This document discusses the importance of geology for civil engineering projects. It explains that engineers must understand the geological conditions of the construction site, as the foundation and materials used must be suitable for the local rocks and soils. The document then focuses on two key applications of geology: road metals and building stones. It provides criteria for suitable road metals, discussing various rock types commonly used. It also briefly defines building stone as rock suitable for construction uses.

1. Engineering Geology
ES-101
Engineering Applications
(Importance of Geology, Road Metals & Important
Building Stones)
Lecture – 8
Course Instructor
Engr. Naeem Bashir Awan
HITEC University, Taxila

2. ▪ Role & Importance of Geology for Civil
Engineering Projects
▪ Road Metals
▪ Building Stones
▪ Stones / Rocks Classifications
▪ Physical Classification
▪ Chemical Classification
▪ Geological Classification
❑ HITEC University, Taxila
Outline:

3. Engineering Applications
▪ Before a Civil Engineer may proceed to design his project, he
must know something about the type of rocks on which the
foundation of his structure has to rest.
▪ This necessitates a thorough investigation of the site, before
the detailed design may be prepared. If he neglects such an
investigation, he can be compared to a surgeon starting the
work of an operation without diagnosis; or a lawyer pleading
his client’s case without prior discussion with him.
▪ The practice, going on in the last few decades all over the
world, is that geologist are called upon to give advice
regarding the foundation conditions of the major and
important projects to be undertaken.
❑ HITEC University, Taxila
Role of Geology in Engineering:

4. Engineering Applications
▪ The service, that is rendered by a geologist in any major Civil
Engineering project is being considered as the most valuable
and important for the project planning and execution of the
project;
• The geologist analyze the conditions of area selected for
the site, the engineer will consider as how to improve the
conditions and to adjust them.
• The geologist, from his analysis finds out the probable
problems and difficulties that are likely to be faced during
the construction, the engineer will solve the problems and
overcome the difficulties.
❑ HITEC University, Taxila
Role of Geology in Engineering:

5. Engineering Applications
• The geologist suggests different sites for the building
materials such as stone, brick earth, sand etc. to be
obtained, the engineer will obtain them economically and
will put them to use.
▪ In addition to the above mentioned few examples, engineer
may have to face a variety of problems in his day-to-day work,
for which fundamental knowledge of Geology is most
essential.
▪ As a matter of fact, Good Engineering means construction of
most economical structures, which will last longer and fulfil
their purposes satisfactorily. But the structure cannot be work
smoothly and successfully until and unless the foundations of
the structures are safe.
❑ HITEC University, Taxila
Role of Geology in Engineering:

6. Engineering Applications
▪ It may be noted that safety of foundation not only depends
upon its correct design and superiority of construction but also
upon the underground geological features.
▪ It has been experienced that majority of modern failures are
not due to faulty design or lack of proper supervision during
construction, but only due to defective bed conditions, which
are not fully detected at the time of selection of the site or
during construction.
▪ It may be noted that it is merely a geological investigation
which lacks proper attention; as the engineers are seldom
qualified to carry out geological works. Moreover, geologists
can not apply their knowledge to Engineering problems as
they are geologists not engineers.
❑ HITEC University, Taxila
Role of Geology in Engineering:

7. Engineering Applications
▪ This gap can only be filled by an engineer who has
considerable knowledge of Geology.
▪ In advanced countries the engineers and geologists have a
common platform where they plan a neat and coordinated
team work and thus contribute more towards the development
of the country.
▪ It has been observed that detailed geological surveys are not
only contribute valuable insurance against difficulties, which
otherwise engineers have to face, during construction but also
economise the cost of construction.
▪ In the excavation of panama canal igneous rocks were broken
down into very small pieces when blasted. These crushed
stones were utilized in the construction of canal saving
millions of rupees. ❑ HITEC University, Taxila
Role of Geology in Engineering:

8. Engineering Applications
▪ Today the knowledge of Geology has become a major part of
studies of a Civil Engineer. Application of Geology to a few
engineering problems is as;
1. Road Metals
• After finalizing the route of a roadway, the engineers
problem is the selection of suitable materials for its
construction. Such a problem also arises, when an
existing road is to be reconditioned.
• In a broad sense, the road metal is an engineering term
which is applied for the broken stones used in the
construction of roads.
• As a matter of fact, a road metal constitutes a major part
of the body of road, and has to bear the stresses caused
by the traffic. ❑ HITEC University, Taxila
Road Metals:

9. Engineering Applications
• It is therefore essential that selection of rock for the road
metal should always be done by keeping in view economic
consideration, amount and type of traffic the road is
expected to bear, topography of the region and availability
of the suitable rock for the road metal.
▪ The essential physical properties and usual tests carried out
to determine the suitability any rock as road metal may be
summarized as below:
o The stone should be quite tough. This can be tested by
breaking it under a hammer.
o The stone should have a high crushing strength, which
can be determined by testing the block usually 10 cm
(4inches) cube by a testing machine in a laboratory.
❑ HITEC University, Taxila
Road Metals :

