Which Compound Liberates Higher Heat Of Hydration In Cement Hydration?

Which Compound Liberates Higher Heat Of Hydration In Cement Hydration
Concept: The four major compounds which are constituents of cement are: a) Tricalcium silicate (C 3 S): 3CaO.SiO 2 b) Dicalcium silicate (C 2 S): 2CaO.SiO 2 c) Tricalcium Aluminate (C 3 A): 3CaO.Al 2 O 3 d) Tetra-calcium Alumino Ferrite (C 4 AF): 4CaO.Al 2,Fe 2 O 3 These compounds are also known as Bogue Compounds,

C 3 S readily reacts with water, produces more heat of hydration and is responsible for the early strength of concrete. C 2 S hydrates more slowly and produce less heat of hydration and are responsible for later strength of concrete.

1. Tricalcium Silicate C 3 S – (25 – 50%) – Normally 40%

It is considered as the best cementing material and is well-burnt cement. It hydrates rapidly generating high heat and develops an early hardness and strength. Raising of C 3 S content beyond the specified limits increases heat of hydration and solubility of cement in water. The heat of hydration is 500 J/g,

2. Dicalcium Silicate (C 2 S) – (25 – 40%) – (Normally 32%)

It hydrates and hardens slowly and takes a long time to add to the strength (after a year or more) i.e. it is responsible for ultimate strength, It imparts resistance to chemical attack. Raising of C 2 S content renders clinkers harder to grind, reduces early strength, decreases resistance to freezing and thawing at an early age and decreases heat of hydration. At an early age, less than a month, C 2 S has little influence on strength and hardness. While after one year, its contribution to the strength and hardness is proportionately almost equal to C 3 S. The heat of hydration is 260 J/g.

3. Tricalcium Aluminate (C 3 A) – (5 – 11%) -(Normally 10.5%).

It rapidly reacts with water and is responsible for the flash set of finely grounded clinkers. The rapidity of action is regulated by the addition of 2-3% of gypsum at the time of grinding the cement. It is most responsible for the initial setting, the high heat of hydration and has a greater tendency to volume changes causing cracking. Raising the C 3 A content reduces the setting time, weakens resistance to sulphate attack and lowers the ultimate strength, heat of hydration and contraction during air hardening. The heat of hydration of 865 J/g.

4. Tetracalcium Alumino Ferrite – (C 4 AF 8 – 14%) (Normally 9%)

It is responsible for the flash set but generates less heat. It has the poorest cementing value. Raising C 4 AF content reduces the strength slightly. The heat of hydration 420 J/g,

The rate of heat evolution of the principal compound if equal amount of each is considered will be in following descending order: C 3 A (865 J/g) > C 3 S (500 J/g) > C 4 AF (420 J/g) > C 2 S (260 J/g), Thus by increasing the C 2 S content the heat of hydration decreases, Note: The development of strength of the four principal compounds of cement with age: The rate of hydration is increased by an increase in the fineness of the cement. However total heat evolved is the same. The rate of hydration of the principal compounds is shown in the figure and will be in the following descending order: C 4 AF > C 3 A > C 3 S > C 2 S Important Points Hydration products of C 2 S are considered better than that of C 3 S. It is because of the lesser time formation of lime when C 2 S hydrates than those in hydration of C 3 S.2C 3 S + 6H → C 3 S 2 H 3 + 3 Ca(OH) 2 2C 2 S + 4H → C 3 S 2 H 3 + Ca(OH) 2 Last updated on Sep 22, 2022 The Chhattisgarh Public Service Commission (CGPSC) has activated the link to submit any objection against the CGPSC AE (Assistant Engineers) Provisional Answer Key.

Which compound produces highest heat of hydration in cement?

Discussion :: Concrete Technology – Section 3 ( Q.No.) –

123 said: (Jan 18, 2015)
C3A generates 320cal/g heat of hydration which is highest. Also it reacts fast with water.

