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Questions and Answers
The curing water should not be more than about ______ °C cooler than the concrete to prevent thermal stresses that result in cracking.
The curing water should not be more than about ______ °C cooler than the concrete to prevent thermal stresses that result in cracking.
11
Fogging and sprinkling with ______ are excellent methods of curing when the ambient temperature is well above freezing and the humidity is low.
Fogging and sprinkling with ______ are excellent methods of curing when the ambient temperature is well above freezing and the humidity is low.
water
Liquid membrane-forming compounds consisting of ______, resins, chlorinated rubber, and other materials can be used to retard or reduce evaporation of moisture from concrete.
Liquid membrane-forming compounds consisting of ______, resins, chlorinated rubber, and other materials can be used to retard or reduce evaporation of moisture from concrete.
waxes
Curing compounds should be able to maintain the relative humidity of the concrete surface above ______ % for seven days to sustain cement hydration.
Curing compounds should be able to maintain the relative humidity of the concrete surface above ______ % for seven days to sustain cement hydration.
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The period of time that concrete should be protected from ______, abnormally high temperatures, and against loss of moisture depends upon a number of factors.
The period of time that concrete should be protected from ______, abnormally high temperatures, and against loss of moisture depends upon a number of factors.
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For concrete slabs on ground and for structural concrete, the length of the curing period for ambient temperatures above ______ °C should be a minimum of 7 days.
For concrete slabs on ground and for structural concrete, the length of the curing period for ambient temperatures above ______ °C should be a minimum of 7 days.
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The type and quality of ______ materials used can affect the length of the curing period.
The type and quality of ______ materials used can affect the length of the curing period.
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Required ______, size and shape of the concrete member can affect the length of the curing period.
Required ______, size and shape of the concrete member can affect the length of the curing period.
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A higher curing ______ provides earlier strength gain in concrete than a lower temperature.
A higher curing ______ provides earlier strength gain in concrete than a lower temperature.
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Isolation joints permit both horizontal and vertical differential ______ at adjoining parts of a structure.
Isolation joints permit both horizontal and vertical differential ______ at adjoining parts of a structure.
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Contraction joints provide for ______ in the plane of a slab or wall.
Contraction joints provide for ______ in the plane of a slab or wall.
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Joints induce controlled ______ caused by drying and thermal shrinkage at preselected locations.
Joints induce controlled ______ caused by drying and thermal shrinkage at preselected locations.
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If no contraction joints are used, or if they are too widely spaced in slabs on ground, random ______ may occur.
If no contraction joints are used, or if they are too widely spaced in slabs on ground, random ______ may occur.
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Construction joints are stopping points in the ______ process.
Construction joints are stopping points in the ______ process.
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A true construction joint should bond new ______ to existing concrete and permit no movement.
A true construction joint should bond new ______ to existing concrete and permit no movement.
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Construction-joint types (a) and (b) are also used as ______ joints.
Construction-joint types (a) and (b) are also used as ______ joints.
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The compacting factor test measures the inherent characteristics of the ______ which relates very close to the workability requirements of concrete.
The compacting factor test measures the inherent characteristics of the ______ which relates very close to the workability requirements of concrete.
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The slump test is responsible for its widespread use due to its ______ and simplicity.
The slump test is responsible for its widespread use due to its ______ and simplicity.
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The compacting factor test is designed primarily for use in the ______ but it can also be used in the field.
The compacting factor test is designed primarily for use in the ______ but it can also be used in the field.
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The ______ test is designed primarily for use in the laboratory but it can also be used in the field.
The ______ test is designed primarily for use in the laboratory but it can also be used in the field.
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The degree of compaction, called the ______ factor, is measured by the density ratio.
The degree of compaction, called the ______ factor, is measured by the density ratio.
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The compacting factor test is particularly useful for ______ mixes of very low workability.
The compacting factor test is particularly useful for ______ mixes of very low workability.
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The range of ______ factor is from 0.78 to 0.95 and concrete with high fluidity has a higher ______ factor.
The range of ______ factor is from 0.78 to 0.95 and concrete with high fluidity has a higher ______ factor.
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ASTM C360 covers the ______ ball penetration test.
ASTM C360 covers the ______ ball penetration test.
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Bleeding is the development of a layer of ______ at the top or surface of freshly placed concrete.
Bleeding is the development of a layer of ______ at the top or surface of freshly placed concrete.
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Some bleeding is normal and it should not diminish the quality of properly placed, finished, and cured ______.
Some bleeding is normal and it should not diminish the quality of properly placed, finished, and cured ______.
