The Compound Of Portland Cement Which Reacts First?

The Compound Of Portland Cement Which Reacts First
Tricalcium Aluminate Tricalcium Aluminate : C 3 A is formed within 24 hours of the addition of water in the cement and is responsible for maximum evolution of heat of hydration. It is the first compound that is formed after addition of water and sets early.

Which component of cement reacts first with water?

Phase 1: Initial mixing reaction The aluminate (C3A) reacts with H2O (Calcium and sulfate ions) to form ettringite (aluminate hydrate). The release of the energy from these reactions causes the initial peak.

What is the chemical reaction of Portland cement?

Composition – ASTM C150 defines portland cement as: hydraulic cement (cement that not only hardens by reacting with water but also forms a water-resistant product) produced by pulverizing clinkers which consist essentially of hydraulic calcium silicates, usually containing one or more of the forms of calcium sulfate as an inter ground addition. The European Standard EN 197-1 uses the following definition: Portland cement clinker is a hydraulic material which shall consist of at least two-thirds by mass of calcium silicates, (3 CaO·SiO 2, and 2 CaO·SiO 2 ), the remainder consisting of aluminium- and iron-containing clinker phases and other compounds. The ratio of CaO to SiO 2 shall not be less than 2.0. The magnesium oxide content ( MgO ) shall not exceed 5.0% by mass. (The last two requirements were already set out in the German Standard, issued in 1909). Clinkers make up more than 90% of the cement, along with a limited amount of calcium sulfate (CaSO 4, which controls the set time), and up to 5% minor constituents (fillers) as allowed by various standards. Clinkers are nodules (diameters, 0.2–1.0 inch ) of a sintered material that is produced when a raw mixture of predetermined composition is heated to high temperature. The key chemical reaction distinguishing portland cement from other hydraulic limes occurs at these high temperatures (>1,300 °C (2,370 °F)) as belite (Ca 2 SiO 4 ) combines with calcium oxide (CaO) to form alite (Ca 3 SiO 5 ).

What is the compound composition of Portland cement?

Chemical composition – Portland cement is made up of four main compounds: tricalcium silicate (3CaO · SiO 2 ), dicalcium silicate (2CaO · SiO 2 ), tricalcium aluminate (3CaO · Al 2 O 3 ), and a tetra-calcium aluminoferrite (4CaO · Al 2 O 3 Fe 2 O 3 ).

Which Bogue compound reacts first with water?

Free General Knowledge: Free Mock Test 10 Questions 10 Marks 7 Mins Explanation: C 3 S readily reacts with water and produces more heat of hydration. It is responsible for early strength of concrete. The quality and density of calcium silicate hydrate formed out of C 3 S is slightly inferior to that formed by C 2 S.

A cement with C 3 S gets attacked by sulphate easily whereas C 2 S is offering better resistance against chemical attacks. C 2 S hydrates rather slowly. It is responsible for the later strength of concrete and produces less heat of hydration. The calcium silicate hydrate formed is rather dense and its specific surface is higher and the quality of the product of hydration of C 2 S is better than that produced in the hydration of C 3 S.

The hydrated aluminates do not contribute anything to the strength of concrete. Their presence is harmful to the durability of concrete, particularly where the concrete is likely to be attacked by sulphates. The calcium hydroxide also reacts with sulphates present in soil or water to form calcium sulphate which further reacts with C 3 A and cause deterioration of concrete.

This is known as sulphate attack, To remedy the sulphate attack, the use of cement with low C 3 A content is found to be effective. Latest MP Vyapam Sub Engineer Updates Last updated on Sep 16, 2022 MP Vyapam Sub Engineer Prelims Answer Key has been released on 22nd November 2022. The objections can be raised in the answer key till 24th November 2022.

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What is the chemical reaction between Portland cement and water called?

Background – Concrete is made by the combination of cement, water, and aggregate of various sizes to make a workable slurry that has the consistency of a thick milk shake.

Name Percent by Weight Chemical Formula
Tricalcium silicate 50% 3Ca0 SiO2
Dicalcium silicate 25% 2Ca0 SiO2
Tricalcium aluminate 10% 3Ca0 Al2 O3
Tetracalcium aluminoferrite 10% 4Ca0 Al2 Fe2 O3
Gypsum 5% CaSO4 H2O

The binding quality of portland cement paste is due to the chemical reaction between the cement and water, called hydration. Portland cement is not a simple chemical compound, it is a mixture of many compounds. Four of these make up 90% or more of the weight of portland cement: tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite.

  1. In addition to these major compounds, several other play important roles in the hydration process.
  2. Different types of cement contain the same four major compounds, but in different proportions.
  3. The cement in concrete needs water to hydrate and harden.
  4. Even though the chemical reactions may be complete at the surface of the concrete, the chemical reactions at the interior of the concrete take much longer to complete.

