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CIV 204 MATERIALS of CONSTRUCTION
Lab Application - Testing of Aggregates
TESTING of AGGREGATES for CONCRETE
The properties of the aggregates affect both the fresh and hardened properties of concrete. It is crucial to know the
properties of the aggregates to be used in the making of concrete in order to obtain the desired quality in a
concrete. Therefore, the tests performed on aggregates are very important.
Definitions (EN 12320)
aggregate -granular material used in construction. Aggregate may be natural, manufactured or recycled.
natural aggregate - aggregate from mineral sources which has been subjected to nothing more than
mechanical processing.
manufactured aggregate - aggregate of mineral origin resulting from an industrial process involving
thermal or other modification.
recycled aggregate -aggregate resulting from the processing of inorganic material previously used in
construction.
aggregate size - designation of aggregate in terms of lower (d) and upper (D) sieve sizes expressed
as d/D
fine aggregate - designation given to the smaller aggregate sizes with D less than or equal to 4 mm
coarse aggregate - designation given to the larger aggregate sizes with D greater than or equal to 4
mm and d greater than or equal to 2 mm.
all-in aggregate - aggregate consisting of a mixture of fine and coarse aggregates.
fines - particle size fraction of an aggregate which passes the 0,063 mm sieve.
grading - particle size distribution expressed as the percentages by mass passing a specified set of
sieves.
SAMPLING
Before conducting any test on aggregates, the first thing to do is sampling. A sample is a representative small
portion from a larger whole or group of materials. There are two methods of reducing the size of an aggregate
sample: Splitting and quartering.
Quartering
Splitting
1. Determination of Particle Size Distribution – Sieving Method (EN 933-1)
In a sieve analysis, a sample of dry aggregate of known weight is separated through a series of sieves with
progressively smaller openings. Once separated, the weight of particles retained on each sieve is measured and
compared to the total sample weight. Particle size distribution is then expressed as a percent retained by weight on
each sieve size. Results are usually expressed in tabular or graphical format.
The test consists of dividing up and separating, by means of series of sieves, a material into several particle size
classification of decreasing sizes. The aperture sizes and the number of sieves are selected in accordance with the
nature of the sample and the accuracy required.
The mass of the particles retained on the various sieves is related to the initial mass of the material.
The cumulative percentages passing each sieve are reported in numerical form or in graphical form.
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CIV 204 MATERIALS of CONSTRUCTION
Lab Application - Testing of Aggregates
Test sieves – set of sieves with given aperture sizes and shape.
Individual retained – the mass or percentage retained on one sieve after test.
Cumulative retained – sum of the mass or percentages retained on the sieve and on all coarser sieves.
Cumulative passing – sum of the mass or percentage passing the sieve (e.g. sum of the retained on all finer
sieves and pan).
The basic series of sieves (according EN 933-2):
0,063 mm; 0,125 mm; 0,250 mm; 0,500 mm; 1 mm; 2 mm; 4 mm; 8 mm; 16 mm; 31,5 mm; 63 mm; 125 mm
Sieves with aperture size of 4 mm and above are perforated plate with square holes and sieves below 4 mm are
from woven wire.
Test portions - depends on maximum aggregate size and is specified in Table 1.
Table 1. Required test portion mass for sieve analysis of aggregates for concrete.
Sieving Procedure
 Pour the washed and dried material (or directly the dry sample) into sieving column. The column comprises a
number of sieves fitted together and arranged, from top to bottom, in order of decreasing aperture sizes with
pan and lid.
 Shake the column, manually or mechanically, then remove the sieves one by one, and shake each sieve
manually ensuring no material is lost.
 Weight the retained material on each sieve with the largest aperture and record the retained masses in gram
as shown in the example below (the first column in the example).
 Calculate the mass retained on each sieve as percentage of the original dry mass M (the second column in
example)
 Calculate the cumulative percentage of the original dry mass passing each sieve down (the third column).

Plot the sieve aperture size (in log scale) vs. cumulative passing (%) chart.
