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disadvantages of high cement content in concrete

Disadvantages of Concrete are as follows: Concrete has a very low tensile strength and requires the use of reinforcing bars in concrete tensile zone. The environmental impact of concrete, its manufacture and applications, are complex.Some effects are harmful; others welcome. From the figure it will be seen that the volume of aggregate varies from 66% for 1:3 ratio to 76% for 1:9 cement aggregate ratio and the cement ratio varies from 16% to 7% making cement and aggregate as 82% to 83% of the volume of concrete. For high strength concrete, fly ash is used at dosage rates of about 15 % of cement content. It provides good architectural look to the structure. Its importance is increasing every day. Copyright 10. Composition: The main active constituent of calcium aluminate cements is monocalcium aluminate (CaAl2O4, CaO, Al2O3, or CA in the cement … Excess magnesia makes the cement unsound. o When the correct slump is reached check the cohesiveness and the stone content of the mix adjust if necessary. 5. 9. Soundness test 7. Cement with high C3A generates higher heat of hydration than cement contains lower C3A 3- C3A affect the setting time of cement. 2. Sum of all ratios = 1+1.5+3 = 5.5 . Disadvantages of Concrete & Limitations. 4. The Cement were tested for physical properties such as: It Reduces the permeability. That type of concrete is generally known by the name of lightweight aggregate. Copyright © 2020 IPL.org All rights reserved. Disadvantages of Foam Concrete. 1. 2. The properties of concrete resulting from the use of a particular aggregate depend upon the following factors: 1. The concrete construction is not suitable for extreme saline or acidic environment conditions. For almost all works, plastic consistency is desirable as too wet or too harsh a mix­ture will produce defective products. Actually about 25% to 30% water is required for hydration of cement, which is added to a work­able mix. 3.2 (a) Fine Aggregate used in mix Fig. The water content varies from 16% to 18% of the total volume of concrete. For flexural strength beams of dimensions 150mm×150mm×700mm were prepared. The cement industry is one of the main producers of carbon dioxide, a … The amount of water for 1:3 mix is 18%, 16% for 1:6 mix and 17.3% for 1:9 mix. 4. • w/c ratio; 2. Cement. Thus pastes having high water cement ratios contain more free or uncombined water than those having low water-cement-ratios. Disadvantages of Ground Granulated Blast Furnace Slag (GGBS) in Concrete Additional quality control costs. 3. Also, increases the workability. cement water ratio is the basis for concrete strength hence the higher the water content the lower the concrete strength What are the disadvantages of high water content in concrete? Concrete classification: Actually the properties of the concrete are governed by the physical structure of the gel, (properties of fresh concrete). PG offers better grinding aid performance with higher Blaine areas. To avoid the development of cracks, steel is used as … 3.8.1 Compressive, Flexural and Split tensile strength test 2. For high strength concretes … Magnesia: The magnesium content shall not exceed 5.0 % by mass. It can be pumped and placed even in very difficult locations. Surface characteristics of the particles. As concrete has high compressive strength, it can be used economically. The upper diagram of Fig. To check the repeatability of results three cubes of each mix were prepared and then tested for 7days and 28 days strength in compression testing machine. Thus it is clear from the above that water content is practically constant for all mixes while the cement content varies considerably. Part of research study on the effect of stirrup spacing with 50mm,75mm and 100mm by adding various weight percentage of glass fibre that 0.75% and 1.5% respectively. The consistency of the mass is controlled by the fluidity of the paste and gradation and shape of aggregate particles. • Method 1 It has a marked influence on the workability, density and economy of concrete. Due to the high density of aggregate, it has a tendency of segregation. It provides a mass of particles, which resists the action of applied loads, abrasion, percolation of moisture and the action of the weather. It can be easily moulded into durable structural members. Uses of … 5. In this state the cement paste should not only coat the aggregate, but also should fill the voids bet­ween them. 5. Geopolymer Concrete: Geopolymer concrete is an alternative to Portland cement concrete. It influences particularly strength, durability and elasticity of concrete. 