Aggregate Crushing Value Test

The aggregate crushing value (ACV) provides relative measure of the resistance of an aggregate to crushing under a gradually applied compressive load.

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OBJECTIVE:

For determination of the aggregate crushing value of coarse aggregate, of size ranging from 10mm to 12.5 mm.

APPARATUS REQUIRED:

• Steel Cylinder
• Tamping Rod
• IS Sieves (12.5mm and 10mm)
• Cylindrical metal measure
• Weight Balance
• Oven
• Compression testing Machine(CTM)

  

  Aggregate Crushing Value Test Apparatus

 PROCEDURE:

Test sample consists of aggregate passing a 12.5mm IS sieve and retained on a 10mm IS sieve. The aggregate to be tested is dried in an oven for a period of not less than 4 hours. Approximately 6kg of the sample is to be prepared.

1. The cylindrical steel cup is filled with 3 equally divided layers of aggregate and each layer is tamped 25 times by the tamping rod. At last the top of the container is leveled.
   
   

   

   Step-1

   
   
2. Remove all the aggregates from the steel cup and weigh it. Note the weight(WA).

   

   Step-2
3. The bigger cup is fixed firmly in position on the base of the machine and the whole of the test sample is added in three layers, each layer being subjected to 25stokes from tamping rod.

   

   Step-3

4. The surface is leveled and the plunger is inserted so that it rests horizontally on the surface. The whole assembly is then placed in the CTM and loaded at a uniform rate so as to reach a load of 40 tones in 10 minutes.

   

   Step-4

5. The load is then released and all aggregate is removed from the cup and sieved on 2.36 mm IS sieve.

   

   Step-5

6. The fraction passing the sieve is weighed to an accuracy of 0.1 g (WB)
   
   

   

   Step-6

CALCULATION:

The ratio of the weight of fines formed to the total sample weight in each test is to be expressed as a percentage, to the first decimal place.

Aggregate crushing Value =(WB/WA) × 100 

TEST RESULTS:

The mean of the two results(to the nearest whole number) is reported as the aggregate crushing value of the tested material.           

(In India, we follow all provisions and standard values given by IS: 2386 (Part IV) for this test.)

Static independency of Ashoka Chakra

Answer = 72
  External indeterminacy = 0  ( as there is no supports)
  Number of closed boxes = 24
Hence internal indeterminacy = 24×3 = 72

Hence total degree of indeterminacy = 0+72 = 72 (Ans.)

City of Arts and Science, Spain

The City of Arts and Sciences is situated at the end of the former riverbed of the river Turia, which was drained and rerouted after a catastrophic flood in 1957. The old riverbed was turned into a picturesque sunken park.

Designed by Santiago Calatrava and Félix Candela, the project began the first stages of construction in July 1996, and was inaugurated April 16, 1998 with the opening of L'Hemisfèric. The last great component of the City of Arts and Sciences, El Palau de les Arts Reina Sofia, was inaugurated on October 9, 2005, Valencian Community Day.

Originally budgeted at €300 million, it has cost nearly three times the initial expected cost. Read more....

Answer : C

Answer : C

Answer : B

HOW TO DETERMINE CONSISTENCY OF MASONRY MORTAR?

APPARATUS

• Standard Cone Apparatus having following parts and dimensions

Penetrating Cone	Conical Container
Weight = 300 g,Height = 150 mm, Base dia = 75 mm	Top dia=150 mm,Height = 180 mm

•  Tamping Rod

Standard Cone Apparatus For Consistency Test of Masonry Mortar

PROCEDURE

1. Fill the conical container with the mortar to a level that is 1 cm below its rim.
2. Compact the mortar inside the container using the tamping rod.
3. Place the container over the base, below the penetrating cone of the apparatus.
4. Lower the penetrating cone so that the apex of the penetrating cone just touches the mortar surface. Clamp the penetrating cone at this position. (refer the pic shown above)
5. Set the dial gauge so as to take the first reading (i.e. D1)
6. Release the cone and allow it to sink into the mortar mix.
7. After complete penetration of the penetrating cone, set the dial gauge again, so as to  take the final reading (i.e. D2).

CALCULATION

Calculate the depth of penetration of the cone (i.e. D) by subtracting the initial reading from final reading.

D = D2 – D1

RESULT

Make two determinations on determinations on different specimens and calculate the average of the two determinations. The result is expressed in mm.

REFERENCE

IS-2250 – Code of practice for preparation and use of masonry mortars.

Answer: C

Civil Quiz

Answer : B

Example of magnetic declination showing a compass needle with a "positive" (or "easterly") variation from geographic north. N_g is geographic or true north, N_m is magnetic north, and δ is magnetic declination

Magnetic declination or variation is the angle on the horizontal plane between magnetic north (the direction the north end of a compass needle points, corresponding to the direction of the Earth's magnetic field lines) and true north (the direction along a meridian towards the geographic North Pole). This angle varies depending on position on the Earth's surface, and changes over time.

Somewhat more formally, Bowditch defines variation as “the angle between the magnetic and geographic meridians at any place, expressed in degrees and minutes east or west to indicate the direction of magnetic north from true north. The angle between magnetic and grid meridians is called grid magnetic angle, grid variation, or grivation.”

By convention, declination is positive when magnetic north is east of true north, and negative when it is to the west. Isogonic linesare lines on the Earth's surface along which the declination has the same constant value, and lines along which the declination is zero are called agonic lines. The lowercase Greek letter δ (delta) is frequently used as the symbol for magnetic declination.

The term magnetic deviation is sometimes used loosely to mean the same as magnetic declination, but more correctly it refers to the error in a compass reading induced by nearby metallic objects, such as iron on board a ship or aircraft.

Magnetic declination should not be confused with magnetic inclination, also known as magnetic dip, which is the angle that the Earth's magnetic field lines make with the downward side of the horizontal plane.

Answer : A

Forth Bridge, Scotland

Cement Tests

Answer: A ( Straight line )

We have seen almost all highways being raised in the middle portion of the road surface with respect to the edges. This cross slope in the transverse direction is called as the Camber (or Cant). It is generally provided with the sole purpose of draining the rain water from the road surface towards the edges.

Answer: Sextant

Sextant is an instrument with a graduated arc of 60° and a sighting mechanism, used for measuring the angular distances between objects( horizontal angles ) and especially for taking altitudes in navigation and surveying.

A man using Sextant for measurement of horizontal angle