The strength of the concrete keeps growing as long as the chemical reactions continue. When water is added to cement, the chemical reaction called hydration takes place and contributes to the final concrete product. The calcium silicates contribute most to the strength of concrete.

Tricalcium silicates are responsible for most of the early strength (first seven days). The original dicalcium silicate hydrates, which form more slowly, contribute to the strength of concrete at later stages. The following word equations describe the production of concrete. Tricalcium silicate + Water (yields) Calcium silicate hydrate + Calcium hydroxide + heat Dicalcium silicate + Water (yields) Calcium silicate hydrate + Calcium hydroxide + heat Of the five chemical reactions important for providing the strength for concrete the above reactions are the most important.

The two calcium silicates, which constitute about 75 percent of the weight of portland cement, react with water to form two new compounds: calcium hydroxide and calcium silicate hydrate. The latter is by far the most important cementing component in concrete.

  1. The engineering properties of concrete—setting and hardening, strength and dimensional stability—depend primarily on calcium silicate hydrate gel.
  2. It is the heart of concrete.
  3. When concrete sets, its gross volume remains almost unchanged, but hardened concrete contains pores filled with water and air that have no strength.

The strength is in the solid part of the paste, mostly in the calcium silicate hydrate and crystalline phases. The less porous the cement paste, the stronger the concrete. When mixing concrete, therefore, use no more water than is absolutely necessary to make the concrete plastic and workable.

What are the reaction of hydration of main compounds in Portland cement?

3.7 Hydrated lime (portlandite) – Portland cement hydration results in the formation of a large amount of portlandite: 20–30% of the hydrated mass of cement according to the respective amounts of C 3 S and C 2 S in the clinker. In concretes having a high w/c, this portlandite appears in the form of large hexagonal crystals, as shown in Figure 3.12,

  1. These portlandite crystals have a marginal impact from a mechanical point of view, so they do not bring any strength to concrete.
  2. Moreover, in submerged concrete this lime can be leached out easily by diffusion, depending on the w/c ratio of the concrete and the purity of the water in which the concrete is submerged.

Finally, the lime can be carbonated by CO 2 in the air. Its only advantage is that it maintains a high pH in the interstitial water and therefore protects reinforcing steel from carbonation-induced corrosion. But when the lime is fully carbonated by the CO 2 contained in air, this protection is lost.

  1. The best way to make this lime beneficial from a mechanical, durability and sustainability point of view is to transform it into so-called secondary C-S-H by making it react with pozzolanic materials or slag, as it will be seen in Chapter 4 ( Aïticin, 2016b ).
  2. Therefore, theoretically the hydration of a blended cement containing a pozzolanic material is: Clinker + pozzolan + gypsum + water = C-S-H + sulphoaluminates.

Such blended cement also has the advantage of improving the sustainability of concrete structures by decreasing their carbon footprint. Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780081006931000035

What are the four main compounds in portland cement?

2 Cementitious materials – Portland cement (OPC) consists of tri and dicalcium silicates, tricalcium aluminate, and tetracalcium alumino ferrite and calcium sulfate as gypsum. It has adhesive and cohesive properties and is capable of binding together mineral fragments in presence of water so as to produce a continuous compact mass of masonary. The Compound Of Portland Cement Which Reacts First Fig.2.1, Manufacturing process of Portland cement. Blended cements are mixtures of Portland cement and other hydraulic or non hydraulic materials (industrial and agricultural wastes such as fly ash, metakaoline, blast furnace slag, rice husk ash, etc.). Paste, mortar and Concretes are shown in Fig.2.2, The Compound Of Portland Cement Which Reacts First Fig.2.2, Representation of OPC paste, mortar and concrete. Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780128178546000027

What is the primary chemical reactions during the hydration of Portland?

Ferrite + gypsum + water ® ettringite + ferric aluminum hydroxide + lime.

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What is the chemical reaction in concrete?

What is in This Stuff? The importance of concrete in modern society cannot be overestimated. Look around you and you will find concrete structures everywhere such as buildings, roads, bridges, and dams. There is no escaping the impact concrete makes on your everyday life.

  • So what is it? Concrete is a composite material which is made up of a filler and a binder.
  • The binder (cement paste) “glues” the filler together to form a synthetic conglomerate.
  • The constituents used for the binder are cement and water, while the filler can be fine or coarse aggregate.
  • The role of these constituents will be discussed in this section.

Cement, as it is commonly known, is a mixture of compounds made by burning limestone and clay together at very high temperatures ranging from 1400 to 1600 ]C. Although there are other cements for special purposes, this module will focus solely on portland cement and its properties.

