HAWASSA UNIVERSITY

COLLEGE OF NATURAL AND COMPUTATIONAL SCIENCES

DEPARTMENT OF GEOLOGY

REVIEW ON ENGINEERING GEOLOGICAL CHARACTERIZATION OF ROCKS

MATERIAL FOR CONSTRACTION PURPOSE IN BLE HORA TOWN OROMIA,
SOUTHER ETHIOPIA

By

GUTU ABIRAHAM NEGASA (GEO/0030/09)

ADVISOR MR. WEGENE TALELGNI

ABSTRACT

The study area is located in west Guji Zone, Oromia regional state, southern Ethiopia. It is
located about 470km from the Addis Ababa, capital city of Ethiopia. It has a latitude of
5°35′Nand longitude of 38°15′E and an altitude of 1716 meters above sea level.

The main objective of the study is engineering geological characterization of rock around
Bule Hora town. To achieve the objective, literature review on engineering geological
characterization of rock from published and unpublished materials was used. In order to have
more information about the study area, environmental condition like climate, physiology,
drainage and geology of the study area have also been reviewed. Based on literature
columinary basalt and pyrophyritic basalt was characterized by strong to very strong
strength, low porosity and low permablity and unweathered. So these rock were suitable for
construction because they had ability of resist weathering.
Contents
ABSTRACT....................................................................................................................................................2
Chapter One................................................................................................................................................6
1 Introduction..............................................................................................................................................6
1.2 previous work........................................................................................................................................7
1.3 Statement of the problem.................................................................................................................7
1.4 Objective of the study........................................................................................................................8
1.4.1 General objective........................................................................................................................8
1.4.2 Specific objectives.......................................................................................................................8
1.5 Methodology.....................................................................................................................................8
1.6 Scope of study area...........................................................................................................................8
1.7 significance of the study....................................................................................................................8
CHAPTER TWO.............................................................................................................................................9
2 Overview of the study area...................................................................................................................9
2.1 Location and accessibility..............................................................................................................9
2.2 physiography...............................................................................................................................10
2.3 Climate.........................................................................................................................................10
2.4 Vegetation...................................................................................................................................10
2.5 Population and land use..............................................................................................................10
Chapter Three............................................................................................................................................11
3. REGIONAL AND LOCAL GEOLOGY..........................................................................................................11
3.1Regional geological...........................................................................................................................11
3.2 Local Geology...................................................................................................................................12
3.2.1 Geological structures....................................................................................................................12
3.2.2 Joint...................................................................................................................................12
3.2.3Columnar joint...........................................................................................................................12
3.2.4 Quartz Vein...............................................................................................................................12
CHAPTER FOUR..........................................................................................................................................14
4. RESULT AND DISSCUSION......................................................................................................................14
4.1 INTROUDUOCTION..........................................................................................................................14
4.2. REVIEW OF ENGINEERING GEOLOGICAL CHARACTERIZATION OF ROCK AROURD BULE HORA......14
4.2.1 Columnar basalt rock...............................................................................................................14
porphyritic basalt......................................................................................................................................15
Chapter Five..............................................................................................................................................16
5. Conclusion and Recommendation.........................................................................................................16
5.1 Conclusion.......................................................................................................................................16
5.2 Recommendation............................................................................................................................17
References.................................................................................................................................................17
Chapter One

1 Introduction
Engineering geological investigation for different Engineering structures like road, tunnel,
building and railway are necessary to evaluate geological condition before selecting site for
construction purpose (Belachow and Metabea, 2019). This is the major ways in which the
engineering structures are protected from the danger. If it is not studied or identified in detail,
the quality of the given construction may affected and expose the construction for different
problems (Bishop A.W, 1973). Rock is one of the fundamental materials preferred for any
Engineering construction. The identification of engineering geological characterization of
rock is an essential part of any design and construction of engineering projects (Chenna
Kesavulu, 1993). Mainly conducted with civil engineering and designing works. In this case,
rocks are intended as foundation materials for construction materials like buildings, road,
dams, canals, tunnels and etc. For any engineering and designing works, the quality of the
rock is the most effective (Franklin, J.A.et al., 1971). Because, the quality of material is one
of the factors that determine the success of any engineering structures .Rock material or
construction materials have various physical and chemical properties which can affect the
engineering structures. Based on their engineering properties there are two types of rocks
which are important for construction (Matula and Holzer, 1978). These are intact rock and
rock mass. Intact rock is a block of rock that hasn’t contains mechanical discontinuities and
which have tensile strength. Whereas rock mass is assemblage of rock blocks with
discontinuities with or without in homogeneity and with anisotropy. The overall effects of
discontinuities are rock mass that contain discontinuities is weaker than the intact rock (Co/e,
A.J, 1968 and Q.J, 1972). In our country, especially around study area, the people use the
Engineering geological materials for construction purpose in a tradition manner; without the
consideration of the Engineering classification of rock quality of the material. In this
traditional manner, the peoples choose quantity, accessibility and cost of the transportation
than quality. This is the major problem of the social community living around the study area.
So, this is what motivated us to do this research and to solve such type of problems.
Therefore, based on the above information before starting any engineering structures
understanding engineering geological characterization is the better and the effective.

