1) the particles of concrete mixture are properly

1)           
A large volume of concrete which is large enough to maintain
the heat of hydration and the volume change without cracking is identified as a
mass concrete.

 

2)           
Flow table use to determine consistency of the fresh concrete.
This method uses when the slump test is not possible to done where the concrete
is too fluid, where it cannot keep the shape when the cone is removed.

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!


order now

 

3)           
The slump test is not good in stiff mixes which have zero
slump or for wet mixes that gives a collapse slumps.

 

4)           
Vebe test cannot be implement where the mixes have high
or medium slump test values. Only dry mixes which has low slump value can done
vebe test.

 

5)           
Concrete consistency is the measure which check the
attraction between ingredients (Cement, Aggregate and water) When the
attraction between parts are very high the consistency is very high.
Consistency depend on the ratio of the mixture ingredients.

 

6)           
Segregation is the separation of the
constituent materials of concrete. A good concrete is one in which all the particles
of concrete mixture are properly distributed to make a homogeneous mixture.
cohesion is the action which keep the mixture united. So, to prevent
segregation of the concrete mixtures it is needing to have cohesion action in
the mixture.

 

7)           
Segregation is the separation from
simple words. It describes the non-homogeneous of the concrete mixture. If the segregation
happens in the mixture the concrete will not yield to the actual strength it
requires.

 

8)           
Bleeding in concrete is water gain of
the concrete mixture. which some of the water from the concrete mixture comes
out to the surface of the concrete in hardening stage. Bleeding can have
observed in a highly wet mix, badly proportioned and insufficiently mixed
concrete. In thin members like roof slab or road slabs and when concrete is
placed in high temperature show excessive bleeding. Due to bleeding, water
comes up and accumulates at the surface of the concrete bed.

 

9)           
Honeycombing is the areas of the
concrete surface that are looks and feel coarse and stony. It may be caused by the
lack of fine material in the mix, In most cases due to incorrect aggregate
grading or poor mixing. This can be corrected by increasing the sand and cement
content of the mix and by proper mixing of the concrete, placing and
compaction. Alternatively, honeycombing may be caused by leakage of grout or
mortar fraction from the concrete at construction or formwork joints while the
pouring of the concrete and while the vibration process. The solution here is
to ensure that joints are well sealed and leak-free.

 

10)       
For very stiff concrete mixes having low
or no slump, the slump test does not
indicate any difference in concretes of different workability. Different concretes
having same slump may have
indeed different workability under the
site conditions.

 

11)       
Bleeding is the
appearance of a watery on the surface of a concrete after compaction
of the concrete mix. It is an indication that there is too much water or
moisture in the concrete mix, or that too much tamping, floating or troweling
has been done. The result is a porous, dusty and weak surface. Bleeding makes
weak joints between lifts in structural work.

 

12)       
Water Cement Aggregate ratio

Amount and
type of aggregate

Amount and
type of cement

Weather
Condition (Temperature/ Wind)

Chemical
Admixtures

 

13)       
When the section is narrow, a highly
workable concrete is applicable to obtain full compaction through less effort.
When the section is disturbed with steel reinforcement and spacing of bars is small,
compaction can be difficult and because of that highly workable concrete is applied
in such cases. If there are no limitations of the critical section or heavy
reinforcement, we can get a wide range of workability for concrete mixture.

 

14)       
Advantage

 

·        
The Vebe is a dynamic test and can be
used on concretes that are too dry for the slump test. 

·        
The test device is standardized in ASTM
and identified by ACI Committee 211 (2002) in its guide for proportioning low
slump concrete. 

·        
Test results are obtained
directly. 

Disadvantages

 

·        
Due to the need to ensure that all
vibration is kept within the test device, the size of the test device makes the
Vebe generally unsuitable for field use. 

·        

The test device only works for low slump concretes. 

·        
No analytical treatment of the test
method has been developed. Such treatment would be complex because the shear
rate declines during the duration of the test as the concrete specimen changes
shape.

