Properties of Stones
The following properties of the stones must be seemed into before deciding on them for engineering works:
Properties of Stones
The following properties of the stones must be seemed into before deciding on them for engineering works:
- Structure
- Texture
- Density
- Appearance
- Strength
- Hardness
- Percentage put on
- Porosity and Absorption
- Weathering
- Toughness
- Resistance to Fire
- Ease in Dressing
- Seasoning
(i) Structure: The shape of the stone can be stratified (layered) or unstratified. Structured stones need to be without problems dressed and suitable for top notch shape. Unstratified stones are hard and tough to dress. They are preferred for the muse works.
(ii) Texture: Fine grained stones with homogeneous distribution appearance appealing and hence they're used for carving. Such stones are typically strong and sturdy.
(iii) Density: Denser stones are stronger. Light weight stones are weak. Hence stones with specific gravity less than 2.4 are taken into consideration improper for buildings.
(iv) Appearance: A stone with uniform and attractive shade is long lasting, if grains are compact. Marble and granite get excellent appearance, when polished. Hence they are used for face works in homes.
(v) Strength: Strength is an crucial property to be seemed into before deciding on stone as constructing block. Indian widespread code recommends, a minimum crushing energy of three.5 N/mm2 for any building block. Table 1.1 indicates the crushing strength of diverse stones. Due to non-uniformity of the material, typically a thing of protection of 10 is used to discover the permissible stress in a stone. Hence even laterite may be used appropriately for a unmarried storey building, because in such structures anticipated load can rarely supply a pressure of zero.15 N/mm2. However in stone masonry homes care need to be taken to test the stresses whilst the beams (Concentrated Loads) are placed on laterite wall.
(vi) Hardness: It is an essential property to be taken into consideration when stone is used for floors and pavement. Coefficient of hardness is to be found by way of undertaking test on trendy specimen in Dory’s trying out device. For street works coefficient of hardness need to be at least 17. For constructing works stones with coefficient of hardness less than 14 should not be used.
(vii) Percentage Wear: It is measured through attrition test. It is an crucial assets to be taken into consideration in selecting aggregate for street works and railway ballast. A right stone ought to now not display wear of more than 2%.
(viii) Porosity and Absorption: All stones have pores and therefore take in water. The response of water with material of stone cause disintegration. Absorption check is designated as percentage of water absorbed by the stone when it is immersed beneath water for twenty-four hours. For a good stone it ought to be as small as viable and in no case more than 5.
(ix) Weathering: Rain and wind purpose loss of excellent look of stones. Hence stones with accurate weather resistance must be used for face works.
(x) Toughness: The resistance to impact is referred to as toughness. It is determined via impact test. Stones with sturdiness index extra than 19 are preferred for street works. Toughness index thirteen to 19 are taken into consideration as medium tough and stones with durability index much less than thirteen are negative stones.
(xi) Resistance to Fire: Sand stones withstand fireplace higher. Argillaceous substances, although poor in power, are proper in resisting fire.
(xii) Ease in Dressing: Cost of dressing contributes to price of stone masonry to a wonderful volume. Dressing is straightforward in stones with lesser strength. Hence an engineer ought to investigate sufficient strength in place of high strength at the same time as deciding on stones for constructing works.
(xiii) Seasoning: The stones received from quarry comprise moisture in the pores. The electricity of the stone improves if this moisture is eliminated before the usage of the stone. The procedure of getting rid of moisture from pores is called seasoning. The quality way of seasoning is to permit it to the action of nature for 6 to 365 days. This could be very much required in the case of laterite stones.