and end if the experiment is noted as initial setting time.

 Final Setting Time. The square needle is replaced with annular collar. Experiment is continued by allowing this needle to freely move after gently touching the surface of the paste. Time lapsed between the addition of water and the mark of needle but not of annular ring is found on the paste. This time is noted as final setting time.

 

(c) Soundness Test:

This test is conducted to find free lime in cement, which is not desirable. Le Chatelier apparatus shown in  is used for conducting this test. It consists of a split brass mould of diameter 30 mm and height 30 mm. On either side of the split, there are two indicators, with pointed ends. The ends of indicators are 165 mm from the centre of the mould.

 

Properly oiled Le Chatelier mould is placed on a glass plate and is filled completely with a cement paste having 0.78 times the water required for standard consistency. It is then covered with another glass plate and a small weight is placed over it. Then the whole assembly is kept under water for 24 hours.

 

The temperature of water should be between 24°C and 50°C. Note the distance between the indicator. Then place the mould again in the water and heat the assembly such that water reaches the boiling point in 30 minutes. Boil the water for one hour. The mould is removed from water and allowed to cool. The distance between the two pointers is measured. The difference between the two readings indicate the expansion of the cement due to the presence of unburnt lime. This value should not exceed 10 mm.

 

(d) Crushing Strength Test:

For this 200 gm of cement is mixed with 600 gm of standard sand confirming to IS 650–1966. After mixing thoroughly in dry condition for a minute distilled potable water P4+ 3 percentage is added where P is the water required for the standard consistency.

 

They are mixed with trowel for 3 to 4 minutes to get uniform mixture. The mix is placed in a cube mould of 70.6 mm size (Area 5000 mm2) kept on a steel plate and prodded with 25 mm standard steel rod 20 times within 8 seconds. Then the mould is placed on a standard vibrating table that vibrates at a speed of 12000 ± 400 vibration per minute.

 

A hopper is secured at the top and the remaining mortar is filled. The mould is vibrated for two minutes and hopper removed. The top is finished with a knife or with a trowel and levelled. After 24 ± 1 hour mould is removed and cube is placed under clean water for curing.After specified period cubes are tested in compression testing machine, keeping the specimen on its level edges.

 

 Average of three cubes is reported as crushing strength. The compressive strength at the end of 3 days should not be less than 11.5 N/mm2 and that at the end of 7 days not less than 17.5 N/mm2.

 

 

Low cost housing

Low Cost Housing is a new concept which deals with effective budgeting and following of techniques which help in reducing the cost construction through the use of locally available materials along with improved skills and technology without sacrificing the strength, performance and life of the structure.

There is huge misconception that low cost housing is suitable for only sub standard works and they are constructed by utilizing cheap building materials of low quality.The fact is that Low cost housing is done by proper management of resources.Economy is also achieved by postponing finishing works or implementing them in phases.

Building Cost

The building construction cost can be divided into two parts namely:

Building material cost : 65 to 70 %

Labour cost : 65 to 70 %

Now in low cost housing, building material cost is less because we make use of the locally available materials and also the labour cost can be reduced by properly making the time schedule of our work. Cost of reduction is achieved by selection of more efficient material or by an improved design.

 

Areas from where cost can be reduced are:-

1) Reduce plinth area by using thinner wall concept.Ex.15 cms thick solid concrete block wall.

2) Use locally available material in an innovative form like soil cement blocks in place of burnt brick.

3) Use energy efficiency materials which consumes less energy like concrete block in place of burnt brick.

4) Use environmentally friendly materials which are substitute for conventional building components like use R.C.C. Door and window frames in place of wooden frames.

5) Preplan every component of a house and rationalize the design procedure for reducing the size of the component in the building.

6) By planning each and every component of a house the wastage of materials due to demolition of the unplanned component of the house can be avoided.

7) Each component of the house shall be checked whether if it’s necessary, if it is not necessary, then that component should not be used.

