Category Archives: CEMENT

Building materials, CEMENT

Types of Cement for Concrete – Top 15 Cement Types

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Types of Cement used in construction are categorised according to their properties, applications, and advantages. Concrete construction involves the use of different varieties of cement, each possessing unique characteristics, benefits, and applications that depend on the materials utilized in their production. This categorization is based on the composition of the materials used in production.

Cement is an integral part of all types of construction ranging from huge skyscrapers, bridges, tunnels, etc to small residential buildings. It is one of the oldest and most used binding materials and an integral ingredient used in the construction sector. There are different types of cement available in the market. Each type of cement has its application depending on its properties. This article is about the cement types mostly used in construction.

15 Types of Cement and Their Uses

Let us have a look at the top 15 cement types widely used in India and other nations. They are,

  • Ordinary Portland cement  
  • Portland pozzolona cement 
  • Portland Slag cement
  • Rapid hardening cement 
  • Hydrophobic Portland cement
  • Low-heat Portland cement 
  • Sulphates resisting Portland cement 
  • Quick setting Cement
  • High alumina cement
  • Masonry cement
  • White cement
  • Coloured cement
  • Expansive cement
  • Air-entraining Portland cement
  •  Hydrographic cement

Ordinary Portland cement (OPC ) – Types of Cement  

OPC stands for Ordinary Portland Cement, which is one of the most commonly used types of cement in construction. It is made from a mixture of limestone, clay, and other materials, heated at high temperatures to produce a fine powder. Mostly, gypsum, calcareous material, and argillaceous substance make up Ordinary Portland Cement. OPC cement has excellent binding properties and provides high compressive strength to the concrete.

Ordinary Portland Cement is versatile and suitable for a wide range of construction applications, including buildings, bridges, and pavements. Ordinary Portland Cement is available in different grades, each with unique characteristics, making it easy to choose the most appropriate type for a specific construction project. Additionally, it has a relatively fast setting time, allowing for faster completion of construction projects. Ordinary Portland cement is more economical and forms a crucial component of high-strength concrete. This kind of cement is well-resistant to deterioration from chemicals, shrinkage, and fractures.

Ordinary Portland Cement
Ordinary Portland Cement

Also read : Best cement of India

Portland pozzolana cement – Types of cement in India

Portland Pozzolana Cement (PPC) is a type of cement made by combining Portland cement clinker with pozzolanic materials like fly ash, volcanic ash, or silica fumes. contains 15% to 35% pozzolanic ingredients, gypsum, and clinker. The pozzolanic materials improve the workability and durability of concrete and reduce the risk of cracking. PPC is preferred in locations with high moisture content, as it is highly resistant to dampness and corrosion. It is also eco-friendly since it uses industrial waste as a raw material. PPC cement is suitable for a wide range of construction applications, including dams, bridges, and buildings.

PPC has an initial setup time of 30 minutes and an ultimate setting time of 600 minutes. It is appropriate for hydraulic and marine structures. sewage works, and underwater concrete laying, such as bridges, piers, dams, and mass concrete works. because PPC has strong resistance to sulphate attack. PPC has a slower setting time than OPC, which may prolong construction time. Its initial strength is also lower than OPC.

Portland Slag Cement (PSC) -Types of cement for concrete

Portland Slag Cement (PSC) is a type of cement made by blending granulated blast furnace slag (GGBFS) with Portland cement clinker. The slag is a waste product from steel manufacturing, making PSC an eco-friendly alternative to traditional cement. PSC has excellent workability, durability, and low heat of hydration. It is widely used in construction applications such as dams, bridges, and underground structures. PSC provides high strength and durability, making it a popular choice for high-performance concrete. It is also known for its resistance to chloride and sulphate attacks. It has good compressive strength.

Rapid hardening cement – Types of cement in India

Rapid Hardening Cement (RHC) is a type of cement that attains high strength in a short time. It is made by grinding Portland cement clinker with a higher amount of C3S and a lower amount of C2S. RHC is suitable for emergency repair works and precast concrete components. Its rapid setting and strength gain properties make it ideal for use in cold weather conditions. It has high resistance to chemical attacks. RHC needs less curing time. The strength of rapid hardening cement at the three days is similar to the 7 days strength of OPC with the same water-cement ratio. So it is suitable for formworks, pavements etc. It has more application than OPC because of its early hardening property. Rapid-hardening cement is expensive. 

