Which Compound Is Present In Maximum Percentage In Portland Cement?

Which Compound Is Present In Maximum Percentage In Portland Cement
ASTM C150 – Five types of portland cements exist, with variations of the first three according to ASTM C150. Type I portland cement is known as common or general-purpose cement. It is generally assumed unless another type is specified. It is commonly used for general construction, especially when making precast, and precast-prestressed concrete that is not to be in contact with soils or ground water.

The typical compound compositions of this type are: 55% (C 3 S), 19% (C 2 S), 10% (C 3 A), 7% (C 4 AF), 2.8% MgO, 2.9% (SO 3 ), 1.0% ignition loss, and 1.0% free CaO (utilizing Cement chemist notation ). A limitation on the composition is that the (C 3 A) shall not exceed 15%. Type II provides moderate sulfate resistance, and gives off less heat during hydration.

This type of cement costs about the same as type I. Its typical compound composition is: 51% (C 3 S), 24% (C 2 S), 6% (C 3 A), 11% (C 4 AF), 2.9% MgO, 2.5% (SO 3 ), 0.8% ignition loss, and 1.0% free CaO. A limitation on the composition is that the (C 3 A) shall not exceed 8%, which reduces its vulnerability to sulfates.

  • This type is for general construction exposed to moderate sulfate attack, and is meant for use when concrete is in contact with soils and ground water, especially in the western United States due to the high sulfur content of the soils.
  • Because of similar price to that of type I, type II is much used as a general purpose cement, and the majority of portland cement sold in North America meets this specification.

Note: Cement meeting (among others) the specifications for types I and II has become commonly available on the world market. Type III has relatively high early strength. Its typical compound composition is: 57% (C 3 S), 19% (C 2 S), 10% (C 3 A), 7% (C 4 AF), 3.0% MgO, 3.1% (SO 3 ), 0.9% ignition loss, and 1.3% free CaO.

  1. This cement is similar to type I, but ground finer.
  2. Some manufacturers make a separate clinker with higher C 3 S and/or C 3 A content, but this is increasingly rare, and the general purpose clinker is usually used, ground to a specific surface area typically 50–80% higher.
  3. The gypsum level may also be increased a small amount.

This gives the concrete using this type of cement a three-day compressive strength equal to the seven-day compressive strength of types I and II. Its seven-day compressive strength is almost equal to 28-day compressive strengths of types I and II. The only downside is that the six-month strength of type III is the same or slightly less than that of types I and II.

  1. Therefore, the long-term strength is sacrificed.
  2. It is usually used for precast concrete manufacture, where high one-day strength allows fast turnover of molds.
  3. It may also be used in emergency construction and repairs, and construction of machine bases and gate installations.
  4. Type IV portland cement is generally known for its low heat of hydration.

Its typical compound composition is: 28% (C 3 S), 49% (C 2 S), 4% (C 3 A), 12% (C 4 AF), 1.8% MgO, 1.9% (SO 3 ), 0.9% ignition loss, and 0.8% free CaO. The percentages of (C 2 S) and (C 4 AF) are relatively high and (C 3 S) and (C 3 A) are relatively low.

A limitation on this type is that the maximum percentage of (C 3 A) is seven, and the maximum percentage of (C 3 S) is thirty-five. This causes the heat given off by the hydration reaction to develop at a slower rate. Consequently, the strength of the concrete develops slowly. After one or two years the strength is higher than the other types after full curing.

This cement is used for very large concrete structures, such as dams, which have a low surface to volume ratio. This type of cement is generally not stocked by manufacturers, but some might consider a large special order. This type of cement has not been made for many years, because portland-pozzolan cements and ground granulated blast furnace slag addition offer a cheaper and more reliable alternative.

  • Type V is used where sulfate resistance is important.
  • Its typical compound composition is: 38% (C 3 S), 43% (C 2 S), 4% (C 3 A), 9% (C 4 AF), 1.9% MgO, 1.8% (SO 3 ), 0.9% ignition loss, and 0.8% free CaO.
  • This cement has a very low (C 3 A) composition which accounts for its high sulfate resistance.
  • The maximum content of (C 3 A) allowed is 5% for type V portland cement.

Another limitation is that the (C 4 AF) + 2(C 3 A) composition cannot exceed 20%. This type is used in concrete to be exposed to alkali soil and ground water sulfates which react with (C 3 A) causing disruptive expansion. It is unavailable in many places, although its use is common in the western United States and Canada.

As with type IV, type V portland cement has mainly been supplanted by the use of ordinary cement with added ground granulated blast furnace slag or tertiary blended cements containing slag and fly ash. Types Ia, IIa, and IIIa have the same composition as types I, II, and III. The only difference is that in Ia, IIa, and IIIa, an air-entraining agent is ground into the mix.

