Absorption of Coarse Aggregate Report By: Sarchia Khursheed

1. 1
Soran University
Faculty of Engineering
Civil Engineering Department
Absorption of Coarse Aggregate
Student: Sarchia Khursheed
Group: 2
Experiment NO.: 2
Date: 18.11.2015
Supervisor: Arianfar Haji
Introduction

2. 2
Absorption is the increase in the mass of aggregate due to water being
absorbed into the pores of the material, but not including water
adhering to the outside surface of the particles, expressed as a
percentage of the dry mass. The aggregate is considered “dry” when it
has been maintained at a temperature of 110 ±5°C for sufficient time
to remove all uncombined water
The laboratory standard for absorption is that obtained after
submerging dry aggregate for approximately 15 hours in water.
Aggregates mined from below the water table may have a higher
absorption, when used, if not allowed to dry. Conversely, some
aggregates, when used, may contain an amount of absorbed moisture
less than the 15 hours soaked condition. For an aggregate that has
been in contact with water and that has free moisture on the particle
surfaces, the percentage of free moisture can be determined by
deducting the absorption from the total moisture content.
The pores in lightweight aggregates may or may not become filled with
water after immersion for 15 hours. In fact, many such aggregates can
remain immersed in water for several days without satisfying most of
the aggregates’ absorption potential. Therefore, this method is not
intended for use with lightweight aggregate.
Objective
To determine the absorption of given sample of coarse aggregates.
Apparatus
 A balance or scale of capacity not less than 3 kg, readable and
accurate to 0.5 g and of such a type and shape as to permit the
basket containing the sample to be suspended from the beam
and the weighed in water.
 A well ventilated oven thermostatically controlled to maintain a
temperature of 100°C to 110°C.
 A wire basket of not more than 6.3 mm mesh or a perforated
container of convenient size.
 A stout water tight container of convenient size.
 A glass container
 Two dry soft absorbent cloths each not less than 75×45 cm

3. 3
 A shallow tray of area no less than 650 cm2
Materials
 Coarse aggregate
 Distilled water
Procedure
I. The sample should be thoroughly washed to remove finer
particles and dust, drained and then placed in the wire basket
and immersed in distilled water at a temperature between 22
and 32oC.
II. After immersion, the entrapped air should be removed by lifting
the basket and allowing it to drop 25 times in 25 seconds. The
basket and sample should remain immersed for a period of 24 +
½ hrs afterwards.
III. The basket and aggregates should then be removed from the
water, allowed to drain for a few minutes, after which the
aggregates should be gently emptied from the basket on to one
of the dry clothes and gently surface-dried with the cloth,
transferring it to a second dry cloth when the first would remove
no further moisture. The aggregates should be spread on the
second cloth and exposed to the atmosphere away from direct
sunlight till it appears to be completely surface-dry. The
aggregates should be weighed (Weight ‘A’).
IV. The aggregates should then be placed in an oven at a
temperature of 100 to 110oC for 24hrs. It should then be
removed from the oven, cooled and weighed (Weight ‘B’).
Data and Calculations

4. 4
Weights
Groups A B
1 306 g 305 g
2 351 g 352 g
3 325 g 325 g
A = Weight of aggregate in SSD condition.
B = Weight of the oven dry aggregate in air (100 – 110°C)
Absorption (%) =
𝐴−𝐵
𝐵
× 100
Group 1:
306 𝑔 − 305 𝑔
305 𝑔
× 100 = 0.328 %
Group 2:
351 𝑔 − 352 𝑔
352 𝑔
× 100 = -0.284 %
Group 3:
325 𝑔 − 325 𝑔
325 𝑔
× 100 = 0 %
Discussion

5. 5
From the weight of aggregate in SSD condition (A) and weight of oven
dry aggregate (B) we can obtain the absorption of coarse aggregate by
this equation (
𝐴−𝐵
𝐵
× 100 ), after obtaining the weights of coarse
aggregate in SSD condition and oven dry condition we use it in the
equation, weight of (A) must be greater than (B) because of
absorption of water, and the rate of absorption must be greater than 0
and less than 2.
In this experiment our result (Group 2) it seems a bad result because
the result is less than 0 and sign is minus, about another two groups,
the result of Group 1 between 0 and 2 may it better than two groups,
about the result of Group 3 it is 0, these results clear that maybe there
are some problems in measuring and process of this test, it be better
to reply this experiments to obtain some probable results.