Example:
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CIV 204 MATERIALS of CONSTRUCTION
Lab Application - Testing of Aggregates
APPLICATION
Sieve
aperture size
(mm)
Retained
(g)
Retained
(%)
Cumulative retained
(%)
Cumulative passing
(%)
16
8
4
2
1
0.5
0.125
PAN
TOTAL
100
90
Cumulative passing (%)
80
70
60
50
40
30
20
10
0
0.125
0.25
0.5
1
2
Sieve aperture size (mm)
3
4
8
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CIV 204 MATERIALS of CONSTRUCTION
Lab Application - Testing of Aggregates
2. Cleanliness and Deleterious Materials.
Aggregates must be relatively clean. Vegetation, soft particles, clay lumps, excess dust and vegetable matter may
affect performance by quickly degrading, which causes a loss of structural support and/or prevents binderaggregate bonding.
Clay
Determination of clay, silt, and dust in fine and coarse aggregate can be tested by sedimentation method.
The aggregate is carefully mixed with water in volumetric cylinder and then let to settle.
The clay particles will form layer with different color and structure on the surface of aggregate.
Organic Impurities
Decaying vegetation may result in aggregates being contaminated with organic matter. This material may have a
retarding effect on the setting of cementitious material and may result in lower strengths of the hardened material
at all ages. Organic impurities can be tested by colorimetric test. Tested aggregate is mixed with sodium hydroxide
(NaOH) or potassium hydroxide (KOH) to prepare colored solution. The color of solution is compared with color of
standard solution after 24 hours, prepared according the standard. If the color of the test solution is darker than the
standard solution, then the aggregate should be rejected.
3. Determination of Particle Shape of Coarse Aggregates.
Particle shape and surface texture are important for proper compaction, deformation resistance and workability.
Rounded particles create less particle-to-particle interlock than angular particles and thus provide better workability
and easier compaction. Flat or elongated particles tend to impede compaction or break during compaction and
thus, may decrease strength. Particle shape can be described by flakiness index or shape index (according EN
933-3, EN 933-4).
Flakiness Index
The flakiness index (FI) is calculated as the mass of particles that pass the bar sieves with parallel slots ,
expressed as a percentage of the mass of the test portion.
Shape Index
Shape index is determined only on the coarse aggregates. The principle of determination of shape index is to
measure the thickness E and length L of each grain in a sample of several hundred stones and then to calculate
the ratio L/E between the thickness and the length of each particle. If this ratio is higher than 3, than the particle is
too long (non-cubic particle). EN 933-4 sets down the amount of measured grains to minimum 100 grains from
each size of the coarse aggregate.
Shape index SI is defined as a ratio between the weight of particles with L/E 3 and weight of all measured
particles in percents.
Shape index caliper
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CIV 204 MATERIALS of CONSTRUCTION
Lab Application - Testing of Aggregates
4. Abrasion Resistance (Los Angeles Test)
The test methods described in ASTM C131 and EN 1097-2 are different each
other. The general concept is provided here.
This test method covers a procedure for testing coarse aggregate resistance to
degradation (due to breaking the aggregates) using the Los Angeles testing
machine. For this test, 5 kg of oven-dried aggregate sample and abrasive
charges made of steel spheres are placed into the drum of the machine. Then,
the machine is started to rotate at 30-33 rpm (revolution per minute). After 500
revolutions (100 revolutions can also be applied to aggregates which are going
to be used in concrete elements facing light abrasion conditions), aggregate
samples are removed from the drum and sieved on No.12 (1.6 mm) sieve. Los
Angeles coefficient is determined by the LA equation given below (m is the
retained fraction of aggregates on 1.6 mm sieve in gram). The aggregates are
assumed to be resistant against abrasion when the weight loss is less than 10
% and 50 % at the end of 100 and 500 revolutions of the cylinder, respectively.