1.2 previous work

According to (Engdasew at al., 2014)reviewed, a geological map is prepared outlining the
various lithology types; and the selection of construction materials and their characterization
depending on the mineral composition, texture and overall fabrics of the rock by laboratory
work included uniaxial Compressive Strength, abrasion resistance, ultrasonic pulse velocity,
bulk density, water absorption, specific gravity, porosity and Petrographic examination and
finally he determined and examined critically with reference to suitability and stability,
taking into consideration the various specifications and time honored standards.
 Volcanic rocks are used extensively as engineering material throughout the world as
aggregates in cement concrete, asphalt concrete, rock fill dams, railway ballast and high way
base courses according to (Goodman, 1992). Construction stone has a wide variety of uses,
but it is convenient and practicable to classify it in two main categories, namely, crushed and
broken stone and dimension stone. Aggregates act as relatively inexpensive inert filler,
providing stability against volume changes and influencing strength and stiffness. Concrete is
great importance as a structural material and special attention has to be paid to the nature of
the aggregates used (Abebe Dinku et al, 2006). The physical properties of aggregates are
inherited from parent materials, while the properties of the parent material intern depend on
its geological formation. Geologically, rocks are classified into three major divisions based
on their origin, namely Igneous, Sedimentary and Metamorphic (Apron and Elham.et al,
2011). Dimension stone is a collective term for various natural stones used for structural or
decorative purposes in construction and monumental applications (Merke, 2000).

1.3 Statement of the problem

The study area is highly developed in construction of road and different buildings. In every
construction, there will be the needs of rock materials. The purpose is the geological factors
that affecting the location, design, construction, operation and investigation. Therefore,
providing Engineering properties of rock material recommendation is very important in site
and rock material selection for engineering structures. To select best site and rock material
for construction and minimize risk against Engineering structure, life and properties, detail
study of the Engineering characterization of the rock is the fundamental issue. The
construction failures are not only related to geologic hazards but also in competency of
construction materials such as rock and soil. However, the study area is enriched with the
different types of rock units, their engineering geological characterization of rock are still not
determined. But it is traditionally quarried and used in different engineering structures
without adequate justification of different types of rock units and their quality in case of
construction purpose. In this traditional manner, the peoples choose quantity, accessibility
and cost of the transportation than quality. Therefore, because of such type of research gap in
case of engineering geological characterization of rocks, we enforced to conduct a scientific
study that can solve such type of problems. The interest of community in and around Bule
Hora town concerning to construction purpose is high. So, this is aiming to understand the
physical properties and engineering geological characterization of rock material before the
construction of any engineering

1.4 Objective of the study

1.4.1 General objective
The main objective of the study was review on engineering geological characterization of
rock material for construction purpose around Bule Hora town.

1.4.2 Specific objectives

The specific objectives include:-

 To understand different types of rock units,

 To understand degree of weathering of the rock,
 To understand degree of filling of secondary material,
 To revies strength and quality of rock material,
 To locate and find site of rock material suitable for construction purpose, and

1.5 Methodology
Review of the engineering charcterization of rock material in the southern Ethiopia is made
based on literature.The following methodological steps were used:

-Collection of secondary data,perivious literatures for selected area.

1.6 Scope of study area

The scope of these research was limited to review and secondary data because of COVID-19
situation .

1.7 significance of the study

The study will be significance to make and characterize rock material for engineering
construction for Bule hora town

1.8 Study Organization

This study is organized in to five chapters. The first chapter is general introduction of the
study includes; previous work, statement of the problem, objective of the study area, general
objective, specific objective,methodology,significance of the study, scope of the study and
also study organization. The second chapter is concerned the over view of the study areas
that include climate vegetation, population and land use and phsiography and. Chapter three
includes regional geology and local geology of the study area structural geology, joint and
columinar joints. Chapter four is concerned mostly with the work of previous researchers,
including; result and discution and chapter five includes; conclusion, recomandution and
referance

CHAPTER TWO OVERVIEW OF THE STUDY AREA

2.1 Location and accessibility
The study area is located in west Guji Zone, Oromia regional state, southern Ethiopia. It is
located about 470km from the Addis Ababa, capital city of Ethiopia. It has a latitude of
5°35′Nand longitude of 38°15′E and an altitude of 1716 meters above sea level. The Addis-
Awassa-Moyale asphalt road is the principal high way pass through the Bule Hora Town and
there are also foot trials and dry weather-road for field working and data collection.
 Fig. 2.1 Location and accessibility map of study area

2.2 Physiography
The physiography of the study area is characterized by many land forms. This land form are
end product of metamorphism process, weathering and tectonic activity. Those land forms
are hill, gentle, steep slope, quarry site and land form.