Cost reduction through adhoc methods

 

Foundation

Normally the foundation cost comes to about 10 to 15% of the total building and usually foundation depth of 3 to 4 ft. is adopted for single or double store building and also the concrete bed of 6″(15 Cms.) is used for the foundation which could be avoided.

It is recommended to adopt a foundation depth of 2 ft.(0.6m) for normal soil like gravely soil, red soils etc., and use the uncoursed rubble masonry with the bond stones and good packing. Similarly the foundation width is rationalized to 2 ft.(0.6m).To avoid cracks formation in foundation the masonry shall be thoroughly packed with cement mortar of 1:8 boulders and bond stones at regular intervals.

It is further suggested adopt arch foundation in ordinary soil for effecting reduction in construction cost up to 40%.This kind of foundation will help in bridging the loose pockets of soil which occurs along the foundation.

In the case black cotton and other soft soils it is recommend to use under ream pile foundation which saves about 20 to 25% in cost over the conventional method of construction.

 

Plinth

It is suggested to adopt 1 ft. height above ground level for the plinth and may be constructed with a cement mortar of 1:6. The plinth slab of 4 to 6″ which is normally adopted can be avoided and in its place brick on edge can be used for reducing the cost. By adopting this procedure the cost of plinth foundation can be reduced by about 35 to 50%.It is necessary to take precaution of providing impervious blanket like concrete slabs or stone slabs all round the building for enabling to reduce erosion of soil and thereby avoiding exposure of foundation surface and crack formation.

 

Walling

Wall thickness of 6 to 9″ is recommended for adoption in the construction of walls all-round the building and 41/2 ” for inside walls. It is suggested to use burnt bricks which are immersed in water for 24 hours and then shall be used for the walls

 

Rat – trap bond wall

It is a cavity wall construction with added advantage of thermal comfort and reduction in the quantity of bricks required for masonry work. By adopting this method of bonding of brick masonry compared to traditional English or Flemish bond masonry, it is possible to reduce in the material cost of bricks by 25% and about 10to 15% in the masonry cost. By adopting rat-trap bond method one can create aesthetically pleasing wall surface and plastering can be avoided.

 

Concrete block walling

In view of high energy consumption by burnt brick it is suggested to use concrete block (block hollow and solid) which consumes about only 1/3 of the energy of the burnt bricks in its production. By using concrete block masonry the wall thickness can be reduced from 20 cms to 15 Cms. Concrete block masonry saves mortar consumption, speedy construction of wall resulting in higher output of labour, plastering can be avoided thereby an overall saving of 10 to 25% can be achieved.

 

Soil cement block technology

It is an alternative method of construction of walls using soil cement blocks in place of burnt bricks masonry. It is an energy efficient method of construction where soil mixed with 5% and above cement and pressed in hand operated machine and cured well and then used in the masonry. This masonry doesn’t require plastering on both sides of the wall. The overall economy that could be achieved with the soil cement technology is about 15 to 20% compared to conventional method of construction.

 

Doors and windows

It is suggested not to use wood for doors and windows and in its place concrete or steel section frames shall be used for achieving saving in cost up to 30 to 40%.Similiarly for shutters commercially available block boards, fibre or wooden practical boards etc., shall be used for reducing the cost by about 25%.By adopting brick jelly work and precast components effective ventilation could be provided to the building and also the construction cost could be saved up to 50% over the window components.

 

Lintels and Chajjas

The traditional R.C.C. lintels which are costly can be replaced by brick arches for small spans and save construction cost up to 30 to 40% over the traditional method of construction. By adopting arches of different shapes a good architectural pleasing appearance can be given to the external wall surfaces of the brick masonry.

 

Roofing

Normally 5″(12.5 cms) thick R.C.C. slabs is used for roofing of residential buildings. By adopting rationally designed insitu construction practices like filler slab and precast elements the construction cost of roofing can be reduced by about 20 to 25%.

 

Filler slabs

They are normal RCC slabs where bottom half (tension) concrete portions are replaced by filler materials such as bricks, tiles, cellular concrete blocks, etc.These filler materials are so placed as not to compromise structural strength, result in replacing unwanted and nonfunctional tension concrete, thus resulting in economy. These are safe, sound and provide aesthetically pleasing pattern ceilings and also need no plaster.

