Concrete Finishing and Curing

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

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

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

<p>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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>Concrete = Has no strength gain</p> Signup and view all the answers

<p>Construction Joints = Permit no movement None of the above = Isolation joints</p> Signup and view all the answers

<p>Contraction Joints = In meters Isolation Joints = Around columns Construction Joints = In structural building systems None of the above = In slabs on ground</p> Signup and view all the answers

<p>Construction Joints = May be used as contraction joints None of the above = May induce controlled cracking</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>Strength = Improved Volume stability = Improved Permeability resistance = Improved Durability = Improved</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>Abrasion resistance = Improved Freezing and thawing resistance = Improved Deicer scaling resistance = Improved Permeability resistance = Improved</p> Signup and view all the answers

<p>Ponding or immersion = Retaining moisture Sealing in the mix water = Retaining moisture Accelerated curing = Accelerating strength gain Spraying or fogging = Retaining moisture</p> Signup and view all the answers

<p>Before brooming = Soft Before curing = Sensitive to moisture After brooming = Slip-resistant After curing = Hard and durable</p> Signup and view all the answers

<p>Ponding or immersion = Temperature control Sealing in the mix water = Moisture control Accelerated curing = Temperature control Spraying or fogging = Moisture control</p> Signup and view all the answers

<p>Hydration = Affected by Strength = Improved by Durability = Improved by Volume stability = Improved by</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>Waxes = Membrane-forming curing compounds Resins = Wet coverings Chlorinated rubber = Fogging and sprinkling Impervious paper = Preventing thermal stresses</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>Type and quality of cementing materials = Important Mixture proportions = Not important Required strength = Important Ambient conditions = Not important</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>$Compacting Factor = \frac{Weight of partially compacted concrete}{Weight of fully compacted concrete}$ = 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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>ASTM C360 = Kelly Ball Test ASTM C143 = Slump Test ASTM C289 = Compacting Factor Test ASTM C138 = Kelly Ball Test</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>Screeding = First stage of finishing Bullfloating or Darbying = Second stage of finishing Floating = Third stage of finishing Troweling = Final stage of finishing</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>Troweling = Requires a floated surface Bullfloating or Darbying = Requires a screeded surface Floating = Requires a compacted surface Screeding = Requires a freshly poured concrete surface</p> Signup and view all the answers

<p>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</p> Signup and view all the answers

<p>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</p> Signup and view all the answers