Tricalcium aluminate Explanation: The initial setting of Portland cement is due to tricalcium aluminate. Tricalcium aluminate (C3A): This is also called Celite.

Which compound is responsible for initial strength of cement?

Ruchir said: (Jun 12, 2018)
Tricalcium Silicate (C3S) hardens rapidly and is largely responsible for initial set and early strength. In general, the early strength of Portland cement concrete is higher with increased percentages of C3S. Dicalcium Silicate (C2S) hardens slowly and contributes largely to strength increases at ages beyond 7 days.

Which component controls the initial setting time of cement?

2 The Setting Time – The setting time of cement includes the initial setting time and the final setting time. The initial time refers to the time that cement turns into paste by mixing with water and begins to lose its plasticity. And the time that cement completely loses its plasticity by mixing with water and begins to have a certain structural strength is known as the final setting time.

1. The national standards prescribe that the initial setting time of Portland cement should not be earlier than 45 min and the final setting time should not be later than 6.5 h.
2. All the products off-grade at the initial setting time are spoiled products and those unqualified at the final setting time are sub-quality products.

The setting time of cement is measured by time determinator. The sample is the standard cement paste of which the temperature is 20 °C ± 3 °C and humidity is more than 90%. Various mineral components of the cement clinker are different in the water consumption of their normal consistency.

1. The finer the cement is ground, the more water the normal consistency will need.
2. The normal consistency of Portland cement is within 24% ~ 30%.
3. The setting time of cement is very important in the construction projects.
4. The initial setting time should not be too fast in order to ensure that there is enough time to complete every process, such as casting, before the initial setting time; and the final setting time should not be too late in order to enable the cement to complete its setting and hardening as soon as possible after pouring and tamping to make the next process occur earlier.

Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9781845699550500049

What is the initial setting time of cement Mcq?

8. What is the initial setting time of cement? Explanation: As per IS code 4031-part 5, the initial setting time of cement is minimum of 30 minutes.

Which compound is used in setting of cement?

Gypsum plays an important role in controlling the rate of hardening of the cement. It is added to concrete and cement to slow down the drying time as cement dries quickly.

Who is responsible for setting and hardening of cement?

Free 10 Questions 30 Marks 10 Mins The setting and hardening of cement after addition of water is due to hydration of some of the constituent compounds of cement such as Tricalcium aluminate, Tricalcium silicate, Dicalcium silicate, and Tetra calcium aluminoferrite.

1. These compounds are known as Bogue’s Compounds.
2. Hydration of Bogues Compounds Tricalcium aluminate (C 3 A): Celite is the quickest one to react when the water is added to the cement.
3. It is responsible for the flash setting.
4. The increase of this content will help in the manufacture of Quick Setting Cement.

The heat of hydration is 865 J/Cal, Tricalcium silicate (C 3 S): This is also called as Alite, This is also responsible for the early strength of the concrete. The cement that has more C­­­­ 3 S content is good for cold weather concreting. The heat of hydration is 500 J/Cal,

Dicalcium Silicate (C 2 S): This compound will undergo reaction slowly. It is responsible for the progressive strength of concrete. This is also called as Belite, The heat of hydration is 260 J/Cal. Tetra calcium Alumino ferrite (C 4 AF): This is called as Felite, The heat of hydration is 420 J/Cal, It has the poorest cementing value but it responsible for 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. A total of 266 candidates have been finally selected out of the total vacancies advertised. Also note that this is for the 2021 cycle.

What causes initial strength in concrete?

1. Introduction – The compressive strength achieved in concrete is one of the most important and desirable properties of concrete. Many admixtures have been tried by experts to achieve the desired compressive strength. This paper aims at achieving compressive strength in concrete; however, the authors of the paper have tried to use a nutrition medium containing a bacterium named Sporosarcina pasteurii as an admixture in concrete.

1. The focus of the work has been to decrease the time taken by the cement to hydrate and achieve maximum strength at early ages.
2. Early strength gain in normal concrete is mainly associated to the water/cement ratio.
3. Mixes with low water cement ratio gain strength more rapidly than those with higher water cement ratio.

This is because the cement grains are closer to one another and a continuous system of gel is established more rapidly. There are actually many different types of accelerators present in the market but the common problems posed by the accelerators are low slump, low initial setting time, and thus reduced workability.