Hydrophobic Portland cement

Hydrophobic Portland Cement (HPC) is a type of cement that repels water due to its chemical composition. It is made by adding water-repellent chemicals to the cement during the grinding process. HPC is suitable for construction projects in areas with high rainfall or moisture content. It is commonly used in the construction of basements, swimming pools, and water storage tanks. HPC also has increased durability and can resist chemical attacks. It consists of admixtures such as acid naphthene soap, oxidized petrolatum, etc., reducing the melting of cement grains. The strength of hydrophobic cement is similar to OPC after 28 days. This type of cement is expensive. 

Low-heat Portland cement 

Low-heat Portland cement is a type of cement that produces less heat during hydration, which reduces the risk of cracking and improves durability. It is typically used in large concrete structures such as dams, bridges, and high-rise buildings, as well as in mass concrete applications. Because the heat of hydration of this type of cement is 20% less than normal cement. It consists of 5% of tricalcium aluminate and 46% of dicalcium silicate. Therefore it produces low heat of hydration. It has excellent wear, impact resistance and workability. 

Sulphate-resisting Portland cement 

Sulphate-resisting Portland cement (SRPC) is a type of cement designed to resist the effects of sulphates, which can cause concrete to deteriorate. It contains lower levels of tricalcium aluminate, which is the component most susceptible to sulphate attack. SRPC is commonly used in construction projects involving soil with high sulphate content or exposure to seawater.

Quick setting Cement

Quick-setting cement is a type of cement that hardens and gains strength rapidly after mixing with water, usually within 5 to 30 minutes. It is used in situations where the rapid setting is necessary, such as in cold weather or for emergency repairs. However, quick-setting cement may not be suitable for projects requiring longer workability or for structures that need to withstand heavy loads over time. It is a special type of cement manufactured by adding aluminium sulphate and reducing the amount of gypsum. It is applicable for underwater concreting and grouting. The setting time of this cement is less because aluminium sulphate is an accelerating admixture. It is also preferable for concrete repair works, tunnelling etc.

High alumina cement

High alumina cement (HAC) is a type of cement that is made from bauxite and limestone with a high percentage of alumina content, typically over 35%. It sets and hardens rapidly, has high early strength, and can withstand high temperatures and acidic environments. It is commonly used in refractory applications such as furnace linings, precast shapes, and high-temperature concretes. However, HAC is not recommended for structural applications due to its high shrinkage and susceptibility to chemical attacks over time. High alumina concrete attains strength within 24 hours. It can withstand high temperatures and fire. It is applicable in refractory concrete. Rapid hardening cement with an initial and final setting time of about 3.5 and 5 hours, respectively.

Masonry cement

Masonry cement is a type of cement that is specifically designed for use in masonry construction, such as bricklaying and plastering. It is a blend of Portland cement, hydrated lime, and sometimes additional additives such as sand, clay, or other minerals. The addition of hydrated lime improves the workability and durability of the cement, and it also enhances the bond strength between the cement and the masonry units. Masonry cement is commonly used in both exterior and interior masonry applications, such as building walls, chimneys, and decorative stonework. Since it has low strength it is not suitable for structural applications. The cost of masonry cement is less. Also, they have high water retentivity and workability. 

White cement

White cement is a type of cement that is similar to Portland cement, but with a white or light-coloured appearance. It is made from raw materials with low iron content, such as limestone, kaolin, and clay, and is often used for decorative or architectural purposes, such as in terrazzo flooring, precast panels, and ornamental concrete. White cement is also used in applications where colour consistency is important, such as in coloured concrete or mortars, as it can be tinted to various shades. It has similar properties to grey cement in terms of setting time, strength development, and durability. White cement is manufactured by using limestone, clay, oil and gypsum. But they are expensive compared to normal cement. 

Coloured cement

Coloured cement is a type of cement that is produced by adding pigments to the raw materials during the manufacturing process. It is available in a wide range of colours, and the pigments used can be natural or synthetic. Coloured cement is used in decorative concrete applications where aesthetics are important, such as stamped concrete, exposed aggregate, and decorative overlays. It can also be used in architectural concrete, including precast panels, masonry units, and concrete countertops. The colour of the cement can be affected by the curing process, and it is important to use a consistent curing method to ensure the desired colour is achieved. Coloured cement consists of colour pigments like chromium, cobalt, ton oxide, manganese oxide etc which gives them colour. It is preferable for floor finishing, window sills stair treads, and other external surfaces. The number of colouring pigments should about be 5 to 10 per cent. 

