Test for stones

the ppt gives complete information regarding the test used to carry out to study the various properties of stone and further use it for construction.

1. TEST FOR STONES

2. PURPOSE AND THE NECESSITY FOR THE TEST OF STONES. Testing evaluates the suitability of specific stone for a particular application. The strength of a stone is tested to determine its resistance to crushing and bending. The density of specific gravity is tested to design a support system capable of carrying the weight of stone.

3. FOLLOWING ARE DIFFERENT TEST FOR STONES….. ACID TEST ATTRITION TEST CRUSHING TEST CRYSTALLISATION TEST FREEZING AND THAWING TEST HARDNESS TEST IMPACT TEST MICRO-SCOPIC TEST SMITHS TEST WATER ABSORPTION TEST

4. ACID TEST Stone weighing 0.5-1N is taken Placed in hydrochloric acid having strength 1% is taken. It is kept for 7 days the solution is agitated at intervals. A good building stone maintain sharp edges and surface free from powder. A poor stone will have broken edges and powder is formed on surfaces IT IS A NATURAL TEST AND CANNOT BE APPLIED ON LIMESTONE. IT IS MAINLY CARRIED OUT ON SANDSTONE Good stone Sharp edges Powder free surface Poor stone Blunt edges Powdered surface Stone placed in hydro-chloric acid 1%

5. ATTRITION TEST The sample of stones is broken into pieces of 60mm in size. Such pieces of weighing 50N are put in both the cylinders of devals attrition test machine The diameter and length of cement is respectively 200mm and 340mm The cylinders are closed , the axis make an angle of 30’ with the horizontal. The cylinders are rotated about with horizontal axis for the 5 hrs at rate of 30 R.P.M After this the contents are taken out from the cylinders are they are passed through a sieve of 1.50mm The quantity of material which is retained on a sieve is measured. The percentage wear is worked out as follows Percentage wear = loss in weight X100 Initial weight DEVAL’S attrition test machine

6. CRUSHING TEST…. The sample of stone is cut into the cube size of 40mmx40mmx40mm The sides of cubes are finely dressed and finished. The minimum number of specimen to be taken is three. Such specimen should be placed in water for about 72hrs prior to the test. Thereafter tested in saturated container. The load bearing surface is than covered with plaster of paris or 5mm thick wood. The load is applied axially on the cube in a crushing test machine The rate of loading is 13.72N/ mmsq per minute Three specimen placed in water for 72 hrs prior to test Covered with plaster of paris 5mm thick wood

7. The crushing strength of a stone per unit area is the maximum load at which its sample crushed or fail divided by the area of the bearing face of specimen. COMPRESSIVE STRENGTH OF A STONE IS FOUND OUT WITH THE HELP OF THIS TEST………

8. CRYSTALLISATION TEST In this test at least 4 cubes of stones with side as 40mm are taken. They are dried for 72 hrs and weighed. They are immersed in 14% solution of sodium sulphate for 2 hrs They are 100’c and weighed The difference in weight is noted. This procedure of drying , weighing, immersing, and reweighing is repeated at least five times Each time the change in weight is noted and it is expressed as a percentage of original weight. Each time the change in weight is noted and it is expressed as a percentage of original weight. IT IS TO BE NOTED THAT THE CRYSTALLISATION OF CALCIUM SULPHATE IN PORES OF STONES CAUSES THE DECAY OF STONES CAUSES THE DECAY OF STONES DUE TO WEATHERING. BUT AS SALCIUM SULPHATE HAS LOW SOLUBILITY IN WATER , IT IS NOT ADOPTED FOR THIS TEST. 4 cubes of stone immersed in 14% of sodium suplhate solution for 2 hrs

9. FREEZING AND THAWING TEST The specimen of a stone is kept in immersed water for 24 hrs. It is than placed in a freeing mixture at -12’C for 24 hrs. It is than thawed and warned at atmospheric temperature. This should be done in a shade to prevent any effect due to wind , sunrays , rain etc.. Such procedure is repeated several times and behaviour of stone is carefully observed.

10. HARDNESS TEST This test is carried out to determine hardness of stone. A cylinder of dia. 25mm and height 25mm is taken out from the sample of stone. It is weighed It is pressed in dorrys testing machine and pressed with a pressure of 22.50N. The annular steel disc of machine is then rotated at a speed of 28RPM During the rotation of disc the coarse sand of standard specifications is sprinkled on the top of the disc. After 1000 revolutions the specimen is taken out and weighed. The coefficient of hardness is found out from the following equation. Coefficient of hardness = 20 – loss in weight in gm 3 Dorry’s test machine

11. IMPACT TEST. THIS TEST IS DONE TO DETERMINE TOUGHNESS OF STONE. A cylinder of diameter 25mm and height 25mm is taken out from the sample of a stone. It is than placed on cast-iron anvil machine. A steel hammer of weight 20N is allowed to fall axially in a Lifting handle Hammer of weight 132- 137N Vertical guide bar Cup 102mm dia and height 50mm Circular base

12. MICROSCOPIC TEST In this test the sample of stone is subjected to the microscopic examination the thin sections of stones are taken and placed under the microscope to study various properties such as average screen size existence of pores fissures veins shakes mineral constituents nature of cementing material presence of any harmful substance texture of stone etc

13. Smith test This test is performed to find out presence of soluble matter in sample of stone. The few chips or pieces of stones are taken and they replace in a glass . Tube is than filled with Clearwater after about an earth. Tube is vigorously stirred and shaken the presence of earth matter will will convert the clear water into dirty water. If water remains clear the stones are durable and free from any soluble matter. On the other hand if the water becomes dirty it will indicate that the stone contains too much of soluble earthy and mineral matters . Stones free from souble and earthy mineral matters. Stones containing souble and earthy mineral matters.

14. Water absorption test for stones.. Water absorption test is carried out to calculate the %age water absorbed by stones. Procedure:  For this test, the stone is 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 W 1 . Now the sample is immersed in distilled water at room temperature (20°c to 30°c) for a period of 24hours. Samples are taken out of the water and surface water is wiped off with a damp cloth and weighed again. Let the weight at this stage is W 2 . Then, the percentage of water absorption by weight of a given stone specimen is given by the following relationship:- Absorption value in percentage = W 2− W 1 /W 1  × 100 Then, the percentage of water absorption by weight of a given stone specimen is given by the following relationship:- Absorption value in percentage = W 2− W 1 /W 1  × 100 Then, the percentage of water absorption by weight of a given stone specimen is given by the following relationship:- Absorption value in percentage = W 2− W 1 /W 1  × 100