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Excessive bleeding increases the ______-cement ratio near the top surface which creates a weak top layer with poor durability.
Excessive bleeding increases the ______-cement ratio near the top surface which creates a weak top layer with poor durability.
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Lack of ______ water on concrete flat work can sometimes lead to plastic shrinkage cracking or a dry surface that is difficult to finish.
Lack of ______ water on concrete flat work can sometimes lead to plastic shrinkage cracking or a dry surface that is difficult to finish.
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The most effective means of reducing bleeding in concrete include reducing the ______ content.
The most effective means of reducing bleeding in concrete include reducing the ______ content.
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Batching is the process of measuring quantities of ______ mixture ingredients by either mass or volume and introducing them into the mixer.
Batching is the process of measuring quantities of ______ mixture ingredients by either mass or volume and introducing them into the mixer.
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Using finer ______ materials can help reduce bleeding in concrete.
Using finer ______ materials can help reduce bleeding in concrete.
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Increasing the amount of ______ in the sand can help reduce bleeding in concrete.
Increasing the amount of ______ in the sand can help reduce bleeding in concrete.
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Truck-mixed concrete is mixed completely in a ______ mixer
Truck-mixed concrete is mixed completely in a ______ mixer
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The process of remixing of concrete, if necessary, with addition of just the required quantity of ______ is known as “Retempering of Concrete”
The process of remixing of concrete, if necessary, with addition of just the required quantity of ______ is known as “Retempering of Concrete”
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Sometimes, a small quantity of extra ______ is also added while retempering.
Sometimes, a small quantity of extra ______ is also added while retempering.
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Many specifications do not permit ______ of concrete.
Many specifications do not permit ______ of concrete.
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The precaution to be taken while transporting concrete is that the ______ obtained at the time of mixing should be maintained while being transported to the final place of deposition.
The precaution to be taken while transporting concrete is that the ______ obtained at the time of mixing should be maintained while being transported to the final place of deposition.
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Concrete can be transported by a variety of methods and ______.
Concrete can be transported by a variety of methods and ______.
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One of the methods adopted for transportation of concrete is ______ and Dumpers.
One of the methods adopted for transportation of concrete is ______ and Dumpers.
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Another method of transporting concrete is by using ______ and Pipe Line.
Another method of transporting concrete is by using ______ and Pipe Line.
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One of the unusual methods of transporting concrete is by using a ______.
One of the unusual methods of transporting concrete is by using a ______.
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Concrete can be transported by a ______ Conveyors.
Concrete can be transported by a ______ Conveyors.
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Study Notes
Curing Concrete
- The curing water should be no more than 11°C (20°F) cooler than the concrete to prevent thermal stresses and cracking.
- Fogging and sprinkling with water are effective curing methods when the ambient temperature is above freezing and the humidity is low.
- Curing compounds can be used to retard or reduce evaporation of moisture from concrete, maintaining a relative humidity above 80% for seven days to sustain cement hydration.
Curing Period and Temperature
- The curing period depends on factors such as cement type, mixture proportions, required strength, size and shape of the concrete member, ambient conditions, and future exposure conditions.
- For concrete slabs on ground and structural concrete, the minimum curing period should be at least 7 days for ambient temperatures above 5°C.
- Higher curing temperatures can provide earlier strength gain, but may decrease 28-day strength.
Jointing Concrete
- There are three common types of joints in concrete construction: 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 caused by drying and thermal shrinkage at preselected locations.
- Construction joints are stopping places in the construction process, bonding new concrete to existing concrete and permitting no movement.
Workability and Compacting Factor
- The compacting factor test measures the degree of compaction achieved by a standard amount of work done, allowing concrete to fall through a standard height.
- The compacting factor is measured by the density ratio, ranging from 0.78 to 0.95, with higher values indicating greater fluidity.
- The test is useful for concrete mixes of very low workability, particularly when compacted by vibration.
Bleeding and Settlement
- Bleeding is the development of a layer of water at the top or surface of freshly placed concrete, caused by sedimentation of solid particles and upward migration of water.
- Excessive bleeding can lead to a weak top layer with poor durability, particularly if finishing operations take place while bleed water is present.
- Effective means of reducing bleeding include reducing water content, increasing cement content, using finer cementitious materials, increasing fines in the sand, using supplementary cementing materials, and using air-entrained concrete.
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Description
This quiz covers different methods of curing concrete, including temperature control, fogging, sprinkling, and using membrane-forming compounds. Learn about the importance of proper curing techniques to prevent cracking and ensure strong concrete.
