Final - aaaskvkl js saskajf lkjsa lfkj lskj lfskj lkjf slj sal;fkj l;s jkflk sjlfk PDF

Preview

Summary

aaaskvkl js lfkjl skajf lkjsa lfkj lskj lfskj lkjf slj sal;fkj l;s jkflk sjlfk jsl jlfks jlaskj flkj asljf...

Description

Addis Ababa Science And Technology University

Addis Ababa Science And Technology University School Of Construction Civil Department Of Civil Engineering Material Engineerin Building Group g And Stones Assignment COTM

Submission Date April 21 2015

Acknowledgement We would like to express our deepest gratitude to many people who was with us through this assignment to all of those who provided support, talked things over, offered comments. We 1

Addis Ababa Science And Technology University

would like to thank our family who helped us provide the enough money to do this project. We would like to thank our friends who helped us edit this amazing project. We would also like to thank our teacher who gave us this opportunity to explore this topic. Last but least we beg forgiveness off all those who have been with us through assignment and whose names we failed to mention.

Group Members

ID Number

1. Adane Firde

ETS 0090/06

2. Aimen Hassen

ETS 0109/06

3. Abraham Belay

ETS 0074/06

4. Abenezer Tesfaye

ETS 0058/06

Content

page

1. Introduction………………………………………………………………………………………………………………………….. 4 2. The Process of Rock Formation……………………………………………………………………………………………… 4 3. Geological Classification………………………………………………………………………………………………………… 4 2

Addis Ababa Science And Technology University 4. Chemical Classification………………………………………………………………………………………………………….. 13 5. Physical Classification……………………………………………………………………………………………………………. 15 6. Quarrying of rocks …………………………………………………………………………………………………………………...15 7. Uses of rocks…………………………………………………………………………………………………………………………..…16 8. Requirment of building stone ……………………………………………………………………………………………………17 9. Maintainance of stone work…………………………………………………………………………………………………..……18 10. Tests on Building Stone………………………………………………………………………………………………………..……19 11. Selection of stone………………………………………………………………………………………………………………………22 12. General types of stone used in Ethiopia …………………………………………………………………………………….23 13. Conclusion…………………………………………………………………………………………………………………………….……23

Introduction The term stone refers to natural rocks after their removal from the earth’s crust. The significance of stone as a building material is illustrated by widespread prehistoric evidence and its sophisticated use in the early civilizations of the world, including the Egyptians, the Incas of Peru, and the Mayans of Central America. Geologically, all rocks can be classified into one of 3

Addis Ababa Science And Technology University

three groups: igneous, metamorphic or sedimentary, according to the natural processes by which they were produced within or on the earth’s surface. Rock is a naturally occurring solid aggregate of one or more minerals or mineraloids. Rocks have been used by mankind throughout history. From the Stone Age rocks have been used for tools. The minerals and metals found in rocks have been essential to human civilization. The Process of Rock Formation The earth's crust is dynamic and is subject to a variety of processes that act upon all types of rocks. Given time and the effect of these processes, anyone of these rocks can be changed into another type. The rocks formed by solidification of magma within the mantle or crust are called intrusive igneous rocks,(e.g. granite and gabbro) and those that form at the surface from lavas are called extrusive igneous rocks(e.g. basalt and rhyolite).

Geological Classification IGNEOUS ROCKS Igneous rock (derived from the Latin word ignis meaning fire) is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava. Igneous rock may form with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. This magma can be derived from partial melts of pre-existing rocks in either a planet's mantle or crust. Typically, the melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition. Over 700 types of igneous rocks have been described, most of them having formed beneath the surface of Earth's crust. Igneous rocks are the oldest, having been formed by the solidification of the molten core of the earth or magma. They form about 95% of the earth’s crust, which is up to 16 km thick. Depending whether solidification occurred slowly within the earth’s crust or rapidly at the surface, the igneous rocks are defined as plutonic or volcanic respectively. In the plutonic rocks, slow cooling from the molten state allowed large crystals to grow which are characteristic of the granites. Volcanic rocks such as pumice and basalt are fine-grained and individual crystals cannot be distinguished by the eye, thus the stones are visually less interesting. Dolerites, formed by an intermediate rate of cooling, exhibit a medium-grained structure. Apart from crystal size, igneous rocks also vary in composition according to the nature of the original magma, which is essentially a mixture of silicates. A high silica content magma produces acid rocks (e.g. Granite) whilst a low silica content forms basic rocks (e.g. basalt and dolerite). Granites are mainly composed of feldspar (white, grey or pink), which determines the overall 4