10. Engineering Applications
o The stone should be sufficiently hard i.e. it should offer a
maximum possible resistance to the abrasion. This can be
tested by putting a weighed quantity of broken pieces of
the stone in a drum along with small cast iron balls. The
drum should be revolved about 2000 times in one hour.
The weight lost by the stone pieces will indicate the
amount of loss by abrasion. More resistant stone shows a
little loss in weight.
o The stone should have adhesive properties i.e. binding
capacity of the road metal with the binding material such
as coal tar etc. to ensure stability of road.
❑ HITEC University, Taxila
Road Metals :

11. Engineering Applications
▪ The main geological requirements for a road metal, as
suggested by Prof. PGH Boswell are as follows
1. The rock should be crystalline in nature.
2. The texture of the rock should be equiangular and
interlocking.
3. The rock should be quite hard and tough.
4. All the constituent minerals should be of equal hardness.
5. The rock should neither be too fresh nor badly altered.
6. The specific gravity of the rock should be moderately
high.
7. The rock should not be too porous.
❑ HITEC University, Taxila
Road Metals :

12. Engineering Applications
▪ It has been experienced that igneous rocks generally satisfy
all mentioned geological requirements.
▪ Basalts, Granites, Dolerites, Quartzites, Limestones,
Sandstones, Slates, Gneisses, Gravels and Kankar are
extensively used as road metal.
1. Basalts as Road Metals:
Basalts are dark colored igneous rocks and are being
considered to the best type of road metals. The rocks
have a very high crushing strength and specific gravity.
Basalts include dolerite, andesite, diorite etc. Basalts are
extensively used as a road metal.
❑ HITEC University, Taxila
Road Metals:

13. Engineering Applications
2. Granites as Road Metals:
Granites are igneous rocks, and are considered to be the
next in utility to basalts. Granites includes gneiss,
pegmatite, syenite etc. These rocks possess almost all
properties of a good road metals. It has been observed
that roads constructed with granites have proved to be
successful under heavy traffic.
3. Dolerite as Road Metals:
Dolerites are dark colored igneous rocks. Due to
interlocking of crystals, the rock is very tough and widely
used as a road metal. Dolerite have a special quality of
holding a firm grip of coal tar.
❑ HITEC University, Taxila
Road Metals :

14. Engineering Applications
4. Quartzites as Road Metals:
Quartzites are hard metamorphic rocks, which are quite
resistant to weathering actions. Quartzite posses almost
all requisite properties for use as a road metal, and are
extensively used.
5. Limestones as Road Metals:
Limestones are considered to be the first class road
metal, when available in good quality. Soft and
fossiliferous limestone should never be used.
Road Metals :

15. Engineering Applications
6. Sandstones as Road Metals :
Sandstones are sedimentary rocks, and possess a
requisite properties for use as a road metal, only when
available in good quality. It may be noted that sandstone
do not possess sufficient binding properties with coal tar.
7. Slates as Road Metals :
Slates generally shows a moderately high percentage of
wear and comparatively low hardness and roughness,
but have fair cementing properties. Slates split up easily
into chips which is highly objectionable for a good road
metal. Clayey varieties easily grind under traffic. Slates
are used as a road metal only for roads of less
importance.
❑ HITEC University, Taxila
Road Metals :

16. Engineering Applications
8. Gneisses as Road Metals :
Gneisses are the metamorphic rocks having the same
composition as that of granites. Gneisses are sometimes
called stratified granites. Harder variety of gneisses are
extensively used as a road metals.
9. Gravels as Road Metals :
Gravels are pebbles are rock fragments above 2mm. In
diameter rounded and smoothed during transportation by
the running water. Gravels of harder rocks and 5 to 10
cm in diameter are used as a road metals.
10. Kankar as Road Metals :
Kankar is suitable as a road metal, except for heavy
iiiiiiitraffic. Inferior varieties are almost useless. Only hard and
iiiiiiicrystalline varieties may be used as a road metal.
Road Metals :

17. Engineering Applications
Building Stones:
Building stone is a broad engineering term used for the rock,
that can be used safely and successfully in different shapes
and sizes for all types of buildings and other various
engineering projects.
1. A heavy and impervious stone is required for all type of
marine engineering works.
2. A stone unaffected by acids or fumes, is required for use
in a manufacturing town or industrial areas.
3. A heavy and hard stone is required for retaining walls and
foundation of buildings.
4. A stone of pleasing color and impervious in nature is
required for the facework of a high class building.
❑ HITEC University, Taxila
Building Stones:

18. Engineering Applications
5. A soft and even grained stone is required for the
ornamental work.
6. A soft and light stone is required for arches.
7. A very hard and resistant stone is required for stair cases
and floor paving.
▪ In addition to the above mentioned suit-abilities of a stone,
the essential physical properties and tests carried out to
determine the suitability of any rock as the building stone.
o The stone must be free from cracks and cavities, and
should be crystalline structure.
o The stone should be sufficiently hard , that can be tested
by scratching it with pen knife; which should not be able
to make any mark.
❑ HITEC University, Taxila
Building Stones :

