Holy Angel University

School of Engineering and Architecture

Department of Civil Engineering
Construction Materials and Testing

Chapter 4
Water Absorption, Abrasion,
Density, and Uniformity of
Aggregates
After this chapter, the student should be able to
Objective ➢ Compute the specific weight and water absorption
➢ Determine the mass percent of wear (abrasion test)
➢ Solve the density of aggregates
➢ Calculate the grain size distribution of aggregates

This chapter focuses on:

Content • Water Absorption
• Abrasion
• Density and Uniformity of Aggregates

➢ Schedule of minimum test requirements governing items of work of the

Related DPWH standard specifications for highways, bridges and airports, 1998,
(volume III). Retrieved from
https://www.gppb.gov.ph/laws/laws/CPESGuidelines2011/Annex11.pdf
Readings
Sivakugan, N., et al. (2018). Civil engineering materials. Australia: Cengage
References Learning

Henderson, P. (2019). Materials for construction: civil engineering

fundamentals. New York: Larsen & Keller

Kultermann, E. (2017). Construction materials, methods, and techniques:

building for a sustainable future (4th ed.). Australia: Cengage Learning
 Chapter 4
Water Absorption, Abrasion, Density, and Uniformity of
Aggregates
Aggregates
Aggregates are inert granular materials such as sand, gravel, or crushed stone that, along with
water and Portland cement, are an essential ingredient in concrete.

For a good concrete mix, aggregates need to be clean, hard, strong particles free of absorbed
chemicals or coatings of clay and other fine materials that could cause the deterioration of concrete.
Aggregates, which account for 60 to 75 percent of the total volume of concrete, are divided into two
distinct categories--fine and coarse. Fine aggregates generally consist of natural sand or crushed stone
with most particles passing through a 3/8-inch sieve. Coarse aggregates are any particles greater than
0.19 inch, but generally range between 3/8 and 1.5 inches in diameter. Gravels constitute the majority
of coarse aggregate used in concrete with crushed stone making up most of the remainder.
Natural gravel and sand are usually dug or dredged from a pit, river, lake, or seabed. Crushed aggregate
is produced by crushing quarry rock, boulders, cobbles, or large-size gravel. Recycled concrete is a
viable source of aggregate and has been satisfactorily used in granular subbases, soil-cement, and in
new concrete.

After harvesting, aggregate is processed: crushed, screened, and washed to obtain proper
cleanliness and gradation. If necessary, a benefaction process such as jigging or heavy media
separation can be used to upgrade the quality. Once processed, the aggregates are handled and stored
to minimize segregation and degradation and prevent contamination.

Aggregates strongly influence concrete's freshly mixed and hardened properties, mixture
proportions, and economy. Consequently, selection of aggregates is an important process. Although
some variation in aggregate properties is expected, characteristics that are considered include:

✓ Grading
✓ Durability
✓ Particle shape and surface texture
✓ Abrasion and skid resistance
✓ Unit weights and voids
✓ Absorption and surface moisture

Grading refers to the determination of the particle-size distribution for aggregate. Grading
limits and maximum aggregate size are specified because these properties affect the amount of
aggregate used as well as cement and water requirements, workability, pumpability, and durability of
concrete. In general, if the water-cement ratio is chosen correctly, a wide range in grading can be used
without a major effect on strength. When gap-graded aggregate is specified, certain particle sizes of
aggregate are omitted from the size continuum. Gap-graded aggregate are used to obtain uniform
textures in exposed aggregate concrete. Close control of mix proportions is necessary to avoid
segregation.

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 Chapter 4
Water Absorption, Abrasion, Density, and Uniformity of
Aggregates
Water Absorption

Water absorption gives an idea on the internal structure of aggregate. Aggregates having more
absorption are more porous in nature and are generally considered unsuitable, unless found to be
acceptable based on strength, impact and hardness tests.

a. Apparatus Required
i. Wire Mesh Bucket - not more than 6.3mm mesh or a
perforated container of convenient size with thin
wire hangers for suspending it from the balance.

ii. Setup of Water Absorption Test - The setup

consists of container for filling water and
suspending the wire basket in it and an airtight
container of capacity similar to that of basket, a
shallow tray and two dry absorbent clothes.