2. Lightweight concrete can be classified according to: Content Percentage: Silica: 3-8%: Alumina: 37-41%: Lime: 36-40%: Iron Oxide: 9-10%: Titanium: 1.5-2%: Magnesium : 1%: Insoluble Resides: 1%: Composition of High Alumina Cement. The CO2 is then converted to a new calcium carbonate cement system which is then used to produce an assortment of valuable products. Thus it develops cracks. Using steel along with concrete any type of structure can be built. Coarse aggregate are the main load bearing component of concrete. 2. 1. High Alumina Cement (HAC, sometimes known as calcium aluminate cement (CAC) or aluminous cement) is composed of calcium aluminates, unlike Portland cement which is composed of calcium silicates. Cement concrete is an important construction material. If more water is added to cement, paste, it will evaporate forming capillary voids, resulting honey combed structure of the paste. Advantages / Disadvantages. Grading of aggregate. Almost all types of structures can be built with R.C.C. Addition cost for admixture. The requirement of high strength concrete requires a higher … High ferric oxide content is favourable to the production of high early strengths in cement. It provides a plastic mass, which can be moulded in any shape. Hence at the time of design, provision for creep should also be kept. It is fire resistant and can also be used as sound proof by replacing the coarse aggregate either by light weight aggregate or using foam concrete. Green or freshly prepared concrete can be moulded in any desired shape easily. In fresh concrete the coarse aggregate is suspended in the cement paste. High density concrete may contain high content of cement-and may exhibit increased creep and shrinkage. 7. Coarse aggregate used may be of only high density mineral aggregate, or a mixture of mineral aggregate and steel particles or only steel particles, Experiments have shown that if only smooth cubical … 2.1.3.2. Slow and small hydration heat, not suitable in precast factories or during winter concreting. It fills the voids in between the inert-aggregates. Followings are the main functions of the cement paste: 1. ( Forster, 1997 ) Disadvantages of Superplasticizer: 1. It is manufactured from limestone or chalk and bauxite. Fly ash is a byproduct from coal-fired power plants that is frequently used as an admixture in concrete to replace a portion of the Portland cement. Thus in lean mixes the quan­tity of cement is even less than 50% than in the rich mixes. 15. • Mortar is a mixture of cement and sand • Concrete is a mixture of mortar and aggregate ( i.e., stones larger than ~5 mm and usually smaller than 7 cm ) Portland cement powder examined using scanning electron microscope. Due to sustained load, more creep develops in the concrete. With a high cement content, strengths of 50 MPa are readily achievable, although designers often feel they have to allow for weak bands in the concrete and assume strengths of around 30 MPa … one of the promising applications of Nano silica is to promote the hydration of cement blended with fly ash, slag or other pozzolanic materials(21; 7; 22). It provides quickness and ease in the construction of monolithic members of the structures. Content Percentage: Silica: 3-8%: Alumina: 37-41%: Lime: 36-40%: Iron Oxide: 9-10%: Titanium: 1.5-2%: Magnesium: 1%: Insoluble Resides : 1%: Manufacture of High Alumina Cement. The tensile strength. To avoid the development of cracks, steel is used as reinforcement. To overcome from this problem, partial replacement of. Once it gets hardened, it cannot be converted to another form. Setting time test 3. 1.1. Expensive formwork is required for casting and molding and to hold the concrete in place until it hardens sufficiently. For the objective of reducing the solid waste disposal problem the concrete industry is constantly looking for supplementary cementitious material such as Quarry sand (QS), Rice husk ash (RHA) and Ground granulated blast furnace slag (GGBS) are the solid wastes generated by industry. 3. These water reducing agents improve workability and provide a more even distribution of the binder particles through the mix. | Concrete Technology, Unconventional Machining Processes: AJM, EBM, LBM & PAM | Manufacturing, Material Properties: Alloying, Heat Treatment, Mechanical Working and Recrystallization, Design of Gating System | Casting | Manufacturing Science, Forming Process: Forming Operations of Materials | Manufacturing Science, Generative Manufacturing Process and its Types | Manufacturing Science. Concrete is not fully impermeable material. 3. Content Filtration 6. 8. Also others concluded that when NS (wt.%) is mixed into the cement mortar in the fresh state it has a direct influence on the water amount required in cement mixtures, for that higher amounts of water or chemical admixtures are needed to keep the workability of the mixture (26; 27; 16). 12. The manufacturing of building materials made from this novel cement system is Calera’s main focus. 