STONE TEST

Question 1

Why Smith’s test done

Answer 1

Find out presence of soluble matter

Question 2

Why Crushing test DONE

Answer 2

COMPRESSIVE STRENGTH

Question 3

WHY Acid test DONE

Answer 3

To check weather resistance of stone/check the presence of CaCO3.

Question 4

WHY Attrition test DONE

Answer 4

To find Rate of wear of stone

Question 5

WHY Impact test DONE

Answer 5

To determine toughness of stone

Question 6

Crystallisation test WHY

Answer 6

Evaluate the stone’s durability against crystallization-induced decay due to weathering.

Question 7

WHY Freezing and thawing DONE

Answer 7

Evaluate the stone’s ability to withstand the stresses associated with freezing and thawing.

Question 8

WHY Hardness test DONE

Answer 8

To determine hardness of stone

Question 9

Water Absorption Test

Answer 9

Water absorption test is carried out to calculate the percentage of water absorbed by stones.

Question 10

Smith’s test

Answer 10

Few pieces of stone immerse in clear water in a glass tube.

After about an hour tube is shaken or stirred vigorously

If water become dirty indicate stone contain soluble earth and mineral matters

Question 11

Crushing test

Answer 11

Cubes of size 40 x 40 x 40 mm

Minimum no of specimen test = 3

Place in water for 72 hour prior to test

The rate of loading is 14 N/mm² per minute

Crushing strength is maximum load at which sample crush divided by area of bearing face

Question 12

Acid test

Answer 12

Sample of stone weight about 0.5 to 1 N is taken

Placed in solution of hydrochloric acid strength of 1% and it is kept for 7 days and agitate at intervals.

Good stone maintain sharp edges and keep its surface free from powder.

Question 13

Attrition test

Answer 13

• Stone broken into pieces of 60 mm size, weighing 50 N is put in the cylinders of Deval’s attrition test machine.
• Diameter and length of the cylinder are 200 mm and 340 mm respectively, their axes makes an angle of 30° with horizontal. Rotate for 5 hours at a rate of 30 rpm
• After this periods, contents are taken out of cylinder and sieve through 1.5 mm mesh

Percentage wear = loss in weight x 100

Question 14

Crystallisation test

Answer 14

Four cubes of 40 mm sides

initial weight

• Dried for 72 hours weighed –> immersed in solution of 14% Na₂SO₄ for 2 hours -> dried at 100°C reweight and difference in weight is noted (5 times repeat)
• Each time express change in weight as percentage of original weight
• Evaluate the stone’s durability against crystallization-induced decay due to weathering.

Question 15

Impact test

Answer 15

• Cylinder of 25 mm diameter and 25 mm height is taken out.

Placed on cast iron anvil machine

• Steel hammer of weight 20 N drop

Height of 1st blow 1 cm, 2nd blow 2 cm and so on

• Blow at specimen break nth blow n represent toughness index

Question 16

Freezing and thawing

Answer 16

Specimen of stone - immerse in water for 24hrs -> freezing mixture at -12°C for 24 hours-> warmed at atmospheric temperature

• Repeat several times and behaviour of stone carefully obser

Question 17

Hardness test

Answer 17

To determine hardness of stone

• Cylinder of diameter 25 mm, height 25 mm – sample
• Weighed and place in Dorry’s testing machine
• Speed 28 rpm, during rotation coarse sand of standard specification sprinkled on top
• After 1000 revolutions specimen is taken out and weighed Coefficient of Hardness = 20 - loss in weight in gm 3

Question 18

Microscopic lest

Answer 18

Sample subjected to microscopic examination

• Study various properties like average grain size, existence of pores, mineral constituents, texture of stone etc.

Question 19

Water Absorption Test

Answer 19

Immerse the cube in distilled water at room temperature 20 to 30°C for 24 hours.

• The test piece shall then be placed on a dry cloth and gently surface dried with the cloth.

It shall be transferred to a second dry cloth when the first one removes no further moisture.

• It is left exposed to atmosphere away from direct sunlight or any other source of heat for not less than 10 min until it

appears to be completely surface dry. The sample shall then be weighed (B).

The stone samples are taken and dried in an oven at 100° C

to 110° C for 24 hours. The sample is then weighed and the weight is recorded as (A).

• Percentage water absorption = x 100