CIVIL ENGINEERING MATERIALS
Module I Syllabus
- Aggregate: Classification, Physical and mechanical properties, soundness, alkali-aggregate reaction, thermal properties of aggregate
- Bricks and Masonry Blocks: Types, properties and field and laboratory tests to evaluate quality
- Lime: classification, properties Cement: types, Portland
- cement: chemical composition of raw material, bogue compounds, hydration of cement, role of water in hydration, testing of cements,
- Fly ash: properties and use in manufacturing of bricks and cement.
1. AGGREGATE:
Classification, Physical and mechanical properties, soundness, alkali-aggregate reaction, thermal properties of aggregate Aggregates are the important constituents of the concrete which give body to the concrete and also reduce shrinkage. Aggregates occupy 70 to 80 % of total volume of concrete. So, we can say that one should know definitely about the aggregates in depth to study more about concrete.
i) Classification of Aggregates Based on Shape:
We know that aggregate is derived from naturally occurring rocks by blasting or crushing etc., so, it is difficult to attain required shape of aggregate. But, the shape of aggregate will affect the workability of concrete. So, we should take care about the shape of aggregate. This care is not only applicable to parent rock but also to the crushing machine used.
Aggregates are classified according to shape into the following types
Rounded aggregates
Irregular or partly rounded aggregates
Angular aggregates
Flaky aggregates
Elongated aggregates
Flaky and elongated aggregates
Rounded Aggregate:
The rounded aggregates are completely shaped by attrition (the resistance of a granular material to wear) and available in the form of seashore gravel. Rounded aggregates result in the minimum percentage of voids (32 – 33%) hence gives more workability. They require a lesser amount of water-cement ratio. They are not considered for high-strength concrete because of poor interlocking behavior and weak bond strength.
i) Classification of Aggregates Based on Shape:
We know that aggregate is derived from naturally occurring rocks by blasting or crushing etc., so, it is difficult to attain required shape of aggregate. But, the shape of aggregate will affect the workability of concrete. So, we should take care about the shape of aggregate. This care is not only applicable to parent rock but also to the crushing machine used.
Aggregates are classified according to shape into the following types
Rounded aggregates
Irregular or partly rounded aggregates
Angular aggregates
Flaky aggregates
Elongated aggregates
Flaky and elongated aggregates
Rounded Aggregate:
The rounded aggregates are completely shaped by attrition (the resistance of a granular material to wear) and available in the form of seashore gravel. Rounded aggregates result in the minimum percentage of voids (32 – 33%) hence gives more workability. They require a lesser amount of water-cement ratio. They are not considered for high-strength concrete because of poor interlocking behavior and weak bond strength.
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Irregular Aggregates:
The irregular or partly rounded aggregates are partly shaped by attrition and these are available in the form of pit sands and gravel. Irregular aggregates may result 35- 37% of voids. These will give lesser workability when compared to rounded aggregates. The bond strength is slightly higher than rounded aggregates but not as required for high strength concrete.
The irregular or partly rounded aggregates are partly shaped by attrition and these are available in the form of pit sands and gravel. Irregular aggregates may result 35- 37% of voids. These will give lesser workability when compared to rounded aggregates. The bond strength is slightly higher than rounded aggregates but not as required for high strength concrete.
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Angular Aggregates:
The angular aggregates consist well defined edges formed at the intersection of roughly planar surfaces and these are obtained by crushing the rocks. Angular aggregates result maximum percentage of voids (38-45%) hence gives less workability. They give 10-20% more compressive strength due to development of stronger aggregate-mortar bond. So, these are useful in high strength concrete manufacturing.
The angular aggregates consist well defined edges formed at the intersection of roughly planar surfaces and these are obtained by crushing the rocks. Angular aggregates result maximum percentage of voids (38-45%) hence gives less workability. They give 10-20% more compressive strength due to development of stronger aggregate-mortar bond. So, these are useful in high strength concrete manufacturing.
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Flaky Aggregates:
When the aggregate thickness is small when compared with width and length of that aggregate it is said to be flaky aggregate, or on the other, when the least dimension of aggregate is less than the 60% of its mean dimension then it is said to be flaky aggregate.
When the aggregate thickness is small when compared with width and length of that aggregate it is said to be flaky aggregate, or on the other, when the least dimension of aggregate is less than the 60% of its mean dimension then it is said to be flaky aggregate.