  • The production of portland cement begins with the quarrying of limestone, CaCO 3,
  • Huge crushers break the blasted limestone into small pieces.
  • The crushed limestone is then mixed with clay (or shale), sand, and iron ore and ground together to form a homogeneous powder.
  • However, this powder is microscopically heterogeneous.

(See flowchart.) Figure 1: A flow diagram of Portland Cement production. The mixture is heated in kilns that are long rotating steel cylinders on an incline. The kilns may be up to 6 meters in diameter and 180 meters in length. The mixture of raw materials enters at the high end of the cylinder and slowly moves along the length of the kiln due to the constant rotation and inclination. Figure 2: Schematic diagram of rotary kiln. As the mixture moves down the cylinder, it progresses through four stages of transformation. Initially, any free water in the powder is lost by evaporation. Next, decomposition occurs from the loss of bound water and carbon dioxide.

This is called calcination, The third stage is called clinkering. During this stage, the calcium silicates are formed. The final stage is the cooling stage. The marble-sized pieces produced by the kiln are referred to as clinker, Clinker is actually a mixture of four compounds which will be discussed later.

The clinker is cooled, ground, and mixed with a small amount of gypsum (which regulates setting) to produce the general-purpose portland cement. Water is the key ingredient, which when mixed with cement, forms a paste that binds the aggregate together.

  1. The water causes the hardening of concrete through a process called hydration.
  2. Hydration is a chemical reaction in which the major compounds in cement form chemical bonds with water molecules and become hydrates or hydration products.
  3. Details of the hydration process are explored in the next section.
  4. The water needs to be pure in order to prevent side reactions from occurring which may weaken the concrete or otherwise interfere with the hydration process.

The role of water is important because the water to cement ratio is the most critical factor in the production of “perfect” concrete. Too much water reduces concrete strength, while too little will make the concrete unworkable. Concrete needs to be workable so that it may be consolidated and shaped into different forms (i.e.

  1. Walls, domes, etc.).
  2. Because concrete must be both strong and workable, a careful balance of the cement to water ratio is required when making concrete.
  3. Aggregates are chemically inert, solid bodies held together by the cement.
  4. Aggregates come in various shapes, sizes, and materials ranging from fine particles of sand to large, coarse rocks.

Because cement is the most expensive ingredient in making concrete, it is desirable to minimize the amount of cement used.70 to 80% of the volume of concrete is aggregate keeping the cost of the concrete low. The selection of an aggregate is determined, in part, by the desired characteristics of the concrete.

  • For example, the density of concrete is determined by the density of the aggregate.
  • Soft, porous aggregates can result in weak concrete with low wear resistance, while using hard aggregates can make strong concrete with a high resistance to abrasion.
  • Aggregates should be clean, hard, and strong.
  • The aggregate is usually washed to remove any dust, silt, clay, organic matter, or other impurities that would interfere with the bonding reaction with the cement paste.

It is then separated into various sizes by passing the material through a series of screens with different size openings. Refer to Demonstration 1 Table 1: Classes of Aggregates

class examples of aggregates used uses
ultra-lightweight vermiculite ceramic spheres perlite lightweight concrete which can be sawed or nailed, also for its insulating properties
lightweight expanded clay shale or slate crushed brick used primarily for making lightweight concrete for structures, also used for its insulating properties.
normal weight crushed limestone sand river gravel crushed recycled concrete used for normal concrete projects
heavyweight steel or iron shot steel or iron pellets used for making high density concrete for shielding against nuclear radiation

Refer to Demonstration 2 The choice of aggregate is determined by the proposed use of the concrete. Normally sand, gravel, and crushed stone are used as aggregates to make concrete. The aggregate should be well-graded to improve packing efficiency and minimize the amount of cement paste needed.

  • Also, this makes the concrete more workable.
  • Refer to Demonstration 3 Properties of Concrete Concrete has many properties that make it a popular construction material.
  • The correct proportion of ingredients, placement, and curing are needed in order for these properties to be optimal.
  • Good-quality concrete has many advantages that add to its popularity.

First, it is economical when ingredients are readily available. Concrete’s long life and relatively low maintenance requirements increase its economic benefits. Concrete is not as likely to rot, corrode, or decay as other building materials. Concrete has the ability to be molded or cast into almost any desired shape.

  • Building of the molds and casting can occur on the work-site which reduces costs.
  • Concrete is a non-combustible material which makes it fire-safe and able withstand high temperatures.
  • It is resistant to wind, water, rodents, and insects.
  • Hence, concrete is often used for storm shelters.
  • Concrete does have some limitations despite its numerous advantages.