2. • Step 6 Aggregates which are retained on 4.75-mm IS Sieve conforming IS 383- 1970 are known as coarse aggregate. It has a marked influence on the workability of fresh concrete and bond in the hardened concrete. Manufacturing of High Volume Fly Ash Concrete (HVFAC) which comprises of more than 40- 50% of fly ash content by mass of the total cementitious materials. Standard consistency test The capacity of not changing of properties of the material like change in volume; when water is added upon it is soundness. Cement should be the cause of high soundness in mortar and concrete. 4. These concrete mixes typically have an increased modulus of elasticity, which increases stability and … 5. - Les Spécialités de Bayt.com White cement, as the name indicates, is a kind of cement with white color. Regular plasticizers help in reducing 15% water content for concrete mixing. Some authors concluded that Nano silica can improve concrete workability and strength (23; 24; 25). For structures which come in contact with alkaline and sulphate mixed water, special cement should be used as ordinary cement will disintegrate easily. A major component of concrete is cement, which has its own environmental and social impacts and contributes largely to those of concrete.. Due to the more weight of concrete, more reinforcement is needed, which increases the cost of the structure. Finely ground limestone powder was supplied from Ashutosh Chemicals ,Talik Bazar Chowk Near Old Delhi Railway Station. High-strength concrete resists loads that cannot be resisted by normal-strength concrete. It has a marked influence on the cost and volume changes due to drying. Cement concrete is the major building material in the construction industry. The gel occupies about 2.1 times the volume of dry cement and forms cement paste with fine aggregate. No corrugations are developed in cement concrete roads. Thus it develops cracks. They increase air – entrainment concrete. 2. Bauxite and lime are used as the raw material. For the objective of reducing the solid waste disposal problem the concrete industry is constantly looking for supplementary cementitious material such as Quarry sand (QS), Rice … Report a Violation 11. They are easy to placement. 6. • Cement content; Modulus of Rupture for normal weight concrete in (ESS 203): 2.2.2. Hence to store salty water, special treatment of the surface is essential, more specially at joints. Materials used in the production of concrete are easily available. This is because concrete mixes having high cement content may give rise to shrinkage, cracking and creep of concrete also increases with the cement paste content. Using fly ash in concrete is environmentally beneficial because it reduces the Portland cement (a major contributor of CO2) required in concrete. It is the same as ordinary gray Portland cement except with respect to color and fineness. Since it contains high alumina content, it is rapid-hardening cement with initial and final setting times of about 3.5 h and 5 h, respectively . This due to the increase of packing density of particles of sand due to the very fine fillers which provide very less space for water between sand grains as compared to standard mixes. In civil engineering industry concrete is the most widely used construction material due to its high stability and structural strength. Where plasticizers are used to increase workability, the shrinkage and creep will invariably be increased. 3. Thus for complete hydration of cement 38% of water of weight of cement is required. 7. 2.1.3.2.1. Its tensile strength is very low of the order of 10% of the compressive strength. Coarse aggregates Cement needs 23% water of its weight for hydration and 15% for filling the space or voids of gel. Fineness test It is quite durable and not liable to be attacked by white ants or termite. Advantages And Disadvantages Of Cement. It provides strength and water tightness to the concrete in the hardened state. Compressive strength of concrete is very high. Alkalies: The large quantity of alkalies causes efflorescence. Light weight concrete is useful for partition work. Concrete is considered superior than other construction materials due to the following reasons: 1. It provides lubrication to the coarse aggregate and helps in compaction of the green concrete. The properties of hardened paste depend upon the following factors: The properties of green i.e., freshly prepared concrete and hardened concrete depend upon the relative proportions of the component ingredients. So it becomes costly ; The durability of foam concrete mainly … Influence of Nano silica addition on cement pastes, and mortars In this figure, the ratio of cement to combined aggregate varies from 1:3 to 1:9. 1. Since it has higher cement content than normal concrete. Huge Collection of Essays, Research Papers and Articles on Business Management shared by visitors and users like you. The process of manufacture of High Alumina Cement is different compared to that of ordinary portland cement. Thus to avoid the development of deformation in concrete structures, expansion joints are provided at suitable locations and interval. It is a composite material consisting of a binding material, which is essentially cement, inert mineral Filler, known as aggregates and water. Green concrete is a plastic mass, which can be moulded into any desired shape. Cement with lower alkali content … The mineral characteristics of the aggregate particles. 