Addis Ababa Science And Technology University

color of the stone, but they are modified by the presence of quartz (colorless to grey or purple), mica (silver to brown), or hornblende (dark colored). The basic rocks such as dolerite and basalt, in addition to feldspar, contain augite (dark green to black) and some-times olivine (green). Although basalt and dolerite have not been used widely as building stones they are frequently used as aggregates, and cast basalt is now being used as a reconstituted stone.

Types of Igneous Rock 1. Intrusive igneous rocks are formed from magma that cools and solidifies within the crust of a planet, surrounded by pre-existing rock (called country rock); the magma cools slowly and, as a result, these rocks are coarse grained. The mineral grains in such rocks can generally be identified with the naked eye. Intrusive rocks can also be classified according to the shape and size of the intrusive body and its relation to the other formations into which it intrudes. Typical intrusive formations are batholiths, stocks, laccoliths, sills and dikes. When the magma solidifies within the earth's crust, it cools slowly forming coarse textured rocks, such as granite, gabbro, or diorite. 2. Extrusive igneous rocks also known as volcanic rocks, are formed at the crust's surface as a result of the partial melting of rocks within the mantle and crust. Extrusive igneous rocks cool and solidify quicker than intrusive igneous rocks. They are formed by the cooling of molten magma on the earth's surface. The magma, which is brought to the surface through fissures or volcanic eruptions, solidifies at a faster rate. Hence such rocks are smooth, crystalline and fine grained. Basalt is a common extrusive igneous rock and forms lava flows, lava sheets and lava plateaus.

GRANITE ROCKS Most granites are hard and dense, and thus form highly durable building materials, virtually impermeable to water, resistant to impact damage and stable within industrial environments. 5

Addis Ababa Science And Technology University

The appearance of granite is significantly affected by the surface finish which may be sawn, rough punched, picked, and fine tooled, honed or polished. It is, however, the highly polished form of granite which is most effective at displaying the intensity of the colors and reflectivity of the crystals. Additionally, granites may be flamed to a spalled surface, produced by the differential expansion of the various crystalline constituents. Because of the high cost of quarrying and finishing granite, it is frequently used as a cladding material (40 mm externally or 20 mm internally) or alternatively cast directly onto concrete cladding units. Granite is available for flooring and for hard landscaping including pavings, setts and kerbs. Polished granite is also used as a kitchen countertop material due to its strength, durability and high-quality finish. BASALT ROCKS Basalt is defined by its mineral content and texture, and physical descriptions without mineralogical context may be unreliable in some circumstances. Basalt is usually grey to black in color, but rapidly weathers to brown or rust-red due to oxidation of its mafic (iron-rich) minerals into rust. Although usually characterized as "dark", basaltic rocks exhibit a wide range of shading due to regional geochemical processes. Due to weathering or high concentrations of plagioclase, some basalts are quite light colored, superficially resembling rhyolite to untrained eyes. Basalt has a fine-grained mineral texture due to the molten rock cooling too quickly for large mineral crystals to grow, although it is often porphyritic, containing the larger crystals formed prior to the extrusion that brought the lava to the surface, embedded in a finer-grained matrix. On Earth, most basalt magmas have formed by decompression melting of the mantle. Basalt commonly erupts on Io, the third largest moon of Jupiter, and has also formed on Earth's Moon, Mars, Venus, and the asteroid Vesta. The crustal portions of oceanic tectonic plates are composed predominantly of basalt, produced from upwelling mantle below, the ocean ridges. Basalt is a fine-grained stone nearly as hard as granite. It can be melted at 2400°C and cast into tile units which are deep steel grey in color. A slightly patterned surface can be created by swirling the molten basalt within the mold. Annealing in a furnace produces a hard virtually maintenance-free shiny textured surface flecked with shades of green, red and bronze. Larger cast units for worktops, in either a honed or polished finish, can be cut to size. Basalt is used in construction (e.g. as building blocks or in the groundwork), making cobblestones (from columnar basalt) and in making statues. Heating and extruding basalt yields stone wool, said to be an excellent thermal insulator. Basalt has high liquidus and solidus temperatures—values at the Earth's surface are near or above 1200 °C (liquidus) and near or below 1000 °C (solidus); these values are higher than those of other common igneous rocks Basalt is one of the most common rock types in the world. Basalt is the rock most typical of large igneous provinces. The largest occurrences of basalt are in the ocean floor that is almost completely made up by basalt. 6

