TOP 5 TESTS ON FRESH CONCRETE
The wet mix of concrete in its plastic state is known as Fresh concrete. Cement, sand and coarse aggregate are the main ingredient of cement concrete. They are blended with water to form a paste.
Each component of concrete has unique qualities. The coarse aggregate acts as the filter. The fine aggregate fills the voids and the cement mix with water and acts as a binder.
Numerous test methods are available for measuring workability. Each test is unique for measuring each aspect.
TERMS RELATED TO FRESH CONCRETE
WORKABILITY
The ease or difficulty to handle concrete is workability. Minimum loss of homogeneity occurs. It measured in terms of placing and transportation.
SEGREGATION
The separation of a coarser particle from concrete is segregation. This leads to honeycombing and decreases density. Concrete should not be thrown from heights.
BLEEDING
The appearance of finishing water on the surface of concrete during compaction is bleeding. The concrete becomes pory and weak.
PROPERTIES OF FRESH CONCRETE
- Concrete should have a good compressive strength of about 4000psi.
- The density of the concrete is 2400 kg/cm³.
- The temperature of the fresh Concrete is 80 to 95°F.
- The pH value of the Concrete is 13.
- It should combat weathering action.
- Concrete should have minimal shrinkage.
- It should oppose abrasion.
- It should have minimum thermal expansion.
- It should have the least creep.
- It should be cost-effective.
- It should have corrosion resistance.
- Concrete must possess good resistance to fire.
TESTING OF FRESH CONCRETE
There are several tests for fresh concrete to determine its property. Each test is unique and has a unique method.
It is easy to discover the consistent quality and uniform strength of the Concrete.
The experiential tests which are used for testing fresh concrete are
- The slump test
- The compacting factor test
- The Vee Bee consistency test
- The flow test
- The Kelly Ball test
These empirical tests are performed to ascertain the physical attribute of the concrete.
THE SLUMP TEST
This circumscribes the consistency of the concrete. The nominal maximum size of the aggregate does not exceed 38mm. This method is adopted either in the laboratory or in fieldwork.
The dimensions of the mould are
Bottom diameter = 200mm
Top diameter = 100mm
Height = 300mm
PROCEDURE:-
The concrete is moulded into four layers and tamped 25 strokes using a tamping rod. The tamping rod is the round edge. The layers penetrate the underlying layer. Later the tamping mould is removed quickly.
Then it is raised slowly in the vertical direction. The sump is measured.
The difference between the heights is measured and noted.
Slump value for different types of concrete are given below.
COMPACTING FACTOR TEST
It is used for concrete having low and medium workability. Compacting factor test is more precise and sensitive than the slump test. It is suitable for concrete which is to be compacted by using vibrators.
PROCEDURE:-
The sample of concrete to be installed in the upper hopper. Later the hopper the trap door is opened. The concrete is allowed to fall. It is covered with trowels.
Later the door of the lower hopper is opened. The concrete is allowed to fall.
The concrete weight and partially compacted concrete weight measurement are taken. The same sample is refilled and heavily tamped. The formula for the compaction factor is
Compaction factor =
wt of Partially compacted concrete/
wt of fully compacted concrete
Each test is carried out with a constant time interval after the mixing is completely mixed.
VEE BEE CONSISTENCY METHOD
Vee bee consistency test determines the time required for vibration. The specimen is in the shape of the conical frustum. The apparatus used for this test is the Vee bee consistometer.
PROCEDURE:-
- The apparatus consists of a vibrator table on elastic supports, metal pots, a standard iron rod, and a sheet metal cone.
- This test is performed in a slump cone. Before lifting the cone, a glass disc is placed above the slump. The glass disc is attached to the swivel arm.
- A glass disc is arranged in the slump. The electrical vibrator is continued.
- The recorded time second is VB degree which represents the consistency of the concrete.
- Based on the Vee bee degree, the workability is calculated.
KELLY BALL TEST
Kelly Ball test is used for measuring the workability of the concrete. The result of this test is more consistent than the slump test.
PROCEDURE:-
The test apparatus consists of
Metal hemisphere = 15cm, weight = 13.6 kg
Graduation scale
Handle
Stem
Frame
Metallic hemisphere
- The concrete base should have a depth of 20cm. The ball is lowered gradually on the concrete surface.
- The distance between the concrete and the ball should be 23cm.
- The depth of penetration is noted immediately.
