Building Stones
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Stones have been used in construction for thousands of years in buildings all over the world. They are classified geologically based on their mode of formation as igneous, sedimentary, or metamorphic rocks. Igneous rocks form from cooling magma, sedimentary rocks form from compressed sediments, and metamorphic rocks form from changes to existing rocks. Stones are also classified chemically based on their dominant composition of silica, calcareous, or argillaceous minerals. Structurally, stones can occur as massive unstratified rocks, stratified layered rocks, or foliated banded rocks. Many historical structures were constructed of stone and it remains an important building material.
Building Stones
- 1. Building Stones Building Construction Material
- 2. Definition • Stones are naturally occurring compact, solid and massive material that make the crust of the earth. • Technically, the stones are called as rocks. The rocks occur in great variety. The rocks posses suitable properties often find use in building stones. It follows that all building stones are rocks in nature, all rocks may not be useful as building stones.
- 4. Introduction • Stones have been used in all type of construction since time immemorial. The pyramids of Egypt, The eiffel tower, The temple of Jagannathpuri, the Taj Mahal, the red fort, the great wall of china and hundreds of historical buildings in each big country are made of stones. The greatest thing about stone is that they are natural and do not required to be manufactured. • Stone, timber and clay had been the most commonly construction used material right from the beginning of the civilization till the advent of Portland cement and hence concrete in the early nineteenth century.
- 6. Classification of Stones • The building stones are classified in three ways: Geologically, Chemically and structurally
- 7. Classification of Stones A ) Geological Classification: • This classification is based on mode of formation of the rock from which building stones are obtained. Three main group recognized are: • I) Igneous Rocks • II) Sedimentary Rocks • III) Metamorphic Rocks
- 8. Classification of Stones Igneous Rocks (Greek word ignis= fire) • All those rocks of the earth that have been formed by the natural process of cooling and crystallization from originally hot and molten magma are grouped as Igneous Rocks. They are the most abundant rocks in the crust when considered depth wise. • In fact the igneous rocks are further distinguished by geologists into three sub classes on the basis of their depth of formation.
- 10. Classification of Stones (a) The Plutonic Rocks • These are formed at greater depth below the surface. They are exposed on the surface by erosion of the overlying secondary rocks with passage of time. They are coarsely crystallized. i.e. the component of crystals can be easily seen without the help of magnifying glasses. Granites, Syenites and gabbros are typically igneous plutonic rocks.
- 12. Classification of Stones (b) The Volcanic Rocks • These are formed on the surface of the earth from lava coming out of numerous volcanoes that erupt from time to time. Basalt and trap rocks are very common examples; the constituents minerals are so small that they can be seen only after magnifying under microscope.
- 14. Classification of Stones (c) The Hypabyssal Rocks. These are formed at shallow depths, about 2-3 km below the surface from magma that could not come out as lava. They show crystal that are partly coarse and partly fine in size. Rock known as porphyries belong to this group.
- 16. Sedimentary Rocks • Sedimentary Rocks (sediment=particle) They are the most widespread rocks found covering a great part of the surface of earth. The Sedimentary rock are formed from any type of preexisting rocks by a simple process of breakdown into smaller particles under the influence of natural agencies like wind, water and ice and atmospheric gases.
- 18. Sedimentary Rocks • The natural process of rock disintegration are called weathering and erosion. The sediments produced by natural agencies are transported by these very natural agencies to riverbed, lake basin, seas and oceans where this deposition takes place for million of years. Gradually, the particles so deposited are compressed under their own load into hard massive rocks, called secondary rocks. Since they are formed of sediments it is quite appropriate to call them sedimentary rocks.
- 20. Sedimentary Rocks • Just like igneous rocks, sedimentary rocks may also be formed in different manners. These sub group of sedimentary rocks are • Clastic Rocks. • Chemically formed Rocks • Organically formed rocks
- 21. Sedimentary Rocks Clastic Rocks • These are sedimentary rocks formed by deposition and consolidation of disintegrated sediments and fragments from the previous rocks in suitable river basins, lake and the sea basins etc. They are most widespread and include such types as sandstones, hales, breccias and conglomerates. Sandstones are made mostly of silica grains fused together or thoroughly compacted under natural environment. They form very good type of building stone.