 

Jack arch roof/floor

They are easy to construct, save on cement and steel, are more appropriate in hot climates. These can be constructed using compressed earth blocks also as alternative to bricks for further economy.

 

Ferrocement channel/shell unit

Provide an economic solution to RCC slab by providing 30 to 40% cost reduction on floor/roof unit over RCC slabs without compromising the strength. These being precast, construction is speedy, economical due to avoidance of shuttering and facilitate quality control.

 

Finishing Work

The cost of finishing items like sanitary, electricity, painting etc., varies depending upon the type and quality of products used in the building and its cost reduction is left to the individual choice and liking.

 

Basic steps of Stadd-pro

In this blog I am going to discuss about STAADPRO as it is mostly use and better user Interface the steps involved are elaborated in following lines :

1. Creating a project file with suitable file name.
2. Fixing the units.
3. Creating the Geometry by JOINT   COORDINATES and MEMBER INCIDENCE command.
4. Applying the member properties as per codal provision and self judgement.
5. Providing support to the structure.
6. Using definition command for loads .
7. Applying loads on floors and other structural components.
8. Providing output units.
9. Defining the codes.
10. Print support reaction command after  perform analysis.
11. Defining design code i.e., IS 456 or IS 13920
11. Design commands as per respective codes
12 .Finally design and result output.

Compression Test of concrete block.


The Compression Test is a laboratory test to determine the characteristic strength of the concrete but the making of test cubes is sometimes carried out by the supervisor on site. This cube test result is very important to the acceptance of insitu concrete work since it demonstrates the strength of the design mix.

The procedure of making the test cubes is as follows:

150 mm standard cube mold is to be used for concrete mix and 100 mm standard cube mold is to be used for grout mix.

Arrange adequate numbers of required cube molds to site in respect with the sampling sequence for the proposed pour.Make sure the apparatus and associated equipment are clean before test and free from hardened concrete and superfluous water .

Assemble the cube mold correctly and ensure all nuts are tightened.Apply a light coat of proprietary mold oil on the internal faces of the mold.Place the mold on level firm ground and fill with sampled concrete to a layer of about 50 mm thick.

Compact the layer of concrete thoroughly by tamping the whole surface area with the Standard Tamping Bar. (Note that no less than 35 tamps / layer for 150 mm mold and no less than 25 tamps / layer for 100 mm mold).Repeat Steps 5 & 6 until the mold is all filled. (Note that 3 layers to be proceeded for 150 mm mold and 2 layers for 100 mm mold).

Remove the surplus concrete after the mold is fully filled and trowel the top surface flush with the mold.Mark the cube surface with an identification number (say simply 1, 2, 3, etc) with a nail or match stick and record these numbers in respect with the concrete truck and location of pour where the sampled concrete is obtained.

Cover the cube surface with a piece of damp cloth or polythene sheeting and keep the cube in a place free from vibration for about 24 hours to allow initial set .Strip off the mold pieces in about 24 hours after the respective pour is cast. Press the concrete surface with the thumb to see any denting to ensure the concrete is sufficiently hardened, or otherwise de-molding has to be delayed for one more day and this occurrence should be stated clearly in the Test Report.

Mark the test cube a reference number with waterproof felt pen on the molded side, in respect with the previous identification number.Place the cube and submerge in a clean water bath or preferably a thermostatically controlled curing tank until it is delivered to the accredited laboratory for testing.

Different test conduct on Stones to select the appropriate stone for construction purpose.

Stones form one of the most important building materials in civil engineering. Stones are derived from rocks, which form the earth's crust and have no definite shape or chemical combination but are mixtures of two or more minerals. The mineral is a substance which is formed by the natural inorganic process and possesses a definite chemical combination and molecular structure. They are strong, durable and descent in appearance.

