ENGINEERING PROPERTIES OF IGNEOUS ROCKS

SPECIAL PAPER/SEMINAR

GLM 481

PRESENTER

NEBEOKIKE, UCHENNA CHARLES

ESUT/2010/107987

DEPARTMENT OF GEOLOGY AND MINING

FACULTY OF APPLIED NATURAL SCIENCES

ENUGU STATE UNIVERSITY OF SCIENCE AND TECHNOLOGY (ESUT)

MAY 2014

OUTLINE

1.0 - INTRODUCTION 1.1 - IGNEOUS ROCK/TYPES, MODE OF FORMATION 1.2 - ENGINEERING PROPERTIES OF IGNEOUS ROCKS 1.3 - ENGINEERING APPLICATION OF IGNEOUS ROCKS

1.4 – ENGINEERING CONSIDERATION OF IGNEOUS

ROCKS 1.5 - CONCLUSION

INTRODUCTION

Engineering properties of igneous rocks describes the strength and mechanical behavior of the rock mass, these properties is mostly the physical characteristics present in the rock E.g the rock texture.

Engineering properties of rock is essential in assessing the strength (bearing capacity of rocks) in engineering construction.

IGNEOUS ROCKS/TYPES,MODE OF FORMATION

Igneous rocks are formed through the cooling, crystallization and solidification of magma.

TYPES OF IGNEOUS ROCKS

INTRUSIVE OR PLUTONIC IGNEOUS ROCKS

These rocks are formed when magma cools and solidifies within the earth’s crust. The magma cools slowly and as a result these rocks are coarse grained E.g Granite

EXTRUSIVE OR VOLCANIC IGNEOUS ROCKS

These rock is formed when magma exist ,cools and solidifies outside or very near the earth’s surface. The magma cools rapidly and as a result these rocks are fine grained E.g Basalt

Figure 1.0 Volcanic eruption showing extrusive and intrusive forms of igneous rock.

Figure 2.0 Extrusive and intrusive types of igneous rocks illustrating grain size.2006 www.wikipedia.com

Figure 3.0 map of Nigeria showing igneous formation. en.encyclopedia.com

ENGINEERING PROPERTIES OF IGNEOUS ROCKS

In Engineering some certain properties of rocks must be assessed to determine its performance in construction condition.

These properties include Rock texture (particle size) Rock stability(strength) Permeability of the rock Mineralogical composition of the rock Rock resistance to weathering

ENGINEERING APPLICATION OF IGNEOUS ROCKS

In areas prone to erosion and landslides igneous rock are used in stabilizing and stone pitching the area.

Crushed rock aggregates are used in construction, industrial and highway engineering

Igneous rock rocks are hard wearing and do not absorb water so are good in the lower courses of a building.

Figure 4.0 Stone pitching done at a culvert. gilmor Engineering Nigeria limited Abuja technology village,lugbe 2013

Figure 5.0 dam construction, using basalt ohio,USA.www.wikimedia.org,2002

ENGINEERING CONSIDERATON OF IGNEOS ROCKS

Coarse grained igneous rock e.g. granite, syenite etc are not aggregates for construction because of its low abrasion resistance but fine grained rocks e.g. basalts are good for aggregates. The water bearing capacity of extrusive rocks is much greater than intrusive rocks, making them unsuitable for reservoir or tunnel construction. Siting of foundations needs to avoid weathered rocks (e.g. dams and bridge pillars)

CONCLUSIONEngineering construction depends largely on the material used, Therefore unaltered igneous rocks should be considered whenever construction is taking place to meet a required standard.

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