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Azhar Bodla said: (Feb 20, 2015) Tricalcium Aluminate (C3A). Hydrates and hardens the quickest. It liberates a large amount of heat almost immediately and contributes somewhat to early strength. Option C is correct.

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Premjeet said: (Apr 24, 2015) Option A should be correct. Option C will be correct for c3s.

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Krishna said: (Feb 28, 2016) Answer is wrong. C3A generates high heat of hydration and setting will be fast if it is more. Gypsum used to control the setting time.

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GIRISH KUMAR SHARMA said: (May 30, 2016) A) Reacts fast with water should be the correct answer.

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DARSHAN H A said: (Jul 4, 2016) Here the correct option is A, it produces a large amount of heat. Among all options, A is best.

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Dilip said: (Jul 14, 2016) Tricalcium aluminate generate less heat of hydration. It react fast with water.

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Ayon Som said: (Aug 9, 2016) Option A is the best & possible answer.

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Adi said: (Aug 12, 2016) The question should be which one of the following is incorrect.

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PRASENJIT MANDAL said: (Aug 13, 2016) Option A must be the answer.

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Aryan’ankur said: (Oct 9, 2016) option B is correct because In this question want to know the incorrect sentence for C3A. BECAUSE we know that, C3A is react fast with water so high heat or generated we also know that C3A is causes initial setting time and C3A doesn’t gv ultimate strength because ultimate strength given by C2s so in this question incorrect sentence is B.

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Swapnil said: (Nov 9, 2016) Yes agree, you are right @Adi.

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Ataullah said: (Nov 16, 2016) I agree with the option A.

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Anshul Thakur said: (Dec 11, 2016) I think the Question should be like “Pick up the incorrect statement from the following” Except from b all options are right about c3a.

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Krishna said: (Dec 19, 2016) I also think the correct answer is A.

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AMIT KUMAR said: (Jan 10, 2017) The correct option is,

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Rahul said: (Feb 8, 2017) I think option D should be discussed because C3A & C4AF are responsible only for the flash set not governs any strength. Although it reacts fast with water is also correct.

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DEVARAJ said: (Mar 18, 2017) Why not option A? Actually, it is the first compound which reacts with water.

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Sanjay Bhargav said: (May 30, 2017) I agree with the Option A.

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Gujjar 22 said: (May 31, 2017) Option A is wrong because c3a react fast and high heat of hydration.

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Mukesh Kumar Saini said: (Jun 15, 2017) I also agree, it is A.
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Rajak said: (Sep 17, 2017) Answer A is correct. You may find everywhere C3A does not contribute in initial setting time and early strength of cement. C2S is responsible for ultimate strength, not C3A. And C3A generate more heat.

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Chandan said: (Aug 16, 2021) C3A – 865J/CAL. C3S – 500J/CAL. C4AF – 420J/CAL. C2S – 260J/CAL.

Civil Engineering – Concrete Technology – Discussion

Which constituent contribute high in heat of hydration?

Heat of hydration is most influenced by the proportion of C 3 S and C 3 A in the cement, but is also influenced by water-cement ratio, fineness and curing temperature. As each one of these factors is increased, heat of hydration increases.

Which cement compound liberates lot of heat during early stage?

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

What are the compounds that contribute much to the hydration of cement?

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.

In addition to these major compounds, several other play important roles in the hydration process. Different types of cement contain the same four major compounds, but in different proportions. The cement in concrete needs water to hydrate and harden. 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.

  1. Tricalcium silicates are responsible for most of the early strength (first seven days).
  2. The original dicalcium silicate hydrates, which form more slowly, contribute to the strength of concrete at later stages.
  3. The following word equations describe the production of concrete.
  4. 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.
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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.

Which compound has highest hydration energy?

Hydration energy increases with an increase in the charge density. So Be2+ has the highest hydration enthalpy.

Which element has maximum hydration energy?

Among the following species, which has the maximum hydration energy? No worries! We‘ve got your back. Try BYJU‘S free classes today! No worries! We‘ve got your back. Try BYJU‘S free classes today! 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 1 : Among the following species, which has the maximum hydration energy?