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Elongated Aggregates:
When the length of aggregate is larger than the other two dimensions then it is called elongated aggregate or the length of aggregate is greater than 180% of its mean dimension.
When the length of aggregate is larger than the other two dimensions then it is called elongated aggregate or the length of aggregate is greater than 180% of its mean dimension.
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Flaky and Elongated Aggregates:
When the aggregate length is larger than its width and width is larger than its thickness then it is said to be flaky and elongated aggregates. The above 3 types of aggregates are not suitable for concrete mixing. These are generally obtained from the poorly crushed rocks
When the aggregate length is larger than its width and width is larger than its thickness then it is said to be flaky and elongated aggregates. The above 3 types of aggregates are not suitable for concrete mixing. These are generally obtained from the poorly crushed rocks
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ii) Classification of Aggregates Based on Size:
Aggregates are available in nature in different sizes. The size of aggregate used may be related to the mix proportions, type of work etc. The size distribution of aggregates is called grading of aggregates. Following are the classification of aggregates based on size:
Aggregates are classified into 2 types according to size
Aggregates are available in nature in different sizes. The size of aggregate used may be related to the mix proportions, type of work etc. The size distribution of aggregates is called grading of aggregates. Following are the classification of aggregates based on size:
Aggregates are classified into 2 types according to size
- Fine aggregate
- Coarse aggregate
Concrete
Fine Aggregate:
When the aggregate is sieved through a 4.75mm sieve, the aggregate passed through it called fine aggregate. Natural sand is generally used as fine aggregate, silt and clay also come under this category. The soft deposit consisting of sand, silt, and clay is termed as loam. The purpose of the fine aggregate is to fill the voids in the coarse aggregate and to act as a workability agent.
Fine Aggregate:
When the aggregate is sieved through a 4.75mm sieve, the aggregate passed through it called fine aggregate. Natural sand is generally used as fine aggregate, silt and clay also come under this category. The soft deposit consisting of sand, silt, and clay is termed as loam. The purpose of the fine aggregate is to fill the voids in the coarse aggregate and to act as a workability agent.
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Coarse Aggregate:
When the aggregate is sieved through 4.75mm sieve, the aggregate retained is called coarse aggregate. Gravel, cobble and boulders come under this category. The maximum size aggregate used may be dependent upon some conditions. In general, 40mm size aggregate used for normal strengths, and 20mm size is used for high strength concrete. The size range of various coarse aggregates given below.
When the aggregate is sieved through 4.75mm sieve, the aggregate retained is called coarse aggregate. Gravel, cobble and boulders come under this category. The maximum size aggregate used may be dependent upon some conditions. In general, 40mm size aggregate used for normal strengths, and 20mm size is used for high strength concrete. The size range of various coarse aggregates given below.
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AAC Block
1.1 Physical Prosperities of Aggregate:
1.1.1 Grading:
Grading is the particle-size distribution of an aggregate as determined by a sieve analysis using wire mesh sieves with square openings. As per IS:2386(Part-1):
Fine aggregate: 6 standard sieves with openings from 150 μm to 4.75 mm. (150 μm, 300 μm, 600 μm, 1.18mm, 2.36mm, 4.75mm)
Coarse aggregate: 5 sieves with openings from 4.75mm to 80mm. (4.75mm, 10mm, 12.5mm, 20mm, 40mm)
Grain size distribution for concrete mixes that will provide a dense strong mixture.
Ensure that the voids between the larger particles are filled with medium particles. The remaining voids are filled with still smaller particles until the smallest voids are filled with a small amount of fines.
1.1 Physical Prosperities of Aggregate:
1.1.1 Grading:
Grading is the particle-size distribution of an aggregate as determined by a sieve analysis using wire mesh sieves with square openings. As per IS:2386(Part-1):
Fine aggregate: 6 standard sieves with openings from 150 μm to 4.75 mm. (150 μm, 300 μm, 600 μm, 1.18mm, 2.36mm, 4.75mm)
Coarse aggregate: 5 sieves with openings from 4.75mm to 80mm. (4.75mm, 10mm, 12.5mm, 20mm, 40mm)
Grain size distribution for concrete mixes that will provide a dense strong mixture.
Ensure that the voids between the larger particles are filled with medium particles. The remaining voids are filled with still smaller particles until the smallest voids are filled with a small amount of fines.