These adverse properties of accelerators refrain most of the experts from using the same in concrete. The use of blended cements presently has also been on rise in construction industry; blended cements with a defined amount of cement replaced with flyash are commonly being used. The addition of flyash to cement, however, has little disadvantage; that is, for flyash to hydrolyse and form into a strong component like cement it needs Ca(OH) 2,

The Ca(OH) 2 is a biproduct of cement hydration process; hence for the flyash to form the C-S-H gel it requires calcium hydroxide in adequate quantity and this can occur only if adequate cement hydrolisation takes place. If calcium carbonate is present in cement, the hydrolisation process takes place quickly and inturn provides Ca(OH) 2 in requisite quantity for flyash to hydrolyse and give the desired compressive strength.

1. Sporosarcina pasteurii formerly known as Bacillus pasteurii is a bacterium with the ability to precipitate calcium carbonate in the presence of any carbonate source.
2. This microorganism is well known for its resistive properties to resist the harsh conditions of sea water and very high temperatures whichare generally found in shallow waters and in Sahara desert.

This bacterium is used in the present work for checking the improvement in the compressive strength of concrete. Sporosarcina pasteurii secretes calcium carbonate. This calcium carbonate inturn acts as a positive catalyst for the cement hydration process as discussed by Ramachandran, Péra et el.

1. And Kakali et al.
2. It was found that the Sporosarcina pasteurii bacteria attain their maximum activity rate at 16 hours and maintain this till the time the nutrition medium is consumed.
3. Thus the secretion of maximum amount of calcium carbonate takes place only 16 hours after the concrete has been mixed, thus providing enough workable time for concrete.

Also it has been seen that this nutritional medium neither allows for the loss in slump nor causes immediate setting of the concrete. In the present work the bacterial admixture has been added in different compositions and concentrations along with other products like urea, sodium carbonate, calcium chloride, and so forth in differing proportions to study its impact on compressive strength at 3, 7, 14, and 28 days of curing.

The compressive strength obtained of bioconcrete that is with Sporosarcina pasteurii bacteria is compared with the strength gained by controlled concrete at 3, 7, 14, and 28 days, respectively. The work also tries to examine the use of sodium carbonate along with the nutrient medium in concrete and simulate the chemical reaction which is the major contribution of the authors to the research wherein earlier only urea had been tried by experts.

The below chemical reactions ( 1 ) and ( 2 ) depict the formation of calcium carbonate that acts like a catalyst for the formation of C-S-H gel which is required for the hydrolization of cement. Using urea, (Kashyap and Radhakrishna ). Using sodium carbonate, (experimental work).

What is the initial setting time of concrete?

Initial Setting Times for Concrete – In standard industrial cases, full strength concrete is recognized at 28 days. At seven days, you should have concrete that is cured to 70% full strength or greater. But to answer the question of, “How long does concrete take to set?” concrete setting time is generally 24 to 48 hours,

How initial setting time of cement is found?

Test Procedure : –

A cement paste is prepared by adding water 0.85P% by weight of cement. The time of mixing should not be less than 3 minutes and should not be more than 5 minutes. Now the paste is filled in the Vicat mould and the top is levelled off. The mould is now placed under the square needle with annular collar and is brought down touch the surface of the paste. Now the square needle with annular collar is suddenly released and allowed to make on impression on the cement paste by its own weight. The impression made by this square needle with annular collar is observed. The whole experiment is repeated with incremental time intervals until such a time when the square needle makes an impression on the paste while the annular collar fails to do so. The time elapsed between the moments when water is added to the cement to the time when the square needle makes an impression on the paste while the annular collar fails to do so is known as the Final Setting Time of the cement. The final setting time of cement should not be more than 600 minutes for Ordinary Portland Cement.

Also Read : Workability of Concrete & Factors Affecting It

How initial setting time of cement is determined?

Free Gujarat Engineering Service 2019 Official Paper (Civil Part 1) 150 Questions 150 Marks 90 Mins The setting time of cement is of two types: 1) Initial Setting Time: It is defined as the time elapsed between the moments when water is added to the cement, to the time when the cement paste starts losing its plasticity.2) Final Setting Time: It is defined as the time elapsed between the moments when water is added to the cement, to the time when the cement paste has completely lost its plasticity.

Apparatus	Test
Le Chatelier apparatus	Soundness
Briquette testing apparatus	Tensile strength
Vicat apparatus	Consistency, Initial and final setting time
Casagrande’s apparatus	Liquid limit determination

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The finally selected candidates will get a salary range between Rs.53100 to Rs.208700.

What is setting of cement and why the initial setting time test is important?

FAQs – What is initial setting time of cement? The initial setting time of concrete is the time when cement paste starts hardening after adding water. It is the time period between the addition of water to cement till the time at 1 mm square section needle fails to penetrate the cement paste, placed in the Vicat’s mold 5mm to 7mm from the bottom of the mold.