Which compound is liberates higher heat?

This set of Concrete Technology Multiple Choice Questions & Answers (MCQs) focuses on “Hydration of Cement”.1. What is hydration of cement? a) Chemical reaction of cement with acid b) Chemical reaction of cement with water c) Chemical reaction of cement with base d) Chemical reaction of cement with salt, and acid View Answer Answer: b Explanation: As water comes into contact with cement particles, hydration reactions immediately starts at the surface of the particles.2.

As the hydration proceeds the deposits of hydrated products on the original cement grains makes the diffusion of water to unhydrated nucleus _ a) Easy b) Very difficult c) Very easy d) Average View Answer Answer: b Explanation: It is difficult thus the rate of hydration decreases with time & as result hydration may take several years.3.

The development of first 28 days strength is on account of the hydration of _ a) C 2 S b) C 3 S c) C 3 A d) C 4 AF View Answer Answer: b Explanation: Higher C 3 S→higher early strength-higher heat generation (roads, cold environments). Higher C S→lower early strength-lower heat generation (dams).4.

Which compound is liberates higher heat? a) C 2 S b) C 3 S c) C 3 A d) C 4 AF View Answer Answer: b Explanation: C3S having a faster rate of reaction accompanied by greater heat generation developes early strength of the paste.5. Which compound is liberates lower heat? a) C 2 S b) C 3 S c) C 3 A d) C 4 AF View Answer Answer: a Explanation: C 2 S hydrates & hardens slowly so results in less heat generation & developes most of the ultimate strength.6.

Which compound may lead to a rapid stiffening of the paste with a large amount of the heat generation? a) C 2 S b) C 3 S c) C 3 A d) C 4 AF View Answer Answer: c Explanation: C 3 A is characteristically fast reacting with water & may lead to a rapid stiffening of the paste with a large amount of the heat generation (Flash-Set)-(Quick-Set).7.

In order to prevent this rapid reaction _ is added to the clinker. a) C 4 AF b) Gypsum c) Water d) Extra cement View Answer Answer: b Explanation: In order to prevent this rapid reaction gypsum is added to the clinker. Gypsum, C3A&water react to form relatively insoluble Calcium-Sulfo-Aluminates. Sanfoundry Global Education & Learning Series – Concrete Technology.

To practice all areas of Concrete Technology, here is complete set of 1000+ Multiple Choice Questions and Answers, Next Steps:

Get Free Certificate of Merit in Concrete Technology Participate in Concrete Technology Certification Contest Become a Top Ranker in Concrete Technology Take Concrete Technology Tests Chapterwise Practice Tests: Chapter 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 Chapterwise Mock Tests: Chapter 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

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What does a higher heat of hydration mean?

Heat of hydration is the heat generated when water reacts in contact with the cement powder. The amount of heat released depends on the cement composition, curing temperature, water to cement ratio, and cement fineness. High temperature resulting from heat of hydration may cause thermal cracking of concrete and consequent reduction of mechanical properties.

Which grade of cement has high heat of hydration and why?

Consider the following statements: High Alumina Cement (HAC) 1. has high early compressive strength and high heat of hydration than OPC-43 grade 2. is not suitable to be used in cold regions Which of these statements is/are correct? Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses No worries! We‘ve got your back. Suggest Corrections 0 : Consider the following statements: High Alumina Cement (HAC) 1. has high early compressive strength and high heat of hydration than OPC-43 grade 2. is not suitable to be used in cold regions Which of these statements is/are correct?

What is the heat of hydration of cement?

Hydration of Cement | Heat of Hydration |Stages of Hydration of Cement The hydration of cement is an exothermic reaction that is carried out when cement comes in contact with water. The reaction will result in several by-products that will contribute to the strength of the concrete or mortar formed. Please enable JavaScript

Fig.1. Hydration Reaction – Changing Microstructure of Cement

The chemical reaction that takes place between the cement and water is referred to as hydration of the cement. The hydration reaction is an exothermic reaction.The cement hydration will liberate a considerable amount of heat. This is called as Heat of liberation or Heat of Hydration.