 

15)       
Mmm

 

16)       
Mmm

 

17)       
Mmm

 

18)       
Laitance is caused by bleeding of
concrete. In case of laitance, along with water certain quantity of cement also
comes to the surface, forming a thin layer of cement paste at the surface. This
formation of cement paste at the surface is known as laitance.

 

19)       
Requirement of concrete workability
varies with different types of construction. For a construction
with use of large percentage of reinforcement, where the gap between reinforcement
is less and compaction cannot be done effective, highly workable concrete such
as self-compacting is recommended.

 

20)       
Within a few hours after the
placing of fresh concrete, concrete may experience cracking owing to the
occurrence of plastic shrinkage and plastic settlement. The cause of plastic
settlement is related to bleeding of fresh concrete. Bleeding refers to the
migration of water to the top of concrete and the movement of solid particles
to the bottom of fresh concrete. The expulsion of water during bleeding results
in the reduction of the volume of fresh concrete. This induces a downward
movement of wet concrete. If such movement is hindered by the presence of
obstacles like steel reinforcement, cracks will be formed.

21)       
Mmm

22)       
Concrete with a low cement
content. Main function of the lean concrete is to provide the uniform surface
to the foundation concrete and to prevent the direct contact of foundation
concrete from the soil. Lean Concrete is used under the foundations.

23)       
A
mixture of concrete or mortar with a
relatively low cement content is called a lean
mix

24)       
A good concrete
is one in which all the ingredients are properly distributed to make a
homogeneous mixture. Segregation is the separation of the constituent materials
of concrete. So, to have a good concrete absence of segregation is important.

25)       
 

Slump test

It is the most common method for measuring the
workability of freshly mixed concrete. It can be performed both in lab and at
site. Uniformity of the concrete regarding workability and quality aspects can
be assessed from batch to batch by observing the nature in which the concrete
slumps. It is not very suitable for very wet or very dry concrete.

Compacting factor test

This test is generally carried out in laboratory but can
be used in site also. It is particularly useful for concrete mixes of very low
workability (or very dry concrete) as they are insensitive to slump test.

Vebe test

Vebe test is a good laboratory test suitable for stiff
concrete mixes having low and very low workability. It consists of a vibrating
table, a metal pot, a sheet of metal cone and a standard iron rod.

26)       
 

When the slump test is
carried out, three types can be observed as True slump, Shear slump and
collaps.

True
Slump – True slump is the only slump that can
be measured in the test. The measurement is taken between the top of the cone
and the top of the concrete after the cone has been removed.

Collapsed
Slump – This is an indication that the
water-cement ratio is too high, i.e. concrete mix is too wet or it is a high
workability mix, for which a slump test is not appropriate.

Shear
Slump – The shear slump indicates that the
result is incomplete, and concrete to be retested.

27)       
With the passage
of time after mixing ingredients of concrete with water, workability of
concrete starts decreasing. This happens because of fluidity loss from the
concrete. Fluidity is the amount of available water in concrete that is being
utilized in hydration of cement paste.

 

28)       
Concrete
workability describe how easily freshly mixed concrete can be mixed, placed,
consolidated and finished with minimal loss of homogeneity. Workability is a
property that directly impacts strength, quality, appearance, and even the cost
of labor for placement and finishing operations.

 

29)       
Compacting factor test is another
method of testing workability of the concrete. It is applicable where the slump
test is not applicable. It uses for very low workability concrete. Compacting factor
is the ratio of weight of partially compacted concrete to the weight of fully
compacted concrete. The test is done by using a apparatus which is build with
two hoppers (Top and Bottom) and a Cylinder at the bottom of the apparatus.

 

30)       
Yield is used to describe the actual volume of concrete produced when a
truck is batched at a ready-mix plant. Occasionally, some contractors or
producers might worry that the amount of concrete batched and delivered to a
jobsite might be greater or less than the amount ordered. In this case, a yield
calculation, based on unit weight, can be performed to discover whether
shortages, or overages, are occurring.