1. What is final setting time of cement? Final setting time is that time period between the time water is added to cement and the time at which 1 mm needle makes an impression on the paste in the mould but 5 mm attachment does not make any impression.
2. What is the need for determining initial and final setting time of cement? Initial setting time is the time when the paste starts losing its plasticity.

The test is important for transportation, placing and compaction of cement concrete. Initial setting time duration is also required to delay the process of hydration or hardening. Final setting time is the time when the paste completely loses its plasticity.It is the time taken for the cement paste or cement concrete to harden sufficiently and attain the shape of the mould in which it is cast.

What is initial and final setting time of PPC cement?

Difference Between OPC and PPC Cement Sheikh Anwarul Mahdi PPC cement full form is Portland Pozzolana Cement, OPC cement full form is Ordinary Portland Cement, Both PPC and OPC cement is used in construction. PPC cement is a variant of OPC cement. These two types of cement differ from each other in terms of component, strength, heat generation, the percentage of several components, durability, grades, cost, eco-friendly nature, application, setting time, curing period, etc.

	Sources	OPC Cement	PPC Cement
1	Definition/ Components	A mixture of limestone and other raw materials like argillaceous, calcareous, and gypsum is prepared and then grinded to prepare OPC (Ordinary Portland Cement).	PPC (Portland Pozzolana Cement) is prepared by adding Pozzolanic materials to OPC. So, the main components are OPC, gypsum, and pozzolanic materials (15~35%) which include calcined clay, volcanic ash, fly ash, or silica fumes.
2	Strength	Initial strength is higher than PPC.	PPC concrete has higher strength than OPC concrete over a longer period of time.
3	Heat of hydration	Generates more heat than PPC in hydration reaction which makes it less suitable for mass casting.	It has a slow hydration process and thus generates less heat than OPC.
4	Durability	OPC concrete is less durable in aggressive weather.	PPC concrete is more durable in aggressive weather.
5	Cost	Costlier than PPC.	Cheaper than OPC.
6	Environmental Impact	Emits CO 2 during the manufacturing process.	It constitutes industrial and natural waste which makes it eco-friendly.
7	Application/	It is suitable where fast construction is required but not suitable for mass concreting due to heat issues as mentioned above.	It is suitable for all types of construction work. For example RCC casting of buildings, mass concreting for bridges, and even plastering and other non-structural works.
8	Setting Time	Lower than PPC. Its initial setting time is 30 minutes and the final setting time is 280 minutes. Its faster setting time helps faster construction.	The setting time of PPC portland is higher than OPC. Its initial setting time is 30 minutes and the final setting time is 600 minutes. Its slower setting time helps to get better finishing.
9		OPC has finiteness of 225 sq.m/kg. It has lower fineness than PPC. So, it has higher permeability resulting in lower durability.	OPC has finiteness of 300 sq.m/kg. It has higher fineness than OPC. So, it has lower permeability resulting in higher durability.
10	Grades available	33 Grade, 43 Grade, and 53 Grade OPC cement are available.	No specified grade of PPC cement is available.
11		Lower than PPC.	Higher than OPC.
12	Resistance against chemical attack	It has lower resistance against alkalis, sulfates, chlorides, etc.	It has higher resistance against alkalis, sulfates, chlorides, etc.

Difference Between OPC and PPC Cement

What is the initial and final setting time of cement as per IS code?

4.6

Cement	Initial setting time	Final setting time
Ordinary Portland cement	30 minute	600 minute
Rapid hardening cement	30 minute	600 minute
High alumina cement	3.5 hour	5.5 hour
Low heat cement	1 hour	600 minute

Which compound of cement is responsible for strength of cement Mcq?

Silica is responsible for strength of cement, alumina imparts quick setting property, Calcium Sulphate delays setting of cement, Magnesium Oxide in large quantity-causes delayed expansion.

Who is responsible for setting and hardening of cement?

Free 10 Questions 30 Marks 10 Mins The setting and hardening of cement after addition of water is due to hydration of some of the constituent compounds of cement such as Tricalcium aluminate, Tricalcium silicate, Dicalcium silicate, and Tetra calcium aluminoferrite.

1. These compounds are known as Bogue’s Compounds.
2. Hydration of Bogues Compounds Tricalcium aluminate (C 3 A): Celite is the quickest one to react when the water is added to the cement.
3. It is responsible for the flash setting.
4. The increase of this content will help in the manufacture of Quick Setting Cement.

