1.The Attrition Test
2.The Crushing Test
3.The Freezing and Thawing Test
4.The Impact Test
5.The Laboratory Hardness Test
6.The Microscopic Test.
1.The Attrition Test
This is also called The Abrasion Test. This test is conducted to determine the percentage of the water of stones that are used for road construction. This is carried out in Deval's Attrition Testing Machine.
In this test, a certain quantity of stone is placed on Deval's Attrition cylinder. The cylinder is rotated about its horizontal axis at the rate of 30 rpm for 5 hours.
After the end of the rotation, the contents of the cylinder are sieved, and the quantity of material retained on the stone is weighed. The percentage weight is the ratio of loss in weight to the initial weight which is expressed as a percentage.
2.The Crushing Test
The Crushing test is performed on the stones which are to be subjected to compressive stress. In this test, a cubical specimen of a 40 mm side is tested in a compression testing machine. The maximum load at which the stone specimen fails by crushing is noted. Then the crushing strength of the stone is the ratio of maximum load at failure and area of bearing face.
3.The Freezing and Thawing Test
This test is conducted for the use of stones in freezing regions, which are temperature goes below freezing point. The test consists of keeping a specimen of stone in water for 24 hours and then placing it in a freezing mixture at 12℃ for 24 hours. The specimen is taken out and thawed (warmed) to atmospheric temperature. The procedure has repeated a minimum of seven times after which the specimen is examined for any damage.
4. The Impact Test
The toughness of a stone is determined by the impact test using an impact testing machine. Here, a stone specimen of 25mm diameter and 25mm height is placed on the machine. A steel hammer of 2 kg weight is allowed to fall down axially on the cylinder from 1 cm height for the first blow, 2cm height for the second blow, 3 cm height for the third blow, and so on. The blow at which the specimen breaks is noted, which is the Toughness Index of the stone.
5.The Laboratory Hardness Test
This test is different from the field hardness test and the attrition test. This test is carried out in Dorry's testing machine. A cylinder of 25mm of the stone is rubbed against a steel disc spindled with coarse sand. The Specimen is subjected to the pressure of 1.25 kg/mm². After 1000 revolution in the machine, the loss in weight is found, and the co-efficient of hardness is determined as,
Co-efficient of hardness = (20−Loss of weight in gm) ➗ 3
6.The Microscopic Test
In this test, a flake specimen of a stone is taken and placed on a microscopic to study the following properties,
- Mineral constituents
- Texture of stone
- Average grain size
- Nature of Cementing material
- Presence of pores, fissures, and veins
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