Podcast Beta
Questions and Answers
What is the typical volume ratio of sand to hydraulic lime when mixed for mortar?
Which type of mortar is primarily used for plastering?
What process is used to prepare lime if a large quantity is required?
Which mortar has gained popularity over lime mortar due to availability in the market?
Signup and view all the answers
What is added to clay mortar to improve its quality?
Signup and view all the answers
What is a characteristic of gauged mortar?
Signup and view all the answers
What type of materials can be added to mud mortar to prevent cracks?
Signup and view all the answers
What is indicated by the usage of colored cement in mortars?
Signup and view all the answers
What is one of the primary roles of sand in mortar and concrete?
Signup and view all the answers
Which of the following is NOT a characteristic of good sand?
Signup and view all the answers
What is the recommended cement to sand proportion for plastering masonry works?
Signup and view all the answers
Why is it important to keep mortar wet during the curing process?
Signup and view all the answers
What happens to the cost of cementing materials when using sand in mortar?
Signup and view all the answers
Which property of sand aids in the formation of silicates in cement?
Signup and view all the answers
What is a disadvantage of using sand that contains salt?
Signup and view all the answers
How does sand help with the adherence of the binding material?
Signup and view all the answers
Which materials are typically used to create mortar?
Signup and view all the answers
What is a primary characteristic of cement when mixed with water?
Signup and view all the answers
What appearance does mortar have when it is initially mixed?
Signup and view all the answers
Which property describes cement mortar?
Signup and view all the answers
Why do engineers prefer using concrete hollow blocks (CHB) for interior walls?
Signup and view all the answers
Which of the following is a common use of mortar in construction?
Signup and view all the answers
What is one of the key benefits of using masonry materials like CHB in construction?
Signup and view all the answers
What is the defining property of mortar when it comes to its consistency?
Signup and view all the answers
What is the primary purpose of determining the initial setting time of cement?
Signup and view all the answers
How much water is used in the setting time test based on the consistency test for 300 gm of cement?
Signup and view all the answers
What does the final setting time measurement indicate?
Signup and view all the answers
What is the effect of a prolonged setting period on the cement structure?
Signup and view all the answers
What is the role of the cross-section of the needle in the initial setting time test?
Signup and view all the answers
Which component of the Vicat apparatus is used to perform the tests for setting time?
Signup and view all the answers
What is the approximate duration for final setting time of ordinary cement?
Signup and view all the answers
What should occur during the initial setting time test according to the procedure?
Signup and view all the answers
How does increased fineness of cement affect bleeding in concrete?
Signup and view all the answers
What risk is associated with cements that gain strength rapidly?
Signup and view all the answers
What is one consequence of increasing the fineness of cement?
Signup and view all the answers
What is the main objective of conducting a fineness test for cement?
Signup and view all the answers
Which statement describes an effect of fine cement on hydration?
Signup and view all the answers
What is a consequence of increasing fineness in relation to dry shrinkage?
Signup and view all the answers
What effect does the fineness of cement have on the rate of strength gain?
Signup and view all the answers
Why is it important to control the fineness of cement during grinding?
Signup and view all the answers
Study Notes
Artificial Sand
- Artificial sand is a by-product of crushing stones
Sand in Mortar and Concrete
- Sand is used in mortar and concrete to:
- Subdivide and spread the binding material
- Fill in gaps between building blocks
- Increase the density of mortar
- Prevent shrinkage
- Facilitate carbon dioxide absorption
- Reduce the cost of cementing materials
- Contribute to the formation of silicates during hardening
Properties of Good Sand
- Chemically inert
- Free from organic or vegetable matter
- Free from salt
- Sharp, angular, and coarse grains
- Well-graded
- Hard
Cement Mortar
- Cement and sand are mixed dry
- Water is added gradually and mixed with shovels
- Common cement to sand proportions:
- Masonry works: 1:6 to 1:8
- Plastering masonry: 1:3 to 1:4
- Plastering concrete: 1:3
Curing
- Cement gains strength gradually through hydration
- Mortar needs to be kept wet until hydration is complete
- Hydraulic lime mixtures have a 2:1 ratio of sand to lime
- Lime is prepared by pounding (small quantities) or grinding (large quantities)
Lime Mortar
- Has good grinding properties
- Fat lime mortar is used for plastering
- Hydraulic lime mortar is used for masonry
- Historically cheaper and widely used, but cement mortar has largely replaced it
Mud Mortar
- Made from wet clay lumps that mature for 1-2 days
- Kneaded until the desired consistency is reached
- Fibrous materials, such as gobber, are added to prevent cracking
- Outer plaster is sprayed or painted with bitumen for durability
- Used for temporary sheds and cheap houses in rural areas
Special Mortars
- Cement Clay Mortar:
- Improves quality of clay mortar
- Clay to cement ratio is 1:1
- Economical and increases durability
- Gauged Mortar:
- Lime mortar with added cement
- Cement, lime, and sand proportions: 1:1:6, 1:2:9, and 1:3:12
- Must be used within 30 minutes after mixing
- Cheaper than cement mortar, with a quality between cement and lime mortar
- Decorative Mortar:
- Made with colored cement
- Used for aesthetic purposes
Fineness of Cement
- Indicates particle size and specific surface area
- Affects hydration rate and strength gain
- Can reduce bleeding but may increase the need for water, leading to shrinkage
- Measured using a fineness test
- Finer cement reacts faster with water, resulting in faster strength development and higher heat of hydration
Setting Time
- Initial Setting Time:
- Cement paste is prepared with water
- A needle is used to penetrate the paste
- Time is measured until the needle no longer penetrates 5 mm into the paste
- Final Setting Time:
- Cement paste is prepared
- A needle with an annular collar is used
- Time is measured until the needle makes an impression but the collar does not
- Typical initial setting time for ordinary cement is around 10 hours
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Explore the essential roles of artificial sand and its properties in mortar and concrete applications. Understand the significance of sand in enhancing the physical characteristics of building materials and the proper mixing techniques for cement mortar. This quiz encompasses fundamental concepts critical to construction practices.
