45 Questions
Match the following types of joints with their descriptions:
Isolation Joints = Permit both horizontal and vertical differential movements Contraction Joints = Provide for movement in the plane of a slab or wall Construction Joints = Stopping points in the construction process None of the above = Random cracks may occur
Match the following joints with their purpose:
Isolation Joints = To isolate slabs-on ground from fixed foundation members Contraction Joints = To induce controlled cracking Construction Joints = To permit movement in the plane of a slab or wall None of the above = To permit both horizontal and vertical differential movements
Match the following joints with their characteristics:
Isolation Joints = Used around columns Contraction Joints = Used to prevent random cracks Construction Joints = Used as stopping points in the construction process None of the above = Used to isolate slabs-on ground from fixed foundation members
Match the following joints with their applications:
Isolation Joints = Around the perimeter of a floor on ground Contraction Joints = In slabs on ground Construction Joints = In structural building systems None of the above = In random crack prevention
Match the following effects with their causes:
Random cracks = No contraction joints or widely spaced contraction joints Controlled cracking = Contraction joints Tensile stresses = Drying and thermal shrinkage None of the above = Higher curing temperature
Match the following materials with their properties:
Concrete = Has no strength gain
Match the following construction joints with their descriptions:
Construction Joints = Permit no movement None of the above = Isolation joints
Match the following joints with their spacing:
Contraction Joints = In meters Isolation Joints = Around columns Construction Joints = In structural building systems None of the above = In slabs on ground
Match the following construction joints with their characteristics:
Construction Joints = May be used as contraction joints None of the above = May induce controlled cracking
Match the following concrete curing methods with their descriptions:
Ponding or immersion = Supplying additional moisture Sealing in the mix water = Reducing the loss of mixing water Accelerated curing = Supplying heat and additional moisture Spraying or fogging = Supplying additional moisture
Match the following concrete properties with the results of curing:
Strength = Improved Volume stability = Improved Permeability resistance = Improved Durability = Improved
Match the following concrete curing methods with their application:
Ponding or immersion = On horizontal surfaces Sealing in the mix water = On vertical surfaces Accelerated curing = On critical structures Spraying or fogging = On large surfaces
Match the following concrete curing methods with their necessary materials:
Ponding or immersion = Water Sealing in the mix water = Impervious paper or plastic sheets Accelerated curing = Live steam or heating coils Spraying or fogging = Water
Match the following concrete properties with their improvement due to curing:
Abrasion resistance = Improved Freezing and thawing resistance = Improved Deicer scaling resistance = Improved Permeability resistance = Improved
Match the following concrete curing methods with their purpose:
Ponding or immersion = Retaining moisture Sealing in the mix water = Retaining moisture Accelerated curing = Accelerating strength gain Spraying or fogging = Retaining moisture
Match the following concrete stages with their properties:
Before brooming = Soft Before curing = Sensitive to moisture After brooming = Slip-resistant After curing = Hard and durable
Match the following concrete curing methods with their environmental control:
Ponding or immersion = Temperature control Sealing in the mix water = Moisture control Accelerated curing = Temperature control Spraying or fogging = Moisture control
Match the following concrete properties with their relation to curing:
Hydration = Affected by Strength = Improved by Durability = Improved by Volume stability = Improved by
Match the following curing methods with their descriptions:
Fogging and Sprinkling = Excellent methods for curing when ambient temperature is above freezing and humidity is low Wet Coverings = Maintaining relative humidity above 80% for 7 days Impervious Paper = Preventing thermal stresses and cracking Membrane-Forming Curing Compounds = Retarding or reducing evaporation of moisture from concrete
Match the following conditions with their recommended curing periods:
Ambient temperatures above 5°C = Minimum of 7 days Concrete slabs on ground = Above 7 days Structural concrete = Less than 7 days Concrete in freezing conditions = No curing period
Match the following materials with their uses:
Waxes = Membrane-forming curing compounds Resins = Wet coverings Chlorinated rubber = Fogging and sprinkling Impervious paper = Preventing thermal stresses