- 22. Clastic Rocks
- 23. Sedimentary Rocks Chemically formed Rocks • Many sedimentary rocks are precipitated from river, lake and especially from seawater by evaporation etc. some of the components of previous rocks are taken in solution during the processes of weathering and erosion. The water may get saturated with these compounds with passage of time and precipitate them. The huge accumulation of these precipitates and evaporates ultimately may form rock deposits of considerable importance. Limestones, Gypsum, anhydrite and rock salts are few examples of chemically formed sedimentary rocks. None of them are used as building stones.
- 25. Sedimentary Rocks Organic formed Sedimentary Rocks • As we know that more than 70 % of the surface of earth is covered with water in the form of sea and oceans. Great variety of life exists in these great water bodies. Many sea animals have their hard parts made up of bones, which are a mixture of calcium and magnesium carbonates. These parts accumulate at proper places on the sea floor. Gradually huge thickness of such deposits get formed and compacted and consolidates with passage of time. These are the organically formed sedimentary rocks. The best example of organically formed sedimentary rock is a great variety of limestone, which now form the greater part of many mountains of the earth including Himalayas. Many massive types of limestone form best type of building stones.
- 26. Organic formed Sedimentary Rocks
- 27. Metamorphic Rocks • (meta= Change; morph= form) These are originally either igneous or sedimentary rocks. The process for their change under the influence of increased temperature, pressure, and chemical environment is called metamorphism. When an existing rock gets subjected to increased temperature or changed stresses and chemically active fluids it undergoes a slow but definite change in its original structure and chemical composition. The new rock so formed is called metamorphic rock.
- 29. Metamorphic Rocks • To well-known example of metamorphic rock are marble and slate. Marble is formed in natural environment by very gradual heating of sedimentary rocks, limestone, in its natural environment. The heating may be caused by rise of magma from below in a limestone area. Similarly, another sedimentary rock, shale may be formed combined action of temperature, pressure & chemically active fluids that it gets changed to a metamorphic rock slate.
- 31. Metamorphic Rocks • The nature of change of an original rock depend on following factors: • (i) The type of agent/s operating ( Temperature, Pressure, chemically active fluid etc.) • The duration of operation of the above agent. • The nature and composition of the original rocks, Some very common metamorphic rocks are Marble, Quartzite, Gneiss, Slate and Schist; The first three rocks are very good building stones in many cases.
- 32. Chemical Classification • On the basis of dominant chemical composition, following three main groups of rocks are commonly recognized: • I.) Siliceous Rocks • These rock have SILICA (SiO2) as the predominant component, that is more than 50 % of the bulk composition of the rock. • These include variety of quartzites. Naturally they are classed among the strongest type of building stones. Some other rocks like granites, sandstones and gneisses are also made up of Silica in combined form.
- 33. Siliceous Rocks
- 34. Chemical Classification 2) Calcareous Rocks. • In these rocks, the dominant component is a carbonate ,generally of calcium but often with magnesium. Most commonly they belong to sedimentary and metamorphic group of rocks. Limestone, dolomite and marbles are entirely carbonate rocks and all form good building stone.
- 36. Chemical Classification 3) Argillaceous Rocks. • They are mostly sedimentary rocks having clay (hydrous alumino silicates of K, Na, Ca, Mg. etc.) as a dominant constituent. They are invariably soft and untrustworthy as building stone and untrustworthy as building stones. Shales, Slates, and Schists are examples.
- 38. Structural Classification • Broadly speaking, in apparent structures, the rock (Stones) may either be found in the form of undifferentiated masses or they occur in very well defined layers or sheets. A third category is foliated rocks.
