Showing posts with label STRUCTURE ANALYSIS. Show all posts
Showing posts with label STRUCTURE ANALYSIS. Show all posts

Sunday 9 April 2017

Interviews and Exams questions : ALL About Cement


1: Name the component that responsible for early strength of concrete:

Ans: C3S ( Tri Calcium silicate ) , that react with water and produces more heat of hydration is responsible for early strength of concrete.


2: Which compound contribute to the later strength of concrete ?
Ans: C2S ( Di Calcium silicate ) that hydrates slowly , contribute to the later strength of concrete .


3: After how many days , the compressive strength developed by C3S and C2S are equal .
Ans: ONE year  

4:For road rapid work which type of cement is recommended :
Ans: Rapid hardening cement

5: In how many  days , about 50% of the total heat evolution occurs.
Ans: During the first 3 days of hydration 

6:Which oxides are responsible for high early strength of cement ?
Ans: High total alumina and high ferric oxide content favour the production of high early strength in cement


Compounds : When components of cements added up with water than they called compound in simple language ..


Tricalcium Silicate (C3S) hardens rapidly and is largely responsible for initial set and early strength.


In general, the early strength of portland cement concrete is higher with increased percentages of C3S.


Dicalcium Silicate (C2S) hardens slowly and contributes largely to strength increases at ages beyond 7 days.


Tricalcium Aluminate (C3A) liberates a large amount of heat during the first few days of hardening and, together with C3S and C2S may somewhat increase the early strength of the hardening cement (this effect being due to the considerable heat of hydration that this compound evolves). It does affect set times.


Tetracalcium Aluminoferrite (C4AF) contributes very slightly to strength gain. However, acts as
a flux during manufacturing. Contributes to the color effects that makes cement gray.aakes cement gray.

Compounds by percentage :



Role of compounds on properties of cement : MOST IMP





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RCC Book: Best suitable for deep study :
1: http://amzn.to/2iMfgUj (Reinforced Concrete Design - Third Edition ) by Devdas Menon (Author), S. Pillai (Author)


Saturday 8 April 2017

TOP 7 : STEEL STRUCTURE




1: With percentage increase of carbon in steel , decreases its
A: Strength
B: Hardness
C: Brittleness
D: Ductility  

2:Poisson's ratio for steel within elastic limit , ranges from
A: 0.15 TO 0.20
B: 0.25 TO 0.24
C: 0.25 TO 0.33
D: 0.33 TO 0.35

3: The slenderness ratio of a column is zero when its length 
A: IS ZERO
B: IS EQUAL TO ITS RADIUS OF GYRATION
C: IS SUPPORTED ON ALL SIDES THROUGHOUT ITS LENGTH
D: IS BETWEEN THE POINTS OF ZERO MOMENTS

4:Maximum permissible slenderness ratio of compression members which carry dead and superimposed load, is
A:350
B:250
C:180
D:80

5:The effective length of a weld, is taken as the actual length
A: Minus the size of weld
B: Minus twice the size of weld
C: Plus the size of weld
D: Plus twice the size of weld

6:A beam is defined as a structural member subjected to
A: Axial loading
B:Transverse loading
C: Axial and transverse loading

7:The best compression member section for column is:
A: Single angle section
B: Double angle section
C: Channel section
D: I-section




Los Angeles Abrasion Test , Why and How To Perform

LOS ANGELES ABRASION TEST:



This is hardness test for aggregates, used in Laboratory  to determine the hardness value or abrasion value 
APPARATUS :

 Los Angeles Abrasion Testing Machine ,
Abrasive Charge – Cast iron or steel balls ,
Test sieve – 1.70 mm IS sieve ,
 Balance of capacity 10 kg , Oven , Tray

The aggregate used in surface course of the highway pavements are subjected to wearing due to movement of traffic. 

When vehicles move on the road, the soil particles present between the pneumatic tyres and road surface cause abrasion of road aggregates. 