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Grading Limit for Single Sized Coarse Aggregates:
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Grading Limits for Fine Aggregates:
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1.1.2 Fineness Modulus:
The results of aggregate sieve analysis is expressed by a number called Fineness Modulus. Obtained by adding the sum of the cumulative percentages by mass of a sample aggregate retained on each of a specified series of sieves and dividing the sum by 100.
The following limits may be taken as guidance:
Fine sand: Fineness Modulus: 2.2 - 2.6
Medium sand: F.M.: 2.6 - 2.9
Coarse sand: F.M.: 2.9 - 3.2
A sand having a fineness modulus more than 3.2 will be unsuitable for making satisfactory concrete.
Importance of Soil Test
1.1.3 Flakiness Index:
The flakiness index of aggregate is the percentage by weight of particles in it whose least dimension (thickness) is less than three-fifths of their mean dimension.
The test is not applicable to sizes smaller than 6.3 mm.
The flakiness index is taken as the total weight of the material passing the various thickness gauges expressed as a percentage of the total weight of the sample taken.
The below table shows the standard dimensions of thickness and length gauges.
The flakiness index of aggregate is the percentage by weight of particles in it whose least dimension (thickness) is less than three-fifths of their mean dimension.
AAC Blocks
1.1.4 Elongation Index:
The elongation index on an aggregate is the percentage by weight of particles whose greatest dimension (length) is greater than 1.8 times their mean dimension.
The elongation index is not applicable to sizes smaller than 6.3 mm.
The elongation index is the total weight of the material retained on the various length gauges expressed as a percentage of the total weight of the sample gauged. The presence of elongated particles in excess of 10 to 15 per cent is generally considered undesirable, but no recognized limits are laid down.
Basement Tricks
1.2 Mechanical Properties of Aggregate
Property # 1. Toughness:
Property # 2. Hardness:
Property # 3. Specific Gravity:
Property # 4. Porosity and Absorption of Water by Aggregate:
Property # 5. Bulking of Sand:
Grid Lines
1.2.1 Toughness:
It is defined as the resistance of aggregate to failure by impact. The impact value of bulk aggregate can be determined as per I.S. 2386, 1963.
Procedure:
The results of aggregate sieve analysis is expressed by a number called Fineness Modulus. Obtained by adding the sum of the cumulative percentages by mass of a sample aggregate retained on each of a specified series of sieves and dividing the sum by 100.
The following limits may be taken as guidance:
Fine sand: Fineness Modulus: 2.2 - 2.6
Medium sand: F.M.: 2.6 - 2.9
Coarse sand: F.M.: 2.9 - 3.2
A sand having a fineness modulus more than 3.2 will be unsuitable for making satisfactory concrete.
Importance of Soil Test
1.1.3 Flakiness Index:
The flakiness index of aggregate is the percentage by weight of particles in it whose least dimension (thickness) is less than three-fifths of their mean dimension.
The test is not applicable to sizes smaller than 6.3 mm.
The flakiness index is taken as the total weight of the material passing the various thickness gauges expressed as a percentage of the total weight of the sample taken.
The below table shows the standard dimensions of thickness and length gauges.
The flakiness index of aggregate is the percentage by weight of particles in it whose least dimension (thickness) is less than three-fifths of their mean dimension.
AAC Blocks
1.1.4 Elongation Index:
The elongation index on an aggregate is the percentage by weight of particles whose greatest dimension (length) is greater than 1.8 times their mean dimension.
The elongation index is not applicable to sizes smaller than 6.3 mm.
The elongation index is the total weight of the material retained on the various length gauges expressed as a percentage of the total weight of the sample gauged. The presence of elongated particles in excess of 10 to 15 per cent is generally considered undesirable, but no recognized limits are laid down.
Basement Tricks
1.2 Mechanical Properties of Aggregate
Property # 1. Toughness:
Property # 2. Hardness:
Property # 3. Specific Gravity:
Property # 4. Porosity and Absorption of Water by Aggregate:
Property # 5. Bulking of Sand:
Grid Lines
1.2.1 Toughness:
It is defined as the resistance of aggregate to failure by impact. The impact value of bulk aggregate can be determined as per I.S. 2386, 1963.
Procedure:
- The aggregate shall be taken as in the case of crushing strength value test i.e., the aggregate should pass through 12.5 mm I.S. sieve and retained on 10 mm I.S. sieve. It should be oven dried at 100°C to 110°C for four hours and then air cooled before test. Now the prepared aggregate is filled upto 1/3rd height of the cylindrical cup of the equipment.