Coloured cement
Coloured cement

Expansive cement

Expansive cement is a type of cement that expands during the early stages of hydration. It contains a mixture of Portland cement clinker, gypsum, and an expansive agent, such as calcium sulphate or anhydrite. Expansive cement can expand up to 3% of its original volume, and this expansion can help offset the shrinkage that occurs as the concrete dries and hardens, reducing the risk of cracking. It is commonly used in applications where shrinkage cracking is a concern, such as in large concrete structures, pavements, and bridge decks. However, the expansion can also cause problems if it is not properly controlled, and it is important to follow the manufacturer’s guidelines for use.

  • K-type expansive cement
  • M-type expansive cement
  • S-type expansive cement

The use of expansive cement is in water retaining structures, concrete repairing, large floor slabs, etc. 

Air-entraining Portland cement

Air-entraining Portland cement is a type of cement that contains an air-entraining agent, such as resins, surfactants, or fatty acids, that creates microscopic air bubbles in the concrete. These air bubbles improve the durability of the concrete by reducing the effects of freeze-thaw cycles, as the water trapped in the bubbles can expand and contract without damaging the concrete. Air-entraining Portland cement is commonly used in cold climates or areas with high humidity, where freeze-thaw cycles can cause damage to concrete structures. However, the use of air-entraining agents can also reduce the compressive strength of the concrete, so it is important to properly balance the amount of air entrainment with the desired strength and workability of the concrete. Air-entraining agents like aluminium powder and hydrogen peroxide are added to the cement. 

Hydrographic cement

Hydrographic cement, also known as underwater cement, is a type of cement that can harden and set even when submerged in water. It is specifically designed for use in underwater construction projects, such as building foundations, bridges, and pipelines. Hydrographic cement contains special additives that allow it to set and harden underwater without being affected by the water, and it can also be mixed with accelerators to speed up the setting time. The cement is typically mixed and applied using specialized equipment, such as pumps or tremies, to ensure proper placement and consolidation.

Building materials, CEMENT

Test of cement on site – Field tests of Cement

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Test of cement on site or field tests of cement is one of the most crucial things to be performed to assure the quality of the construction. Every structure is made up of hundreds of different building materials, such as sand, cement, aggregates, bricks, tiles, marble, and so on. However, the quality of the building materials is crucial for producing a high-quality structure and should be regularly evaluated at various phases of construction. Cement is the most important material used in construction and is responsible for the overall strength of the structure. In order to guarantee excellence in building, cement quality must be properly.

This article is about the various test of cement on-site or field tests of cement to ensure quality.

  1. Test of cement on site – Significance
  2. How to check cement quality?
  3. Test of cement on site / Field tests of cement
    1. Checking the manufacturing date of cement
    2. Visual checking for Lumps for the test of cement on site.
    3. Feel test of cement on site
    4. Heat of cement
    5. Colour
    6. Water float test
    7. Setting test
    8. Conclusion

Test of cement on site – Significance

Cement plants are generally found in isolated areas near limestone mines. Generally, clinker is produced by cement companies at a centralised clinkerization plant. Clinkers are either ground at the clinkerization facility or transported to strategically placed grinding units for grinding and cement bag packing. The manufactured and packed cement is transported and delivered to the prescribed destinations by road or rail. Even with the finest protection, the cement still has the potential of absorbing moisture while being transported. After absorbing moisture, the cement tends to harden, deteriorating its quality. Because of these unforeseen concerns, cement must be tested for quality before being used in construction. Basically, cement testing is carried out in accredited laboratories.

How to check cement quality?

The characteristics of cement are often determined by laboratory tests. Lab tests need time, specialised equipment, and expertise to evaluate and interpret the data. All of the cement’s qualities might not be able to be tested on-site. To address this issue, cement tests are divided into two types.

  • Field Tests of Cement

This article is about the field tests of cement.

test of cement on site
FIELD TEST OF CEMENT

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Test of cement on site / Field tests of cement

Some simple field tests can be used to confirm the quality of cement. Generally, these tests do not require the use of costly equipment or professional skills, and the results are obtained quickly. We can determine whether to accept or reject the cement by doing these quick tests, analysing the findings, and drawing conclusions about its quality. These are preliminary evaluations, and the cement’s quality is confirmed by factors such as how smooth it feels to the touch and its colour etc.