Addis Ababa Science And Technology University

SEDIMENTARY ROCKS Sedimentary rocks are produced by the weathering and erosion of older rocks. In the earliest geological time these would have been the original igneous rocks, but subsequently other sedimentary and metamorphic rocks too will have been reworked. Weathering action by water, ice and wind breaks the rocks down into small fragments which are then carried by rivers and sorted into size and nature by further water action. Most deposits are laid down in the oceans as sedimentary beds of mud or sand, which build up in layers, become compressed and eventually are cemented together by minerals such as calcium carbonate (calcite), quartz (silica), iron oxide or dolomite (magnesium and calcium carbonate) remaining in the groundwater. The natural bedding planes associated with the formation of the deposits may be thick or thin but are potentially weak; this is used to advantage in the quarrying process. I masonry, to obtain maximum strength and durability stones should be laid to their natural bed except for cornices, cills and string courses which should be edge-bedded. Stones which are face-bedded will ten to delaminate. When quarried, stone contain quarry sap and may be worked and carve more easily than after exposure to the atmosphere. Sedimentary rocks are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles (detritus) to settle and accumulate or minerals to precipitate from a solution. Particles that form a sedimentary rock by accumulating are called sediment. Before being deposited, sediment was formed by weathering and erosion in a source area, and then transported to the place of deposition by water, wind, ice, mass movement or glaciers which are called agents of denudation. The sedimentary rock cover of the continents of the Earth's crust is extensive, but the total contribution of sedimentary rocks is estimated to be only 8% of the total volume of the crust. Sedimentary rocks are only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata, forming a structure called bedding. The study of sedimentary rocks and rock strata provides information about the subsurface that is useful for civil engineering, for example in the construction of roads, houses, tunnels, canals or other structures. Sedimentary rocks are also important sources of natural resources like coal, fossil fuels, drinking water or ores. Places where large-scale sedimentation takes place are called sedimentary basins. The amount of sediment that can be deposited in a basin depends on the depth of the basin, the so-called accommodation space. Depth, shape and size of a basin depend on tectonics, movements within the Earth's lithosphere. Where the lithosphere moves upward (tectonic uplift), land eventually rises above sea level, so that and erosion removes material, and the area becomes a source for new sediment. Where the lithosphere moves downward (tectonic subsidence), a

7

Addis Ababa Science And Technology University

basin forms and sedimentation can take place. When the lithosphere keeps subsiding, new accommodation space keeps being created.