The steel reamed wheels of animal driven vehicles also cause considerable abrasion of the road surface. 

Therefore, the road aggregates should be hard enough to resist abrasion. 

The principle of Los Angeles abrasion test is to produce abrasive action by use of standard steel balls which when mixed with aggregates and rotated in a drum for specific number of revolutions also causes impact on aggregates. 

The percentage wear of the aggregates due to rubbing with steel balls is determined and is known as Los Angeles Abrasion Value.



Key point of los angles test:

Rotate the machine at a speed of 30 – 33 revolutions per minute. The number of revolutions is 500 for grading A, B, C & D and 1000 for grading E, F & G. The machine should be

5 kg of sample for grading A, B, C & D and 10 kg for grading E, F & G

THE CALCULATION PART:

Original weight of aggregate sample = W1 g
Weight of aggregate sample retained = W2 g
Weight passing 1.7mm IS sieve = W1 - W2 g
Los Angeles Abrasion Value = (W1 - W2) / W1 X 100







Los angeles abrasion value should lies in below given range for different types of roads

Types of pavement layers                                         Max. Permissible Abrasion Value in %

1:WBM , SUB BASE COURSE                                                      60%

2:WBM BASE COURSE WITH BITUMEN SURFACE               50%

3: BITUMEN BOUND MACADAM                                             50%

4:WBM SURFACING COURSE                                                    40%

5: BITUMINOUS PENETRATION MACADAM                              40%

6:BITUMINOUS SURFACING DRESSING CEMENT
 CONCRETE SURFACING COURSE                                              35%

7:BITUMINOUS CONCRETE SURFACING COURSE                   30%

Monday 15 August 2016

Friday 12 August 2016

Highway Design-Parking Along Highways and Arterial Streets

Highway Parking Design
These paragraphs below deal with parking as it pertains to the mainlanes of a controlled access highway, the frontage roads for such a facility, and parking along urban and suburban arterials. Rest areas as parking facilities are not considered in this article.

Emergency Parking

Parking on and adjacent to the mainlanes of a highway will not be permitted except for emergency situations. It is of paramount importance, however, that provision be made for emergency parking. Shoulders of adequate design provide for this required parking space.

Curb Parking

In general, curb parking on urban/suburban arterial streets and frontage roads
should be discouraged. Where speed is low and the traffic volumes are well below capacity, curb parking may be permitted. However, at higher speeds and during periods of heavy traffic movement, curb parking is incompatible with arterial street service and desirably should not be permitted. Curb parking reduces capacity and interferes with free flow of adjacent traffic.
Elimination of curb parking can increase the capacity of four-to-six lane arterials by 50 to 60 percent. If curb parking is used on urban/suburban arterials or frontage roads under the conditions stated above, the following design requirements should be met:
  • provide parking lanes only at locations where needed
  • parallel parking preferred
  • confine parking lanes to outer side of street or frontage road
  • require that parking lane widths be 10 feet [3.0 meters]
  • restrict parking a minimum of 20 feet [6 meters] back from the radius of the intersection to allow for sight distance, turning clearance and, if desired, a short right turn lane.

Thursday 11 August 2016

Difference between Bridge and Flyover

The difference between Bridge and Flyover is based on the purpose of its usage and the location where it is built.

Bridges
  • Bridges are built to connect two points separated by a naturally occurring region like valley, river, sea or any other water bodies, etc.
  • They are usually lengthy depending upon the width of the valley or river.
  • Construction over river is tedious since foundation has to be carried out on the river bed.
  • Bridges are usually built for trains, buses and cars.

Flyovers
  • It is a structure which joints two or more points which are separated by an accessible route/s or a man made structure to cut the traffic for faster mode of travelling.
  • They are usually made over road junctions, roads, streets, etc.
  • The name itself suggests that you are flying over a traffic zone.
  • They are usually built for road vehicles.

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