 

 

 1)           
A large volume of concrete which is large enough to maintain
the heat of hydration and the volume change without cracking is identified as a
mass concrete.

 

2)           
Flow table use to determine consistency of the fresh concrete.
This method uses when the slump test is not possible to done where the concrete
is too fluid, where it cannot keep the shape when the cone is removed.

 

3)           
The slump test is not good in stiff mixes which have zero
slump or for wet mixes that gives a collapse slumps.

 

4)           
Vebe test cannot be implement where the mixes have high
or medium slump test values. Only dry mixes which has low slump value can done
vebe test.

 

5)           
Concrete consistency is the measure which check the
attraction between ingredients (Cement, Aggregate and water) When the
attraction between parts are very high the consistency is very high.
Consistency depend on the ratio of the mixture ingredients.

 

6)           
Segregation is the separation of the
constituent materials of concrete. A good concrete is one in which all the particles
of concrete mixture are properly distributed to make a homogeneous mixture.
cohesion is the action which keep the mixture united. So, to prevent
segregation of the concrete mixtures it is needing to have cohesion action in
the mixture.

 

7)           
Segregation is the separation from
simple words. It describes the non-homogeneous of the concrete mixture. If the segregation
happens in the mixture the concrete will not yield to the actual strength it
requires.

 

8)           
Bleeding in concrete is water gain of
the concrete mixture. which some of the water from the concrete mixture comes
out to the surface of the concrete in hardening stage. Bleeding can have
observed in a highly wet mix, badly proportioned and insufficiently mixed
concrete. In thin members like roof slab or road slabs and when concrete is
placed in high temperature show excessive bleeding. Due to bleeding, water
comes up and accumulates at the surface of the concrete bed.

 

9)           
Honeycombing is the areas of the
concrete surface that are looks and feel coarse and stony. It may be caused by the
lack of fine material in the mix, In most cases due to incorrect aggregate
grading or poor mixing. This can be corrected by increasing the sand and cement
content of the mix and by proper mixing of the concrete, placing and
compaction. Alternatively, honeycombing may be caused by leakage of grout or
mortar fraction from the concrete at construction or formwork joints while the
pouring of the concrete and while the vibration process. The solution here is
to ensure that joints are well sealed and leak-free.

 

10)       
For very stiff concrete mixes having low
or no slump, the slump test does not
indicate any difference in concretes of different workability. Different concretes
having same slump may have
indeed different workability under the
site conditions.

 

11)       
Bleeding is the
appearance of a watery on the surface of a concrete after compaction
of the concrete mix. It is an indication that there is too much water or
moisture in the concrete mix, or that too much tamping, floating or troweling
has been done. The result is a porous, dusty and weak surface. Bleeding makes
weak joints between lifts in structural work.

 

12)       
Water Cement Aggregate ratio

Amount and
type of aggregate

Amount and
type of cement

Weather
Condition (Temperature/ Wind)

Chemical
Admixtures

 

13)       
When the section is narrow, a highly
workable concrete is applicable to obtain full compaction through less effort.
When the section is disturbed with steel reinforcement and spacing of bars is small,
compaction can be difficult and because of that highly workable concrete is applied
in such cases. If there are no limitations of the critical section or heavy
reinforcement, we can get a wide range of workability for concrete mixture.

 

14)       
Advantage

 

·        
The Vebe is a dynamic test and can be
used on concretes that are too dry for the slump test. 

·        
The test device is standardized in ASTM
and identified by ACI Committee 211 (2002) in its guide for proportioning low
slump concrete. 

·        
Test results are obtained
directly. 

Disadvantages

 

·        
Due to the need to ensure that all
vibration is kept within the test device, the size of the test device makes the
Vebe generally unsuitable for field use. 

·        

The test device only works for low slump concretes. 

·        
No analytical treatment of the test
method has been developed. Such treatment would be complex because the shear
rate declines during the duration of the test as the concrete specimen changes
shape.