- This test can be performed in the field and also in the sites. It can be done for a shorter period of about 15 seconds.
THE FLOW TEST
The flow test is used to determine consistency, cohesiveness and non-segregation. The test procedure of the flow test is measuring concrete spread.
PROCEDURE:-
The mould is similar to the slump test apparatus.
Base diameter = 25 cm
Upper diameter = 17 cm
Height = 12 cm
Diameter of tamping rod = 1.6 cm
Length of tamping rod = 61 cm
- The flow table apparatus consists of a flow table 76mm in diameter. Concentric circles are marked on this table.
- The mould is filled with a layer of concrete.
- By using the tamping rod, tamped 25 times and excess concrete levelled.
- The mould is then lifted slowly and allowed to fall.
- The diameter of the flow of concrete is measured. Then the flow Percentage is calculated.
Flow (%) = Avg spread in dia(cm)*100
25
The flow test is done in the laboratory. The value of the flow test varies from 0 to 150. The spread of the concrete also indicates the segregation tendency.
The wet mix of concrete in its plastic state is known as Fresh concrete. Cement, sand and coarse aggregate are the main ingredient of cement concrete. They are blended with water to form a paste.
Each component of concrete has unique qualities. The coarse aggregate acts as the filter. The fine aggregate fills the voids and the cement mix with water and acts as a binder.
Numerous test methods are available for measuring workability. Each test is unique for measuring each aspect.
TERMS RELATED TO FRESH CONCRETE
WORKABILITY
The ease or difficulty to handle concrete is workability. Minimum loss of homogeneity occurs. It measured in terms of placing and transportation.
SEGREGATION
The separation of a coarser particle from concrete is segregation. This leads to honeycombing and decreases density. Concrete should not be thrown from heights.
BLEEDING
The appearance of finishing water on the surface of concrete during compaction is bleeding. The concrete becomes pory and weak.
PROPERTIES OF FRESH CONCRETE
- Concrete should have a good compressive strength of about 4000psi.
- The density of the concrete is 2400 kg/cm³.
- The temperature of the fresh Concrete is 80 to 95°F.
- The pH value of the Concrete is 13.
- It should combat weathering action.
- Concrete should have minimal shrinkage.
- It should oppose abrasion.
- It should have minimum thermal expansion.
- It should have the least creep.
- It should be cost-effective.
- It should have corrosion resistance.
- Concrete must possess good resistance to fire.
TESTING OF FRESH CONCRETE
There are several tests for fresh concrete to determine its property. Each test is unique and has a unique method.
It is easy to discover the consistent quality and uniform strength of the Concrete.
The experiential tests which are used for testing fresh concrete are
- The slump test
- The compacting factor test
- The Vee Bee consistency test
- The flow test
- The Kelly Ball test
These empirical tests are performed to ascertain the physical attribute of the concrete.
THE SLUMP TEST
This circumscribes the consistency of the concrete. The nominal maximum size of the aggregate does not exceed 38mm. This method is adopted either in the laboratory or in fieldwork.
The dimensions of the mould are
Bottom diameter = 200mm
Top diameter = 100mm
Height = 300mm
PROCEDURE:-
The concrete is moulded into four layers and tamped 25 strokes using a tamping rod. The tamping rod is the round edge. The layers penetrate the underlying layer. Later the tamping mould is removed quickly.
Then it is raised slowly in the vertical direction. The sump is measured.
The difference between the heights is measured and noted.
Slump value for different types of concrete are given below.
COMPACTING FACTOR TEST
It is used for concrete having low and medium workability. Compacting factor test is more precise and sensitive than the slump test. It is suitable for concrete which is to be compacted by using vibrators.
PROCEDURE:-
The sample of concrete to be installed in the upper hopper. Later the hopper the trap door is opened. The concrete is allowed to fall. It is covered with trowels.
Later the door of the lower hopper is opened. The concrete is allowed to fall.
The concrete weight and partially compacted concrete weight measurement are taken. The same sample is refilled and heavily tamped. The formula for the compaction factor is
Compaction factor =
wt of Partially compacted concrete/
wt of fully compacted concrete
Each test is carried out with a constant time interval after the mixing is completely mixed.
VEE BEE CONSISTENCY METHOD
Vee bee consistency test determines the time required for vibration. The specimen is in the shape of the conical frustum. The apparatus used for this test is the Vee bee consistometer.
