Slump and Compaction Factor Test

 Slump and Compaction Factor Test

Slump and Compaction Factor Test

1. Slump Test: • Most common method • Frustum having top diameter 10cm, bottom dimension around 20 cm, height of 30 cm • Concrete to be tested in filled in the mould in four layers where each layer is compacted 25 no of times with the help of rod • Mould is removed immediately by lifting it in upward direction which causes the concrete to subsidize and the subsidence of the concrete is referred as slump which may also defined as difference of the height of the mould and the top level of the subsidize concrete. Higher the value of Slump, more is the workability • This test is not suitable for the concrete which process either very high workability or very low workability. • It is not a suitable method for very wet or very dry concrete • If the concrete slumps evenly it is called true slump. • If one half of the cone slides down, it is called shear slump. • In case of a shear slump, the slump value is measured as the difference in height between the height of the mould and the average value of the subsidence. Shear slump also indicates that the concrete is non-cohesive and shows the characteristic of segregation

2. Compaction Factor Test: • It is more precise and sensitive than slump test • This test is used for the concrete possessing medium and low workability for which slump test is not suitable. • Principle of this test is based upon finding the degree of compaction achieved by the standard amount of work done by the concrete when allowed to fall from known height • This degree of compaction is represented in terms of compaction factor that represents the density ratio : Density of concrete obtained during test to the Density of fully compacted concrete Compacting Factor= Weight of partially compacted concrete/ Weight of fully compacted concrete

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TYPES OF TEST ON BRICKS - IS code 3495 - civil engineering study

Types of Tests On Bricks IS code 3495 

Following tests are conducted on bricks to determine its suitability for construction work.

• Absorption test
• Crushing strength test
• Hardness test
• Shape and size
• Color test
• Soundness test
• Structure of brick
• Presence of soluble salts (Efflorescence Test)

 

 WATER Absorption Test on Bricks - 3495 PART 2

• Absorption test is conducted on brick to find out the amount of moisture content absorbed by brick under extreme conditions. 

Apparatus:

• Oven, 
• Weight balance, 
• Tray

PROCEDURE

• Take any five random bricks from a lot of brick as a specimen.
• Dry the specimen in a ventilated oven at a temperature of 105°C to 115°C till it achieves considerably constant mass.
• Cool the specimen to room temperature and take its weight (M1).

Testing:

• When the specimen is completely dry, then immerse it in the clean water at the room temperature (27 ±2°C) for 24 hours.
• Remove the specimen from the water after 24 hours and wipe out water with a damp cloth and weigh the specimen.
• Take the weight (M2) of the specimen after 3 minutes of removing from the water.
• Points to be Taken Care:

• When you take M1, If the Specimen is warm while touching, it shall not be used for the test. Test it when you feel it cool.

Result:

• Note down the M1 and M2.
• Percentage of Water absorption of brick by its mass, after 24-hour immersion in cold water is calculated by the following formula
• (M2-M1)/M1*100

• For a good quality brick the amount of water absorption should not exceed 20% of weight of dry brick.

TYPE                         WATER ABSORBTION

FIRST CLASS         < 20%     OR 15% AVERAGE

SECOND CLASS     < 22.5%  OR 20% AVERAGE

THIRD CLASS         < 25%      OR 25% AVERAGE

 

Crushing Strength or Compressive Strength Test on Bricks - IS 3495 PART 1

• Place the specimen with flat face s horizontal and mortar filled face facing upwards between plates of the testing machine.
• Apply load axially at a uniform rate of 14 N/mm2 (140 kg/cm2) per minute till failure occurs and note maximum load at failure.
• The load at failure is maximum load at which the specimen fails to produce any further increase in the indicator reading on the testing machine.

•  Compressive Strength of Bricks = Maximum Load at Failure (N)/Average area of bed face (mm2)
• The average of result shall be reported.

• Crushing strength of bricks is determined by placing brick in compression testing machine. 
• After placing the brick in compression testing machine, apply load on it until brick breaks. 
• Note down the value of failure load and find out the crushing strength value of brick. 

compressive strength in N/mm2

>10.5     first class

7.5  second class

5.5  third class

 

compressive strength of common bricks should not be used if it is  less than 3.5N/mm2

 

 

Bricks Class Designation	Average compressive strength of Bricks
	Not less than (N/mm2)	Less than (N/mm2)
350	35	40
300	30	35
250	25	30
200	20	25
175	17.5	20
150	15	17.5
125	12.5	15
100	10	12.5
75	7.5	10
50	5	7.5
35	3.5	5

 

Efflorescence Test on Bricks - IS 3495 PART - 3

• A good quality brick should not contain any soluble salts in it. 
• If soluble salts are there, then it will cause efflorescence on brick surfaces.

Type	area affected
Nill Effloresence	Very Low
Slight	0-10%
Moderate	10-50%
Heavy	>50%
Serious	>50% + deposit are  present in powder forms Heavy Flakes

 

WARPAGE TEST - IS 3495 PART 4

• check the bricks for warpage of brick like concave and convex warpage with the help of glass or stell surface

 

Hardness Test on Bricks

• A good brick should resist scratches against sharp things. 
• So, for this test a sharp tool or finger nail is used to make scratch on brick.
•  If there is no scratch impression on brick then it is said to be hard brick.

for any doubt finger nail means

 

Shape and Size Test on Bricks (dimension test) - IS 1077

• Shape and size of bricks are very important consideration. All bricks used for construction should be of same size. The shape of bricks should be purely rectangular with sharp edges.
• Standard brick size consists length x breadth x height as 19cm x 9cm x 9cm.
• To perform this test, select 20 bricks randomly from brick group and stack them along its length , breadth and height and compare. 
• So, if all bricks similar size then they are qualified for construction work.