The air-entrainment must meet the minimum and maximum optional specification found in the ASTM manual. These types are only available in the eastern United States and Canada, only on a limited basis. They are a poor approach to air-entrainment which improves resistance to freezing under low temperatures.

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Which of the following has highest percentage in Portland cement?

(A)- CaO: 40-50%, SiO2: 30-40%, Al2O3and Fe2O3 : 10-20%

What is the maximum percentage of lime in Portland cement?

It can be seen that the percentage of lime in cement is 62 – 65%, i.e approximately 60 – 67%.

What is the percentage of calcium oxide in cement?

Contact Burns From Wet Cement – The major constituent of Portland cement, an alkaline substance, is calcium oxide (64%), combined with oxides of silicon, aluminum, magnesium, sulfur, iron, and potassium. There is considerable variability in the calcium oxide content of different grades of cement, with concrete having less and fine-textured masonry cement having more.63 The addition of water exothermically converts the calcium oxide to calcium hydroxide (Ca 2 ), a strongly corrosive alkali with a pH of 11 to 13.

  • As the cement hardens, the calcium hydroxide reacts with ambient carbon dioxide and becomes inactive.
  • Both the heat and the Ca(OH) 2 produced in this exothermic reaction can result in significant burns.
  • Because of its low solubility and consequent low ionic strength, long exposure to Ca(OH) 2 is required to produce injury.

This usually occurs when workers spill concrete into their boots or kneel in it for a prolonged period. The burn wound and the resultant protein denaturation of tissues produce a thick, tenacious, ulcerated eschar. Concrete burns are insidious and progressive.

What may appear initially as a patchy, superficial burn might in several days become a full-thickness injury requiring excision and skin grafting.67 The pain associated with these burns is often severe and more intense than the appearance of the wound might suggest ( Fig.38.22 ). Interestingly, many workers are not warned of the dangers of prolonged contact with cement, and because the initial contact with cement is usually painless, exposure may not be realized until the damage is done.

Treatment is as follows. Remove any loose particulate cement or lime, usually by brushing off, remove contaminated clothing, and irrigate the wound copiously with tap water (the pH of the effluent is tested and irrigation continued if the effluent is still alkaline).

Apply compresses of dilute acetic acid (vinegar) to neutralize the remaining alkali and provide relief of pain after irrigation. Apply antibiotic ointment to the eschar during the early postburn period. Sutilains ointment (Travase, Flint Pharmaceuticals, Deerfield, IL) is often recommended because it contains proteolytic enzymes that help speed eschar separation, but any common topical burn preparation is acceptable.

The depth of burns from wet cement can be difficult to assess in the first several days. If it becomes apparent that the burns are full-thickness burns, early excision and skin grafting are recommended. Cement burns should be differentiated from cement dermatitis, which is far more common.

What is the most common type of Portland cement?

This article is about the building product of cement. For the Australian heritage-listed production site, see Portland Cement Works Precinct, Bags of portland cement wrapped and stacked on a pallet. 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 is usually made 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.

Its name is derived from its resemblance to Portland stone which was quarried on the Isle of Portland in Dorset, England. It was named by Joseph Aspdin who obtained a patent for it in 1824. His son William Aspdin is regarded as the inventor of “modern” portland cement due to his developments in the 1840s.

What is the most important component of cement?

Detailed Solution. The correct answer is Limestone. Limestone is the main ingredient of cement.

What is the role of Fe2O3 in Portland cement?

It was founded that the optimal quantity of Fe2O3 is 0,01 % by weigth of cement in the presence of polymer powder PAV-22, because it increases the hardened cement stone flexural strength, and slightly decrease the compressive strenght.

What is the maximum grade of cement?

In India maximum grade of concrete used is M60 mostly, and the concrete used above this grade will be designed as self-compacting concrete to ensure compaction.

Which chemical composition has highest content in cement OPC?

Concrete Technology Questions and Answers – Types of Cement This set of Concrete Technology Multiple Choice Questions & Answers (MCQs) focuses on “Types of Cement”.1. Which chemical compostion has highest content in OPC? a) Alumina b) Silica c) Lime d) Iron Oxide View Answer Answer: c Explanation: Lime forms nearly two-third (2/3) of the cement.

2. Excess in lime causes _ a) The cement to shrink and integrate b) The cement to shrink and disintegrate c) The cement to expand and integrate d) The cement to expand and disintegrate View Answer

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Answer: d Explanation: Sufficient quantity of lime forms di-calcium silicate (C2SiO2) and tri-calcium silicate in the manufacturing of cement.3. Silica in excess causes _ a) The cement to set slowly b) The cement to set quickly c) The cement to expand d) The cement to disintegrate View Answer Answer: a Explanation: Silica gives strength to the cement.