  • Checking the manufacturing date of cement
  • Visual checking for lumps
  • Feel test of cement
  • The heat of cement test
  • Colour test of cement
  • Water float tests
  • Setting tests
Test of cement on site
Field tests of cement

Checking the manufacturing date of cement

When stored under perfect conditions, the cement must be utilised within 90 days of manufacture. The manufacturing date and batch number are imprinted on each cement bag. By verifying the manufacturing date, we can get a good indication of how old the cement is and decide whether to use it. In addition, every batch of cement is accompanied by a Manufacturers Test Certificate, which can be requested and examined to verify the dates of manufacture.

Visual checking for Lumps for the test of cement on site.

Cement can be inspected for visible lumps. To establish the potential existence of lumps, you can press the cement bag’s corners. This test determines if the cement has hardened or not.

Feel test of cement on site

Feel a pinch of cement between the figures. Cement has to feel smooth and not grainy. By this test, we can rule out the presence of any adulterated material like sand mixed with cement.

Heat of cement

Put your hand inside a bag of cement that is open. If the cement is of good quality and has not yet begun to hydrate, the hand feels cool.

Colour

Cement is usually greenish-grey in colour. We can verify and confirm the colour of the cement on-site. However, the type and source of the ingredients can affect the colour of the cement.

Water float test

This test is performed to find out whether there are impurities in cement. A cement hand is thrown into a bucket of water. The cement floats for a while before settling down if it is good cement free of impurities or other foreign objects. Impurities in the water can cause the cement to settle instantly.

Setting test

A thick paste of cement is applied to a glass piece and slowly immersed in water for 24 hours. The cement piece won’t break or alter shape while it sets and maintains its original shape. This cement is regarded as excellent.

Conclusion

We have the opportunity to contact cement manufacturers through their customer services if we have any questions about the product’s quality and they will be happy to help. It is possible to confirm field observations with laboratory tests. Cement quality should never be compromised during construction. Because the most crucial component that affects the durability and quality of a structure is cement.

ALSO READ : WHAT ARE THE PROPERTIES OF CEMENT?

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CEMENT

Physical Properties of Cement – Significance and impacts

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The physical properties of cement have a significant impact on a structure’s serviceability, strength, and durability. The most important and highly recognized structural material used in construction is cement. All types of construction, from large skyscrapers, bridges, and tunnels to modest residential structures, use cement. It stands out as a crucial component of industrial buildings such as power plants, refineries, steel plants, cement mills, bridges, and other infrastructure.

Cement, when mixed with sand and aggregates, forms concrete, and when mixed with sand, it forms mortar. The serviceability, strength, and durability of a structure are entirely dependent on the quality of cement used for concrete and mortar; similarly, the properties of cement are directly related to the Cement Manufacturing Process, which involves the proportioning of ingredients, grinding, packing, and storing, among other things.

The cement properties are classified into PHYSICAL PROPERTIES and CHEMICAL PROPERTIES

  1. Physical Properties of Cement
    1. The fineness of cement – Physical properties of cement
    2. The soundness of cement – Physical Properties of Cement
      1. Causes of Unsoundness of cement
    3. Consistency of cement
    4. Strength of cement
    5. Setting time of cement
    6. Hydration of cement – The most important Physical Properties of Cement

Physical Properties of Cement

The physical properties of cement are critical in ensuring cement quality. Let us explore the physical properties of cement in depth. Physical properties distinguish different cement blends used in construction. Some critical parameters influence cement quality. Good cement has the following physical properties and is based on the following factors.

  • Fineness of Cement
  • Soundness of cement
  • Consistency of cement
  • Strength of cement
  • Setting time of Cement
  • Hydration reaction of cement

The fineness of cement – Physical properties of cement

The Fineness of cement is the measure of the particles of cement or the specific surface area of cement. The hydration rate of cement is directly related to its fineness. The higher the fineness of cement higher the specific surface area available per unit volume of cement. ie More area is available for cement and water action (hydration). This increases the rate of hydration and early gaining of strength in concrete. Bleeding can also be reduced by an increase in the fineness of the cement. But this in turn leads to dry shrinkage which can be managed by using more water.

Fineness can be determined by using a sieve analysis test, air permeability test or a sedimentation method.

The soundness of cement – Physical Properties of Cement

Soundness refers to the ability of hardened cement paste not to shrink or expand and retains its volume. If there is any change in volume, cracks may develop and the cement can be distinguished as unsound cement. Unsound cement can affect the durability and life of the structure. Soundness can also be defined as the volume stability of cement.

