Stones by ar


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Stones by ar

  1. 1. Mehran University of Engineering& Technology SZAB Khairpur Mir’s Civil Engineering Materials 1st Term 1st Year B.E.Civil Presented By: ABDUL RAUF NOOHANI
  2. 2. STONES
  3. 3. STONES: The stones which are suitable for the construction of the structures such as retaining walls, abutments, dams, barrages, roads etc are known as building stones. Building stones should possess enough strength and durability. Stones have been considered as one of the popular building material from the olden days due to their availability in abundance from the natural rocks.
  4. 4. COMMON USES OF BUILDING STONE: It is used in foundations of buildings, It is used in construction of dams, barrages, etc, In its crushed (powdered form) it is used as artificial sand, It is used as raw material for manufacturing of cement, In its broken form it is used as material for construction of road and railway tracks, It is used as decorative material in buildings, It is also used as parts of buildings such as lintels and arches, etc, It is also used as thin slabs for building roofing, It is also used for ornamental works in buildings, In its broken form it is in the manufacturing of concrete,
  5. 5. CHARACTERISTICS OF GOOD BUILDING STONES: There are so many characteristics of good building stones, but some important characteristics are given below.
  6. 6. (1) Hardness: Hardness denotes several qualities of stones such as resistance to cutting and resistance to abrasion ( rub with each other). Specially stones are used in case of roads and railway tracks. To check the hardness of stones various tests are conducted in the laboratories. The more important tests to check the hardness is Loss Angles Abrasion test. It depends upon the nature of its constituent minerals.
  7. 7. (2) Durability: Durability is the power of stone to resist atmospheric and other external effects. It depends upon: Chemical composition, Physical structure, Resistance to weathering effects, Place where it is used Stone which contain silicates will be durable than those stone which contain calcareous substances.
  8. 8. (3) Porosity and Absorption : Stone can hold water in two ways Either through porosity or absorption For building purposes, the better stones are those which are less porous because they will absorb less moisture. Porous stones damaged easily. (4) Decomposition: Gases and acids in rain water dissolve some constituents of stone and cause the stone decay. (5) Disintegration: In cold countries water freezes and expands and thus disintegrates the stones.
  9. 9. Reliability: When exposed to fire stone should be reliable (good in quality). Weight: This is an important characteristic of stone. It depends upon the type of structure of stone in which we shall use. E.g. we shall use heavy stones in the construction of the dams, bridges, etc. Strength: It is power of stone to sustain pressure or resistance to crushing force. Average crushing strength of stone is 3 tons per square inch.
  10. 10. Appearance and color: Highly colorful stones are preferred for architectural purpose but those are soft and thus less durable. Therefore, lighter stones are preferred than to darker ones. Physical Strength: Crystalline structures are more durable than non-crystalline structure stone.
  11. 11. Seasoning Qualities: A good building stone should have good seasoning qualities. All the stones contain some moisture which is known as quarry sap stones. The period 3-6 months are enough for seasoning. Fire resistance: A good building stone should be fire resistant. Some stones such as basalt and trap resist fire very well but some varieties of igneous and metamorphic stones are very weak against fire.    
  12. 12. EXAMINATION AND TESTING OF STONES: It is very important to examine the stone before its selection for any particular type of engineering structure. For this purpose various types of tests are to be conducted to find out the suitability of stone for engineering structure. There are so many tests but some important among them are as follows.
  13. 13. (1) Crushing test: For this test 04 cubic cm finely dressed different samples of stones are used. Their type is made flat and horizontal and covered with plaster of Paris. They are tested in a compression testing machine. The load must be applied axially and the changes in the blocks at the corresponding load are recorded. The blocks or samples which bear more loads are to be selected.
  14. 14. (2) Crystallization or weathering test : For this test 04 cubic cm different samples of stones are first weighed and then immersed in a 14 % solution of sodium sulphate (NA2SO4) at room temperature for two hours and dried at 1000C . They are again weighed. This process of weighing, immersing in salt solution, drying and reweighing is repeated for 10 to 15 times. A stone which is not much affected by salt solution is supposed to have very good weathering properties.
  15. 15. (3) Porosity and Absorption test : To ascertain the relative qualities of different stones, they are immersed in water for 24 hours and the amount of water absorbed by each specimen is noted. Greater absorption of water by the stone means that it is porous and can not resist weathering forces well. The test specimen which absorbs the smallest amount of water is the best.
