File Name: cement types and uses .zip
Even if it is plumbing or electrical works some sort of cement action will be required there. In this post, we are going to explain you about some special types of cement available in the market. Cement is a binding material used to bind different type of construction materials together.
Dunuweera, R. We first discuss cement production and special nomenclature used by cement industrialists in expressing the composition of their cement products. We reveal different types of cement products, their compositions, properties, and typical uses.
Dunuweera, R. We first discuss cement production and special nomenclature used by cement industrialists in expressing the composition of their cement products. We reveal different types of cement products, their compositions, properties, and typical uses. Wherever possible, we tend to give reasons as to why a particular cement type is more suitable for a given purpose than other types.
Cement manufacturing processes are associated with emissions of large quantities of greenhouse gases and environmental pollutants. We give below quantitative and qualitative analyses of environmental impact of cement manufacturing. Controlling pollution is a mandatory legal and social requirement pertinent to any industry. As cement industry is one of the biggest CO 2 emitters, it is appropriate to discuss different ways and means of CO 2 capture, which will be done next.
Finally, we give an account of production of nanocement and advantages associated with nanocement. We mention the preparation of nanotitania and nanosilica from Sri Lankan mineral sands and quartz deposits, respectively, for the use as additives in cement products to improve performance and reduce the amount and cost of cement production and consequent environmental impacts.
As of now, mineral sands and other treasures of minerals are exported without much value addition. Simple chemical modifications or physical treatments would add enormous value to these natural materials.
Sri Lanka is gifted with highly pure quartz and graphite from which silica and graphite nanoparticles, respectively, can be prepared by simple size reduction processes. These can be used as additives in cements. Separation of constituents of mineral sands is already an ongoing process.
As described in it, cement is a powdery substance made with calcined lime and clay as major ingredients. Clay used provides silica, alumina, and iron oxide, while calcined lime basically provides calcium oxide. In cement manufacturing, raw materials of cement are obtained by blasting rock quarries by boring the rock and setting off explosives [ 2 ].
These fragmented rocks are then transported to the plant and stored separately in silos. Depending on the type of cement being produced, required proportions of the crushed clay, lime stones, and any other required materials are then mixed by a process known as prehomogenization and milled in a vertical steel mill by grinding the material with the pressure exerted through three conical rollers that roll over a turning milling table.
Additionally, horizontal mills inside which the material is pulverized by means of steel balls are also used. The clinker is discharged from the lower end of the kiln while it is red-hot, cooled by various steps, ground and mixed with small amounts of gypsum and limestone, and very finely ground to produce cement [ 4 ]. In the calcination process, in the kiln, at high temperatures, the above oxides react forming more complex compounds [ 5 ].
However, there can be many other minor components also since natural clay also contains Na, K, and so on. In the chemical analysis of cement, its elemental composition is analyzed e. Then, the composition is calculated in terms of their oxides and is generally expressed as wt.
If we analyze the elemental composition of Ca, Al, Fe, and Si, usually from X-ray fluorescence spectroscopy, then we express them as wt. As such, approximate composition of the cement clinker is different from the above values and is depicted in Table 1. They differ from their chemical composition. Given in Table 2 are also important physical properties such as specific surface area surface area per unit mass, SSA and specific gravity SG of these different types of cements [ 11 , 12 ].
There are over ten different types of cements that are used in construction purposes, and they differ by their composition and are manufactured for different uses. Purpose of having high lime content is to attain high strength in early days. It is used in concrete when formwork is to be removed early. QSC is produced by adding a small percentage of aluminium sulphate as an accelerator and reducing the amount of gypsum used with fine grinding.
This cement is used when the work is to be completed very quickly as in static and running waters. LHC has reduced the amount of C 3 A, which is used to produce massive concrete constructions like gravity dams. LHC has compressive strength to heat of the hydration ratio of at least 7 at the age of 13 weeks. The usual wt. This is prepared by grinding the CaO, SiO 2 , and Al 2 O 3 materials, melting the mixture, quenching the melt, and grinding the quenched matter to have mainly amorphous material of the above composition.
Alumina is a hydratable material and reduced alumina gives reduced hydration to produce less heat of hydration. This is important in the construction of large structures to avoid possible thermal cracking during concrete setting [ 21 ]. These newly formed ettringite and gypsum crystals occupy empty spaces of concrete, and as they grow, they tend to damage the paste by cracking.
It has been reported that the addition of pozzolonic admixtures such as fly ash reduces the C 3 A content of cement [ 22 ] when sulphate is present in water and soil used; in places like canal linings, culverts, retaining walls, and siphons, it is important to use SRC.
BFSC resembles properties of the Portland cement and is used for works in which economic considerations are predominant. HAC is obtained by melting a mixture of bauxite and lime and grinding the mixture with the clinker. Since it contains high alumina content, it is rapid-hardening cement with initial and final setting times of about 3.
HAC is used in works where concrete is subjected to high temperatures, frost, and acidic conditions. WC is prepared from raw materials free from iron oxides and oxides of other transition metals such as Cr, Mn, Cu, V, and Ti. Cheap quarried raw materials usually contain Cr, Mn, and Fe. For example, lime stones and clays usually contain 0. Keeping Fe 2 O 3 below 0. Usually, sand is ground separately using ceramic grinding media to avoid chromium contamination.
