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Questions and Answers
What is the primary purpose of precise control during the firing of masonry units?
What is the primary purpose of precise control during the firing of masonry units?
- To decrease the size of the kiln compartments.
- To increase the production rate.
- To reduce the energy consumption of the kiln.
- To achieve a specific firing curve that suits raw materials. (correct)
Which factor does NOT affect the properties of masonry?
Which factor does NOT affect the properties of masonry?
- Workmanship and supervision during construction.
- Properties of the mortar.
- Properties of the masonry units.
- Consistency of weather during construction. (correct)
Which variability is NOT typically associated with masonry properties?
Which variability is NOT typically associated with masonry properties?
- Natural variation in materials.
- Difficulty of controlling site-batched mortar.
- Database errors in design calculations. (correct)
- Variability in site workmanship.
What does the typical coefficient of variation (CV) for compression indicate?
What does the typical coefficient of variation (CV) for compression indicate?
What failure mechanism occurs in masonry due to mortar joints?
What failure mechanism occurs in masonry due to mortar joints?
Which of the following statements about masonry strength is true?
Which of the following statements about masonry strength is true?
Which process occurs after firing in the manufacture of masonry units?
Which process occurs after firing in the manufacture of masonry units?
What is the primary reason for ensuring compatibility of the units and mortar in masonry?
What is the primary reason for ensuring compatibility of the units and mortar in masonry?
What material was primarily used in the earliest known uses of masonry?
What material was primarily used in the earliest known uses of masonry?
Which structure is noted as the last great example of a gravity masonry structure?
Which structure is noted as the last great example of a gravity masonry structure?
What does modern masonry, particularly fired clay brick, provide?
What does modern masonry, particularly fired clay brick, provide?
Which of the following is NOT a characteristic of gravity masonry structures?
Which of the following is NOT a characteristic of gravity masonry structures?
What was a significant ancient masonry construction technique mentioned?
What was a significant ancient masonry construction technique mentioned?
Which of these is an example of a modern use of masonry?
Which of these is an example of a modern use of masonry?
What is one of the earliest regions known for masonry construction?
What is one of the earliest regions known for masonry construction?
What type of kiln was used for the convict bricks brought by the First Fleet?
What type of kiln was used for the convict bricks brought by the First Fleet?
What significantly reduces masonry strength?
What significantly reduces masonry strength?
Which factor is NOT related to the reduction of masonry strength?
Which factor is NOT related to the reduction of masonry strength?
What is used for compressive strength testing of masonry units?
What is used for compressive strength testing of masonry units?
As the joint thickness increases, what happens to compressive strength?
As the joint thickness increases, what happens to compressive strength?
For traditional bricks with a height-to-thickness ratio of 7.6, what is the compressive strength factor?
For traditional bricks with a height-to-thickness ratio of 7.6, what is the compressive strength factor?
What does the adjustment for joint thickness account for?
What does the adjustment for joint thickness account for?
Which of the following statements is correct regarding weaker units?
Which of the following statements is correct regarding weaker units?
What must be tested for masonry to be classified as Special Masonry?
What must be tested for masonry to be classified as Special Masonry?
What is the default characteristic tensile strength value across bed joints in masonry when not tested?
What is the default characteristic tensile strength value across bed joints in masonry when not tested?
Which type of bending in masonry is associated with tensile stress normal to the bed joints?
Which type of bending in masonry is associated with tensile stress normal to the bed joints?
In masonry, what is the effect of various levels of bending stress in joints during analysis?
In masonry, what is the effect of various levels of bending stress in joints during analysis?
What is the value of tensile strength that can be used for special masonry, subject to testing?
What is the value of tensile strength that can be used for special masonry, subject to testing?
What is a characteristic of masonry's flexural behavior?
What is a characteristic of masonry's flexural behavior?
What does the weakest link analogy suggest about vertical bending in masonry?
What does the weakest link analogy suggest about vertical bending in masonry?
In horizontal bending of masonry, which of the following describes a mode of failure?
In horizontal bending of masonry, which of the following describes a mode of failure?
How does AS 3700 address the analysis of joints subjected to bending stress?
How does AS 3700 address the analysis of joints subjected to bending stress?
What type of shear action occurs in a bracing wall?
What type of shear action occurs in a bracing wall?
How is shear strength in masonry typically determined?
How is shear strength in masonry typically determined?
What is the range of elastic modulus values for short-term loading according to AS 3700?