- 39. Structural Classification 1) The Massive or Unstratified Rocks. • These rocks occur in huge masses without showing any layered structure in them. Igneous and many metamorphic rocks and some sedimentary rocks may be seen occurring as big masses. Granite and Quartzite often occur in massive form.
- 40. The Massive or Unstratified Rocks
- 41. Structural Classification • 2) The Stratified Rocks. • Most sedimentary rocks occur in distinct layers of same and different color and composition. Their different layers are also called beds and are separated by planes of weaknesses called bedding planes
- 43. Structural Classification 3) Foliated Rocks • Very often a third group of rock is distinguished as foliated rocks in which there is profuse development of well defined band of different composition. This is seen as schists and gneisses. The foliated rocks do not yield building stone of good quality.
- 44. Foliated Rocks
- 45. Quarrying of Stones • It is known that stones occur in nature in the form of natural rock masses forming hills or walls of valleys. These have to be broken and extracted from those natural outcrops for using in the construction. The process of extraction of suitable stones from their natural place of occurrence for use in construction is called quarrying.
- 47. Quarrying of Stones • Quarrying is different than mining used for extraction of ores for metal in that in mining we go deep below the surface, the top surface is left in tact, and the ores are extracted from under the earth. In quarrying, however, the process of extraction starts from the surface.
- 49. Selection of Quarrying Site • Engineers and Contractors have to keep in mind following factors while deciding about the location of quarry site • (i) Availability of Sound Rock. • A quarry can be opened up where a sound rock that can yield good quality of building stones existing in sufficiently larger area. These is essential because quarrying operation require quite heavy initial investment in men and machinery and these have to be economically viable.
- 50. Availability of Sound Rock
- 51. Selection of Quarrying Site • (ii) Distance of Area of Construction: • Quarrying is a common operation. The quarrying site must necessarily be close to a main road so that stones extracted from it can be transported to any outside place at economic rate.
- 52. Distance of Area of Construction
- 53. Selection of Quarrying Site (iii) Availability of Water and dumping space • In quarrying operations, large number of equipments, men and machines are often required. Sufficient safe distance from quarrying must be available. Often lot of water is also required for the workers and even during cutting operations when machines are to be used. This must be available locally. Dumping space is required for storing the broken stone and also for dumping useless rock fragments obtained during quarrying. Further, adequate drainage outlet for removing any underground or surface waters immediately after rain must be provided at the quarry.
- 54. Availability of Water and dumping space
- 55. Preparatory Steps • Once a site for quarrying of Stone is decided. Following predatory steps becomes necessary for starting operations • i) Selection of method of Quarrying • Quarrying can be done manually or with the help of machines. Mechanized quarrying is the advanced and preferred method of the quarry, the nature of the rock and the commercial demand.
- 56. Selection of method of Quarrying
- 57. Preparatory Steps • (ii) Preparation of a layout • A scheme for operation process or layout of the quarry has to be prepared after selecting method of quarrying. This should include the face of attack, the progression of attack and various stages in which the block of rocks are removed.
- 58. Preparation of a layout
- 59. Preparatory Steps • (iii) Removal of overburden • The upper surface of natural bedrock is quite often covered with some thickness of soil or weathered rock called overburden. Such overburden as well as loosely held rock pieces have to be removed well before the start of quarrying operations.
- 61. Methods of Quarrying A. Quarrying Without Blasting • In this methods, skilled persons remove blocks of rocks from the places of occurrence. They may use hand tools or even light channeling machines called channellizers. No explosive material is used for breaking the stones.
- 63. Methods of Quarrying • B) Quarrying by blasting This method involves use of explosives for breaking stones from very hard rock like quartzite and sandstones, basalts, traps, and non-ornamental granites. It has been observed that quarrying of these types of hard rock becomes very laborious and costly by other methods. • The basic principle employed in this method is to explode a small quantity of an explosive at a calculated depth within the body of the rock. • The force generated due to explosion is sufficient to only create cracks and loosen rock block of good size.