The main uses of stone as a building material are:

As a principal material for foundation of civil engineering works, and for the construction of walls, arches, abutments and dams.In stone masonry in places where it is naturally available.As coarse aggregate in cement concrete (crushed form of rock).

Tests which are to be conducted on stones for selecting it as a building material.

Acid Test: Acid test is used to investigate how much atmospheric action can be resisted by stone.  In this test 100 grams of stones in chipped form are kept in a 5% solution of hydrochloric acid or sulphuric acid. After 3 days stones in chipped form are taken out and dried. If the edges of stones are sharp as earlier, it indicates that stone can resist weathering actions.

Smith's Test: This test is used for finding out the presence of soluble matter in stones. In this test few sample of stones are place in a glass or test-tube filled with clean water. Stones are kept in water for 1 hour. After this the glass or test-tube is vigorously shaken. Due to presence of earthy material and clay impurities water is converted to dirty water. Slightly cloudiness of water will prove that the stones are good and durable. If water becomes too dirty, it indicates that stone contains too much soluble impurities and it is not suitable for construction.

 
Crushing Strength: Crushing test is used to investigate the compressive strength of stone. In this test stone is cut into cubes of dimension 40mm. Sides of cube are finely dressed and finished. Cubes of stones are then kept in water for 72 hours. Then 5mm thick layer of plywood or plaster of paris is applied on the load bearing surface. Load is applied axially on load bearing surface using universal testing machine or crushing testing machine until cracks appear on the stone or stone starts crushing.
     Crushing strength of the stone is the maximum load at which it crushes divided by the area of the load bearing surface. 

Water Absorption Test: In this test, 50 grams of stones in chipped form are places in an oven at 105 degree celsius for 3 hours then cooled at room temperature. Weight of stones is then taken (W1). Then stones are places in distilled water for 3 days. After 3 days weight of stones is taken (W2).

     Percentage '%' of water absorption should not exceed 15%, otherwise stone is not suitable for construction.

Crystallization Test: 4 cubes of stone with dimension 40mm are taken. Stones are dried for 3 days and weighed. Then stones are immersed in 14% solution of Sodium Sulfate (Na2SO4) for 2 hours. After this stones are dried at 100 degree Centigrade  and weighed. Difference in weight is noted .Process of drying, weighing, immersion and reweighing is repeated at least 5 times. Each time, change in weight is noted and it is expressed as a percentage of original weight.

PERCENTAGE OF WEAR SHOULD NOT EXCEED 2% FOR GOOD STONE.

Hardness Test: This test is carried out to determine the hardness of stone. First weight of specimen is taken (W1). The specimen is filled in a test cylinder of diameter 25 mm and height 25 mm. Then cylinder is placed in Dorry's testing machine and force of 12.50 N is applied. The disc of testing machine is rotated at 28 revolutions per minute.During the rotation of the disc, coarse sand of standard specification is sprinkled on the top of disc. After 1000 revolutions specimen is weighed (W2).

Impact Test: This test is carried out to determine the toughness of stone. This test requires an 'Impact Testing Machine'. In this test stones are filled in test cylinder of diameter 25 mm and height 25 mm. The cylinder is placed on machine and steel hammer of weight 20 N is allowed to fall on the specimen in cylinder. The height of first fall is 1 cm, height of second fall is 2 cm and so on. The height at which specimen breaks is recorded. If specimen breaks at 'n cm' then 'n' is the toughness index of stone.  
Microscopic Test: In this test specimen of stones is placed under microscope and various properties are studied such as grain size, texture of stone, pores, veins, shakes etc.

Attrition Test: This test is carried out to test the resistance to abrasion (ability to withstand grinding action)  of stone. This test is carried out in 'Attrition Test Machine'. In this test specimen of stone is weighed (W1). Then stones are transferred to drum and drum is inclined to 30 degree to the horizontal. Then stones are revolved ate 2000 revolution per hour for 5 hours. After this stones are sieved on a 2 mm sieve. Stones retained on sieve are weighed (W2) and loss in weight percentage gives the percentage of wear.