19. Engineering Applications
o The stone should be sufficiently tough, which can be
tested by breaking it under a hammer.
o The stone should be sufficiently durable i.e. should not
be easily effected by weathering agents. Durability of
stone can be tested by studying the effects of
hydrochloric and sulphuric acids.
o The stone should be quite impervious, any stone
absorbing more then 5% of water should be rejected.
o The stone for heavy engineering works should have a
specific gravity usually not less than 2.60, which can be
determined by weighing a given volume of stone and
comparing with the weight of the same volume of water.
❑ HITEC University, Taxila
Building Stones :

20. Engineering Applications
▪ Following stones are used as a building materials.
1. Granite as a building stone:
Granite is a very hard igneous rock composed of quartz,
feldspar and mica. It can take an ornamental finish and
fine polish. On account of its hardness, durability and
variety of colors, it is considered to be the most valuable
stone for all types of important structures.
Larger blocks of granite are used as a building stone and
smaller ones are used as a railway ballast or road metal
and the chippings of concrete aggregates and artificial
stone.
❑ HITEC University, Taxila
Important Building Stones:

21. Engineering Applications
2. Sandstone as a building stone:
Sandstone is a sedimentary rock, consisting of sand
grains cemented together by lime, silica, magnesia,
aluminum, iron oxide etc. Its durability depends upon
nature of the cementing materials.
Sandstones are found in variety of colors e.g., yellow,
grey, brown, pink, red and black.
3. Slate as a building stone :
Slate is a metamorphic clayey rock, found in variety of
colors e.g., dark blue, bluish black and green. The
durability, and facility with which it can be split into thin
sheets has made it an excellent building material for use
in roof covering, paving and sills of doors and windows.
Important Building Stones:
❑ HITEC University, Taxila

22. Engineering Applications
4. Marble as a building stone:
Marble is a metamorphic rock, found in a variety of colors
e.g., grey, red, white, blue, yellow, green and black. It is
sufficiently hard and takes a fine polish. It is used
extensively as a building stone especially for decorative
purpose in columns, staircases, floors etc., where
economy is not the main consideration.
The course grained marbles are used for important
monumental and architectural buildings whereas fine
grained pure white marbles are used for statues.
❑ HITEC University, Taxila
Important Building Stones :

23. Engineering Applications
5. Limestone as a building stone:
Limestone is a sedimentary rock, consisting mostly of
carbonate of lime. There are many varieties of limestone,
which differ from one another in composition, texture, and
hardness.
Only a compact and durable limestone is suitable for
building purposes. All other varieties of limestones are
used in cement and lime manufacture.
6. Serpentine:
Serpentine is a metamorphic rock, found in green,
yellowish green or dark green in color. It is soft rock and
can be cut with knife. It is used in superior buildings for
indoor decorating purposes only.
Important Building Stones :
❑ HITEC University, Taxila

24. Engineering Applications
Stones are Rocks that can be classified by
Three Ways
Physical
Classification
Chemical
Classification
Geological
Classification
Stones Classifications:
❑ HITEC University, Taxila

25. Engineering Applications
Physical classification of stone or rock is based on the general
structure of the rocks. According to this classification, different
stones / rocks can be of the following three types.
1. Stratified Rocks: A stratified rock means layered rock.
Sedimentary rock shows layering. The planes between two
layers is called bedding plane. Rocks can be easily
breakdown or split along the bedding planes. Limestone and
sandstone rocks are some of the stratified rocks.
2. Unstratified Rocks: These rocks do not show any type of
layering, thus there is no bedding plane. These are
crystalline rocks that are hard and show good compressive
strength. Granite, basalt, marble are the examples of
unstratified rocks.
❑ HITEC University, Taxila
Physical Classification:

26. Engineering Applications
3. Foliated Rocks: Foliated rocks shows thin layering of
minerals within the body of rock along a definite direction.
Foliated rocks split along these thin layering planes. These
planes are usually not parallel to each other and are
considered as weak planes of the rocks. Gneiss rocks shows
foliated structures.
❑ HITEC University, Taxila
Physical Classification:

27. Engineering Applications
According to chemical classification rocks may be classified as
follows;
1. Argillaceous Rocks: Argillaceous rocks are composed of
fine to very fine sediments like clay. These rocks are
consolidated and have very low permeability. Claystone and
mudstone are famous argillaceous rocks.
2. Calcareous Rocks: These rocks are composed of calcium
carbonates, that’s why also called carbonate rocks.
Limestone and marble represent calcareous group of rocks.
3. Siliceous Rocks: These are hard rocks with very good
compressive strength. These are composed of Silica.
Sandstone, granite and quartzite rocks are example of
siliceous rocks.
❑ HITEC University, Taxila
Chemical Classification:

28. Engineering Applications
This classification of rocks is based on rock composition,
structures and mode of formation. According to this classification
rocks are of three types;
1. Igneous Rocks (Lecture 2)
I. Volcanic Rocks
II. Plutonic Rocks
III. Hypabyssal Rocks
2. Sedimentary Rocks (Lecture 3)
3. Metamorphic Rocks (Lecture 4)
Geological Classification of Rocks is explained in lecture
2,3 and 4.
❑ HITEC University, Taxila
Geological Classification:

29. ❑ HITEC University, Taxila
The End
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