laboratory test

1. Koya University
Faculty of Engineering
Civil Department - 2nd Stage
Concrete Technology
Test no: 4
Density, Specific Gravity & Absorption of Coarse
Aggregate
Student Name: Muhammad Saleem Asaad
Group: B
Expr Date: 13-12-2015
Submission Date:31-1-2016
Introduction

2. Relative density (specific gravity) is the characteristic
generally used for calculation of the volume occupied by the
aggregate in various mixtures containing aggregate, including
Portland cement concrete, bituminous concrete and other
mixtures that are proportioned or analyzed on an absolute
volume basis. Relative density (specific gravity) is also used
in the computation of voids in aggregate. Relative density
(specific gravity) (SSD) is used if the aggregate is wet, that is,
if its absorption has been satisfied.
Conversely, the relative density (specific gravity) (OD) is used
for computations when the aggregate is dry or assumed to be
dry.
Apparent density and apparent relative density (apparent
specific gravity) pertain to the solid material making up the
constituent particles not including the pore space within the
particles which is accessible to water.
Absorption values are used to calculate the change in the mass
of an aggregate due to water absorbed in the pore spaces within
the constituent particles, compared to the dry condition, when
it is deemed that the aggregate has been in contact with water
long enough to satisfy most of the absorption potential.

3. APPARATUS:
1. Balance.
2. Sample Container.
3. Water Tank.
4. Sieve 4.75-mm (No. 4) or other sizes as needed.
5. Oven 110±5 oC.

4. Test Procedure:
Take a sample of coarse aggregate, and sieve it with
4.75mm sieves. Ignores the materials passing through
4.75mm sieve.
Wash the sample to remove dust.
Put the sample in the oven at 105°C for 24hours.
Get the sample out of the oven, leave it to cool then
determine its mass.
Submerge the sample in water for 24hours.
Remove the sample from the water and roll it in a large
absorbent cloth until all visible films of water are removed.
Wipe the larger particles individually. Take care to avoid
evaporation of water from aggregate pores during the
operation of surface- drying.
Take the required mass of the sample in its (S.S.D)
(saturated surface dry) condition.
After weighing, immediately place the S.S.D sample in the
sample container and determine its mass in water at 23±1°C.
Take care to remove all entrapped air before weighing by
shaking the container while immersed.
Dry the test sample to constant weight at a temperature
of 110±5°C, Cool in air at room temperature 1 to 3 hours, or
until the aggregate has cooled to a temperature that is
comfortable to handle (approximately 50 °C), and determine
the mass.

5. Calculation
A = mass of oven-dry test sample in air, g,
B = mass of saturated-surface-dry test sample in air, g,
C = apparent mass of saturated test sample in water, g.
a) Relative Density (Specific Gravity):
𝑹𝒆𝒍𝒂𝒕𝒊𝒗𝒆 𝒅𝒆𝒏𝒔𝒊𝒕𝒚(𝑶𝑫)=
𝐴
𝐵−𝐶
=
996
1004−637.1
=2.71g
𝑹𝒆𝒍𝒂𝒕𝒊𝒗𝒆 𝒅𝒆𝒏𝒔𝒊𝒕𝒚 (𝑺𝑺𝑫) =
𝐵
𝐵−𝐶
=
1004
1004−637.1
=2.74g
𝑨𝒑𝒑𝒂𝒓𝒆𝒏𝒕 𝒔𝒑𝒆𝒄𝒊𝒇𝒊𝒄 𝒈𝒓𝒂𝒗𝒊𝒕𝒚 =
𝐴
𝐴−𝐶
=
996
996−637.1
=2.78g
b) Density
𝑫𝒆𝒏𝒔𝒊𝒕𝒚 (𝑶𝑫), 𝒌𝒈/𝒎𝟑 =
𝐴
𝐵−𝐶
×997.5
=
996
1004−637.1
×997.5 =2703.22g

6. 𝑫𝒆𝒏𝒔𝒊𝒕𝒚 (𝑶𝑫), 𝒍𝒃/𝒇𝒕𝟑 =
𝐴
𝐵−𝐶
× 𝟔𝟐.𝟐𝟕
=
996
1004−637.1
× 𝟔𝟐.𝟐𝟕=168.75g
𝑫𝒆𝒏𝒔𝒊𝒕𝒚 (SSD), 𝒌𝒈/𝒎𝟑 =
𝐵
𝐵−𝐶
×997.5
=
1004
1004−637.1
×997.5 =2733.15g
𝑫𝒆𝒏𝒔𝒊𝒕𝒚 (SSD), 𝒍𝒃/𝒇𝒕𝟑 =
𝐵
𝐵−𝐶
× 𝟔𝟐.𝟐𝟕
=
1004
1004−637.1
× 𝟔𝟐.𝟐𝟕=170.62g
𝑨𝒑𝒑𝒂𝒓𝒆𝒏𝒕 𝑫𝒆𝒏𝒔𝒊𝒕𝒚, 𝒌𝒈/𝒎𝟑 =
𝐴
𝐴−𝐶
×997.5
=
996
996−637.1
×997.5 =2773.05g
𝑨𝒑𝒑𝒂𝒓𝒆𝒏𝒕 𝑫𝒆𝒏𝒔𝒊𝒕𝒚, 𝒍𝒃/𝒇𝒕𝟑 =
𝐴
𝐴−𝐶
× 𝟔𝟐.𝟐𝟕
=
996
996−637.1
× 𝟔𝟐.𝟐𝟕=137.11g
c) Absorption
𝑨𝒃𝒔𝒐𝒓𝒑𝒕𝒊𝒐𝒏, %=(
𝐵−𝐴
𝐴
) × 100=(
1004−996
996
) × 100=0.80%

7. Discussion
This test is consisting of density, specific gravity and absorption. density
is defined as the mass of unit volume of a material while specific gravity
is used for calculation of the volume occupied by the aggregate and
absorption is defined as the increase in mass of aggregate from
penetration water to pore space, by this test we can know density and
relative density and absorption of an aggregate. During this test may be
have some factors that Couse error of the result for example if the
temperature not suitable when determine OD and SSD and wet mass of
aggregate or error in reading the balance.in conclusion we can say this
test is useful for determine absorption, density and specific gravity basis
of oven dry, saturated surface dry and apparent.