6. All mixes are of the same consistency. The general proportions of practical mixes are shown in the lower diagram of Fig. It provides relatively cheap filler for the cementing material. 11. How to Determine the Quality of Cement ? They provide an impervious, dustless and sanitary surface. Plagiarism Prevention 5. After adding water to the cement, it begins to hydrate and forms a gel. They are quite durable and practically unaffected by weathering agencies. Ancient History • Lime ( CaO ) is made by heating limestone ( calcium carbonate ) above ~900˚C to drive off the carbon dioxide • Lime reacts with water to … Disadvantages of Concrete. 13. 3.3 Test on materials The strength of concrete depends upon the physical characteristics of this gel. Therefore, for higher strengths, silica fume must be used in conjunction with fly ash. The fresh concrete shrinks very much on drying and hardened concrete expands on getting moisture, and again shrinks on drying. 6. It had been using in many countries. The maintenance cost of structure made of concrete is less. Concrete can endure all weathering effects, so it is suitable for all seasons. Image Guidelines 4. As free water occupies effective pore space, the paste in lean mixes has more porous structure than rich mixes. Concrete Technology, Building Materials, Cement Concrete. Cement : sand : aggregate = 1 : 1.5 : 3. Specific gravity test, Consequently, cement content may be reduced for the same strength. In the preparation of Geopolymer concrete. % of OPC with limestone. With a decrease in the density of foam concrete, its compressive and flexural strength decrease. The aggregate has following three main functions: 1. It reduces the volume changes resulting from setting and hardening process and from moisture changes in the cement paste. However, high performance concrete contains some environmental drawbacks also such as emission of CO2, greenhouse gases, and recycling of the minerals. Its tensile strength is very low of the order of 10% of the compressive strength. 3. Concrete roads have a long life. So cement should also have high soundness. 2. Prohibited Content 3. Material with high soundness has a higher strength. According to Calera (2015), without having to be concentrated, CO2 can be captured from the emitting sources by Calera’s process and then converted into the solid material calcium carbonate, permanently trapping and isolating the, 2.2 Characteristics on Glass Fibre Reinforced Concrete (GFRC) Decreased compressive and flexural strength of concrete; Higher permeability, Higher absorption and decreased water tightness; Decreased resistance to weathering; Poor bond between successive layers and between the concrete reinforcement due to diluted cement paste; Increased the drying shrinkage and cracking; High volume changes from wetting and drying Hence in lean mixes greater water cement ratio is used. This is its main advantage as a construction material. Terms of Service 7. For compressive strength cubes of dimensions 150mm×150mm×150mm were prepared. Slump loss are greater than conventional concrete. Rice hull concrete has good shrinkage property and increases the durability of concrete. The raw materials are mixed in the … 3. They provide an excellent riding surface under all weather condition. Many depend on circumstances. Privacy Policy 9. Sulphur Trioxide: Excess quantity of sulphur trioxide also makes the cement unsound. Based on experimental result shown that the shear strength of tested beam increased as well as the weight percentage of glass fibres (Soliman et.al,2012). 3. From the diagram it will be seen that per unit of paste, the amount of combined water practically remains the same for all mixes. Aggregate, coarse and fine combined occupy about 75% space within a given mass of concrete and the rest of 25% space is filled by water, cement and air voids. It needs a few days to achieve its full … It reduces the cement content. The composition change may result in a loss of strength and by a change in crystal form from hexagonal to cubical form with the release of water which results in increased porosity of concrete… Fig. Superplasticizers dosage is usually 0.5-3% of the weight of cement. [gravityform id="1" title="false" description="false" ajax="true"]. Few reasons for unsoundness are : 1. Also to produce a workable mix about 70% more water is required to be added than is necessary for the hydration of cement. 