Match the following curing methods with their effects:
Fogging and Sprinkling = Reducing evaporation of moisture Wet Coverings = Retarding moisture loss Impervious Paper = Maintaining humidity above 80% Membrane-Forming Curing Compounds = Preventing thermal stresses
Match the following concrete types with their required curing periods:
Concrete slabs on ground = Minimum of 7 days Structural concrete = Minimum of 7 days Concrete in hot weather = Less than 7 days Concrete in freezing conditions = No curing period
Match the following characteristics with their importance in curing:
Type and quality of cementing materials = Important Mixture proportions = Not important Required strength = Important Ambient conditions = Not important
Match the following curing methods with their requirements:
Fogging and Sprinkling = Ambient temperature above freezing and low humidity Wet Coverings = Maintaining relative humidity above 80% Impervious Paper = Retarding moisture loss Membrane-Forming Curing Compounds = Reducing evaporation of moisture
Match the following factors with their effects on curing period:
Type and quality of cementing materials = Affects curing period Mixture proportions = Affects curing period Required strength = Affects curing period Future exposure conditions = Does not affect curing period
Match the following curing methods with their benefits:
Fogging and Sprinkling = Preventing moisture loss Wet Coverings = Reducing evaporation of moisture Impervious Paper = Maintaining humidity above 80% Membrane-Forming Curing Compounds = Sustaining cement hydration
Match the following tests with their primary usage:
Slump Test = Measuring the workability of fresh concrete Compacting Factor Test = Determining the degree of compaction achieved by a standard amount of work done Kelly Ball Test = Measuring the penetration of a Kelly ball into the concrete surface Vibrating Table Test = Compacting concrete for low workability mixes
Match the following characteristics with the corresponding test:
Measuring the degree of compaction achieved = Compacting Factor Test Measuring the penetration of a Kelly ball = Kelly Ball Test Determining workability by flow of concrete = Slump Test Measuring the weight of partially compacted concrete = Compacting Factor Test
Match the following ranges with the corresponding test:
0.78 to 0.95 = Compacting Factor Test 0 to 250 mm = Slump Test 0 to 10 inches = Kelly Ball Test 0 to 100 kPa = Compacting Factor Test
Match the following statements with the corresponding test:
It is more precise and sensitive than the slump test = Compacting Factor Test It is used to measure the workability of concrete = Slump Test It is used to measure the penetration of a Kelly ball = Kelly Ball Test It is used for laboratory and field tests = Compacting Factor Test
Match the following equations with the corresponding test:
$Compacting Factor = \frac{Weight of partially compacted concrete}{Weight of fully compacted concrete}$ = Compacting Factor Test $Slump = \frac{Height of slump}{Initial height}$ = Slump Test $Penetration = \frac{Distance of penetration}{Time}$ = Kelly Ball Test $Workability = \frac{Flow of concrete}{Time}$ = Slump Test
Match the following apparatus with the corresponding test:
Mold and tamping rod = Slump Test Hopper, cylinder, and plate = Compacting Factor Test Kelly ball and guiding rod = Kelly Ball Test Vibrating table = Compacting Factor Test
Match the following characteristics with the corresponding test:
Measures the inherent characteristics of concrete = Compacting Factor Test Measures the flow of concrete = Slump Test Measures the penetration of a Kelly ball = Kelly Ball Test Measures the weight of partially compacted concrete = Compacting Factor Test
Match the following standards with the corresponding test:
ASTM C360 = Kelly Ball Test ASTM C143 = Slump Test ASTM C289 = Compacting Factor Test ASTM C138 = Kelly Ball Test
Match the following ranges with the corresponding characteristic:
0.78 to 0.95 = Compacting Factor 0 to 250 mm = Slump 0 to 10 inches = Kelly Ball Penetration 0 to 100 kPa = Concrete Strength
Match the following methods with their purpose in compacting concrete:
Hand Compaction = Compacting concrete manually Compaction by Vibration = Removing air from concrete using vibrations Internal vibrator = Consolidating concrete in walls and columns External vibrator = Compacting concrete from outside the formwork
Match the following finishing methods with their purposes:
Screeding = Cutting off excess concrete to bring the top surface to proper grade Bullfloating or Darbying = Eliminating high and low spots and embedding large aggregate particles Floating = Embedding aggregate particles and removing imperfections Troweling = Creating a smooth, hard, dense surface
Match the following equipment with their uses:
Bullfloat or Darby = Eliminating high and low spots and embedding large aggregate particles Steel trowel = Creating a smooth, hard, dense surface Internal vibrator = Consolidating concrete in walls and columns External vibrator = Compacting concrete from outside the formwork
Match the following concrete defects with their causes:
Loss of strength = Air not removed fully from concrete High and low spots = Improper finishing of concrete Voids and humps = Inadequate floating of concrete Weak surface = Inadequate or lack of troweling
Match the following stages of concrete finishing with their sequences:
Screeding = First stage of finishing Bullfloating or Darbying = Second stage of finishing Floating = Third stage of finishing Troweling = Final stage of finishing
Match the following compaction methods with their advantages:
Hand Compaction = Simple and cost-effective Compaction by Vibration = Effective in removing air from concrete Internal vibrator = Suitable for compacting concrete in restricted spaces External vibrator = Effective for compacting large areas of concrete
Match the following finishing methods with their requirements:
Troweling = Requires a floated surface Bullfloating or Darbying = Requires a screeded surface Floating = Requires a compacted surface Screeding = Requires a freshly poured concrete surface
Match the following compaction methods with their limitations:
Hand Compaction = Not effective for large areas of concrete Compaction by Vibration = May cause damage to adjacent structures Internal vibrator = Limited accessibility in compacting large areas External vibrator = May not be effective for compacting concrete in restricted spaces
Match the following finishing methods with their advantages:
Troweling = Produces a smooth, hard, dense surface Bullfloating or Darbying = Eliminates high and low spots effectively Floating = Embeds aggregate particles and removes imperfections Screeding = Brings the top surface to proper grade
Study Notes
Brooming and Curing
- Brooming should be performed before concrete has thoroughly hardened, but when it is sufficiently hard to retain the scoring impression and produce a slip-resistant surface.
- Curing is the process of maintaining a satisfactory moisture content and temperature in concrete for a sufficient period of time to develop desired properties.
Curing Methods
- Three curing methods: supplying additional moisture, sealing in the mix water, and accelerated curing.
- Supplying additional moisture: ponding, immersion, spraying, or fogging, and saturated wet coverings.
- Sealing in the mix water: covering with impervious paper or plastic sheets, or applying membrane-forming curing compounds.
- Accelerated curing: supplying heat and additional moisture to accelerate strength gain.
Curing Compounds and Period
- Curing compounds should maintain the relative humidity of the concrete surface above 80% for seven days to sustain cement hydration.
- Curing period depends on factors such as type and quality of cementing materials, mixture proportions, required strength, size and shape of the concrete member, ambient conditions, and future exposure conditions.
Jointing Concrete
- Three types of joints: isolation joints, contraction joints, and construction joints.
- Isolation joints: permit horizontal and vertical differential movements at adjoining parts of a structure.
- Contraction joints: provide for movement in the plane of a slab or wall, inducing controlled cracking at preselected locations.
- Construction joints: stopping places in the process of construction, bonding new concrete to existing concrete and permitting no movement.
Workability and Compacting Factor
- Compacting factor test: measures the degree of compaction achieved by a standard amount of work done by allowing the concrete to fall through a standard height.
- The compacting factor is measured by the density ratio, i.e., the ratio of the density actually achieved in the test to the density of the same concrete fully compacted.
- Range of compaction factor: from 0.78 to 0.95, with higher fluidity concrete having a higher compaction factor.
Finishing of Concrete
- Finishing methods: strikeoff, screeding, bullfloating, darbying, floating, and troweling.
- Screeding (strikeoff): cutting off excess concrete to bring the top surface of a slab to proper grade.
- Bullfloating (darbying): eliminating high and low spots and embedding large aggregate particles.
- Floating: embedding aggregate particles just beneath the surface, removing slight imperfections, and compacting the mortar at the surface.
- Troweling: producing a smooth, hard, dense surface, which should be done on a surface that has been floated.
Learn about the importance of brooming and tining in concrete finishing and the process of curing concrete to achieve desired properties.
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