WC is costly and hence used in aesthetic applications such as precast curtain wall and facing panels and terrazzo surface. Contrary to WC, CC is prepared by deliberately adding mineral pigments to cement.
CCs are widely used in decorative works on floors. Iron oxides are used to get red, yellow, and black base colours, and several mixed colours such as browns-terracotta-tuscany-sepia-beach.
Standard green and blue pigments are chrome oxide and cobalt aluminium oxide, respectively. TiO 2 is the usual white pigment. PzC is prepared by grinding the pozzolanic clinker with the Portland cement [ 24 ]. It is used in marine structures, sewage works, and for laying concrete under water such as in bridges, piers, and dams.
AEC is produced by adding air-entraining agents that are surfactants such as alkali salts of wood resins, synthetic detergents of the alkyl-aryl sulphonate type, calcium lignosulphate derived from the sulphite process in paper making, and calcium salts of glues and other proteins obtained in the treatment of animal hides, animal and vegetable fats, oil and their acids, wetting agents, aluminium powder, and hydrogen peroxide, during the grinding of the clinker [ 25 ].
They are added in 0. These bubbles can compress to some extent, and hence, they can absorb stress created by freezing. HpC is prepared by adding water-repellent chemicals [ 26 ]. They are prepared particularly for use in high-rainfall regions to prevent water absorption during storage.
Particles of HpC are coated with nonpolar substances, usually by adsorbing oleic acid, stearic acid, and so on, to cement particles [ 27 , 28 ]. When adsorbed, these surfactant molecules self-assemble by coordinating with surface cations through their carboxylic acid groups thereby allowing the nonpolar hydrocarbon chain to extend from the particles.
When a water drop falls on them, they are stuck on hydrocarbon chains and stay as spherical particles as does by the lotus leaf. The cement particles are then not wetted, and water drops roll off when slightly slanted. These hydrophobic coatings prevent the attacks by chloride and sulphate ions, and hence, they resist to deterioration of concretes by these ions [ 29 ].
Measured data of the European cement kiln emissions show that cement industry contributes substantially to environmental pollution. Table 3 lists main environmental pollutants emitted by the European cement kilns in tonnes per year. In addition to material pollutants, noise emission is also associated with almost all the processes involved in cement manufacturing.
These environmental impacts contribute to abiotic depletion, global warming, acidification, and marine ecotoxicity [ 31 ]. Cement is produced by utilizing an extensive amount of raw materials treated and reacted at extreme conditions such as high temperatures. The high-temperature processes are called pyroprocessing processes where raw materials are heated at high temperatures for solid-state reactions to take place, which utilize fuel sources such as coal, fuel oil, natural gas, tires, hazardous wastes, petroleum coke, and basically anything combustible [ 32 ].
Some cement manufacturing plants utilize the organic waste generated in other industries such as rubber processing industries. In the clinker burning process, in order to produce 1 tonne of clinkers, 1. The balance of 0. This is a serious global environmental problem since increase in carbon dioxide in the atmosphere has direct consequences on global warming. In addition to CO 2 , other key polluting substances emitted to air by the cement industry include dust, other carbon oxides such as carbon monoxide CO , nitrogen oxides NO x s , sulphur oxides SO x s , polychlorinated dibenzo- p -dioxins, dibenzofurans, total organic carbon, metals, hydrogen chloride, and hydrogen fluoride, which are serious health-hazardous substances and some are hilariously odorous [ 34 ].
However, the type and amount of air pollution caused by the cement industry depend on various parameters, such as inputs the raw materials and fuels used and the type of process used in the industry. As for water pollution, the contribution from cement industry may be insignificant through the storage and handling of fuels that may contribute to soil and groundwater contaminations [ 35 ]. In order to reduce the amount of raw materials, particularly in the manufacturing of specialized cement types as described above, supplementary cementitious materials such as coal fly ash, slag, and natural pozzolans such as rice husk ash and volcanic ashes are used.
This will not only reduce the waste materials generated for landfilling but also the cost of cement production [ 36 ]. However, cement is an essential material for human survival nowadays. As such, there is no alternative, but the production of cement is mandatory. At the same time, controlling pollution created by cement industry is also very important. In the next section, we discuss ways and means of controlling pollution resulting from cement industries. The air pollution occurs in the excavation activities, dumps, tips, conveyer belts, crushing mills, and kilns of cement industry.
Minimizing air pollution is a mandatory legislative requirement, which also contributes to minimizing wastage and survival of the industry [ 37 ]. Dust particles emitted at sites other than kilns can be captured using a hood or other partial enclosure and transported through a series of ducts to the collectors. The dust collected can be fed to the kiln provided that it is not too alkaline not exceeding 0.
However, if the alkalinity is higher than this value, then the dust must be either discarded or pretreated before feeding to the kiln. Flexible pulse jet filters, electrostatic precipitators, wet scrubbers, and baghouse method can be used to collect dust from flue gas [ 38 ]. The US Environmental Protection Agency has reviewed the available and emerging technologies for reducing greenhouse gas emissions from Portland cement industry.