The heat of hydration is 865 J/Cal, Tricalcium silicate (C 3 S): This is also called as Alite, This is also responsible for the early strength of the concrete. The cement that has more C­­­­ 3 S content is good for cold weather concreting. The heat of hydration is 500 J/Cal,

1. Dicalcium Silicate (C 2 S): This compound will undergo reaction slowly.
2. It is responsible for the progressive strength of concrete.
3. This is also called as Belite,
4. The heat of hydration is 260 J/Cal.
5. Tetra calcium Alumino ferrite (C 4 AF): This is called as Felite,
6. The heat of hydration is 420 J/Cal,
7. It has the poorest cementing value but it responsible for 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. A total of 266 candidates have been finally selected out of the total vacancies advertised. Also note that this is for the 2021 cycle.

Which component is mostly responsible for initial set and early strength?

Composition of cement Composition of cement Introduction Portland cement gets its strength from chemical reactions between the cement and water. The process is known as, This is a complex process that is best understood by first understanding the chemical composition of cement. Manufacture of cement Portland cement is manufactured by crushing, milling and proportioning the following materials:

Lime or calcium oxide, CaO: from limestone, chalk, shells, shale or calcareous rock Silica, SiO 2 : from sand, old bottles, clay or argillaceous rock Alumina, Al 2 O 3 : from bauxite, recycled aluminum, clay Iron, Fe 2 O 3 : from from clay, iron ore, scrap iron and fly ash Gypsum, CaSO 4,2H 2 0: found together with limestone

The materials, without the gypsum, are proportioned to produce a mixture with the desired chemical composition and then ground and blended by one of two processes – dry process or wet process. The materials are then fed through a kiln at 2,600º F to produce grayish-black pellets known as clinker.

Chemical shorthand Because of the complex chemical nature of cement, a shorthand form is used to denote the chemical compounds. The shorthand for the basic compounds is:

Compound	Formula	Shorthand form
Calcium oxide (lime)	Ca0	C
Silicon dioxide (silica)	SiO 2	S
Aluminum oxide (alumina)	Al 2 O 3	A
Iron oxide	Fe 2 O 3	F
Water	H 2 O	H
Sulfate	SO 3	S

Chemical composition of clinker The cement clinker formed has the following typical composition:

Compound	Formula	Shorthand form	% by weight 1
Tricalcium aluminate	Ca 3 Al 2 O 6	C 3 A	10
Tetracalcium aluminoferrite	Ca 4 Al 2 Fe 2 O 10	C 4 AF	8
Belite or dicalcium silicate	Ca 2 SiO 5	C 2 S	20
Alite or tricalcium silicate	Ca 3 SiO 4	C 3 S	55
Sodium oxide	Na 2 O	N	) )Up to 2
Potassium oxide	K 2 O	K
Gypsum	CaSO 4,2H 2 O	C S H 2	5

Representative weights only. Actual weight varies with type of cement. Source: Mindess & Young Properties of cement compounds These compounds contribute to the properties of cement in different ways Tricalcium aluminate, C 3 A:- It liberates a lot of heat during the early stages of hydration, but has little strength contribution.

Gypsum slows down the hydration rate of C 3 A. Cement low in C 3 A is sulfate resistant. Tricalcium silicate, C 3 S:- This compound hydrates and hardens rapidly. It is largely responsible for portland cement’s initial set and early strength gain. Dicalcium silicate, C 2 S: C 2 S hydrates and hardens slowly.

It is largely responsible for strength gain after one week. Ferrite, C 4 AF: This is a fluxing agent which reduces the melting temperature of the raw materials in the kiln (from 3,000 o F to 2,600 o F). It hydrates rapidly, but does not contribute much to strength of the cement paste.

1. By mixing these compounds appropriately, manufacturers can produce different types of cement to suit several construction environments.
2. References: Sidney Mindess & J.
3. Francis Young (1981): Concrete, Prentice-Hall, Inc., Englewood Cliffs, NJ, pp.671.
4. Steve Kosmatka & William Panarese (1988): Design and Control of Concrete Mixes, Portland Cement Association, Skokie, Ill.

pp.205. Michael Mamlouk & John Zaniewski (1999): Materials for Civil and Construction Engineers, Addison Wesley Longman, Inc., : Composition of cement

How initial setting time of cement is determined?

Free Gujarat Engineering Service 2019 Official Paper (Civil Part 1) 150 Questions 150 Marks 90 Mins The setting time of cement is of two types: 1) Initial Setting Time: It is defined as the time elapsed between the moments when water is added to the cement, to the time when the cement paste starts losing its plasticity.2) Final Setting Time: It is defined as the time elapsed between the moments when water is added to the cement, to the time when the cement paste has completely lost its plasticity.

Apparatus	Test
Le Chatelier apparatus	Soundness
Briquette testing apparatus	Tensile strength
Vicat apparatus	Consistency, Initial and final setting time
Casagrande’s apparatus	Liquid limit determination

The setting time of cement is determined using the Vicat apparatus. 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.