Concrete has a relatively low tensile strength (compared to other building materials), low ductility, low strength-to-weight ratio, and is susceptible to cracking. Concrete remains the material of choice for many applications regardless of these limitations.

  1. Hydration of Portland Cement Concrete is prepared by mixing cement, water, and aggregate together to make a workable paste.
  2. It is molded or placed as desired, consolidated, and then left to harden.
  3. Concrete does not need to dry out in order to harden as commonly thought.
  4. The concrete (or specifically, the cement in it) needs moisture to hydrate and cure (harden).

When concrete dries, it actually stops getting stronger. Concrete with too little water may be dry but is not fully reacted. The properties of such a concrete would be less than that of a wet concrete. The reaction of water with the cement in concrete is extremely important to its properties and reactions may continue for many years.

Cement Compound Weight Percentage Chemical Formula
Tricalcium silicate 50 % Ca 3 SiO 5 or 3CaO, SiO 2
Dicalcium silicate 25 % Ca 2 SiO 4 or 2CaO, SiO 2
Tricalcium aluminate 10 % Ca 3 Al 2 O 6 or 3CaO, Al 2 O 3
Tetracalcium aluminoferrite 10 % Ca 4 Al 2 Fe 2 O 10 or 4CaO, Al 2 O 3, Fe 2 O 3
Gypsum 5 % CaSO 4,2H 2 O

Table 2: Composition of portland cement with chemical composition and weight percent. When water is added to cement, each of the compounds undergoes hydration and contributes to the final concrete product. Only the calcium silicates contribute to strength. Tricalcium silicate is responsible for most of the early strength (first 7 days). Dicalcium silicate, which reacts more slowly, contributes only to the strength at later times. Tricalcium silicate will be discussed in the greatest detail. The equation for the hydration of tricalcium silicate is given by: Tricalcium silicate + Water->Calcium silicate hydrate+Calcium hydroxide + heat 2 Ca 3 SiO 5 + 7 H 2 O -> 3 CaO,2SiO 2,4H 2 O + 3 Ca(OH) 2 + 173.6kJ Upon the addition of water, tricalcium silicate rapidly reacts to release calcium ions, hydroxide ions, and a large amount of heat. The pH quickly rises to over 12 because of the release of alkaline hydroxide (OH – ) ions. This initial hydrolysis slows down quickly after it starts resulting in a decrease in heat evolved. The reaction slowly continues producing calcium and hydroxide ions until the system becomes saturated. Once this occurs, the calcium hydroxide starts to crystallize. Simultaneously, calcium silicate hydrate begins to form. Ions precipitate out of solution accelerating the reaction of tricalcium silicate to calcium and hydroxide ions. (Le Chatlier’s principle). The evolution of heat is then dramatically increased. The formation of the calcium hydroxide and calcium silicate hydrate crystals provide “seeds” upon which more calcium silicate hydrate can form. The calcium silicate hydrate crystals grow thicker making it more difficult for water molecules to reach the unhydrated tricalcium silicate. The speed of the reaction is now controlled by the rate at which water molecules diffuse through the calcium silicate hydrate coating. This coating thickens over time causing the production of calcium silicate hydrate to become slower and slower. Figure 3: Schematic illustration of the pores in calcium silicate through different stages of hydration. The above diagrams represent the formation of pores as calcium silicate hydrate is formed. Note in diagram (a) that hydration has not yet occurred and the pores (empty spaces between grains) are filled with water. Diagram (b) represents the beginning of hydration. In diagram (c), the hydration continues. Although empty spaces still exist, they are filled with water and calcium hydroxide. Diagram (d) shows nearly hardened cement paste. Note that the majority of space is filled with calcium silicate hydrate. That which is not filled with the hardened hydrate is primarily calcium hydroxide solution. The hydration will continue as long as water is present and there are still unhydrated compounds in the cement paste. Dicalcium silicate also affects the strength of concrete through its hydration. Dicalcium silicate reacts with water in a similar manner compared to tricalcium silicate, but much more slowly. The heat released is less than that by the hydration of tricalcium silicate because the dicalcium silicate is much less reactive. The products from the hydration of dicalcium silicate are the same as those for tricalcium silicate: Dicalcium silicate + Water->Calcium silicate hydrate + Calcium hydroxide +heat 2 Ca 2 SiO 4 + 5 H 2 O-> 3 CaO,2SiO 2,4H 2 O + Ca(OH) 2 + 58.6 kJ The other major components of portland cement, tricalcium aluminate and tetracalcium aluminoferrite also react with water. Their hydration chemistry is more complicated as they involve reactions with the gypsum as well. Because these reactions do not contribute significantly to strength, they will be neglected in this discussion. Although we have treated the hydration of each cement compound independently, this is not completely accurate. The rate of hydration of a compound may be affected by varying the concentration of another. In general, the rates of hydration during the first few days ranked from fastest to slowest are: tricalcium aluminate > tricalcium silicate > tetracalcium aluminoferrite > dicalcium silicate. Refer to Demonstration 4 Heat is evolved with cement hydration. This is due to the breaking and making of chemical bonds during hydration. The heat generated is shown below as a function of time. Figure 4: Rate of heat evolution during the hydration of portland cement The stage I hydrolysis of the cement compounds occurs rapidly with a temperature increase of several degrees. Stage II is known as the dormancy period. The evolution of heat slows dramatically in this stage.