What is the range of elastic modulus values for short-term loading according to AS 3700?
What does the friction factor represent in masonry shear strength calculations?
What does the friction factor represent in masonry shear strength calculations?
What happens to the long-term modulus of elasticity in masonry compared to the short-term modulus?
What happens to the long-term modulus of elasticity in masonry compared to the short-term modulus?
Which property is defined as the combination of shear strength and shear friction in masonry?
Which property is defined as the combination of shear strength and shear friction in masonry?
What is the role of density in the context of masonry properties?
What is the role of density in the context of masonry properties?
In masonry, what does the shear strength $f 'ms$ typically relate to?
In masonry, what does the shear strength $f 'ms$ typically relate to?
Study Notes
History of Masonry Use
- Earliest masonry applications were used in Egypt, Mesopotamia and the Indus valley (ca 8,000 BCE)
- Earliest uses of kiln-fired bricks date back to 5,000 BC
- Single brick structure provides: Strength + Water-tightness + Thermal protection
- First Fleet brought bricks to Australia
- Convict built hand-moulded wet clay bricks using clamp kilns
- Masonry uses include: Bridges, Vaults, Arched doorways, Retaining walls, Tunnels, Buildings, etc.
- Massive masonry walls were the standard until the 19th century
- Gravity was the force used to keep walls stable with no tensile stresses present
Manufacture of Masonry Units
- Modern Kiln Tunnel and Gas Burners are monitored and controlled by a computer room to ensure appropriate firing curve
- Firing is an important step in masonry unit manufacture and is dependent on raw materials
Masonry Properties
- Masonry Properties Depend on:
- Properties of the masonry units
- Properties of the mortar
- Compatibility of the units and mortar
- Bonding pattern
- Workmanship and supervision during construction
- Variability in Properties:
- Natural variation in materials
- Variation in the manufacturing process
- Variations in site workmanship
- Difficulty of controlling site-batched mortar
- Variation in porosity, moisture content etc
- Typical Coefficient of Variation (CV) is 0.15 for compression and 0.30 for flexural tension
- Masonry strength is always less than the compressive strength of the units alone
- Masonry strength is reduced by:
- Weaker units (lower tensile strength)
- Greater thickness of joints
- Weaker mortar (i.e.lower stiffness)
- To accommodate the lower elastic modulus of mortar compared to units, tensile stresses are induced in the units
- An unconfined strength based on a height-to-thickness of five is used for compressive strength tests
- AS 3700 (Australian Standards) provides tabulated compressive strengths (f 'mb) based on unit strength and mortar class
- Higher strengths from compressive tests can be used but the masonry is then Special Masonry and must be tested during construction
- Compressive Strength is reduced as the joint thickness increases for a given unit height
- Tensile strength is usually tested by the bond wrench method
- A characteristic value of 0.2 MPa across the bed joints is used for design, unless tested
- A value up to 1.0 MPa can be used for Special Masonry, subject to testing.
- Masonry is anisotropic because of the bed and perpend (perpendicular) joints
- Three types of flexure in masonry:
- Vertical bending (tensile stress normal to the bed joints)
- Horizontal bending (tensile stress parallel to the bed joints)
- Two-way bending (principal tensile stress at an angle to the bed joints).
- Vertical Bending - joints usually have different levels of bending stress
- Two modes of horizontal bending failure:
- Through bed and perpend joints: When units are strong relative to bond
- Through perpend joints and units: When bond is strong relative to the units
- Shear resistance in masonry combines shear strength and shear friction
- Shear strength f 'ms is related to bond at the unit-mortar interface and is usually proportional to f 'mt
- The friction factor is the slope of the shear strength line
- Values for the elastic modulus E are required for deflection and relative movement calculations
- AS 3700 provides values for short-term and long-term loading, where values are proportional to f 'm and range from 500 f 'm to 1000 f 'm for short-term loading
- Long-term modulus of elasticity is approximately 1/2 to 2/3 of the short-term modulus due to creep, mostly in the mortar
- In the absence of more accurate data, the Australian loading code gives masonry density values, for example 0.19 kN/m2 for each 10 mm thickness of clay brickwork
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Description
Explore the rich history and essential properties of masonry through this informative quiz. From ancient applications in Egypt to modern manufacturing techniques, you will learn about the various uses and characteristics that define masonry. Test your knowledge about the development and significance of this crucial building material.