- The diameter and depth of the cup are 102 mm and 50 mm respectively. After filling the cup upto 1/3rd of its height, the aggregate is tamped with 25 strokes of the rounded end of the tamping rod. After this operation the cup shall be further filled upto 2/3rd of its height and a further tamping of 25 strokes given.
- The cup finally shall be filled to over flowing and tamped with 25 strokes and surplus aggregate removed and the weight of aggregate noted. The value of weight will be useful to repeat the experiment. Now the hammer of the equipment weighting 14.0 kg or 13.5 kg is raised till its lower face is 380 mm above the upper surface of the aggregate and., allowed to fall freely on the aggregate and the process is repeated for 15 times.
- The crushed aggregate is now removed from the cup and sieved through 2.36 mm I.S. sieve.
- The fraction passing through the sieve is weighed accurately.
- Let the weight of oven dry sample in the cup = W kg.
- Weight of aggregate passing 2.36 mm sieve = W1 kg.
- Then impact value = [(W1/W) x 100]
1.2.2 Hardness:
It is defined as the resistance to wear by abrasion, and the aggregate abrasion value is defined as the percentage loss in weight on abrasion.
roof centering
Deval Attrition Test:
This test has been covered by IS 2386 Part (IV)-1963. In this test particles of known weight are subjected to wear in an iron cylinder rotated 10,000 (ten thousand) times at the rate of 30 to 33 revolutions per minute. After the specified revolution of the cylinder the material is taken out and sieved on 1.7 mm sieve and the percentage of material finer than 1.7mm is determined. This percentage is taken as the attrition value of the aggregate. The attrition value of about 7 to 8 usually is considered as permissible.
Dorry Abrasion Test:
This test has not been covered by Indian standard specifications. In this test a cylindrical specimen having its diameter and height of 25 cm is subjected to abrasion against a rotating metal disk sprinkled with quartz sand. The loss in weight of the cylinder after 1000 (one thousand) revolutions is determined.
Then the hardness of rock sample is expressed by an empirical relation as follows:
Hardness or sample = 20 – Loss in weight in grams/3
For good rock this value should not be less the 17. The rock having this value of 14 is considered poor.
Los-Angeles Test:
This test has been covered by IS 2386 (Part-IV) 1963. In this test, aggregate of the specified grading is placed in a cylindrical drum of inside length and diameter of 500 mm and 700 mm respectively. This cylinder is mounted horizontally on stub shafts. For abrasive charge, steel balls or cast-iron balls of approximately 48 mm diameter and each weighting 390 grams to 445 gram are used. The numbers of balls used vary from 6 to 12 depending upon the grading of the aggregate. For 10 mm size aggregate 6 balls are used and for aggregates bigger than 20 mm size usually 12 balls are used.
Basement Belt
PROCEDURE:
For the conduct of test, the sample and the abrasive charge are placed in the Los-Angeles testing machine and it is rotated at a speed of 20 to 33 revolutions per minute. For aggregates up to 40 mm size the machine is rotated for 500 revolutions and for bigger size aggregate 1000 revolutions. The charge is taken out from the machine and sieved on 1.7 mm sieve.
It is defined as the resistance to wear by abrasion, and the aggregate abrasion value is defined as the percentage loss in weight on abrasion.
roof centering
Deval Attrition Test:
This test has been covered by IS 2386 Part (IV)-1963. In this test particles of known weight are subjected to wear in an iron cylinder rotated 10,000 (ten thousand) times at the rate of 30 to 33 revolutions per minute. After the specified revolution of the cylinder the material is taken out and sieved on 1.7 mm sieve and the percentage of material finer than 1.7mm is determined. This percentage is taken as the attrition value of the aggregate. The attrition value of about 7 to 8 usually is considered as permissible.
Dorry Abrasion Test:
This test has not been covered by Indian standard specifications. In this test a cylindrical specimen having its diameter and height of 25 cm is subjected to abrasion against a rotating metal disk sprinkled with quartz sand. The loss in weight of the cylinder after 1000 (one thousand) revolutions is determined.
Then the hardness of rock sample is expressed by an empirical relation as follows:
Hardness or sample = 20 – Loss in weight in grams/3
For good rock this value should not be less the 17. The rock having this value of 14 is considered poor.