  • The dormancy period can last from one to three hours.
  • During this period, the concrete is in a plastic state which allows the concrete to be transported and placed without any major difficulty.
  • This is particularly important for the construction trade who must transport concrete to the job site.
  • It is at the end of this stage that initial setting begins.
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In stages III and IV, the concrete starts to harden and the heat evolution increases due primarily to the hydration of tricalcium silicate. Stage V is reached after 36 hours. The slow formation of hydrate products occurs and continues as long as water and unhydrated silicates are present.

Refer to Demonstration 5 Strength of Concrete The strength of concrete is very much dependent upon the hydration reaction just discussed. Water plays a critical role, particularly the amount used. The strength of concrete increases when less water is used to make concrete. The hydration reaction itself consumes a specific amount of water.

Concrete is actually mixed with more water than is needed for the hydration reactions. This extra water is added to give concrete sufficient workability. Flowing concrete is desired to achieve proper filling and composition of the forms, The water not consumed in the hydration reaction will remain in the microstructure pore space. Figure 5: Schematic drawings to demonstrate the relationship between the water/cement ratio and porosity. The empty space (porosity) is determined by the water to cement ratio. The relationship between the water to cement ratio and strength is shown in the graph that follows. Figure 6: A plot of concrete strength as a function of the water to cement ratio. Low water to cement ratio leads to high strength but low workability. High water to cement ratio leads to low strength, but good workability. The physical characteristics of aggregates are shape, texture, and size.

  • These can indirectly affect strength because they affect the workability of the concrete.
  • If the aggregate makes the concrete unworkable, the contractor is likely to add more water which will weaken the concrete by increasing the water to cement mass ratio.
  • Time is also an important factor in determining concrete strength.

Concrete hardens as time passes. Why? Remember the hydration reactions get slower and slower as the tricalcium silicate hydrate forms. It takes a great deal of time (even years!) for all of the bonds to form which determine concrete’s strength. It is common to use a 28-day test to determine the relative strength of concrete.

  1. Concrete’s strength may also be affected by the addition of admixtures.
  2. Admixtures are substances other than the key ingredients or reinforcements which are added during the mixing process.
  3. Some admixtures add fluidity to concrete while requiring less water to be used.
  4. An example of an admixture which affects strength is superplasticizer.

This makes concrete more workable or fluid without adding excess water. A list of some other admixtures and their functions is given below. Note that not all admixtures increase concrete strength. The selection and use of an admixture are based on the need of the concrete user.

TYPE FUNCTION
AIR ENTRAINING improves durability, workability, reduces bleeding, reduces freezing/thawing problems (e.g. special detergents)
SUPERPLASTICIZERS increase strength by decreasing water needed for workable concrete (e.g. special polymers)
RETARDING delays setting time, more long term strength, offsets adverse high temp. weather (e.g. sugar )
ACCELERATING speeds setting time, more early strength, offsets adverse low temp. weather (e.g. calcium chloride)
MINERAL ADMIXTURES improves workability, plasticity, strength (e.g. fly ash)
PIGMENT adds color (e.g. metal oxides)

Table 3: A table of admixtures and their functions. Durability is a very important concern in using concrete for a given application. Concrete provides good performance through the service life of the structure when concrete is mixed properly and care is taken in curing it.

  1. Good concrete can have an infinite life span under the right conditions.
  2. Water, although important for concrete hydration and hardening, can also play a role in decreased durability once the structure is built.
  3. This is because water can transport harmful chemicals to the interior of the concrete leading to various forms of deterioration.

Such deterioration ultimately adds costs due to maintenance and repair of the concrete structure. The contractor should be able to account for environmental factors and produce a durable concrete structure if these factors are considered when building concrete structures.

What are the minor compound in portland cement?

Minor constituents it’s the oxides less than 10% of cements weight which consists of magnesia (MgO), alkali oxides (Na2O and K2O), titania (TiO2), phosphorous pentoxide (P2O5) and gypsum.

Which one of the following compounds is responsible for quick setting of cement *?