 

15)       
Mmm

 

16)       
Mmm

 

17)       
Mmm

 

18)       
Laitance is caused by bleeding of
concrete. In case of laitance, along with water certain quantity of cement also
comes to the surface, forming a thin layer of cement paste at the surface. This
formation of cement paste at the surface is known as laitance.

 

19)       
Requirement of concrete workability
varies with different types of construction. For a construction
with use of large percentage of reinforcement, where the gap between reinforcement
is less and compaction cannot be done effective, highly workable concrete such
as self-compacting is recommended.

 

20)       
Within a few hours after the
placing of fresh concrete, concrete may experience cracking owing to the
occurrence of plastic shrinkage and plastic settlement. The cause of plastic
settlement is related to bleeding of fresh concrete. Bleeding refers to the
migration of water to the top of concrete and the movement of solid particles
to the bottom of fresh concrete. The expulsion of water during bleeding results
in the reduction of the volume of fresh concrete. This induces a downward
movement of wet concrete. If such movement is hindered by the presence of
obstacles like steel reinforcement, cracks will be formed.

21)       
Mmm

22)       
Concrete with a low cement
content. Main function of the lean concrete is to provide the uniform surface
to the foundation concrete and to prevent the direct contact of foundation
concrete from the soil. Lean Concrete is used under the foundations.

23)       
A
mixture of concrete or mortar with a
relatively low cement content is called a lean
mix

24)       
A good concrete
is one in which all the ingredients are properly distributed to make a
homogeneous mixture. Segregation is the separation of the constituent materials
of concrete. So, to have a good concrete absence of segregation is important.

25)       
 

Slump test

It is the most common method for measuring the
workability of freshly mixed concrete. It can be performed both in lab and at
site. Uniformity of the concrete regarding workability and quality aspects can
be assessed from batch to batch by observing the nature in which the concrete
slumps. It is not very suitable for very wet or very dry concrete.

Compacting factor test

This test is generally carried out in laboratory but can
be used in site also. It is particularly useful for concrete mixes of very low
workability (or very dry concrete) as they are insensitive to slump test.

Vebe test

Vebe test is a good laboratory test suitable for stiff
concrete mixes having low and very low workability. It consists of a vibrating
table, a metal pot, a sheet of metal cone and a standard iron rod.

26)       
 

When the slump test is
carried out, three types can be observed as True slump, Shear slump and
collaps.

True
Slump – True slump is the only slump that can
be measured in the test. The measurement is taken between the top of the cone
and the top of the concrete after the cone has been removed.

Collapsed
Slump – This is an indication that the
water-cement ratio is too high, i.e. concrete mix is too wet or it is a high
workability mix, for which a slump test is not appropriate.

Shear
Slump – The shear slump indicates that the
result is incomplete, and concrete to be retested.

27)       
With the passage
of time after mixing ingredients of concrete with water, workability of
concrete starts decreasing. This happens because of fluidity loss from the
concrete. Fluidity is the amount of available water in concrete that is being
utilized in hydration of cement paste.

 

28)       
Concrete
workability describe how easily freshly mixed concrete can be mixed, placed,
consolidated and finished with minimal loss of homogeneity. Workability is a
property that directly impacts strength, quality, appearance, and even the cost
of labor for placement and finishing operations.

 

29)       
Compacting factor test is another
method of testing workability of the concrete. It is applicable where the slump
test is not applicable. It uses for very low workability concrete. Compacting factor
is the ratio of weight of partially compacted concrete to the weight of fully
compacted concrete. The test is done by using a apparatus which is build with
two hoppers (Top and Bottom) and a Cylinder at the bottom of the apparatus.

 

30)       
Yield is used to describe the actual volume of concrete produced when a
truck is batched at a ready-mix plant. Occasionally, some contractors or
producers might worry that the amount of concrete batched and delivered to a
jobsite might be greater or less than the amount ordered. In this case, a yield
calculation, based on unit weight, can be performed to discover whether
shortages, or overages, are occurring.