The cement manufacturing quality also has a very serious impact on cement quality. Inadequate heating can leave excess lime in cement. Even though cement plants have full-fledged quality labs to check the ingredients in detail, still cement has to be checked for its soundness before being used for any structure. Le Chatelier apparatus is used to test the soundness of cement.

Causes of Unsoundness of cement

The soundness of cement is affected by the presence of excess lime and magnesia. The excess lime hydrates very slowly to form slaked lime and will affect the properties of cement. The hydration difference between free lime (CaO) and slaked lime can change the volume of concrete on hardening and these changes make cement unsound.

Excess magnesia also reacts with water and affects the hydration process making cement unsound.

Gypsum is added to control the setting time of cement. Excess gypsum can react with Tricalcium aluminate to form calcium sulphoaluminate which can expand the concrete while hardening. The addition of gypsum has to be done with utmost care or else can make the cement unsound.

Consistency of cement

The consistency of cement is the ability of cement-water paste to flow under normal conditions. The optimum water-cement ratio has to be maintained in dry mixes to make it workable. Consistency of cement is the measure of the optimum water-cement ratio of a cement paste which can allow a Vicat apparatus plunger to penetrate a depth of 5-7 mm measured from the bottom of the mould. In that case, we can consider the paste is at normal consistency. The optimum water percentage for normal consistency ranges from 26% – 33%. The standard consistency test is conducted using a Vicat apparatus.

Physical properties of Cement - Finishing concrete

Strength of cement

Cement is the material responsible for imparting strength to mortar and concrete. The cement hydrates react with water and induce strength in concrete. The strength of cement has to be checked before it can be used for work. The strength can be affected by a lot of factors like water-to-cement ratio, ingredient proportioning, curing conditions, age, etc. The cement has to be checked for compressive, tensile, and flexural strength. The strengths are measured as grades in the cement bags

The strength is determined by checking the compressive strength of the cement.

Setting time of cement

The setting time of cement starts from the point water is added to the cement to a point where the cement reacts with water and hardening of the paste. It is the time taken from the production stage to the hardening stage which involves activities like, mixing, conveying, placing, and hardening. The setting time depends on a lot of factors like the fineness of cement, water-cement ratio, chemical content, and the presence of admixtures, etc. The setting time has to be adjusted in line with the structural requirements but has to ensure that the initial settling time should not be too low and the final setting time should not be too high.

The initial setting time is when the mix starts to stiffen and attains its plasticity. The initial setting time is 30 minutes for cement.

The final setting time is when the cement hardens to a point where it can take loads. The final setting time is 10 hours.

Hydration of cement – The most important Physical Properties of Cement

For using cement in any construction work, it is necessary to mix cement with water. On mixing water with the cement, a chemical reaction happens between water and cement leading to heat generation. This process of heat generation is known as the heat of hydration. It is very critical in mass concrete work and works done in hot and humid conditions.

When water is added to cement, a chemical reaction takes place between cement and water and is called hydration. Hydration generates heat, which can control the quality of the cement and helps in maintaining curing temperature in cold conditions. While using in mass concrete the heat generation tends to be very high which can cause undesired stresses in the structure. The heat of hydration is affected mostly by the presence of C3S and C3A in cement, water-cement ratio, fineness, and curing temperature. The heat of hydration of Portland cement is calculated by determining the difference between the dry and the partially hydrated cement.

Physical properties of cement

Building materials, CEMENT

Soundness test on Cement – Procedure and Calculation

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The soundness of the cement is the ability to resist volume changes after hardening. The soundness test on cement is significant because,using unsound cement leads to cracks and hamper the structural quality. A sound cement is one of the key materials used in construction. Therefore it is essential to determine its quality before using it in construction. 

Cement tests – Categories

Cement is one of the oldest and most used binding materials and an integral ingredient used in the construction sector. The quality, serviceability, and stability of a structure are directly related to the quality of cement used in it. Hence it is necessary to analyse the quality of cement before using it for works. The tests for determining cement quality are split into two major categories.

Field tests on Cement

The quality of cement is determined using some simple field tests. These tests do not require any sophisticated types of equipment and professional skills and get the results very quickly. By conducting these simple tests and analyzing the results we will get an idea about the cement quality and can immediately decide on accepting or rejecting it.

Following are the common field tests conducted to ensure the quality of cement

These are first look tests and the quality of cement is ensured by its smoothness to touch, the colour of cement, etc.

