Mod 3 - Wood 2021 -3- Treatment and Fasteners Flashcards
What are the properties of concrete that make it favorable as a building material?
- Corrosion resistant
- Strong in compression
- Fire resistant
- Durable
- Architecturally pleasing
- Wear resistant
- Watertight
- Sound resistant
- Quick construction/year-round construction
Define Workability in the context of concrete.
The ease of placing and finishing the plastic (fluid) concrete
What is Finishability?
Ease and quality with which the surface of fresh concrete can be shaped, smoothed, and finished
What is Segregation in concrete?
The separation of the aggregates from the cement paste during construction
What is Bleeding in concrete?
The formation of water on the surface of the fresh concrete
Define Durability in terms of concrete.
The concrete’s ability to resist weathering action, chemical attack, water penetration, or abrasion while maintaining the properties of the mix design
What is Consolidation in concrete?
The proper placement of plastic concrete to fully fill the formwork leaving no voids
What does Consistency refer to in concrete?
The workability or fluidity of fresh concrete
What is Slump in concrete?
The consistency of freshly mixed concrete measured by the vertical distance fluid concrete settles
What is the Water/Cement ratio?
Ratio of water and cement used in a particular concrete mix, expressed as mass of water/mass of cement
What is Hydration in concrete?
The reaction between water and cement that causes hardening
What ingredients are needed to make concrete?
- Water
- Fine Aggregates
- Coarse Aggregates
- Admixtures
- Air
Which ingredient in concrete is usually the most expensive?
Cement
What is the relationship between concrete strength and time?
Concrete’s strength increases over time as hydration continues
What is the standard strength evaluation time for concrete?
28 days
How does a low Water/Cement ratio affect concrete properties?
- Higher compressive strength
- Improved durability
- Reduced shrinkage and cracking
- Increased weathering resistance
- Better bond with reinforcement
- Lower permeability
What is the typical curing time for concrete cylinders in a laboratory?
28 days
What are the main concrete tests conducted at a jobsite?
- Slump Test
- Density/Air Content Test
- Compressive Strength Test
What is Plastic Concrete?
Concrete in its fresh, unhardened state before it has set or cured
What is the difference between Entrapped and Entrained Air?
- Entrapped Air: unintentional, larger, irregular
- Entrained Air: intentional, tiny, well-distributed
How is the Water/Cement ratio calculated?
Water/Cement Ratio (W/C) = Weight of Cement / Weight of Water
What is the minimum Water/Cement ratio required for hydration?
Approximately 0.25
How does concrete perform in Compression and Tension?
Strong in compression and weak in tension
What is the difference between Strength and Durability?
- Strength: ability to withstand applied loads
- Durability: ability to resist environmental degradation
Why do we use aggregates in concrete?
- Reduce cost
- Reduce drying shrinkage
- Increase ductility
What aggregate characteristics produce quality concrete?
- Aggregate strength
- Particle size distribution
- Shape and texture
- Surface texture
- Absorption and moisture content
- Chemical composition
- Cleanliness
How does aggregate strength affect concrete properties?
Stronger aggregates improve the concrete’s overall strength
What are the maximum size limitations for coarse aggregates?
- 1/5 of the narrowest dimension of forms
- 1/3 the depth of slabs
- 3/4 of minimum clear spacing between reinforcing bars
- 1/3 of smallest internal diameter of the hose or 40 mm
Define Relative Density in concrete.
Indication of how dense the rock materials are relative to water
What is Absorption in the context of concrete aggregates?
The ability of a material to take in and retain water
What is Bulk Density?
Mass of a material per unit of volume, including solid particles and void spaces
What is Void Content?
Volume of empty spaces within a material not occupied by solid particles
Differentiate between Fine and Coarse Aggregates.
- Fine Aggregates: particles smaller than 4.75 mm
- Coarse Aggregates: particles larger than 4.75 mm
What is Fineness Modulus (F.M.) and its typical ranges?
F.M. characterizes particle size distribution; typical ranges are 2.3-3.1 for fine aggregates and 5.0-8.0 for coarse aggregates
What three aggregate properties does CSA A23.1 govern?
- Grading
- Material Fineness and Particle shape
- Durability
What are ASR and ACR in relation to concrete durability?
Chemical reactions affecting durability, causing cracking, deformation, and loss of material
What is the product of burning a mixture of limestone and clay to produce cement?
Clinker
Name the 4 types of Portland Cement used in Canada.
- Type GU: General use Hydraulic Cement
- Type HE: High Early Strength Hydraulic Cement
- Type MS: Moderate Sulphate Resistant Hydraulic Cement
- Type HS: High Sulfate Resistant Hydraulic Cement
Fill in the blank: Proper moisture content of concrete will _______.
reduce voids from mixing and transportation
Fill in the blank: A visual feature known as _______ is a result of not properly vibrating concrete.
honeycomb
Fill in the blank: Finishing concrete with excessive bleed water results in _______.
cracking of the concrete
Fill in the blank: A slump test is an indication of the _______ of concrete.
consistency
Fill in the blank: When concrete is dropped from height or moved laterally, _______ may occur in the mix.
segregation