b. Reference: IS 2386(Part 3):1963 Methods of Test for Aggregates. Reaffirmed- Dec 2016

c. Procedure: (For Aggregate Coarser Than 6.3mm)

i. About 2 kg of aggregate sample is taken, washed to remove fines and then
placed in the wire basket. The wire basket is then immersed in water, which
is at a temperature of 220C to 320C.

ii. Immediately after immersion the entrapped air is removed from the sample
by lifting the basket 25 mm above the base of the tank and allowing it to
drop, 25 times at a rate of about one drop per second.

iii. The basket, with aggregate are kept completely immersed in water for a
period of 24 ± 0.5 hour.

iv. The basket and aggregate are weighed while suspended in water, which is
at a temperature of 220C to 320C

v. The basket and aggregates are removed from water and dried with dry
absorbent cloth.

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 Chapter 4
Water Absorption, Abrasion, Density, and Uniformity of
Aggregates
vi. The surface dried aggregates are also weighed.

vii. The aggregate is placed in a shallow tray and heated to 100 to 1100C in the
oven for 24 ± 0.5 hours. Later, it is cooled in an airtight container and
weighed.

d. Calculation:
W1 = Weight of saturated aggregates in air.
W2 = Weight of oven dry aggregates in air

Water Absorption (%)= [(W1-W2)*100]/W2

Abrasion
Abrasion test is carried out to test the hardness property of aggregates. The principle of Los Angeles
abrasion test is to find the percentage wear due to relative rubbing action between the aggregate and
steel balls used as abrasive charge.

a. Apparatus Required
i. Balance - should be accurate up to 1 g.

ii. Sieves - Sieves required are 80, 63, 50,

40, 25, 20, 12.5, 10, 6.3, 4.75 (as per
gradation of aggregate) and 1.7 mm

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 Chapter 4
Water Absorption, Abrasion, Density, and Uniformity of
Aggregates

iii. Los Angeles Testing Machine -

Inside Length = 50 cm, and Inside
Diameter = 70 cm

iv. Abrasive Charges - Diameter = 48 mm and Weight = 390 to 445 g

b. Reference: IS 2386(Part 4):1963 Methods of Test for Aggregates for Concrete-

Mechanical Properties. Reaffirmed Dec 2016

c. Procedure:

✓ Gradation of Aggregate
i. Gradation of the Aggregate should be carried out so as to assess the Grade
of the Aggregate (A to G)

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 Chapter 4
Water Absorption, Abrasion, Density, and Uniformity of
Aggregates
✓ Procedure for Los Angeles Abrasion Test

ii. The test sample shall consist of clean aggregate which has been dried in an
oven at 105 to 110°C to substantially constant weight and shall conform to
one of the gradings shown in Table 1. The grading or gradings used shall
be those most nearly representing the aggregate furnished for the work.

iii. The test sample and the abrasive charge shall be placed in the Los Angeles
abrasion testing machine and the machine rotated at a speed of 20 to 33
rev/min. For gradings A, B, C and D, the machine shall be rotated for 500
revolutions; for gradings E, F and G, it shall be rotated for 1000 revolutions
as mentioned in the table below.

iv. The machine shall be so driven and so counter-balanced as to maintain a

substantially uniform peripheral speed. If an angle is used as the shelf, the
machine shall be rotated in such a direction that the charge is caught on
outside surface of the angle.

v. At the completion of the test, the material shall be discharged from the
machine and a preliminary separation of the sample made on a sieve
coarser than the l.70 mm IS Sieve.

vi. . The material coarser than the 1.70 mm IS Sieve shall be washed dried in
an oven at 105 to 110°C to a substantially constant weight, and accurately
weighed to the nearest gram (B).

d. Calculation:

The difference between the original weight and the final weight of the test sample is
expressed as a percentage of the original weight of the test sample. This value is reported
as the percentage of wear.