  • Silica in excess causes the cement to set slowly.4.
  • Alumina in excess causes _ a) Reduces the strength of the cement b) Inceases the strength of the cement c) No change d) Sometimes increase or decrease the strength of the cement View Answer Answer: a Explanation: Alumina supports to set quickly to the cement.

It also lowers the clinkering temperature. Alumina in excess reduces the strength of the cement.5. Which compound gives the colour to the cement? a) Lime b) Silica c) Iron Oxide d) Alumina View Answer Answer: c Explanation: Iron oxide pigments are in the form of particles ranging approximately from 0.1 to 1.0 micron.

  1. The difference in color between one pigment and another is due to the shape and surface structure of the particle.
  2. Check this: | 6.
  3. Which cement contains high percentage of C 3 S and less percentage of C 2 S? a) Rapid Hardening Cement b) Ordinary Portland Cement c) Quick Setting Cement d) Low Heat Cement View Answer Answer: a Explanation: This cement contains high percentage of C 3 S and less percentage of C 3 S.

This is infact high early strength cement.7. When concrete is to be laid under water _ is to used. a) Rapid Hardening Cement b) Ordinary Portland Cement c) Quick Setting Cement d) Low Heat Cement View Answer Answer: c Explanation: When concrete is to be laid under water, quick setting cement is to used.

  • This cement is manufactured by adding small percentage of aluminum sulphate (Al 2 SO 4 ) which accelerates the setting action.8.
  • Which of the following is correct for Low Heat Cement? a) Suitable for use in cold weather areas b) Heat of hydration is reduced by tri calcium aluminate content c) This cement requires longer period of curing d) This cement contains high aluminate %age usually between 35-55%.

View Answer Answer: b Explanation: In this cement the heat of hydration is reduced by tri calcium aluminate content. It contains less percentage of lime than ordinary port land cement. It is used for mass concrete works such as dams etc. Sanfoundry Global Education & Learning Series – Concrete Technology.

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Which cement has maximum percentage of dicalcium silicate?

Rapid Hardening cement has a maximum percentage of C 3 S. Rapid Hardening Cement is also called high early strength cement. The increased rate of strength is due to the fact that a higher proportion of tri-calcium silicate (C 3 S) is contained in Rapid Hardening Cement along with finer grinding of the cement clinker.

Is SiO2 present in Portland cement?

Four main oxides present in ordinary portland cement are : CaO, Al2O3, SiO2 and Fe2O3. Identify the correct ascending order of their proportions in a typical composition of OPC. No worries! We‘ve got your back. Try BYJU‘S free classes today! No worries! We‘ve got your back. Suggest Corrections 0 : Four main oxides present in ordinary portland cement are : CaO, Al2O3, SiO2 and Fe2O3. Identify the correct ascending order of their proportions in a typical composition of OPC.

Why gypsum is added to portland cement?

Gypsum slows down the process of setting of the cement so that it gets sufficiently hardened.

Why is gypsum used in portland cement?

(2) The Mixing Amount of Gypsum – Gypsum is called the retarding agent of cement which is mainly used for regulating the setting time of cement and is an indispensable component. Without gypsum, cement clinker can condense immediately by mixing with water and release heat.

The major reason is that C 3 A in the clinker can dissolve in water quickly to generate a kind of calcium aluminate hydrate, a coagulant agent, which will destroy the normal use of cement, the retardation mechanism of gypsum is: when cement is hydrated, gypsum reacts with C 3 A quickly to generate calcium sulfoaluminate hydrate (ettringite) which deposits and forms a protection film on the cement particles to hinder the hydration of C 3 A and delay the setting time of cement.

If the content of gypsum is too little, the retardation affect will be unobvious. Too much gypsum will accelerate the setting of cement because gypsum can generate a coagulating agent itself. The appropriate amount of gypsum depends on the content of C 3 A in the cement and that of SO 3 in gypsum, and it also related to the fineness of cement and the content of SO 3 in clinker.

  • The amount of gypsum should account for 3% ~ 5% of the cement’s mass.
  • If the content of gypsum exceeds the limit, it will lower the strength of cement and it can even lead to poor dimensional stability, which will cause the expanded destruction of cement paste.
  • Thus, the national standard requires that the content of SO 3 should not be more than 3.5%.
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What is the percentage of Portland cement?

ASTM C150 – Five types of portland cements exist, with variations of the first three according to ASTM C150. Type I portland cement is known as common or general-purpose cement. It is generally assumed unless another type is specified. It is commonly used for general construction, especially when making precast, and precast-prestressed concrete that is not to be in contact with soils or ground water.