  1. The mixing of cement with water will result in rapid evolution of heat that will last for few minutes.
  2. This evolution of heat is probably due to the reaction of a solution of aluminates and the sulfates.
  3. This rapid heat and reaction are depressed by the addition of gypsum.
  4. The Early heat of hydration is due to the hydration of C3S.

The rate of development of heat is greatly influenced by the fineness of the cement. The normal cement generally produces 89-90J/g in 7 days and 100J/g in 28 days. The hydration process is not instantaneous. The reaction is faster in the early stages and will go decreasing with the time period.

Which Compound Liberates Higher Heat Of Hydration In Cement Hydration
Table.1: Bogues Compounds

Hydration is an exothermic process, that will liberate heat through chemical reactions. The process of hydration can be easily followed by monitoring the production of heat that accompanies the reaction. This is done by civic mortar from a batch of concrete and weighing it into a bottle which is placed into an insulated container.

A thermistor is then impeded into the fresh mortar. The output of the thermistor is recorded by the computer. The result is plotted as a curve of temperature v/s the time. The area under the major peak can be related to the early strength development. The five stages involved in the hydration of cement are explained with respect to the figure-2.

There are Five stages of cement hydration:

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Initial Hydrolysis Advertisements Induction Period or the Dormant Period Acceleration Deceleration Steady State

    Fig.2.The Heat of Hydration – Calorimetry curve.

    /ol> Stage 1- Initial Hydrolysis: The initial dissolution of cement will result in the sort release of heat shown by the first peak in the calorimetry curve. Stage 2 – Induction or Dormant Period: After the initial dissolution process, the hydration products are precipitated on the surface of each cement particle.

    The layer acts as a protective barrier and temporarily delays the dissolution of the particle. This slows down the reaction for a period of several hours. This is called as the Dormant Period. The existence of the dormant period allows the concrete to be transported to the construction site and placed and finished in the forms.

    Heat of Hydration of Cement || Hydration of Cement #2 ||

    Stage 3 – Hydration Acceleration: The end of the dormant period shows the beginning of the setting at which time the cement starts to react more rapidly with water. This will result in the formation of new hydration products. Stage 4- Hydration Deceleration: This period will undergo formation of hydration products but the rate of reaction and the dissolution is very controlled and slow.

    What chemicals are involved in hydration?

    In chemistry, a hydration reaction is a chemical reaction in which a substance combines with water. In organic chemistry, water is added to an unsaturated substrate, which is usually an alkene or an alkyne. This type of reaction is employed industrially to produce ethanol, isopropanol, and butan-2-ol.

    Which has more hydration energy nacl or KCL?

    Which is more soluble in water $NaCl$ or $KCl$? Answer Verified Hint: We must have to know that the solubility is the ability of a compound, it may be a liquid, solid or gaseous substance to dissolve in solvent and there is a formation of a solution.

      Complete answer: Note:

    Among these given compounds, sodium chloride is more soluble in water than potassium chloride. Because the solubility of a compound mainly depends upon the hydration energy and lattice energy. If the hydration energy of the compound is greater than lattice energy, the solubility is more.

    Here, the lattice energy of potassium chloride is greater than its hydration energy. Therefore, potassium chloride is insoluble in water. But for sodium chloride, the hydration energy of sodium chloride is greater than its lattice energy. Hence, it is highly soluble in water. And the size of sodium ions is smaller than potassium ions.

    Therefore, the sodium ion can easily create a hydration sphere around the ion than potassium ions. If the potassium chloride is dissolved in water, there is a formation of potassium and chloride ions. And when the sodium chloride is mixed with water, due to the covalent bonds, the salts will dissolve in water.We must know that the sodium chloride is more soluble than potassium chloride due to its small size and high hydration energy.

    Which one of the following is highly hydrated?

    Solution : ` Li^(o+)` due to highest positive charge density gets hydrated to maximum extent.

    Which has maximum hydration energy Li+ Na+ K+ Rb+?