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 Chapter 4
Water Absorption, Abrasion, Density, and Uniformity of
Aggregates
A = weight in gm of oven-dried sample.
B = weight in gm of fraction retained on 1.70 mm IS Sieves after washing and oven-
dried up to constant weight

Aggregate Abrasion Value = ((A-B)/A) X 100

Density of Aggregate
Specific Gravity is defined as the ratio of Weight of Aggregate to the Weight of equal
Volume of water. The specific gravity of an aggregate is considered to be a measure of strength or
quality of the material. Aggregates having low specific gravity are generally weaker than those with
high specific gravity. This property helps in a general identification of aggregates.

a. Apparatus Required

i. Wire Mesh Bucket - not more than 6.3mm mesh or a

perforated container of convenient size with thin
wire hangers for suspending it from the balance.

ii. Setup of Water Absorption Test - The setup

consists of container for filling water and
suspending the wire basket in it and an airtight
container of capacity similar to that of basket, a
shallow tray and two dry absorbent clothes.

iii. Pycnometer - Pycnometer of 1000 ml for aggregates

finer than 6.3 mm

b. Reference: IS 2386(Part 3):1963 Methods of test for Aggregates for Concrete:

Determination of Specific Gravity. Reaffirmed- Dec 2016

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 Chapter 4
Water Absorption, Abrasion, Density, and Uniformity of
Aggregates
c. Procedure: (For Aggregate Coarser Than 6.3mm)

i. About 2 kg of aggregate sample is taken, washed to remove fines and then

placed in the wire basket. The wire basket is then immersed in water, which
is at a temperature of 220C to 320C.

ii. Immediately after immersion the entrapped air is removed from the sample
by lifting the basket 25 mm above the base of the tank and allowing it to
drop, 25 times at a rate of about one drop per second.

iii. The basket, with aggregate are kept completely immersed in water for a
period of 24 ± 0.5 hour.

iv. The basket and aggregate are weighed while suspended in water, which is
at a temperature of 220C to 320C

v. The basket and aggregates are removed from water and dried with dry
absorbent cloth.

vi. The surface dried aggregates are also weighed.

vii. The aggregate is placed in a shallow tray and heated to 100 to 1100C in the
oven for 24 ± 0.5 hours. Later, it is cooled in an airtight container and
weighed.

d. Procedure: (For Aggregate Finer Than 6.3mm)

i. A clean, dry pycnometer is taken and its empty weight is determined.

ii. About 1000g of clean sample is taken into the pycnometer, and it is
weighed.

iii. Water at 270C is filled up in the pycnometer with aggregate sample, to just
immerse sample.

iv. Immediately after immersion the entrapped air is removed from the sample
by shaking pycnometer, placing a finger on the hole at the top of the sealed
pycnometer.

v. Now the pycnometer is completely filled up with water till the hole at the
top, and after confirming that there is no more entrapped air in it, it is
weighed.

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 Chapter 4
Water Absorption, Abrasion, Density, and Uniformity of
Aggregates
vi. The contents of the pycnometer are discharged, and it is cleaned.

vii. Water is filled up to the top of the pycnometer, without any entrapped air.
It is then weighed.

viii. For mineral filler, specific gravity bottle is used and the material is filled
up to one-third of the capacity of bottle. The rest of the process of
determining specific gravity is similar to the one described for aggregate
finer than 6.3 mm.

e. Observation and Recording:

Observation Table for Specific gravity of Aggregate coarser than 6.3 mm

Observation Table for Specific gravity of Aggregate finer than 6.3 mm

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 Chapter 4
Water Absorption, Abrasion, Density, and Uniformity of
Aggregates
f. Remarks:

✓ The specific gravity of aggregates normally used in construction ranges from about
2.5 to 3.0 with an average value of about 2.68.

✓ Specific gravity of aggregates is considered as an indication of strength. Material

having higher Specific Gravity is generally considered as having higher strength.
Water absorption of aggregate is a measure of porosity. This value is considered
as a measure of resistance to frost action, and as a measure of sustaining
weathering action.

References:

http://sknlazoce.blogspot.com/2018/08/basic-concepts-in-construction.html
https://www.slideshare.net/engrnaveedhussain1/material-testing-lab-equipments?from_action=save
https://www.azom.com/materials-equipment.aspx?cat=116
http://site.iugaza.edu.ps/mymousa/files/Material_-Testing-lab-manual.pdf
https://pubs.usgs.gov/bul/0329/report.pdf
https://www.cement.org/cement-concrete-applications/concrete-materials/aggregates
http://www.iricen.gov.in/LAB/res/pdf/test-17.pdf
http://www.iricen.gov.in/LAB/res/pdf/test-15.pdf
http://www.iitk.ac.in/ce/test/IS-codes/is.2386.3.1963.pdf
http://www.iricen.gov.in/LAB/res/pdf/test-18.pdf

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