The typical compound compositions of this type are: 55% (C 3 S), 19% (C 2 S), 10% (C 3 A), 7% (C 4 AF), 2.8% MgO, 2.9% (SO 3 ), 1.0% ignition loss, and 1.0% free CaO (utilizing Cement chemist notation ). A limitation on the composition is that the (C 3 A) shall not exceed 15%. Type II provides moderate sulfate resistance, and gives off less heat during hydration.

This type of cement costs about the same as type I. Its typical compound composition is: 51% (C 3 S), 24% (C 2 S), 6% (C 3 A), 11% (C 4 AF), 2.9% MgO, 2.5% (SO 3 ), 0.8% ignition loss, and 1.0% free CaO. A limitation on the composition is that the (C 3 A) shall not exceed 8%, which reduces its vulnerability to sulfates.

  1. This type is for general construction exposed to moderate sulfate attack, and is meant for use when concrete is in contact with soils and ground water, especially in the western United States due to the high sulfur content of the soils.
  2. Because of similar price to that of type I, type II is much used as a general purpose cement, and the majority of portland cement sold in North America meets this specification.

Note: Cement meeting (among others) the specifications for types I and II has become commonly available on the world market. Type III has relatively high early strength. Its typical compound composition is: 57% (C 3 S), 19% (C 2 S), 10% (C 3 A), 7% (C 4 AF), 3.0% MgO, 3.1% (SO 3 ), 0.9% ignition loss, and 1.3% free CaO.

  1. This cement is similar to type I, but ground finer.
  2. Some manufacturers make a separate clinker with higher C 3 S and/or C 3 A content, but this is increasingly rare, and the general purpose clinker is usually used, ground to a specific surface area typically 50–80% higher.
  3. The gypsum level may also be increased a small amount.

This gives the concrete using this type of cement a three-day compressive strength equal to the seven-day compressive strength of types I and II. Its seven-day compressive strength is almost equal to 28-day compressive strengths of types I and II. The only downside is that the six-month strength of type III is the same or slightly less than that of types I and II.

Therefore, the long-term strength is sacrificed. It is usually used for precast concrete manufacture, where high one-day strength allows fast turnover of molds. It may also be used in emergency construction and repairs, and construction of machine bases and gate installations. Type IV portland cement is generally known for its low heat of hydration.

Its typical compound composition is: 28% (C 3 S), 49% (C 2 S), 4% (C 3 A), 12% (C 4 AF), 1.8% MgO, 1.9% (SO 3 ), 0.9% ignition loss, and 0.8% free CaO. The percentages of (C 2 S) and (C 4 AF) are relatively high and (C 3 S) and (C 3 A) are relatively low.

A limitation on this type is that the maximum percentage of (C 3 A) is seven, and the maximum percentage of (C 3 S) is thirty-five. This causes the heat given off by the hydration reaction to develop at a slower rate. Consequently, the strength of the concrete develops slowly. After one or two years the strength is higher than the other types after full curing.

This cement is used for very large concrete structures, such as dams, which have a low surface to volume ratio. This type of cement is generally not stocked by manufacturers, but some might consider a large special order. This type of cement has not been made for many years, because portland-pozzolan cements and ground granulated blast furnace slag addition offer a cheaper and more reliable alternative.

  • Type V is used where sulfate resistance is important.
  • Its typical compound composition is: 38% (C 3 S), 43% (C 2 S), 4% (C 3 A), 9% (C 4 AF), 1.9% MgO, 1.8% (SO 3 ), 0.9% ignition loss, and 0.8% free CaO.
  • This cement has a very low (C 3 A) composition which accounts for its high sulfate resistance.
  • The maximum content of (C 3 A) allowed is 5% for type V portland cement.

Another limitation is that the (C 4 AF) + 2(C 3 A) composition cannot exceed 20%. This type is used in concrete to be exposed to alkali soil and ground water sulfates which react with (C 3 A) causing disruptive expansion. It is unavailable in many places, although its use is common in the western United States and Canada.

  1. As with type IV, type V portland cement has mainly been supplanted by the use of ordinary cement with added ground granulated blast furnace slag or tertiary blended cements containing slag and fly ash.
  2. Types Ia, IIa, and IIIa have the same composition as types I, II, and III.
  3. The only difference is that in Ia, IIa, and IIIa, an air-entraining agent is ground into the mix.

The air-entrainment must meet the minimum and maximum optional specification found in the ASTM manual. These types are only available in the eastern United States and Canada, only on a limited basis. They are a poor approach to air-entrainment which improves resistance to freezing under low temperatures.