Discussion :: Building Materials – Section 3 ( Q.No.2 ) –

PRITHVI said: (May 30, 2014)
Early gain of strength is caused due to tricalcium silicate and thus setting time too.

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Vikas said: (Feb 19, 2016) Tricalcium silicate responsible for early setting of cement.

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Sonu said: (Jul 29, 2016) Answer is wrong C3S (Tricalcium Silicate) is responsible for initial setting and Di Calcium silicate (c2s) contributes strength after 7 days.

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Sohan Jangra said: (Sep 29, 2016) Answer is right, When water is mixed with cement to form a paste, reaction starts. In its pure form, the finely ground cement is extremely sensitive to water. Out of the three main compounds, viz. C3A, C3S, and C2S, reacts quickly with water to produce a jelly-like compound which starts solidifying. The action of changing from a fluid state to a solid state is called ‘setting’ and should not be confused with ‘hardening’.

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Devaraj said: (Dec 31, 2016) Silica indicates strength aluminium indicates settings times.

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Laxman Prasad said: (Mar 8, 2017) How long time due to tri-calcium aluminate gains the initial setting by cement?

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Chandrima said: (Apr 22, 2017) I think it is Tri calcium silicate.

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Amitkumarsachin said: (Jul 1, 2017) C3S is responsible to early strength not early setting time, C3A is responsiblefor early setting time.

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Ramavtar said: (Dec 13, 2017) C3S is correct.

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Shekhar Kumar said: (Jan 27, 2018) Properties of cement compounds These compounds contribute to the properties of cement in different ways Tricalcium silicate, C3S:- This compound hydrates and hardens rapidly. It is largely responsible for portland cement’s initial set and early strength gain. Dicalcium silicate, C2S:- C2S hydrates and hardens slowly. It is largely responsible for strength gain after one week. Tricalcium aluminate, C3A:- It liberates a lot of heat during the early stages of hydration, but has little strength contribution. Gypsum slows down the hydration rate of C3A. Cement low in C3A is sulphate resistant. Tetracalcium alumino Ferrite, C4AF:- This is a fluxing agent which reduces the melting temperature of the raw materials in the kiln (from 1650o C to 1450o C). It hydrates rapidly but does not contribute much to the strength of the cement paste. By mixing these compounds appropriately, manufacturers can produce different types of cement to suit several construction environments.

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Rabindra said: (Apr 10, 2018) The Answer is right because it is asking the for the early setting time of cement which is due to tricalcium aluminate but for the early strength of cement, tricalcium silicate and ultimate strength or final strength is due to dicalcium silicate. So don’t be confused be clear.

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Basavaraj said: (Aug 21, 2018) C3S for initial setting. C3A for the flash setting. C2s for Ultimate strength.

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ABHISHEK YADGIRI MUDIRAJ said: (Sep 19, 2018) C3S and C2S for strength and C3A for the early setting of cement.

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Sunil Kumawat said: (Oct 31, 2018) C3A is responsible for both flash and initial setting time.

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Muttu said: (Apr 29, 2019) Option A is the correct answer.

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OPSC AEE said: (Oct 29, 2019) Give ans is right. Here asked about initial setting, not asked speeds the setting. Kindly read the que again.

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Aditya said: (Jan 30, 2020) The setting and hardenings of cement paste is mainly due to the hydration and hydrolysis.

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Dharanidharan said: (Feb 21, 2020) Answer C is correct. Be because. C3s strenth property. C3a time &hydration property.

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Nitesh said: (Mar 9, 2020) Hello guys, the answer is right, because C2S is responsible for early STRENGTH of cement in the INITIAL stage, in this question ask the initial setting time of cement.

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Joey said: (Jun 15, 2020) C3S – early strength. C2S – ultimate strength. C3A – the initial setting of cement. Heat of hydration C3A > C3S > C4AF > C2S.

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Sushant Kumar Sahu said: (Jul 29, 2020) When water is added in cement, first tricalcium aluminate is reacted with water and it is responsible for initial setting of cement.

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Priyanka said: (Apr 2, 2021) Early strength – C3S. Early setting – C3A.

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Black Lover said: (May 19, 2021) I think option A is correct.

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Him said: (Aug 7, 2021) I’m agree with you, Thanks @Joey.

Civil Engineering – Building Materials – Discussion

Which compound reacts faster with water?

Problems –

  1. Predict the products of the following reactions:
    1. \(Be_ +2H_ O_ \longrightarrow\)
    2. \(Ne_ +2H_ O_ \longrightarrow\)
    3. \(Cl_ +2H_ O_ \longrightarrow\)
    4. \(Li_2O_ +2H_ O_ \longrightarrow\)
  2. True/False
    1. Metal oxides form basic solutions in water
    2. Difluorine does not react with water.
    3. Beryllium has a large atomic radius.
    4. Sodium is the alkali element that reacts most violently with water.
  3. Why are do we called Group 1 and 2 metals “alkali” and “alkaline”?
  4. How is aluminum affected by water?
  5. Will the following reaction create an acidic or basic solution?