 

Dimension Test

Dimension should not greater than below value Length -19×20= 380 ± 12 cm Breadth - 9×20 = 180 ± 6 cm Height - 9×20 = 180 ± 6 cm here 20 indicate 20 no of bricks used in sample

 

Color Test of Bricks

• A good brick should possess bright and uniform RED color throughout its body.

 

Soundness Test of Bricks

• Soundness test of bricks shows the nature of bricks against sudden impact.
• In this test, 2 bricks are chosen randomly and struck with one another. 
• Then sound produced should be clear bell ringing sound and brick should not break. 
• Then it is said to be good brick.Soundness Test of Bricks

 

Structure of Bricks

• To know the structure of brick, pick one brick randomly from the group and break it. 
• Observe the inner portion of brick clearly. It should be free from lumps and homogeneous.Structure of Bricks

 

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 Test on building Materials

Test on aggregates	Aggregate Sample Requirement	Sieve Size recommended to calculate weight loss
Crushing Value Test	Passing through 12.5 mm sieve and retained on 10 mm sieve	2.36 mm
Impact Value Test	Passing through 12.5 mm sieve and retained on 10 mm sieve	2.36 mm
Los Angeles Abrasion Test	Passing through 12.5 mm sieve and retained on 10 mm sieve	1.70 mm
Deval Attrition Test	Passing through 12.5 mm sieve and retained on 10 mm sieve	1.70 mm

 

• For making concrete, aggregate impact value should be less than 45.
• Aggregates used for concrete should have a specific gravity between 2.6 to 2.8.

Angularity

• Angularity is a measure of angularity of aggregate sample. It gives a general idea of shape, void ratio, denseness, packaging and compactness of the aggregate sample.

• Angularity Number = 67−W×100w×G
• where
• W = Aggregate weight filled in the cylinder
• w = Weight of the water filled in the cylinder
• G = specific gravity of aggregate

The angularity number ranges from 0 to 11 for aggregates suitable for making concrete.

• If the angularity number is zero, the solid volume of aggregate is 67% and
•  if angularity number is 11, the solid volume of the aggregate is 56%. 
• Angularity number represents the most practicable rounded aggregates and 
• the angularity number 11 indicates the most angular aggregates that can be tolerated for making concrete which is not so unduly harsh and uneconomical.

Non-destructive testing:

• Non-destructive tests are used to find the strength of existing concrete elements. They are classified as follows.

1. Half-cell electrical potential method:

It is used to detect the corrosion potential of reinforcing bars in concrete.

2. Schmidt or Rebound hammer test:

It is used to evaluate the surface hardness of concrete.

3. Carbonation depth measurement test:

It is used to determine whether moisture has reached the depth of the reinforcing bars.

4. Permeability test:

It is used to measure the flow of water through the concrete.

5. Penetration resistance or Windsor probe test:

It is used to measure the surface hardness and hence te strength of the surface and near-surface layers.

6. Ultrasonic pulse velocity test:

It is mainly used to measure the time of travel of ultrasonic pulse passing through the concrete and hence concrete quality.

1. Kelly ball test:

It is a test that is performed to find the workability of concrete

It is a simple field testing machine that determines the depth to which a 15 cm diameter metal hemisphere weighing 13.6 kg, will sink under its own weight into the fresh concrete. Based on the depth of the penetration workability of concrete is determined.

2. Cone Penetrometer Test (CPT):

The cone penetration test (CPT) has been widely used in geotechnical engineering as an in-situ test to map soil profiles and assess soil properties.

The smaller the size of cube it more close to its parent geometry.

For cube test two types of specimens either cubes of 15 cm × 15 cm × 15 cm or 10 cm × 10 cm × 10 cm depending upon the size of aggregate are used. For most of the works cubical moulds of size 15 cm × 15 cm × 15 cm are commonly used.

This concrete is poured in the mould and tempered properly so as not to have any voids. After 24 hours these moulds are removed and test specimens are put in water for curing. The top surface of these specimen should be made even and smooth. This is done by putting cement paste and spreading smoothly on whole area of specimen.

As per the IS 456-2000, the test results of the sample shall be the average of the strength of three specimens. The individual variation should not be more ± 15% of average than of the average. If more, the test results of the sample are invalid.

An aggregate is said to be elongated if its greatest dimension is greater than 1.8 times the mean diameter.

Test on Cement

• The fineness of the cement is checked to test the proper grinding of the cement which significantly influences the rate of hydration. These two methods is used for determination of the fineness of cement:

1) Air permeability method ( Blaine) 

• The fineness of cement is measured as the specific surface. Specific surface is expressed as the total surface area in square meters of all the cement particles in one kilogram of cement. The higher the specific surface is, the finer cement will be. 

• Fineness test is performed on the Blaine apparatus. It is practically a manometer in the U-tube form. One arm of the manometer is provided at the top with a conical socket to form an airtight fit with the conical surface of the cell.

2) Sieving method 

• This method serves only to demonstrate the presence of coarse cement particles. This method is primarily suited to checking and controlling the production process. The fineness of cement is measured by sieving it on standard sieves. The proportion of cement of which the grain sizes are larger than the specified mesh size is thus determined.  

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