SANDSTONES Deposits of sand cemented together by calcium carbonate, silica, iron oxide and dolomite produce calcareous, siliceous, ferruginous and dolomitic sand-stones respectively. Depending upon the nature of the original sand deposit, the sandstones may be fine or coarse in texture. Sandstones range in color from white, buff and grey through to brown and shades of red depending upon the natural cement; they are generally frost-resistant. Typical finishes are sawn, split faced and clean rubbed, although a range of tooled finishes .For cladding, sandstone is normally 75 mm to 100 mm thick and fixed with non-ferrous cramps and corbels. Sandstones are quarried in Scotland, the North of England, Yorkshire and Derbyshire; they include the old and new red sandstones, York Stone and Millstone Grit. 1. Calcareous sandstones are not durable in acid environments, which may cause the slow dissolution of the natural calcium carbonate cement of the stone. Pure calcite is white, so these sandstones are generally white in color. 2. Siliceous sandstones are predominantly grains of silica (sand) cemented with further natural silica, and are therefore durable even in acid environments. Siliceous sandstones are generally grey in color. 3. Ferruginous sandstone are bound with oxides of iron which may be brown, ochre or red. They are generally durable. 4. Dolomitic sandstones are bound with a mixture of magnesium and calcium carbonates, and therefore do not weather well in urban environments. They are generally off-white and buff in color. Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any color, but the most common colors are tan, brown, yellow, red, grey, pink, white and black. Since sandstone beds often form highly visible cliffs and other topographic features, certain colors of sandstone have been strongly identified with certain regions. Sandstone has been used for domestic construction and housewares since prehistoric times, and continues to be used. Sandstone was a popular building material from ancient times. It is relatively soft, making it easy to carve. It has been widely used around the world in constructing temples, homes, and other buildings. It has also been used for artistic purposes to create ornamental fountains and statues.

8

Addis Ababa Science And Technology University

Some sandstones are resistant to weathering, yet are easy to work. This makes sandstone a common building and paving material including in asphalt concrete. However, some that have been used in the past, such as the Collyhurst sandstone used in North West England, have been found less resistant, necessitating repair and replacement in older buildings.[1] Because of the hardness of individual grains, uniformity of grain size and friability of their structure, some types of sandstone are excellent materials from which to make grindstones, for sharpening blades and other implements. Non-friable sandstone can be used to make grindstones for grinding grain. The formation of sandstone involves two principal stages. First, a layer or layers of sand accumulates as the result of sedimentation, either from water (as in a stream, lake, or sea) or from air (as in a desert). Typically, sedimentation occurs by the sand settling out from suspension; i.e., ceasing to be rolled or bounced along the bottom of a body of water or ground surface (e.g., in a desert or erg). Finally, once it has accumulated, the sand becomes sandstone when it is compacted by pressure of overlying deposits and cemented by the precipitation of minerals within the pore spaces between sand grains. The most common cementing materials are silica and calcium carbonate, which are often derived either from dissolution or from alteration of the sand after it was buried. Colors will usually be tan or yellow (from a blend of the clear quartz with the dark amber feldspar content of the sand). A predominant additional colorant in the southwestern United States is iron oxide, which imparts reddish tints ranging from pink to dark red (terracotta), with additional manganese imparting a purplish hue. Red sandstones are also seen in the Southwest and West of Britain, as well as central Europe and Mongolia. The regularity of the latter favors use as a source for masonry, either as a primary building material or as a facing stone, over other construction. All sandstone are composed of the same general minerals. These minerals make up the framework components of the sandstones. Such components are quartz, feldspars, and lithic fragments. Matrix may also be present in the interstitial spaces between the framework grains.

LIMESTONES Lime stones consist mainly of calcium carbonate, either crystallized from solution as calcite or formed from accumulations of fossilized shells deposited by various sea organisms. They are generally classified according to their mode of formation. Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). Most limestone is composed of skeletal fragments of marine organisms such as coral or foraminifera. 9

Addis Ababa Science And Technology University

Limestone makes up about 10% of the total volume of all sedimentary rocks. The solubility of limestone in water and weak acid solutions leads to karst landscapes, in which water erodes the limestone over thousands to millions of years. Most cave systems are through limestone bedrock. Limestone has numerous uses: as a building material, as aggregate for the base of roads, as white pigment or filler in products such as toothpaste or paints, and as a chemical feedstock. 1. Crystallized limestone when water containing calcium bicarbonate evaporates, it leaves a deposit of calcium carbonate. In the case of hot springs the material produced is travertine, and in caves stalactites and stalagmites or onyx-marble result. 2. Dolomitic limestone have had the o...