PROCEDURE:-
- The apparatus consists of a vibrator table on elastic supports, metal pots, a standard iron rod, and a sheet metal cone.
- This test is performed in a slump cone. Before lifting the cone, a glass disc is placed above the slump. The glass disc is attached to the swivel arm.
- A glass disc is arranged in the slump. The electrical vibrator is continued.
- The recorded time second is VB degree which represents the consistency of the concrete.
- Based on the Vee bee degree, the workability is calculated.
KELLY BALL TEST
Kelly Ball test is used for measuring the workability of the concrete. The result of this test is more consistent than the slump test.
PROCEDURE:-
The test apparatus consists of
Metal hemisphere = 15cm, weight = 13.6 kg
Graduation scale
Handle
Stem
Frame
Metallic hemisphere
- The concrete base should have a depth of 20cm. The ball is lowered gradually on the concrete surface.
- The distance between the concrete and the ball should be 23cm.
- The depth of penetration is noted immediately.
- This test can be performed in the field and also in the sites. It can be done for a shorter period of about 15 seconds.
THE FLOW TEST
The flow test is used to determine consistency, cohesiveness and non-segregation. The test procedure of the flow test is measuring concrete spread.
PROCEDURE:-
The mould is similar to the slump test apparatus.
Base diameter = 25 cm
Upper diameter = 17 cm
Height = 12 cm
Diameter of tamping rod = 1.6 cm
Length of tamping rod = 61 cm
- The flow table apparatus consists of a flow table 76mm in diameter. Concentric circles are marked on this table.
- The mould is filled with a layer of concrete.
- By using the tamping rod, tamped 25 times and excess concrete levelled.
- The mould is then lifted slowly and allowed to fall.
- The diameter of the flow of concrete is measured. Then the flow Percentage is calculated.
Flow (%) = Avg spread in dia(cm)*100
25
The flow test is done in the laboratory. The value of the flow test varies from 0 to 150. The spread of the concrete also indicates the segregation tendency.
- Concrete should have a good compressive strength of about 4000psi.
- The density of the concrete is 2400 kg/cm³.
- The temperature of the fresh Concrete is 80 to 95°F.
- The pH value of the Concrete is 13.
- It should combat weathering action.
- Concrete should have minimal shrinkage.
- It should oppose abrasion.
- It should have minimum thermal expansion.
- It should have the least creep.
- It should be cost-effective.
- It should have corrosion resistance.
- Concrete must possess good resistance to fire.
TESTING OF FRESH CONCRETE
There are several tests for fresh concrete to determine its property. Each test is unique and has a unique method.
It is easy to discover the consistent quality and uniform strength of the Concrete.
The experiential tests which are used for testing fresh concrete are
- The slump test
- The compacting factor test
- The Vee Bee consistency test
- The flow test
- The Kelly Ball test
These empirical tests are performed to ascertain the physical attribute of the concrete.
THE SLUMP TEST
This circumscribes the consistency of the concrete. The nominal maximum size of the aggregate does not exceed 38mm. This method is adopted either in the laboratory or in fieldwork.
The dimensions of the mould are
Bottom diameter = 200mm
Top diameter = 100mm
Height = 300mm
PROCEDURE:-
The concrete is moulded into four layers and tamped 25 strokes using a tamping rod. The tamping rod is the round edge. The layers penetrate the underlying layer. Later the tamping mould is removed quickly.
Then it is raised slowly in the vertical direction. The sump is measured.
The difference between the heights is measured and noted.
Slump value for different types of concrete are given below.
COMPACTING FACTOR TEST
It is used for concrete having low and medium workability. Compacting factor test is more precise and sensitive than the slump test. It is suitable for concrete which is to be compacted by using vibrators.
PROCEDURE:-
The sample of concrete to be installed in the upper hopper. Later the hopper the trap door is opened. The concrete is allowed to fall. It is covered with trowels.
Later the door of the lower hopper is opened. The concrete is allowed to fall.
The concrete weight and partially compacted concrete weight measurement are taken. The same sample is refilled and heavily tamped. The formula for the compaction factor is
Compaction factor =
wt of Partially compacted concrete/
wt of fully compacted concrete
Each test is carried out with a constant time interval after the mixing is completely mixed.
VEE BEE CONSISTENCY METHOD
Vee bee consistency test determines the time required for vibration. The specimen is in the shape of the conical frustum. The apparatus used for this test is the Vee bee consistometer.