  16. 16. (4) Attrition test: This is the test to check the wear and tear of stone. To conduct this test different angular pieces of stones are weighed and charged into a cylindrical drum along with the iron blocks provided. The drum is then rotated at the rate of 30 to 33 rmp. About 100 to 150 revolutions are made and the % age of wear is noted. The machine used may be Devals attrition machine. The stone which ears less is considered to be the best.
  17. 17. (5) Acid test: This is the best test to find out the action of acids on the stone. For this test about 50 to 100 grams sample of stone is immersed in a solution of 1 % HCl or H2SO4 for about a week. The sample being agitated (pressed, disturbed) at intervals. If the edges of stone are retained and there is no deposition of any loose particles on the surface, it indicates that the stone is good other wise weak and bad.
  18. 18. (6) Smith’s test: This test is carried out to find out whether the specimens possess crystalline structure. Small stone chips are kept for about half an hour in a glass of water filled to one third. The glass containing the specimens and water is moved quickly by giving it a circular motion with the hand. If the specimen gives out earthy matter and water gets milky appearance, it shows that the stone particles are not properly cemented together.
  19. 19. (7) Hardness test: This test is conducted to find out the resistance of stone to abrasion. The sample piece of stone is cleaned and rubbed by piece of rubbing material/paper. The rubbed face of the stone is examined through a microscope. If marks of rubbing are visible, it shows that the stone is soft and it can not be used for roads, pavements, etc.
  20. 20. (8) Fire test: For very important buildings, fire resistance of stone is also examined. For this test a small hut or a wall panel of stone is built. One side of it is subjected to 9500C and the behaviour of the stone under fire is studied. If the cracks developed are deep. Then it should not be used for important buildings.
  21. 21. (9) Microscopic test: This is a geological test in which a thin slice of the sample is examined through the microscopic to determine the following physical properties of stone. The texture of the stone. The nature of the building materials/stones. The size, shape and nature of the individual grains or crystals. The kind and nature of the mineral present. The presence of pores, if any.  
  22. 22. DETERIORATION OF STONES: Deterioration of stone is the process of their breaking or their decay. Atmospheric agencies such as: rain,temperature,wind,frost, and living organisms, etc are responsible for their deterioration and these agencies bring about physical and chemical changes in the stones and disintegrate them. So, the stones which can resist the effect of all these agencies are said to be durable. Some preservative materials which are used to preserve the stones from deterioration are: coal tar, linseed oil, barium hydrate solution, alum soap solution (mixture of alum and soft soap). By applying some of above preservative materials, stones can be preserved from the decaying.
  23. 23. CLASSIFICATION OF ROCKS (STONES) OR VARIETIES OF STONES: There are three main classes of rocks. (1) CHEMICAL CLASSIFICATION: Chemically stones are stones are classified into three groups. (i) Argillaceous Rocks: Argillaceous or clay stones are those stones which contain (alumina Al2O3) (clay) as principal constituent. These stones are less durable stones. All clay stones belong to this group. The examples of argillaceous rocks are Slate, Laterite, etc.
  24. 24. (ii) Silicious Rocks: The stones which contain (Silica SiO2) as principal constituent are called silicious rocks. These stones are durable stones. The examples of silicious rocks are granite, Quartzite and Sand stone etc.
  25. 25. • (ii) Calcareous Rocks: • The stones which contain calcareous material (CaCO3) as principal constituent are called calcareous rocks. They also contain some proportion of siliceous and clay matter. • The examples of calcareous rocks are marble stone and lime stone, etc.
  26. 26. (2) PHYSICAL CLASSIFICATION: Physically rocks are classified as: (i) Stratified Rocks: The rocks which are split into thin slabs or layers easily are called stratified rocks. All sedimentary rocks are essentially stratified and metamorphic rocks may be either stratified or unstartified depending upon its parent rock. The examples of stratified rocks are Slate, Sand stone and Lime stone.
  27. 27. • (ii) Unstratified Rocks: • These rocks do not show sign of stratification and can not be easily split into thin slabs or layers are called unstratified rocks. All igneous rocks are essentially unstratified and metamorphic rocks may be either stratified or unstartified. • The examples of unstratified rocks are Granite, Basalt and Lime Trap.
  28. 28. • (3) GEOLOGICAL CLASSIFICATION: • Geologically stones are stones are classified into three groups. • (i) Igneous or Primary Rocks: • These are primary rocks which are formed from molten magma. They represent different structural features depending upon the condition of solidification and composition. Generally igneous rocks are strong and durable. • These are also called unsratified or eruptive rocks. • The examples of igneous rocks are granite, basalt, trap, etc.
