Testing of stones

Stones
Bahram Nawabi
2012UCE1790
2nd Year 1st Sem
Construction Materials

Contents:
• Stones
• - Rocks
• - Quarrying of stones
• - Uses of stones (1-2)
• - Characteristic of good building
stones
• Tests of stones
• - Different types of stones tests
• - Why should we test and …
• Preservation of stones

STONES
Stone has been defined as the
natural, hard substance formed
from minerals and earth material
which are present in rocks.

Rocks
Rock may be defined as the portion of
the earth’s crust having no definite
shape and structure.

Quarrying of stones
The only operation involved in the
production of natural stone is the
quarrying process.
The open part of the natural rock
from which useful stone is
obtained is known as quarry.

Uses of stones-1
Use of stone as building material
depends upon the:
 Nature of the work
 Type of the structural element
 Quality
 Availability
 Transportation cost

Uses of stones-2
For structural purposes:
 Granite
 Gneiss
 Trap
 Sandstone
 Limestone
 Marble
 Quartzite
 Slate
are most useful.

Valley National Bank building, Arizona

Characteristics of good building stones
A good building stone should have:
 Appearance
 Structure strength
 Weight
 Hardness
 Toughness
 Seasoning
 Weathering
 Workability
 Fire resistance
 Specific gravity
 Thermal movement

Testing of stones
To choose and utilize stones and for
their satisfactory performance, it is
necessary to test them for its strength
properties, durability and quality.

Different types of test
• Acid test
• Attrition test
• Absorption test
• Brad’s test
• Crushing strength test
• Crystallization test
• Freezing and thawing test
• Hardness test
• Impact test
• Microscopic test
• Smith’s test
• Specific gravity test
• Durability test

• Acid test:
This test is carried out on stone to
check the weathering resistance.

• Attrition test:
The aim of this test is to determine the resistance
of the stone to abrasion, specially for those
stones which are to be used for path ways, pavements
and roads subjected to the grinding action of the
traffic.
percent wear=(M1-M2)/M1*100
Where;
M1= Initial mass of stone ballast.
M2= Final mass of stone ballast
Deval’s Attriton Machine;

• Water absorption test:
The water absorption test is carried
out to determine the quality of stone.
% Absorption= (M1-
M2)/M1*100

• Brad’s test:
This test is conducted for frost
resistance.

• Crushing strength test:
This test is conducted on a compression testing
machine.
The test samples are dressed from all sides.
The diameter of the test pieces known as specimen,
is not less than 40 mm.

• Hardness test:
The hardness test is conducted on
Dory's testing machine.
Coefficient of hardness= 20-loss of mass in
gm/3
Alternatively the hardness test may be performed by scratching
the stone with a knife on Mohr’s scale.

• Impact test:
Is carried out on an impact machine to
determine the toughness of stone.

• Microscopic examination:
This is basically a geologists test. Thin
sections of stone are taken and placed under a
microscope to study the following properties:
i. Average grain size
ii. Texture of the stone
iii. Mineral constituents
iv. Type of cementing material
v. Presence of pores, fissures, veins, shakes etc.
vi. Presence of harmful constituents
vii. Condition of fractured surfaces.

• Smith’s test:
This test is conducted to find out the
presence of water soluble matter present in
the stone. It is only a qualitative test.

• Weathering resistance (Crystallization)test:
This test is conducted as per Indian Standard
Specific
a1= 100*(M3-M1)/M1
V1= (M3-M2)/μ
a2= 100*(M4-M1)/M1
V2= (M4-M5)/μ
Where;
a1= original absorption of the specimen at the end of 24
hr immersion
a2= final absorption of the specimen after 30 cycles
V1= original volume of the specimen at the end of 24 hr
immersion
V2= final volume of the specimen after 30 cycles of
test
μ= density of water

a1= 100*(M3-M1)/M1
V1= (M3-M2)/μ
a2= 100*(M4-M1)/M1
V2= (M4-M5)/μ
Where;
a1= original absorption of the specimen at the end of
24 hr immersion
a2= final absorption of the specimen after 30 cycles
V1= original volume of the specimen at the end of 24 hr
immersion
V2= final volume of the specimen after 30 cycles of
test
μ= density of water
Increase in absorption due to weathering= 100*(a2-
a1)/a1

• Specific gravity test:
This procedure is adopted for
determination of specific gravity of stone, as
per IS : 1121-1974
Gt=(M2-M1)/((M4-M2)-M3-M2)

• Durability test:
The durability (soundness) test is
performed to find out the capacity of stone
to resist disintegration and decomposition.
Durability value= change in the mass= (M1-
M2)*100

Why should we test and which
tests are appropriate?
• • Failure mode effect analysis
• – What can go wrong?
• – What can we test for this?
• – How can we manage the risk?
• • Is it safe?
• • Will it last?
• • Is it strong enough?

Different types of test -flexural

Different types of test - compressive

Different types of test – porosity

Different types of test – slip

Different types of test – salt

Preservation of stones
The various natural agents,
Like:
• Rain
• - Physical action
• - Chemical action
• Frost
• Wind
• Temperature changes
• Vegetable growth
• Mutual decay
• Chemical agents
• Lichens
are deteriorate the stones with time.
Due to preventing from these deteriorations on stones there
are some preservations.

1) Coal tar:
If coal tar is applied on stone surface, it
preserves stone.
But the colour of coal tar produces objectionable
appearance and surface coated with coal tar
absorbs heat of the sun. Hence this preservative is
not generally adopted because it spoils the beauty of
stones.

2) Linseed oil:
This preservative may be used either as raw
linseed oil or boiled linseed oil. The raw linseed oil
does not disturb the original shade of stone. But it
requires frequent renewal usually one in a year. The
boiled linseed oil lasts for along period, but it makes
the stone surface dark.

3) Paint:
An application of paint on stone surface
serves as a preservative. The paint changes the
original colour of stone. It is applied under pressure,
if deep penetration is required.

4) Paraffin:
This preservative may be used alone or it may be
dissolved and naphtha and then applied on stone
surface. It changes the original colour of stone.

5) Solution of alum and soap:
The alum and soft soap are taken in
proportion of about 0.75N and 0.50N respectively
and they are dissolved in a liter of water. This
solution, when applied on stone surface, acts as
preservative.

6) Solution of baryta:
A solution of barium hydroxide Ba(OH)2, when
applied on stone surface, acts as a preservative.
This preservative is used when the decay of stone is
mainly due to calcium sulphate, CaSO4. Following
chemical reaction takes place:
Ba(OH)2+CaSO4 = BaSO4+Ca(OH)2
The barium sulphate is insoluble and it is least
affected by atmospheric agencies. The calcium
hydroxide absorbs Carbon-di-Oxide from atmosphere
and forms Calcium Carbonate CaCO3 which adds to
the strength of stone.

Sources
1. ) Engineering materials, By Rangwala.
2. ) Basic Civil Engineering, By Dr.B.C.
Punmia
3. ) Internet, (Wikipedia.com, Google
image)

Testing of stones

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Testing of stones