  • Checking manufacturing date
  • Visual checking of lumps
  • Feel test
  • Heat of cement
  • colour
  • Water float test
  • Setting test

These basic tests give an approximate characteristic of cement. These are easy and quick but not accurate, however help in concluding the acceptance of cement for works.

Laboratory tests for Cement

The laboratory tests defines the physical and chemical properties of cement. It is not possible to check all the cement properties at the site. The main laboratory tests conducted on cement is as follows.

Lab tests require time. But it provides accurate results. In this article, we are going to describe the Soundness test on cement.

Soundness test of cement

The soundness of the cement is the ability to resist volume changes after hardening. The soundness test on cement is significant because usage of unsound cement leads to cracks and hamper the structural quality.

The chemical composition of cement consists of lime. About 60 to 70% of cement is lime. The main function of lime is to help cement in the setting process. A good quality cement do not change its volume after hardening. Following are the reasons for the unsoundness of cement.

  • If the cement has an excess amount of lime, expansion or contraction in volume occurs after setting.
  • Another reason for unsoundness is the inadequate burning of cement. This leads to cracks, disintegration and a decrease in durability.
  • Improper grinding and mixing of raw materials during the manufacturing process of cement.
  • Due to the high proportion of magnesium content or sulphate content.

Therefore Soundness test is performed to determine whether the cement shows volume changes or not.

Relevant IS code for soundness test of cement

  • IS 4031 (Part 3)-1988
  • ASTM C 151-09
  • BS EN 196-3: 2005

Apparatus required

Soundness of cement is calculated by using Le-chatelier’s apparatus.

  • Le-Chatelier mould
  • Balance
  • Water bath
  • Vernier Calliper
  • Pan and trowel

Le-chatelier mould is made using brass. It consists of a spring-tensioned split cylinder and an indicating long arm in its either side. The internal diameter and height of the cylinder are 30mm and 30mm. The size of glass plates is 50mm x 50 mm. For each test, we need three such moulds. The test should be performed at a temperature of 27 ± 2°C and relative humidity of 50 to 80 per cent as per IS code.

Le-Chatliers for testing soundness of cement
Le-Chatliers for testing soundness of cement

Procedure for soundness test on Cement

Before Performing the test, calculate the standard consistency of cement to find out the water required to obtain the normal consistency(P).

  • Take about 100 gm of cement and add 0.78-times the water needed to make cement paste with normal consistency.
  • Then grease the glass plate and the Le-chatelier mould to avoid the sticking of cement on its surface.
  •  Fill the cement paste and strike out the excess cement using a trowel.
  • Cover the mould with another glass plate and place a weight above the glass plate.
  • Then immerse the whole assembly inside the water bath for 24 hours. 
  • After 24 hours, take out the mould from water and measure the distance between the indicators.
  • Note this measurement as L1. After that place, the assembly in the water bath 
  • Boil the water for 25 to 30 minutes and leave them for 3 hours.
  • After that, allow them to cool till it reaches the room temperature.
  • Now take out the assembly and measure the distance between the indicators and mark them as L2. 

Calculation

Volume expansion of cement = L1 – L2

L1 is the distance between the indicators after immersing in water for 24 hours

L2 is the distance between the indicators after immersing in water at boiling temperature for 3 hours

This value differs for different types of cement. The expansion of volume for Ordinary portland cement, portland pozzolanic cement, low heat cement and rapid hardening cement should not exceed 10mm. For high alumina cement, super sulphate cement, the volume expansion should not exceed 5mm. Because it contains excess lime or magnesium which is not suitable for construction.

Building materials, CEMENT

Heat of hydration test of Cement – Process and Procedure

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The heat of hydration is the heat liberated from the reaction between cement and water. Cement is a binding material. It consists of ingredients such as lime, Silica, Alumina etc. Water is added to cement to make it adhesive so that we can use it in construction. This article is about the heat of hydration of cement.

Cement test – Categories

Cement is the oldest and most used binding material and an integral ingredient used in the construction sector. The quality, serviceability, and stability of a structure are directly related to the quality of cement used in it. Hence it is necessary to analyse the quality of cement before using it for works. They are as follows.

Also read : Cement tests – Laboratory and Field Tests

Also Read : Best cement of India -2021

Field tests on Cement

The cement quality is by simple field tests. However, these tests do not require any sophisticated types of equipment and professional skills and get the results very quickly. By conducting these simple tests and analysing the results we will get an idea about the cement quality so that, we can immediately decide on accepting or rejecting it.