2.3 Climate
The study area is characterized mostly by semi-arid climate. The area has two rainy seasons
in which maximum rainfall observed in September to October, main dry season occurs from
December to February with high evaporation, short dry season occurs from June to August,
and the rest months have minimum average of rainfall and temperature. Average annual
rainfall ranges between 350mm to 900mm. The average annual temperature ranges between
19ºC to 26ºC.
2.4 Vegetation
The area is highly vegetated. The vegetation covers the area includes dense deciduous trees
and scarce bushy trees, and for cash crop coffee, inset, and chat are the common for most
peoples around the town at study area. The study area is covered by different vegetation
which are mostly short trees and other land crops which cultivates by local people. Those
vegetation are like; Eteha, Bekanisa, Agemssa, Ejersa, (All are in Local name).

2.5 Population and land use

At the study area population density is densely populated at the town and scarcely populated
around the town, the inhabitants are mainly Guji peoples and there are also small amounts of
Burji, and other local peoples. The Oromo language is mostly spoken around the town and
Amharic language is spoken by half of the peoples at the town. Bule Hora town collected
informal reports of a growing number of private investors in coffee pulping/processing
factories and coffee plantations in the district; however, many of their informants expressed
concern voiced that this had been at the expense of local farmers. The four major crops
grown in this district are maize, wheat, barley and haricot beans in that order, with some long
cycle sorghum and teff as well; in some parts Ensete or the false banana is also grown, which
offers a degree of security during famines.

CHAPTER THREE REGIONAL AND LOCAL GEOLOGY

3.1Regional geological
According to the Holmes(1951),(Almoda ,1983),(Chen et al.1984;Berhe 1990) works,there
are two main East Africa Orogenic Belts (i.e., MB and ANS) relevant to the geology of
Ethiopia. The Mozambique belt, first named by consists of high grade gneisses and
migmatites with in folded schists, marbles and amphibolite’s intruded by granites and
pegmatite . This orogenic belt extends from Mozambique in the south to Ethiopia in the north
. It is characterized by a meridional trend with a similarly oriented structural fabric and
generally consists of rocks having ages between 1300 and 480 Ma (Cahen et al. 1984). In
east and northeast Africa important tectonic thermal events occurred between 950 and 900
Ma. The highly metamorphosed and deformed gneissic rocks of southern Ethiopia are
thought to be part of the Mozambique belt (Gilboy 1970; ChateKazmin 1978a). These rocks,
presumably of middle-Proterozoic age, make up about 70% of the Agere Maryam area. The
metamorphic grade generally falls between middle and upper amphibolite facies, reaching
granulite facies along the western margin of the map area and further west (Davidson, 1983).
Green schist facies sedimentary rocks, mafic-ultra mafic comp-lexes and intrusive occur
extensively in Saudi Arabia. Similar rocks of island arc affinity have been observed in the
Eastern Desert of Egypt and the Red Sea Hills of Sudan (Kroner, 1985). These occurrences
in Saudi Arabia and northeast Africa, comprising the Arabian-Nubian Shield, are generally
believed to be of Pan-African age, i.e. 1100-500 Ma (Kroner 1979; Gass 1981). The mafic-
ultramafic rocks of the Arabian-Nubian Shield believed to continue southwards into Ethiopia
and Kenya (Berheand Rothery 1986; Kazmin et al. 1978; Kazmin 1978a). In southern
Ethiopia they are partly represented by the meta-volcanic and meta- sedimentary rocks and
the ultra-mafic of the Adola belt. These rocks, exposed in the eastern part of the map area
and constituting about 5% of it, are the possible northward continuation of the Moyale low
grade belt (Berhe and Rothery, 1986). Similar rocks are exposed in western and northern
Ethiopia (Davidson 1983; Kazmin 1972). Little is known as to the relationship between the
Mozambique belt and the Arabian-Nubian Shield. Almond (1983) suggested that a major
time break existed between stabilization of the Mozambique belt and onset of sedimentation
and volcanism in the Shield. Volcanic rocks of Cenozoic age are widespread in various parts
of Ethiopia. Those occurring in the map area are associated with the Main Ethiopian Rift and
the Southern Plateau flanking it to the east. They cover about 15% of the study area

To obtain background geological information, review of “Geological Map of Ethiopia” with

a scale of 1:20000000, and the accompanying explanatory note “Geology of Ethiopia” by
Mengesha Tefera, published in 1996 were reviewed. According to the map, the project site is
situated within the area that was covered by sand, silt, clay, diatomite, limestone and beach
sand of alluvial and lacustrine origins.
3.2 Local Geology
3.2.1 Geological structures
I reviesed in that study area, there are different types of geological structures including
foliation, joint and vein are observed.