\(NaH +2H_ O_ \longrightarrow\)

Which compound reacts fastest water?

Alkali metals – 2:18 Reaction of sodium (Na) and water Reaction of potassium (K) in water The alkali metals (Li, Na, K, Rb, Cs, and Fr) are the most reactive metals in the periodic table – they all react vigorously or even explosively with cold water, resulting in the displacement of hydrogen.

What is Bogue compounds in cement?

Answer (Detailed Solution Below) – Option 1 : C 3 S, C 2 S, C 3 A and C 4 AF Free 10 Questions 30 Marks 10 Mins Concept There are four compounds (Called Bogue’s Compounds) formed as a result of hydration of cement: Alite : C 3 S, or Tricalcium Silicate Belite : C 2 S, or Dicalcium Silicate Aluminate phase : C 3 A, or Tricalcium Aluminate Ferrite phase : C 4 AF, or Tetracalcium Aluminoferrite Bogue Compounds a) Dicalcium Silicate (C 2 S) : This compound will undergo a reaction slowly.

It is responsible for the progressive strength of concrete. This is also called as Belite. A higher percentage of C 2 S results in slow hardening, less heat of hydration, and great resistance to chemical attack. b) Tricalcium silicate (C 3 S) : This is also called as Alite. It undergoes hydration within one week and helps in the development of strength in the early stages of concrete (aka hardening).

It has the best cementitious property among all the other Bogue’s Compounds. Tricalcium Silicate (C 3 S) hardens rapidly and is largely responsible for the initial set and early strength. The cement that has more C ­­­­3 S content is good for cold weather concreting.

C) Tricalcium aluminate (C 3 A): Celite is the quickest one to react when water is added to the cement. It is responsible for the flash setting. The increase of this content will help in the manufacture of Quick Setting Cement. It provides weak resistance against sulphate attack and contribution to the development of strength is significantly less than the above two bogue compounds.

d) Tetra calcium Alumino ferrite (C 4 AF): This is called Felite. It has the poorest cementing value but it responsible for the long-term gain of strength of the cement. Last updated on Sep 22, 2022 UPPSC AE Final Result Out on 1st December 2022. The candidates appeared for the interview from 17th October to 15th November 2022.

What is a chemical reaction with water called?

Hydrolysis, in chemistry and physiology, a double decomposition reaction with water as one of the reactants.

Which decomposition reaction is used in cement industry?

The decomposition reaction of silver bromide into silver and bromine by light is used in the manufacturing of cement. No worries! We‘ve got your back. Try BYJU‘S free classes today! Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses Open in App Suggest Corrections 0 : The decomposition reaction of silver bromide into silver and bromine by light is used in the manufacturing of cement.

Which of the following is the main reaction in the setting of cement?

Setting of cement is:(A) exothermic reaction (B) endothermic reaction(C) neither endothermic nor exothermic (D) none of these. Answer Verified Hint: Setting is called as the action of changing from a fluid state to a solid state. During setting when water reacts with cement it liberates heat.

Complete step by step answer: So, the correct answer is Option A. Note: Wet cement is strongly corrosive and can cause severe skin burns and even if they come in contact with mucous membranes it can cause severe eye or respiratory irritation.

Cement is known to a binder that is used in construction sites.Depending upon the ability of the cement to set in the presence of water, cement is divided into:(1). Non-hydraulic cement(2). Hydraulic cementNon – hydraulic cement is that which does not set in wet conditions or under water.

It sets as it dries and reacts with carbon dioxide in the air. It does not get attacked by the chemicals after setting. Hydraulic cement is that which sets and becomes adhesive due to a reaction with dry ingredients and water. Hydraulic cements consist of a mixture of silicates and oxides. The process of formation of cement includes the calcination process of limestone that is calcium carbonate.

The reaction of burning of limestone is:$ } }_ }} \to } }_ }}$From this reaction carbon is removed from limestone and the formation of lime occurs. Then, after this lime reacts with silicon dioxide to produce dicalcium silicate and tricalcium silicate.

The reaction can be written as:$ } }_ }} \to } } }_ }} \\ } }_ }} \to } } }_ }} \\ $Then, lime reacts with aluminium oxide to form tricalcium aluminate.$ } }_ }} }_ }} \to } } }_ }} }_ }}$At last, calcium oxide, aluminium oxide and ferric oxide react together to form cement.$ } }_ }} }_ }} } }_ }} }_ }} \to } } }_ }} }_ }} } }_ }} }_ }}$When cement is mixed with water it starts to set and causes hydration chemical reactions.

