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Questions and Answers
What type of cement should be avoided in constructions subjected to frequent freezing-and-thawing?
Which cement is particularly beneficial in conditions exposed to excessive sulphate?
What is the maximum allowable final setting time for Low Heat Portland Cement?
In which applications is Quick Setting Portland Cement most suitable?
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What characteristic distinguishes White and Colored Portland Cement from 33 grade ordinary Portland cement?
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Which of the following is NOT a suitable use for Low Heat Portland Cement?
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How should Portland cement be stored to avoid moisture problems?
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What feature is associated with the composition of Portland Puzzolana Cement?
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What is the primary reason for the addition of gypsum in the manufacture of rapid hardening portland cement?
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What is a notable characteristic of rapid hardening cement compared to ordinary cement?
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For what specific condition should high alumina cement not be used?
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What is one of the main uses of supersulphated Portland cement?
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Which property of rapid hardening cement poses a challenge during its use?
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What is one advantage of using rapid hardening cement in construction?
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What environmental factors make high alumina cement particularly useful?
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Why is rapid hardening cement more expensive than ordinary cement?
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Which type of cement is unsuitable for very large masses of concrete?
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Which characteristic is associated with Sulphate resistant cement?
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What is the maximum percentage of C3S in Ordinary Portland cement?
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In terms of composition, which oxide is found in the highest percentage in Ordinary Portland cement?
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What is a characteristic of Rapid hardening cement?
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Which cement type reacts with silica during burning to enhance strength?
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What feature distinguishes High Alumina Cement regarding hydration?
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Which of the following oxides has the lowest percentage in Ordinary Portland cement?
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Which statement is incorrect regarding the properties of Portland cement?
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What is the typical temperature range in a cement kiln?
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Which compounds contribute to the phenomenon known as 'Flash set' of cement?
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Which statement about cement setting and hardening is incorrect?
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What is the correct order of heat evolution for the four compounds of cement?
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In descending order, what is the correct rate of heat of hydration for the Bogue compounds?
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Approximately what percentage of bound water by weight is required for complete hydration of cement?
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Which of the following pairs related to cement is not matched correctly?
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What is the minimum surface area required for ordinary Portland cement? (in mm2/g x 102)
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Which compound must be reduced to produce low heat cements?
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What is the water-to-cement (w/c) ratio required for complete hydration of cement?
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High alumina cement is primarily produced by fusing which materials?
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Which statements contribute to achieving high early strength in cement? Select the correct combination.
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Identify the correct ascending order of the four main oxides in ordinary Portland cement.
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Which type of cement is suitable for very large structures?
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Which apparatus is used to test the consistency of cement?
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Study Notes
Types of Cement
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Rapid Hardening Portland Cement (RHC) has a high lime content and is obtained by finer grinding of OPC clinker.
- RHC achieves the same strength in one day that ordinary cement achieves in three days.
- It has higher shrinkage and requires more water for workability.
- Cost is about 10% higher than ordinary cement.
- Uses: Repairing roads and bridges, situations where load is applied quickly.
High Alumina Cement
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Uses: Resistant to fire, seawater, acidic water, and sulfates.
- Used as refractory concrete, in industries, and widely for precasting.
- Not recommended: For temperatures exceeding 18°C.
Super Sulphated Portland Cement
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Uses: Similar to common Portland cement.
- Preferred: In hydraulic engineering installations and constructions in moist conditions.
- Examples: RCC pipes in groundwater, concrete structures in sulfate-bearing soils, sewers carrying industrial effluents, concrete exposed to concentrated sulphates of weak mineral acids.
- Not recommended: Constructions exposed to frequent freezing-and-thawing or moistening-and-drying conditions.
Sulphate Resisting Portland Cement
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Uses: Beneficial in conditions where concrete is exposed to the risk of deterioration due to sulfate attack.
- Examples: Concrete in contact with soils or ground waters containing excessive sulphate, concrete in seawater or exposed directly to the sea coast.
Low Heat Portland Cement
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Properties: Less heat is evolved during its setting.
- Meets specific expansion limits for Le Chatelier and autoclave tests.
- Minimum initial setting time should not be less than 60 minutes, and final setting should not be more than 600 minutes.
- Uses: Large mass concrete works (dams, large raft foundations).
Portland Puzzolana Cement
- Uses: Low heat evolution, suitable for mass concrete works like dams and high-temperature applications.
Quick Setting Portland Cement
- Uses: Laying concrete underwater or in running water.
White and Colored Portland Cement
- Properties: Compressive and transverse strength is 90% of that of 33 grade ordinary Portland cement.
- Uses: Terrazzo flooring, face plaster of walls (stucco), ornamental works, and casting stones.
Air Entraining Cement
Storage of Cement
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Storage: Portland cement is stored in 50 kg sacks (0.035 m3 capacity).
- Storage requirements: Airtight room, avoiding moisture and dampness.
- Placement: Some distance from walls and at some height from floors.
- Stacking: Covered with suitable coverings to prevent air circulation, and not more than ten bags should be stacked one over another.
Cement Properties
- Setting Time: Stiffening of cement without strength development is caused by tetracalcium aluminoferrite (C4AF).
Cement Composition
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Ordinary Portland Cement (OPC): Four main oxides present are CaO, A12O3, SiO2, and Fe2O3.
- The correct ascending order of their proportions in a typical composition of OPC is Fe2O3, SiO2, Al2O3, CaO.
Key Facts
- The temperature range in a cement kiln is 1300°C to 1500°C.
- Cement is adhesive as well as cohesive material.
- Portland cement is of a hydraulic type.
- For civil engineering works, generally calcareous cements are used.
- For hydraulic structures, a cement with a small percentage of C3S and more C2S is recommended.
- The product C-S-H gel is known as tobermorite gel.
- The rate of heat evolution in descending order for the following compounds is C3A, C4AF, C3S, C2S.
- The rate of heat of hydration of the four Bogue compounds in descending order is C3S, C3A, C2S, C4AF.
- The bound water (by weight)% required for complete hydration of cement is about 23%.
- Ordinary Portland cement should have a surface area not less than 3250 mm2/g x 102.
- To produce low heat cements, it is necessary to reduce the C3A compound.
- For complete hydration of cement, the w/c ratio needed is more than 0.25 but less than 0.35.
- High alumina cement is produced by fusing together a mixture of limestone and bauxite.
- High early strength of cement is obtained as a result of fine grinding and burning at higher temperatures.
Cement Types and Characteristics
- Air entraining Portland cement: Greater resistance to frost attack.
- Low heat Portland cement: Suitable for very large structures.
- Hydrophobic Portland cement: Safe storage under unfavorable conditions of humidity.
- Rapid hardening Portland cement: Unsuitable for very large masses of concrete.
- Ordinary Portland cement: The percentage of C3S is a maximum and is of the order of 50%.
- Rapid hardening cement: The percentage of C2S and C3S are the same and the same order of 40%.
- Low heat cement: Reacts with silica during burning and causes particles to unite together and develop strength.
- Sulphate resistant cement: Preserves the form of brick at high temperatures and prevents shrinkage.
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Description
This quiz explores different types of cement, including Rapid Hardening Portland Cement, High Alumina Cement, and Super Sulphated Portland Cement. It highlights their unique properties, uses, and considerations in construction applications. Test your knowledge on how these cements differ and where they are best applied.