- 65. Dressing of Stones • By dressing of stones is meant the process of giving a proper size, shape and finish to the roughly broken stone as obtained from quarry. This is done either manually or mechanically or in some case using both the methods.
- 67. Dressing of Stones • Stones as obtained from quarries are very rough and irregular in shape. Besides, they may be too bulky to be used in construction, Hence various objectives of dressing are: • (a) To reduce the size of blocks to easily portable units. This is often done at the quarry itself because transport of big rock may be costly. • (b) To give a proper shape to the stone • We can use stones in foundation as blocks, in walls as small units, in floor as slabs and in column as rounded or square pillars. Each situation requires a proper shape that has to be given under the process of dressing. • (c) To obtain an appealing finish Stones always come in rough and rugged forms. For use in building construction in walls and exteriors, they have to be given an aesthetic appealing finish. A stone house has its own distinction, beauty and indivuality in a concrete jungle.
- 69. Dressing of Stones Method of dressing of stones • Dressing of stones can be done both manually or mechanically. • Manually, Skilled workers can work wonders on suitable types of stones with chisels, hammers and abrasives. Not only they can give excellent finish and polish stones but also may do carving and engraving that can withstand centuries. • Mechanically, special saw fitted machines can cut slabs and any other shape from rough rocks. These are called rock cutters. The grinding and polishing machines are fitted with wheels or discs with abrasives capable enough to give polish and fine finish to any desired degree even on the hardest of stones.
- 71. Dressing of Stones • The Traditional Dressing methods applied in manual dressing are described below: • Pitched dressing • In this method, only the edges of a block are leveled skillfully by use of hammers. The surface is left in original cut. • Hammer Dressing • In this method of dressing edge as well as the face are reduced to even regular surface. It has pitted appearance on the surface. • Chisel Dressing • In this method straight grooves are made with the help of a chisel at all four edges. The superfluous stone from the centre is removed. Chisel drafted stones are specially used in plinths and corner of the building. • Rough Tooling • The edges are first made square by using chisel and hammer. Then a series of grooves of variable width are developed over the surface of stone.
- 73. Dressing of Stones • Punched Dressing • It is done on the stone that have been already been roughed. A series of parallel ridges are made on the stone surface using hammer and chisel. It is also called furrowed finish. • Closed picked fine tooling • This is extreme type of dressing in which almost every type of projecting irregularity is removed from all four sides of stones. Its surface is given fine finish and an appealing look.
- 75. Dressing of Stones • Boasted Finish • It is a very common type of finish in which the surface of the stone is covered with parallel marks that may run in a particular direction on a particular face. A boaster which is actually a wide-edge chisel is used for the purpose and hence the same. • Numerous other types of finishes are given to stones in the dressing process depending upon the skill of the worker and fancy of the owner.
- 77. Selection of Stones For Construction • Three factors are generally considered by an engineer while deciding use of stone in construction jobs: First • The type of building and the situation where stone is to be used such as : • First • 1) Residential building or a public building, such as for school, department office, community centre etc. • 2) Commercial building like cinema hall, shopping complex stadium, etc • 3) a monument building such as templr, mosque, church, fort etc.
- 78. Type Of Building
- 79. Selection of Stones For Construction Second: • The precise location in the building where the stone shall give a preferential benefit in terms of cost, appearance, and durability such as in foundations, superstructures, arches, columns, beams, plinths, or flooring, sills and cantilever.
- 80. Selection of Stones For Construction
- 81. Selection of Stones For Construction Third • Cost of construction with stones. This will depend on factors of availability of stone, in nearby area, their extraction, transportation and dressing before putting them in use. Sometimes a desired quantity of stone may not be available locally. It may have to be imported from other states or even from other countries. • It is only after through analysis of factors as mentioned above that the engineer will be able to decide about using stone in the construction at hand.
- 82. Selection of Stones For Construction
- 83. References • Building Construction : Dr B.C. Punmia • Civil Engineering Material : Prof. Singh • Internet Web Sites
- 84. Thanks…