Los-Angeles Test:
This test has been covered by IS 2386 (Part-IV) 1963. In this test, aggregate of the specified grading is placed in a cylindrical drum of inside length and diameter of 500 mm and 700 mm respectively. This cylinder is mounted horizontally on stub shafts. For abrasive charge, steel balls or cast-iron balls of approximately 48 mm diameter and each weighting 390 grams to 445 gram are used. The numbers of balls used vary from 6 to 12 depending upon the grading of the aggregate. For 10 mm size aggregate 6 balls are used and for aggregates bigger than 20 mm size usually 12 balls are used.
Basement Belt
PROCEDURE:
For the conduct of test, the sample and the abrasive charge are placed in the Los-Angeles testing machine and it is rotated at a speed of 20 to 33 revolutions per minute. For aggregates up to 40 mm size the machine is rotated for 500 revolutions and for bigger size aggregate 1000 revolutions. The charge is taken out from the machine and sieved on 1.7 mm sieve.
- Let the weight of oven dry sample put in the drum = W Kg.
- Weight of aggregate passing through 1.7 sieve = W1 Kg.
- Then abrasion value = [(W1/W) x 100]
The abrasion value should not be more than 30% for wearing surfaces and not more than 50% for concrete used for other than wearing surface. The results of Los Angeles test show good correlation not only the actual wear of aggregate when used in concrete, but also with the compression and flexural strength of concrete made with the given aggregate.
1.2.3 Specific Gravity and Water Absorption:
The specific gravity of a substance is the ratio of the weight of unit volume of the substance to the unit volume of water at the stated temperature. In concrete making, aggregates generally contain pores both permeable and impermeable hence the term specific gravity has to be defined carefully. Actually, there are several types of specific gravity. In concrete technology specific gravity is used for the calculation of quantities of ingredients. Usually, the specific gravity of most aggregates varies between 2.6 and 2.8.
Specific gravity of certain materials as per concrete hand book CA-1 Bombay may be assumed as shown in Table
Absolute Specific Gravity:
It can be defined as the ratio of the weight of the solid, referred to vacuum, to the weight of an equal volume of gas free distilled water both taken at the standard or a stated temperature, usually it is not required in concrete technology. Actually, the absolute specific gravity and particle density refer to the volume of solid material excluding all pores, while apparent specific gravity and apparent particle density refer to the volume of solid material including impermeable pores, but not the capillary pores. In concrete technology apparent specific gravity is required.
Apparent Specific Gravity:
It can be defined as the ratio of the weight of the aggregate dried in an oven at 100°C to 110°C for 24 hours to the weight of water occupying a volume equal to that of the solid including the impermeable pores. This can be determined by using pycno-meter for solids less than 10 mm in size i.e., sand.
Bulk Specific Gravity:
It can be defined as the ratio of the weight in air of a given volume of material (including both permeable and impermeable voids) at the standard temperature to the weight in air of an equal volume of distilled water at the same standard temperature (20°C). The specific gravity of a material multiplied by the unit weight of water gives the weight of 1 cubic metre of that substance. Sometimes this weight is known as solid unit weight. The weight of a given quantity of particles divided by the solid unit weight gives the solid volume of the particles.
Solid vol. in m3 = 3 wt. of substance in kg/specific gravity x 1000
Bulk Density: The weight of aggregate that would fill a container of unit volume is known as bulk density of aggregate.
Voids:
With respect to a mass of aggregate, the term voids refers to the space between the aggregate particles. Numerically this voids space is the difference between the gross volume of aggregate mass and the space occupied by the particles alone. The knowledge of voids of coarse and fine aggregate is useful in the mix design of concrete.
1.2.3 Specific Gravity and Water Absorption:
The specific gravity of a substance is the ratio of the weight of unit volume of the substance to the unit volume of water at the stated temperature. In concrete making, aggregates generally contain pores both permeable and impermeable hence the term specific gravity has to be defined carefully. Actually, there are several types of specific gravity. In concrete technology specific gravity is used for the calculation of quantities of ingredients. Usually, the specific gravity of most aggregates varies between 2.6 and 2.8.