Test samples and number of spheres should comply with one of the following limitations:
GRADINGS of TEST SAMPLES (ASTM C131)
APPLICATION
Measured parameter
Weight of the aggregate before test (g)
Weight of the aggregate fraction retained on 1.6 mm sieve (g)
Calculated Parameters
LA coefficient
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Measured value
Calculated value
CIV 204 MATERIALS of CONSTRUCTION
Lab Application - Testing of Aggregates
5. Determination of Bulk Density (Unit Weight)
This test method covers the determination of bulk density (“unit weight”) of
aggregate in compacted or loose condition, and calculated voids between
particles in fine, coarse, or mixed aggregates based on the same
determination.
o
To do this test, aggregate samples, which are oven dried at 110±5 C to
constant mass, are filled in a measure, size of which is determined by the
maximum aggregate size. The measure is filled in 3 equal layers and each
layer is rodded 25 times by tamping rod. When the measure is filled, the
excess aggregates are struck off by using the side of tamping rod so that the
surface of the measure is leveled. Then, knowing the volume of the measure
and the weight of aggregates inside the measure, unit weight is calculated as weight over volume. The unit weight
calculated by this procedure is called as “dry rodded unit weight” and if no rodding operation is applied, it is called
as “dry loose unit weight”.
APPLICATION
Parameter
Self-weight of the container (g)
Weight of the container filled with water (g)
Loose weight of concrete in container (g)
Compacted (rodded) weight of aggregate in container (g)
Parameter
3
Volume of the container (m )
3
Loose unit weight of the aggregate (kg/m )
3
Compacted (rodded) unit weight of the aggregate (kg/m )
Measured value
Calculated value
5.1 Determination of Specific Gravity, and Water Absorption Capacity of
Coarse Aggregate
The amount of sample should conform to the given limits:
Procedure:
 Immerse the sample in water at room temperature for a period of 24 hours. Remove the sample from the water
and roll it in a large absorbent cloth until all visible films of water are removed. Obtain the weight of the sample
in saturated surface dry condition (SSD) (B).
 After determining B, immediately place the sample in a wire basket and determine its weight in water (C).
o
 Dry the sample to constant weight at a temperature of 105±5 C, allow it to cool to room temperature and weigh
(A).
Calculations:
Specific gravity - Dry (SG-dry) = A / (B – C)
Apparent specific gravity (SG-app) = A / (A – C)
Specific gravity – SSD (SG-ssd) = B / (B – C)
Absorption Capacity (%) = (B – A) / A × 100
APPLICATION
Parameter
Dry weight of the sample (g)
Weight of the sample in SSD condition (g)
Weight of the sample in water (g)
Parameter
Specific gravity – dry
Specific gravity – ssd
Water absorption capacity (%)
Measured value
Calculated value
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CIV 204 MATERIALS of CONSTRUCTION
Lab Application - Testing of Aggregates
5.2 Determination of Density, Relative Density (Specific Gravity), and Water
Absorption Capacity of Fine Aggregate
Apparatus:
Balance, flask, small cone mold, tamping rod.
Preparation of Sample:
Place approximately 1 kg of fine aggregate in a pan and cover it with water and permit to stand 24 hr. Then, spread
the sample on a flat surface exposed to a gently moving current of warm air and stir frequently to secure uniform
drying. Continue drying until saturated surface dry condition is maintained. For the determination of this condition
either cone method or eye inspection shall be employed.
Procedure:
Saturated surface dry sample shall be divided into two equal sections. One of which shall be weighed (B) and
o
dried to constant weight at a temperature of 105±5 C and after cooling weighted (A). The other section shall be
introduced into the flask which is filled with some water. The flask then shall be rolled on a flat surface in order to
o
eliminate all air bubbles. It shall be placed in a constant temperature water bath maintained at 23±2 C. After 1 hr.,
the flask shall be filled with water up to 500 ml mark and weighed (C).
D: Weight of flask filled with water up to 500 ml mark.
Calculations:
Specific gravity – oven dry = A / (B + D – C)
Specific gravity - ssd = B / (B + D – C)
Apparent specific gravity = A / (A + D – C)
Absorption Capacity (%) = (B – A) / A × 100
APPLICATION
Measured Parameters
Weight of the sample in SSD condition (g)
Weight of the sample in oven-dry condition (g)
Weight of the flask + sample + water (g)
Weight of the flask + water (g)
Parameter
Specific gravity – dry
Specific gravity – ssd
Apparent specific gravity
Water absorption capacity (%)
Measured value
Calculated value
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