The hydration of the constituents occurs slowly and the material solidly and hardens.$CaO.A + 6 O \to 3CaO.A,6 O + \operatorname $ During setting and hardening of cement, some amount of heat is liberated due to hydration and the chemical reactions that occur.As the release of heat takes place.

How does water and cement react together?

Concrete Summary Concrete is everywhere. Take a moment and think about all the concrete encounters you have had in the last 24 hours. All of these concrete structures are created from a mixture of cement and water with added aggregate. It is important to distinguish between cement and concrete as they are not the same.

Cement is used to make concrete! (cement + water) + aggregate = concrete Cement is made by combining a mixture of limestone and clay in a kiln at 1450] C. The product is an intimate mixture of compounds collectively called clinker. This clinker is finely ground into the powder form. The raw materials used to make cement are compounds containing some of the earth’s most abundant elements, such as calcium, silicon, aluminum, oxygen, and iron.

Water is a key reactant in cement hydration. The incorporation of water into a substance is known as hydration. Water and cement initially form a cement paste that begins to react and harden (set). This paste binds the aggregate particles through the chemical process of hydration.

  1. In the hydration of cement, chemical changes occur slowly, eventually creating new crystalline products, heat evolution, and other measurable signs.
  2. Cement + water = hardened cement paste The properties of this hardened cement paste, called binder, control the properties of the concrete.
  3. It is the inclusion of water (hydration) into the product that causes concrete to set, stiffen, and become hard.

Once set, concrete continues to harden (cure) and become stronger for a long period of time, often up to several years. The strength of the concrete is related to the water to cement mass ratio and the curing conditions. A high water to cement mass ratio yields a low strength concrete.

  1. This is due to the increase in porosity (space between particles) that is created with the hydration process.
  2. Most concrete is made with a water to cement mass ratio ranging from 0.35 to 0.6.
  3. Aggregate is the solid particles that are bound together by the cement paste to create the synthetic rock known as concrete.

Aggregates can be fine, such as sand, or coarse, such as gravel. The relative amounts of each type and the sizes of each type of aggregate determines the physical properties of the concrete. sand + cement paste = mortar mortar + gravel = concrete Sometimes other materials are incorporated into the batch of concrete to create specific characteristics.

These additives are called admixtures. Admixtures are used to: alter the fluidity (plasticity) of the cement paste; increase ( accelerate ) or decrease (retard) the setting time; increase strength (both bending and compression ); or to extend the life of a structure. The making of concrete is a very complex process involving both chemical and physical changes.

It is a material of great importance in our lives.

Which compound starts hydration and responsibility for early setting of cement?

Free Gujarat Engineering Service 2019 Official Paper (Civil Part 1) 150 Questions 150 Marks 90 Mins Explanation: The initial setting of Portland cement is due to tricalcium aluminate. Tricalcium aluminate (C 3 A):

This is also called Celite. It is the quickest one to react when the water is added to the cement. It is responsible for the flash setting.

​ ​ Tricalcium silicate (C 3 S):

This is also called Alite, Tricalcium silicate hydrates quickly and contributes more to the early strength

​ Tricalcium silicate (C 2 S):

This is also called as Belite, The contribution of dicalcium silicate takes place a fter 7 days and may continue for up to 1 year.

​ Tetra calcium Alumino ferrite (C 4 AF):

This is called as Felite, Tetracalcium alumino-ferrite is comparatively inactive. ​

The rate of hydration is highest for C 4 AF and heat of hydration is highest for C 3 A. From the above, the decreasing order of rate of hydration of Portland cement compounds is C 4 AF > C 3 A > C 3 S > C 2 S. For the heat of hydration, decreasing order of heat of hydration of portland cement is C 3 A > C 3 S > C 4 AF > C 2 S Latest GPSC Engineering Services Updates Last updated on Oct 1, 2022 The Gujarat Public Service Commission (GPSC) has released a new notification for the GPSC Engineering Services Recruitment 2022. The commission has released 28 vacancies for the recruitment process. Candidates can apply for the applications from 15th October 2022 to 1st November 2022 and their selection will be based on Prelims, Mains and Interview. Candidates with a Graduation degree as the basic GPSC Engineering Services Eligibility Criteria are eligible to appear for the recruitment process. The finally selected candidates will get a salary range between Rs.53100 to Rs.208700.

What happens when cement touches water?

Cement contains calcium oxide, which isn’t dangerous but when water is added it becomes calcium hydroxide, which is highly alkaline and caustic. Contact with wet cement results in cement poisoning.