Specific gravity of certain materials as per concrete hand book CA-1 Bombay may be assumed as shown in Table
Absolute Specific Gravity:
It can be defined as the ratio of the weight of the solid, referred to vacuum, to the weight of an equal volume of gas free distilled water both taken at the standard or a stated temperature, usually it is not required in concrete technology. Actually, the absolute specific gravity and particle density refer to the volume of solid material excluding all pores, while apparent specific gravity and apparent particle density refer to the volume of solid material including impermeable pores, but not the capillary pores. In concrete technology apparent specific gravity is required.
Apparent Specific Gravity:
It can be defined as the ratio of the weight of the aggregate dried in an oven at 100°C to 110°C for 24 hours to the weight of water occupying a volume equal to that of the solid including the impermeable pores. This can be determined by using pycno-meter for solids less than 10 mm in size i.e., sand.
Bulk Specific Gravity:
It can be defined as the ratio of the weight in air of a given volume of material (including both permeable and impermeable voids) at the standard temperature to the weight in air of an equal volume of distilled water at the same standard temperature (20°C). The specific gravity of a material multiplied by the unit weight of water gives the weight of 1 cubic metre of that substance. Sometimes this weight is known as solid unit weight. The weight of a given quantity of particles divided by the solid unit weight gives the solid volume of the particles.
Solid vol. in m3 = 3 wt. of substance in kg/specific gravity x 1000
Bulk Density: The weight of aggregate that would fill a container of unit volume is known as bulk density of aggregate.
Voids:
With respect to a mass of aggregate, the term voids refers to the space between the aggregate particles. Numerically this voids space is the difference between the gross volume of aggregate mass and the space occupied by the particles alone. The knowledge of voids of coarse and fine aggregate is useful in the mix design of concrete.
- Percentage voids = [(Gs – g)/Gs] x 100
- where Gs = specific gravity of aggregate and g is bulk density in kg/litre
Unit Weight:
The weight of a unit volume of aggregate is called as unit weight. For a given specific gravity, greater the unit weight, the smaller the percentage of voids and better the gradation of the particles, which affects the strength of concrete to a great extent.
Method of Determination of Specific Gravity of Aggregate:
Specific gravity test of aggregates is done to measure the strength or quality of the material while water absorption test determines the water holding capacity of the coarse and fine aggregates. The main objective of these test is to
The weight of a unit volume of aggregate is called as unit weight. For a given specific gravity, greater the unit weight, the smaller the percentage of voids and better the gradation of the particles, which affects the strength of concrete to a great extent.
Method of Determination of Specific Gravity of Aggregate:
Specific gravity test of aggregates is done to measure the strength or quality of the material while water absorption test determines the water holding capacity of the coarse and fine aggregates. The main objective of these test is to
- To measure the strength or quality of the material.
- To determine the water absorption of aggregates
Specific Gravity is the ratio of the weight of a given volume of aggregate to the weight of an equal volume of water. It is the measure of strength or quality of the specific material. Aggregates having low specific gravity are generally weaker than those with higher specific gravity values.
Observations of Test
Weight of saturated aggregate suspended in water with basket = W1g Weight of basket suspended in water = W2 g Weight of saturated surface dry aggregate in air = W3g Weight of oven dry aggregate = W4 g Weight of saturated aggregate in water = W1 – W2 g Weight of water equal to the volume of the aggregate = W3–(W1–W2)g
Formulas:
(1) Specific gravity = W3 / (W3– (W1– W2))
(2) Apparent specific gravity = W4/ (W4– (W11– W2))
(3) Water Absorption = ((W3 – W4) / W4) X 100
The size of the aggregate and whether it has been artificially heated should be indicated. Though high specific gravity is considered as an indication of high strength, it is not possible to judge the suitability of a sample aggregate without finding the mechanical properties such as aggregate crushing, impact and abrasion values.
Observations of Test
Weight of saturated aggregate suspended in water with basket = W1g Weight of basket suspended in water = W2 g Weight of saturated surface dry aggregate in air = W3g Weight of oven dry aggregate = W4 g Weight of saturated aggregate in water = W1 – W2 g Weight of water equal to the volume of the aggregate = W3–(W1–W2)g
Formulas:
(1) Specific gravity = W3 / (W3– (W1– W2))
(2) Apparent specific gravity = W4/ (W4– (W11– W2))
(3) Water Absorption = ((W3 – W4) / W4) X 100
The size of the aggregate and whether it has been artificially heated should be indicated. Though high specific gravity is considered as an indication of high strength, it is not possible to judge the suitability of a sample aggregate without finding the mechanical properties such as aggregate crushing, impact and abrasion values.