15 Questions
What are the main components of mortar for masonry work?
Sand, cement or lime, and water
Why should the thickness of mortar in brickwork not exceed 15 mm?
Due to high shrinkage
What is the function of mortar in masonry work?
Joint the units together, seal any gaps to resist wind and rain penetration, and take up the tolerances between building units
What is one of the requirements for mortar in masonry work?
Adhere to the vertical face of the units
Why should mortar permit movement in masonry work?
To allow movement to occur in the form of microcracks within the mortar rather than cracking of the bricks or blocks
What type of sand is recommended for mortar in masonry work?
Well graded – even distribution of particle sizes from fine to coarse
What is the result of using sand containing silt and clay in mortar?
Unacceptable shrinkage movement
What is the principal binding ingredient in modern binders?
Ordinary Portland cement
What does non-hydraulic lime lack, resulting in poor water retention?
Setting and hardening strength
What does adding air-entraining agent as a binder supplement accomplish?
Good workability characteristics
When is sulphate resisting Portland cement used in place of Ordinary Portland cement?
To combat sulphate attack in prolong wet conditions
What is the effect of air entrainment exceeding 12% of the volume?
Serious reduction in bonding performance
Which type of masonry unit has a coefficient of linear thermal expansion between 11 - 15 x 10^-6/K?
Calcium silicate masonry units
What are the properties achieved by using cement and sand (1:3) by volume?
High strength, good durability, density, and hardness
What is the main drawback of using sand lacking in finer particles in mortar?
'Harsh unmanageable mortar'
Study Notes
Mortar Components
- Main components of mortar for masonry work: cement, sand, water, and lime
Mortar Thickness
- Thickness of mortar in brickwork should not exceed 15 mm to ensure adequate bond strength
Mortar Function
- Function of mortar in masonry work: to bond masonry units together, fill gaps, and provide a level surface
Mortar Requirements
- One of the requirements for mortar in masonry work: to permit movement in masonry work to accommodate thermal and moisture changes
Sand Requirements
- Recommended type of sand for mortar in masonry work: clean, sharp, and free from impurities
- Effect of using sand containing silt and clay in mortar: reduces mortar strength and workability
Binders
- Principal binding ingredient in modern binders: cement
- Non-hydraulic lime lacks: water retention, resulting in poor durability
Air-Entraining Agent
- Adding air-entraining agent as a binder supplement: improves workability and resistance to freeze-thaw damage
Cement Types
- Sulphate resisting Portland cement is used in place of Ordinary Portland cement: in exposure to seawater, acidic, or sulphate-rich environments
Air Entrainment
- Effect of air entrainment exceeding 12% of the volume: reduces mortar strength and durability
Masonry Units
- Type of masonry unit with a coefficient of linear thermal expansion between 11 - 15 x 10^-6/K: extruded concrete masonry units
Cement and Sand Proportions
- Properties achieved by using cement and sand (1:3) by volume: suitable for general masonry work
Sand Quality
- Main drawback of using sand lacking in finer particles in mortar: reduces mortar workability and increases the risk of segregation
Test your knowledge about the composition and functions of masonry mortar, which is used to joint masonry units and resist wind and rain penetration. Learn about the requirements and components of mortar for masonry work.
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