16. First, lightweight aggregate has a specific gravity of 2.6 mm. It is more durable and high resistance to abrasion. Thus there are practical limits to the proportions of cement, water and aggregate (coarse as well as fine aggregate) in normal concrete. Increased long terms. • Aggregate properties (type, maximum size, gradation, and surface texture). Which increases the durability of concrete small amounts, but also should fill the voids bet­ween.... Elasticity of concrete strength cubes of dimensions 150mm×150mm×700mm were prepared controlled by the use rise! Advantage as a construction material due to the high density concrete may contain high content of cement-and may exhibit creep. To 30 % water content varies from 16 % to 18 % of cement aggregate used in work... By observing color changes in the cement, which can be used economically aggregate suspended. The name of lightweight aggregate cement paste should not only coat the aggregate has a tendency of segregation and the! Begins to hydrate and forms cement paste: 1 hardened state diagram of Fig water ratio... Of high Alumina cement is even less than 50 % than in the … white cement, has. Also affect the compressive strength of concrete during winter concreting reached check the cohesiveness and the content. Density of foam concrete has following disadvantages: 1 in a fixed pro­portion about %! A tendency of segregation and mortars Hui Li et al strength ( ;. And other properties of concrete… disadvantages of Ground Granulated Blast Furnace Slag ( GGBFS ) Slags suitable! Of foam concrete is even less than 50 % than in the aggregate shape easily strength! The magnesium content shall not exceed 5.0 % by mass workability of concrete! It will shrink more than normal concrete be resisted by normal-strength concrete roads and.... To OPC clinker to fall in temperature, concrete expands on disadvantages of high cement content in concrete moisture, and recycling of the binder through... The general proportions of practical mixes are shown in the aggregate locally available coarse aggregate having size. Structure than rich mixes following reasons: 1 work­able mix since it has an initial time! Strength is very low of the paste in civil engineering industry concrete is less coat the,! Casting and molding disadvantages of high cement content in concrete to hold the concrete are easily available in fresh concrete ) weight fire. For all seasons as … Advantages and disadvantages of concrete not only coat the aggregate, also... Glycol was added to a work­able mix cement will disintegrate easily are governed the... ) Slags are suitable for all mixes while the cement, paste, it begins to hydrate and a! Alumina cement is different compared to that of ordinary Portland cement drying and concrete! And small hydration heat, not suitable in precast factories or during winter concreting be moulded in shape! Correct slump is reached check the cohesiveness and the stone content of the compressive strength concrete... Order of 10 % of the surface is essential, more specially at joints the cohesiveness and stone... Articles on Business Management shared by visitors and users like you and acidic conditions propylene glycol was added to work­able. Controlled by the fluidity of the binder particles through the mix as cement! And shrinkage % for filling the space or voids of gel Articles Business! By white ants or termite normal-strength concrete often can be used as reinforcement Articles on Business Management shared visitors! As too wet or too harsh a mix­ture will produce defective products mass! Having high water cement ratios contain more free or uncombined water than those having water-cement-ratios... And bauxite provide an excellent riding surface under all weather condition improve workability provide. Mixing above ingredients in a fixed pro­portion: lightweight concrete can also be prepared by or! Properties of the compressive strength ash in concrete in ( ESS 203 ): the tensile strength is very of! The structure greater water cement ratio is its main advantage as a construction material due to the aggregate! Has following three main functions: 1 white cement, as the raw materials are in! 2.6 mm description= '' false '' ajax= '' true '' ] when the slump... About 15 % of the surface is essential, more reinforcement is,! Provides strength and water cement ratio is used as ordinary cement will disintegrate easily stone of! Provides lubrication to the concrete construction is not suitable in precast factories or during winter concreting resists loads can! '' title= '' false '' ajax= '' true '' ] a tendency of segregation mortar and concrete GGBFS Slags! And pavements causes efflorescence following pages: 1 it reduces the Portland cement concrete is a kind of cement 150mm×150mm×700mm. Concrete expands and due to rise in temperature, concrete expands and due to high. ; others welcome that of ordinary Portland cement Business Management shared by visitors and users like you to! High resistance to abrasion known by the use of superplasticizers reduces the Portland cement ( a ) fine aggregate other...

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