The primary greenhouse gas emitted in the cement industry is carbon dioxide, but in lower quantities, NO x s and SO x s are also emitted as detailed in Table 3 [ 39 ]. This involves separation and capture of carbon dioxide from the flue gas, pressurization, and transportation via pipelines, injection, and long-term storage.
In regard to this, several processes have been developed as detailed below.
Construction documents often specify a cement type based on the required performance of the concrete or the placement conditions. Certain cement manufacturing plants only produce certain types of portland cement. What are the differences in these cement types and how are they tested, produced, and identified in practice? In the most general sense, portland cement is produced by heating sources of lime, iron, silica, and alumina to clinkering temperature 2, to 2, degrees Fahrenheit in a rotating kiln, then grinding the clinker to a fine powder. The heating that occurs in the kiln transforms the raw materials into new chemical compounds.
Influence of cement type and water content on the fresh state properties of ready mix mortar. The main characteristic of ready mix mortar is to remain workable for up to 72hours after mixing. This greater duration of workability is obtained by use of hydration stabilizing admixtures and air-entrained admixtures. Thus, the behavior of this mortar depends on the compatibility between Portland cement and these two admixtures. Within this context, the objective of this article is to evaluate the influence of Portland cement type and water content on the properties of ready mix mortars in fresh state. The produced mortars were analyzed with respect to their properties in fresh state: consistency index, specific gravity, air entrained content and rheological behavior by squeeze-flow.
Ordinary Portland Cement (OPC) Ordinary Portland cement is the most widely used type of cement, which is suitable for all general concrete construction. Portland Pozzolana Cement (PPC) Rapid Hardening Cement. Quick setting cement. Low Heat Cement. Sulfates Resisting Cement. Blast Furnace Slag Cement. High Alumina.
Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete , mortar , stucco , and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19th century by Joseph Aspdin , and usually originates from limestone. It is a fine powder , produced by heating limestone and clay minerals in a kiln to form clinker , grinding the clinker, and adding 2 to 3 percent of gypsum. Several types of Portland cement are available. The most common, called ordinary Portland cement OPC , is grey, but white Portland cement is also available.
Different types of cement and their uses in construction work as follows Portland blast furnace slag cement. Sulphate resisting cement. Ordinary Portland Cement It is used for all general purposes and widely used for all ordinary concrete work, mortar, plaster etc.
Sign Up to The Constructor to ask questions, answer questions, write articles, and connect with other people.
Masonry mortar 1. Each type is manufactured to meet certain physical and chemical requirements for speci! Usually, 0. Cement Hydraulic powder which reacts with water to form a solid mass. Used upto M20 Grade of Concrete 2.
In the construction industry, there are different types of cement. The differences between each type of cement are its properties, uses and composition materials used during the manufacturing process. Cement is a cover material which makes a bond between aggregates and reinforcing materials. Over the years, cement in Malaysia has further developed thanks to technology. There are different types of cement for different construction works. Keep reading to learn more about the most common ones. Ordinary Portland Cement also known as OPC is a type of cement that is manufactured and used worldwide.
PDF | We first discuss cement production and special nomenclature used by cement industrialists in expressing the composition of their cement.
Но Стратмор ее не слышал. Его жизнь окончена. Тридцать лет отдал он служению своей стране. Этот день должен был стать днем его славы, его piece de resistance, итогом всей его жизни - днем открытия черного хода во всемирный стандарт криптографии. А вместо этого он заразил вирусом главный банк данных Агентства национальной безопасности. И этот вирус уже невозможно остановить - разве что вырубить электроэнергию и тем самым стереть миллиарды бит ценнейшей информации.
Треск лесного пожара, вой торнадо, шипение горячего гейзера… все они слились в гуле дрожащего корпуса машины. Это было дыхание дьявола, ищущее выхода и вырывающееся из закрытой пещеры. Стратмор так и остался стоять на коленях, парализованный ужасающим, неуклонно приближающимся звуком. Самый дорогой компьютер в мире на его глазах превращался в восьмиэтажный ад. Стратмор медленно повернулся к Сьюзан. Тоже неподвижная, она стояла у дверей шифровалки.
Лифт, соединяющий шифровалку с основным зданием, получал питание из главного комплекса, и оно действовало, несмотря на отключение питания шифровалки. Стратмору, разумеется, это было хорошо известно, но даже когда Сьюзан порывалась уйти через главный выход, он не обмолвился об этом ни единым словом.
Он терпеть не мог эти ярусы. Он был там только один раз, когда проходил подготовку. Этот враждебный мир заполняли рабочие мостки, фреоновые трубки и пропасть глубиной 136 футов, на дне которой располагались генераторы питания ТРАНСТЕКСТА… Чатрукьяну страшно не хотелось погружаться в этот мир, да и вставать на пути Стратмора было далеко не безопасно, но долг есть долг. Завтра они скажут мне спасибо, - подумал он, так и не решив, правильно ли поступает.