These are first look tests and the quality of cement is ensured by its smoothness to touch, the colour of cement, etc.

  • Checking manufacturing date
  • Visual checking of lumps
  • Feel test
  • Heat of cement
  • colour
  • Water float test
  • Setting test

These basic tests give an approximate characteristic of cement. These are easy and quick but not accurate, however help in concluding the acceptance of cement for works. For more details about field tests you can go through our earlier article Field tests of Cement – A significant step towards quality

Laboratory tests for Cement

The laboratory tests define the physical and chemical properties of cement. So it is not possible to check all the cement properties at the site. The main laboratory tests conducted on cement is as follows.

Lab tests require time. But it provides accurate results.

What is heat of hydration?

Hydration process
Hydration process

Cement consists of chemical compounds which help in the setting and hardening process. The chemical compounds Alite (C3S), Belite (C2S), Celite (C3A) and Felite (C4AF) are collectively called Bogue compounds. These inactive compounds are formed during the clinkering process. These compounds on addition of water initiates a chemical reaction with water known as hydration process.Hydration is an exothermic reaction. That is, it emits a sufficient amount of heat. Also, hydration liberates 89-90cal/gm of heat in 7 days and 90-100cal/gm in 28 days. The physical properties of cement depend on the rate of hydration. Improper hydration process results in low strength and deterioration of structures. Chemical compounds responsible for hydration are as follows.

Also Read : Physical properties of cement

Also Read : Water to cement ratio

  • Tricalcium silicate, C3S
  • Dicalcium silicate, C2S
  • Tricalcium aluminate, C3A
  • Tetracalcium aluminoferrite, C4AF
  • Gypsum, CSH2
Chemical reaction during hydration process
Chemical reaction during hydration process

During the hydration process, hydration products like Tobermorite gel (C-S-H gel), calcium hydroxide and other small compounds are formed. These substances deposit on the outer periphery of the nucleus of hydrated cement grains. Moreover, hydration is a slow reaction that occurs for 2 to 5 hours. The initial period of the hydration process is the Induction or dormant period. The hydration process stops after the reaction between the entire cement particle. The tobermorite gel occupies 50 to 60 % of the volume of hydrated cement. 

STAGES OF HYDRATION
STAGES OF HYDRATION

Apparatus for heat of hydration test

The heat of hydration test is conducted at a standard room temperature of 27 degrees celsius. The apparatus for this test is

  1. Calorimeter
  2. Mortar and pestle 
  3. Glass/Plastic vials
  4. Stopwatch or timer
  5. Sieve
  6. Muffle furnace
  7. Weighing balance

The calorimeter determines the heat of the paste. Glass vial has a dimension of 80×20 mm. Muffle furnace maintains the temperature. Before performing the test, the calorimeter temperature is to be made uniform. The heat of hydration should be determined at the 7th and 28 days.

Procedure for heat of hydration test

  • To find the heat of hydration, firstly we have to measure the heat released from the unhydrated cement using a calorimeter.
  • Then we have to measure the heat of hydration from hydrated cement
  • For that take 60 grams of cement and add 24 ml of water. 
  • Then fill this mixture in three glasses and seal them with wax to avoid the entry of air. 
  • The standard temperature should be 27 degrees celsius. 
  • Then measure the heat of the solution using a calorimeter. 

Heat of hydration = Heat released from hydrated cement – Heat released from unhydrated cement

For low heat cement, The heat of hydration for 7 days should not be greater than 66 cal/g and for 28 days should not be greater than 75 cal/gm. 

Building materials, CEMENT

Consistency test on cement – Significance and Procedure

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The consistency of cement mortar is its ability to flow. The consistency test on cement is performed to determine the water necessary for attaining standard consistency or normal consistency.

Cement is the most important and highly recognized binding material used in construction. Cement is an integral part of all types of construction ranging from huge skyscrapers, bridges, tunnels, etc to small residential buildings. For industrial structures like power plants, refineries, steel plants, cement plants, bridges, roads, etc. cement is the main component. Cement, when mixed with sand and aggregates, forms concrete and with sand makes mortar. The serviceability, strength, and durability of a structure are closely related to cement used in various works.