3.2.2 Joint
At that study area, this structure is associated with quartz vein and observed in biotite schist,
gneisses and columnar joint is available on basalt.

3.2.3Columnar joint; In that study this type of geological structure is observed on basalt at
south west of Bule Hora University, which is oriented 1200/400 in North West direction
(strike and dip).

CHAPTER FOUR RESULT AND DISSCUSION

4.1 INTROUDUOCTION
Geology constructions materials are the material which used for different purpose of
engineering construction works. The secondar data I revied to reveal the performance of the
rock mass in term of constructions material quality.
4.2. REVIEW OF ENGINEERING GEOLOGICAL CHARACTERIZATION OF ROCK
AROURD BULE HORA
Engineering properties of rocks was coolectvely nomenclature which include all other
properties rocks are relevant in two ways:

i) After their extraction from natural beds (original place) or

ii) Without extraction (In original place) i.e. insitu conditions.
The first set include all those properties for which a rock must be tested for selection as a
material for construction such as a building stone, road stone or aggregate for concrete
making. The second set of the properties include the qualities of a natural bed rock (in their
original place) as and where it exists. That would determine its suitability or otherwise as a
construction site for a proposed engineering project. But in this paper because of lack of
primary data I was not used the secondar method,I only revies the secondar data.

Obviously, in both cases, the economy and safety of an engineering project are greatly
dependent upon the proper understanding and determination of the engineering properties of
rocks. Engineering properties of rock are controlled by the discontinuities within the rock
mass and the inherent properties of the intact rock. Therefore, engineering properties must
account for the properties of the intact rock and for the properties of the rock mass as a
whole. Rock material (intact rock) means rock body without discontinuities and can be in
original place or aggregate, while rock mass is rock body with discontinuities and it is
bedrock, rock outcrop (rock as it occurs in situ). Engineering properties of rocks are very
essential properties to be determined in every project of civil engineering, construction
engineering and structural engineering.

4.2.1 Columnar basalt rock

Basalt rock is one of extrusive igneous rocks which are mostly used in engineering
construction purpose. It is one of geological construction material. This rock is found in the
southwest of Bule hora town. This basalt is with columnar joint. Columnar joint is formed
due to time gap during the magma cooling which columnar joint. The texture of is phaneritic
texture. It is characterized by vertical columnar joint.
pyrophyritic basalt
It is formed by two stage of cooling. First slow cooling and followed by rapid cooling. It has
greenish weathered color and dark light fresh color, with pyrophyritic textures. It is poorly
exposed . As I revised it has also one geological construction materials in which found
southern of Bule Hora town and are used different engineering structure which building,
aggregate for asphalt and dimension it is black fresh color and browns weathered color along
joint surface.

Many rock had less strength to very less strength,high permeability and high porosity and
under going to weathering.Invers of this word many rock such as columinary basalt and
pyrophyritic basalt had strong to very strong strength,low permeability and low porosity and
unweathered.Such kind of rock those had high strength was used for construction or they had
no impact on construction.When we used those weathered on it had impact on life and
property through failure. In the other case it possible to estimate the durability of this rock
based on its mineral composition. Since fresh color of the rock is black and it indicates that
magnesium. If it so it has the resistance to weathering and can stay for long period of time
without get weather. But further investigation regarding to laboratory is required.
Chapter Five

5. Conclusion and Recommendation

5.1 Conclusion
This paper was focused on engineering charcterization of rock material for construction
purpose incase of bule hora and this was done through collecting secondary data,reading
written material and literature review.As I revied that area was covered by basaltic rock
whith dominated columnar joint.

In that area it has been attempted to assess the quality of geological construction materials for
different engineering structure such as building, aggregate and asphalt road. Those geological
construction materials are like columnar basalt and porphyritic basalt which are found that
area.

The strength of the basalt rock in site one which is basaltic rock characterized by very strong
rock, strong rock type and weak to very weak and slightly weathered to completely
weathered in the case of high weathered degree.Those under go to high weathering was not
use to construction purpose.So feresh one was suitable for engineering construction.
5.2 Recommendation
Based on above the conclusion the following recommendation

In that area are geological construction materials used for different purpose by society of
those area but while using those materials the mostly consider the quantity and transportation
rather than considering it is quality. So this may cause the serious problem in the any
engineering structures there for quality consideration is better for construction materials.

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