PROCEDURE:-
- The apparatus consists of a vibrator table on elastic supports, metal pots, a standard iron rod, and a sheet metal cone.
- This test is performed in a slump cone. Before lifting the cone, a glass disc is placed above the slump. The glass disc is attached to the swivel arm.
- A glass disc is arranged in the slump. The electrical vibrator is continued.
- The recorded time second is VB degree which represents the consistency of the concrete.
- Based on the Vee bee degree, the workability is calculated.
KELLY BALL TEST
Kelly Ball test is used for measuring the workability of the concrete. The result of this test is more consistent than the slump test.
PROCEDURE:-
The test apparatus consists of
Metal hemisphere = 15cm, weight = 13.6 kg
Graduation scale
Handle
Stem
Frame
Metallic hemisphere
- The concrete base should have a depth of 20cm. The ball is lowered gradually on the concrete surface.
- The distance between the concrete and the ball should be 23cm.
- The depth of penetration is noted immediately.
- This test can be performed in the field and also in the sites. It can be done for a shorter period of about 15 seconds.
THE FLOW TEST
The flow test is used to determine consistency, cohesiveness and non-segregation. The test procedure of the flow test is measuring concrete spread.
PROCEDURE:-
The mould is similar to the slump test apparatus.
Base diameter = 25 cm
Upper diameter = 17 cm
Height = 12 cm
Diameter of tamping rod = 1.6 cm
Length of tamping rod = 61 cm
- The flow table apparatus consists of a flow table 76mm in diameter. Concentric circles are marked on this table.
- The mould is filled with a layer of concrete.
- By using the tamping rod, tamped 25 times and excess concrete levelled.
- The mould is then lifted slowly and allowed to fall.
- The diameter of the flow of concrete is measured. Then the flow Percentage is calculated.
Flow (%) = Avg spread in dia(cm)*100
25
The flow test is done in the laboratory. The value of the flow test varies from 0 to 150. The spread of the concrete also indicates the segregation tendency.
PROCEDURE:-
The sample of concrete to be installed in the upper hopper. Later the hopper the trap door is opened. The concrete is allowed to fall. It is covered with trowels.
Later the door of the lower hopper is opened. The concrete is allowed to fall.
The concrete weight and partially compacted concrete weight measurement are taken. The same sample is refilled and heavily tamped. The formula for the compaction factor is
Compaction factor =
wt of Partially compacted concrete/
Each test is carried out with a constant time interval after the mixing is completely mixed.
VEE BEE CONSISTENCY METHOD
PROCEDURE:-
- The apparatus consists of a vibrator table on elastic supports, metal pots, a standard iron rod, and a sheet metal cone.
- This test is performed in a slump cone. Before lifting the cone, a glass disc is placed above the slump. The glass disc is attached to the swivel arm.
- A glass disc is arranged in the slump. The electrical vibrator is continued.
- The recorded time second is VB degree which represents the consistency of the concrete.
- Based on the Vee bee degree, the workability is calculated.
KELLY BALL TEST
PROCEDURE:-
The test apparatus consists of
Metal hemisphere = 15cm, weight = 13.6 kg
Graduation scale
Handle
Stem
Frame
Metallic hemisphere
- The concrete base should have a depth of 20cm. The ball is lowered gradually on the concrete surface.
- The distance between the concrete and the ball should be 23cm.
- The depth of penetration is noted immediately.
- This test can be performed in the field and also in the sites. It can be done for a shorter period of about 15 seconds.
The flow test is used to determine consistency, cohesiveness and non-segregation. The test procedure of the flow test is measuring concrete spread.
PROCEDURE:-
The mould is similar to the slump test apparatus.
Base diameter = 25 cm
Upper diameter = 17 cm
Height = 12 cm
Diameter of tamping rod = 1.6 cm
Length of tamping rod = 61 cm
- The flow table apparatus consists of a flow table 76mm in diameter. Concentric circles are marked on this table.
- The mould is filled with a layer of concrete.
- By using the tamping rod, tamped 25 times and excess concrete levelled.
- The mould is then lifted slowly and allowed to fall.
- The diameter of the flow of concrete is measured. Then the flow Percentage is calculated.
Flow (%) = Avg spread in dia(cm)*100
25
The flow test is done in the laboratory. The value of the flow test varies from 0 to 150. The spread of the concrete also indicates the segregation tendency.
0 Comments
Please do not enter any spam link in comment box