Cement tests – Categories

Cement is one of the oldest and most used binding materials and an integral ingredient used in the construction sector. The quality, serviceability, and stability of a structure are directly related to the quality of cement used in it. Hence it is required to analyse the quality of cement before using it for works. The tests for determining cement quality are split into two major categories.

Field tests on Cement

The quality of cement is determined using some simple field tests. These tests do not require any sophisticated types of equipment and professional skills and get the results very quickly. By conducting these simple tests and analyzing the results we will get an idea about the cement quality and can immediately decide on accepting or rejecting it.
Following are the common field tests conducted to ensure the quality of cement.

These are first look tests and quality of cement is ensured by its smoothness to touch, the colour of cement, etc.

  • Checking manufacturing date
  • Visual checking of lumps
  • Feel test
  • Heat of cement
  • colour
  • Water float test
  • Setting test

These basic tests give an approximate characteristic of cement. These are easy and quick but not accurate, however help in concluding the acceptance of cement for works.

Also read : Field tests for cement

Laboratory tests for Cement

The laboratory tests are conducted to define the physical and chemical properties of cement. It is not possible to check all the cement properties at the site. The main laboratory tests conducted on cement is as follows.

  • Fineness Test
  • Compressive Strength Test
  • Consistency Test on cement
  • Setting time
  • Soundness Test
  • Tensile strength Test
  • Heat of hydration

Lab tests require time. But it provides accurate results. In this article we are going to describe about Consistency test on cement.

Significance of Consistency test on Cement

The strength of concrete depends on the quality of cement. In order to achieve good strength, the mortar should be consistent. The standard consistency of cement is when the Vicat plunger penetrates to a point 5 to 7 mm from the bottom of the Vicat mould. This is a trial and error method.The consistency test determines the water necessary for attaining standard consistency or normal consistency. The consistency of cement is necessary to conduct other tests like compressive strength, setting time determination etc. Because consistency gives the quantity of water in cement paste. The hydration of cement occurs in presence of water. Also, the consistency depends on the composition and fineness of the cement. Excess use of water makes cement brittle after hardening. The lower water-cement ratio affects the rate of hydration which in turn affects its strength. That is why determination of consistency is essential.

Relevant IS code for consistency test on cement

  • IS 4031 (Part 4)-1988
  • ASTM C 187
  • BS EN 196-3:2005

Apparatus used for consistency test on cement

The Vicat apparatus is used to determine the consistency of cement. It consists of a plunger, a movable rod weighing 300 g, graduated scale, non-porous plate, split mould and Vicat mould. The diameter of the plunger is 10mm and the length is 50mm. The graduate scale measures the depth of penetration. The Vicat mould is a cone frustum with 80 mm diameter. The test should be conducted at a standard temperature of 27 C. The humidity should be 65%. A stop clock is used to measure the time from the addition of water to the drying of cement. As per IS code, the time of gauging is not less than 3 minutes, nor more than 5 min.

Consistency Test on Cement - Vicats Apparatus
Consistency Test on Cement – Vicats Apparatus

Procedure of consistency test for cement

  • The first step is the preparation of cement paste. For this take 400 gm of cement in a tray.
  • Add water of about 28% by weight of cement. Start the stopwatch at the time of adding water. 
  • Now thoroughly mix the cement paste. Place the mould above the non-porous plate and fill the paste into the Vicat mould.
  • Remove the excess cement paste using a trowel and slightly tap the mould to remove the entrapped air. 
  • Attach the standard plunger in the Vicat apparatus. After placing the mould lower the plunger till it gently touches the surface. 
  • Then release the plunger quickly and measure the depth of penetration from the bottom. 
  • Repeat the procedure by increasing the water content until the plunger penetrates up to 5mm to 7mm. 
  • Then calculate the standard consistency.

Calculation

The standard consistency is expressed in terms of the percentage of the quantity of added water to the weight of cement. The consistency of cement ranges from 26% to 33%.

Standard consistency = ( Quantity of water added / Weight of cement) x 100

Precaution

We should take certain precautions before starting the test so that to obtain accurate results.

  • Clean the Vicat mould properly and grease the inside surface
  • Take immense care while attaching the plunger. Make sure it is vertical.
  • Place the apparatus on a levelled surface.
  • Maintain the standard temperature and humidity throughout the test.

Conclusion

Finding out standard consistency of cement is essential because the amount of water added in cement affect the setting time of cement, Less water added than this standard consistency would not complete chemical reaction thus resulting in the reduction concrete of strength and more water would increase water-cement ratio and so would reduce its strength.