10 Flashcards
(106 cards)
What causes movement in building components?
- Thermal movement
- Moisture movement
- Elastic deformation and creep
- Construction tolerances and other considerations
Steel movement types in buildings
Thermal, elastic deformation.
Concrete movement types in buildings
Thermal, elastic deformation, creep, and reversible moisture.
Concrete masonry movement types in buildings
Thermal, elastic deformation, creep, and reversible moisture.
Brick masonry movement types in buildings
Thermal, elastic deformation, creep, and irreversible moisture.
Wood movement types in buildings
Thermal, elastic deformation, creep, and reversible moisture.
Annual temperature range that a component is subjected to
This is the difference between the maximum and minimum temperatures of the component.
Thermal Movement
Generally the most critical movement, because it occurs in all components, particularly those exposed to the exterior climate, such as exterior walls.
Moisture movement in steel, copper, and aluminum
Moisture movement in steel, copper, and aluminum
These materials are generally dimensionally stable with respect to moisture.
Moisture movement in portland cement
Materials with a portland cement base tend to shrink due to moisture loss.
Moisture movement in concrete and masonry
Clay masonry units expand on absorption of water or water vapor. This expansion is irreversible.
Moisture movement in wood
Wood shrinks and swells, depending on the ambient air’s humidity and temperature, changing in dimensions.
Material with the highest coefficient of thermal expansion
Plastics.
Creep Deflection
Time-dependent additional deflection of the beam is known as________.
Elastic Deformation
Building components are designed to remain elastic under loads. Also known as instantaneous deformation. These are routinely determined for all types of structures and are a part of the structural calculations.
Joint detailing of an expansion joint
The filler of the joint must be elastomeric to allow for unrestrained movement of the components.
Joint detailing of a control joint
This filler can be elastomeric or nonelastomeric. The detailing must allow for unrestrained shrinkage of the components.
Difference between expansion joint and control joint
Control joints occur in concrete masonry or masonry walls. Expansion joints are provided in almost all components because temperature-induced movement is universal.
Purpose of sealing a joint
Primary reason: to prevent water penetration. Control of air leakage, dust penetration, and noise transmission are additional benefits.
In addition to joint sealants, what other components are important to a sealed joint?
- Substrate
- Primer
- Sealant Backup
- Bond Breaker
What is important for sealed joints with regards to the substrate?
The chemical compatibility of the sealant with the substrate material is critical to the adhesion of the sealant.
Purpose of a primer in sealed joints
Improve adhesion of the sealant to substrate.
Backer rod functions
- Controls depth and shape of sealant
- Allows the tooling of the sealant, which gives adhesion between the sealant and substrate
- Acts as a temporary joint seal until the sealant is applied
Bond Breaker
This is required only if the third surface is hard and unyielding (e.g., concrete, metal, masonry).