    Correct option 1 Li+ > Na+ > K+ > Rb+ > Cs+ Explanation:Li⊕ having minimum radius so maximum hydration and maximum hydration radii.

    Which ion liberates the most hydration energy?

    varun 304 Points 5 years ago Hello, Be2+ is the right answer because see the below explanation below The hydration enthalpies of alkali metal ion decreases with increase in ionic sizes So, the order is Li+>Na+>K+>Rb+>Cs So hydration enthalpy for Li+ is more But Be2+ is also there right So ionic size for Li+>Be2+ so the size of Be2+ is less so hydration energy for Be2+ is more than Li+ AND WE HAVE ALSO OTHER METGOD TO SOLVE THIS PROBLEM ie small the size of ion the greater the hydration energy so BE2+ IS THE ANSWER please approve me if the answer is correct THANK YOU somi teez 105 Points 5 years ago hi, The extent of hydration of ion decreases with increase in ionic size, Li+>Na+>K+>Rb+>Cs and Be + is next to lithium, we know, atomic size decreases across a period so, the ionic size of Li+ > Be + hence, Be + has greatest hydration energy among all. if you go the answer approve it.

    What is the heat of hydration of cement?

    Hydration of Cement | Heat of Hydration |Stages of Hydration of Cement The hydration of cement is an exothermic reaction that is carried out when cement comes in contact with water. The reaction will result in several by-products that will contribute to the strength of the concrete or mortar formed. Please enable JavaScript

    Fig.1. Hydration Reaction – Changing Microstructure of Cement

    The chemical reaction that takes place between the cement and water is referred to as hydration of the cement. The hydration reaction is an exothermic reaction.The cement hydration will liberate a considerable amount of heat. This is called as Heat of liberation or Heat of Hydration.

    • The mixing of cement with water will result in rapid evolution of heat that will last for few minutes.
    • This evolution of heat is probably due to the reaction of a solution of aluminates and the sulfates.
    • This rapid heat and reaction are depressed by the addition of gypsum.
    • The Early heat of hydration is due to the hydration of C3S.

    The rate of development of heat is greatly influenced by the fineness of the cement. The normal cement generally produces 89-90J/g in 7 days and 100J/g in 28 days. The hydration process is not instantaneous. The reaction is faster in the early stages and will go decreasing with the time period.

    Which Compound Liberates Higher Heat Of Hydration In Cement Hydration
    Table.1: Bogues Compounds

    Hydration is an exothermic process, that will liberate heat through chemical reactions. The process of hydration can be easily followed by monitoring the production of heat that accompanies the reaction. This is done by civic mortar from a batch of concrete and weighing it into a bottle which is placed into an insulated container.

    • A thermistor is then impeded into the fresh mortar.
    • The output of the thermistor is recorded by the computer.
    • The result is plotted as a curve of temperature v/s the time.
    • The area under the major peak can be related to the early strength development.
    • The five stages involved in the hydration of cement are explained with respect to the figure-2.

    There are Five stages of cement hydration:

    Initial Hydrolysis Advertisements Induction Period or the Dormant Period Acceleration Deceleration Steady State

      Fig.2.The Heat of Hydration – Calorimetry curve.

      /ol> Stage 1- Initial Hydrolysis: The initial dissolution of cement will result in the sort release of heat shown by the first peak in the calorimetry curve. Stage 2 – Induction or Dormant Period: After the initial dissolution process, the hydration products are precipitated on the surface of each cement particle.

      • The layer acts as a protective barrier and temporarily delays the dissolution of the particle.
      • This slows down the reaction for a period of several hours.
      • This is called as the Dormant Period.
      • The existence of the dormant period allows the concrete to be transported to the construction site and placed and finished in the forms.

      Stage 3 – Hydration Acceleration: The end of the dormant period shows the beginning of the setting at which time the cement starts to react more rapidly with water. This will result in the formation of new hydration products. Stage 4- Hydration Deceleration: This period will undergo formation of hydration products but the rate of reaction and the dissolution is very controlled and slow.