  29. 29. (ii) Sedimentary or Secondary Rocks: • These are secondary rocks and are formed by the denudation and deposition of previously existing rocks due to weathering actions. Water (rain) is the most powerful and principal weathering agent. The other destructive agents are frost, winds and chemical actions. The destructive agents break up the surface of earth which gets further broken up when carried down by rains and rivers. When the velocity of water in the rivers those broken particles are deposited in the river bed and thus sedimentary rocks are formed. • These are also called aqueous and stratified rocks. • (OR) • The rocks which are formed by gradual deposition are called Sedimentary Rocks. • Examples: Lime stone, sand stone, etc.
  30. 30. • (iii) Metamorphic or Tertiary Rocks: • Rocks which are formed due to metamorphic action of pressure or internal heat or by both (or) alteration of original structure due to heat and excessive pressure) are called Metamorphic Rocks. • Examples: Marble etc.
  31. 31. • QUARRYINFG OF STONES: • Stones are extracted from natural rocks in different sizes. The various methods which are involved in the extraction of stones from rock beds are collectively termed as “Quarrying of Stones”. • Open part of the natural rock from which useful material is obtained is known as quarry. • For this purpose particular rock is inspected (checked) for particular work and then quarrying operations are to be started.
  32. 32. • Methods of quarrying: • It is depending upon the rock and purpose for which it is to be used. • Commonly two methods are used for quarrying. • (1) Quarrying by digging • (2) Quarrying by blasting
  33. 33. • (1) Quarrying by digging: • This is done by three methods. • (a) By driving steel wedges into fissures: • Fissures, cracks, planes of cleavages are all weak points in the rock and by taking the advantage of these weak points, steel wedges are driven in these natural fissures or cracks, so that rock splits easily. •
  34. 34. • (b) By drilling artificial line of holes: • Some times line of holes (in rows) is drilled with the help of chisel and hammer. Thus, the solidity of rock mark is divided into small portions and artificial fissures are made. Steel wedges are driven in these artificially made fissures. Then all the wedges are hammered simultaneously and consequently the rock cracks along the face of holes.
  35. 35. (c) By swelling hard wooden pegs: •Some times hard wooden pegs are driven in either natural or artificially made fissures and are kept soaked with water. And in this way rock is splitted. •
  36. 36. (d) Quarrying by blasting: When the rock is very hard and unfissured then quarrying is done by blasting. Blasting is the process of loosening the hard and closely packed material with the help of explosive materials. Various explosives which are used for blasting purposes are: •Gun powder or black powder •Dynamite •Cordite Detonator •Fuses
  37. 37. But mostly two explosives are used which are gun powder and dynamite. Where gun powder is the mixture of potassium nitrate, charcoal and sulphur and dynamite is the mixture of nitroglycerine. There are four main operations are involved in blasting. •Boring hole in the rock •Charging with the explosives •Tamping •Firing.
  38. 38. DRESSING OF STONES: Dressing of stones is a process in which their surfaces are prepared to a form, fit to be used for any constructional purpose. Dressing is according to the type of work and demand. Purpose of Dressing: •To give them good looking. •To provide horizontal and vertical joints in the masonry. •To make them fit, to be used for particular construction. •Generally to give them neat/good appearance.
  39. 39. • Methods of Dressing Rough dressing Fair dressing OR • Dressing at quarry site • Dressing at construction site • Scabbling ,Hammering , Self faced, quarry faced Chisel Tooled, Fluted , Pointed • OR dressing dressing dressing dressing • Rock faced dressing
  40. 40. (1) ROUGH DRESSING OR DRESSING AT QUARRY SITE: There are three main methods of rough dressing, which are a sunder: (i) Scabbling: In scabbling only irregular angels are taken off with a scabbling hammer and therefore that dressing is called scabbling. (ii) Hammer Dressing: In hammer dressing stones are roughly dressed at a site with the help of quarry hammer and therefore work is called hammer dressing.
  41. 41. • (iii) Self faced, quarry faced (OR) Rock faced Dressing: In this type of dressing, stone are only splitted into either as face stones or as corner stones and nothing special is done.
  42. 42. • (2) FAIR DRESSING OR DRESSING AT BUILDING SITE: There are four main methods of Fair dressing, which are a sunder: • (i) Chiseled Dressing: About one inch width on all the four sides of the exposed surfaces of the stones is chiseled to give them a better appearance. This work is done with the help of chisel made of cast iron.
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