Construction material course

1. Construction Material
CENG-2092

2. 1. INTRODCUTION
General out line
 Classification of Engineering(construction) Material.
 Mechanical Properties of Materials.
 Nature and Performance of Materials Under Load.

3. Classification of Engineering(construction)Material.
Defn; Construction Material is any material which is used in
construction industry. Examples: cement, soil, aggregates, asphalt,
etc

4. Mechanical Properties of Material(Static
stress-strain properties)
 Application of forces on solid bodies under equilibrium results
in the development of internal resisting forces and the body
undergoes deformations to a varying degree.
 Internal forces are called stresses.
 Internal deformations are called strains.
 These properties are concerned with the following properties

5. Tensile strength (TS)
 It is the ability of a material to withstand tensile ( stretching )
loads without breaking. Example the stretching rod.
 Strength: is the ability of a material to resist applied forces
without fracturing.

6. Toughness
 It is the ability of the materials to withstand bending or
 It is the application of shear stresses without fracture.
 So the rubbers and most plastic materials do not
shatter(break), therefore they are tough.
 For example, if a rod is made of high-carbon steel then it will
be bend without breaking under the impact of the hammer.
 If a rod is made of glass then it will broken by impact
loading.

7. Toughness (CON’T)

8. Malleability
 It is the capacity of material to withstand
deformation under compression without rupture or,
 The malleable material allows a useful amount of
plastic deformation to occur under compressive
loading before fracture occurs.

9. Hardness
 It is the ability of a material to withstand scratching
(abrasion) or indentation by another hard body.
 It is an indication of the wear resistance of the material.
 For example, a hardened steel ball being pressed first into a
hard material and then into a soft material by the same load.
 As it is seen below the ball makes a small indentation in the
hard material and deeper impression in the softer material.

10. Hardness(CON’T)

11. Ductility(CON’T)
 It refer to the capacity of materials to undergo
deformation under tension without rupture.
 Example, in wire drawing , tube drawing operation
e.t.c

12. Stiffness
 It is the measure of a material's ability not to deflect under an
applied load.
 For example, consider steel and cast iron(more rigid).
 Steel is very strong than the cast iron ,but cast iron is preferred
for machine beds and frames.
 This is because it is more rigid and less likely to deflect with
consequent loss of alignment and accuracy.
• material which is rigid is not necessarily strong. Example see the
following fig(a and b)

13. Stiffness(con’t)

14. Brittleness
 It is the property of a material that shows little or no plastic
deformation before fracture when a force is applied.
 Also it is usually said as the opposite of ductility and
malleability.
 For example concrete is brittle material.

15. Elasticity
 It is the ability of a material to deform under load and return to
its original size and shape when the load is removed.
 If it is made from an elastic material , it will be the same length
before and after the load is applied, despite the fact that it will be
longer while the load is being applied.
 All materials posses elasticity to some degree and each has its
own elastic limits.

16. Elasticity

17. Plasticity
 It is the state of a material which has been loaded beyond its
elastic limit so as to cause the material to deform permanently.
 This property is the opposite of elasticity.
 The ductility and malleability are particular causes .
 Under such conditions the material takes a permanent set and
will not return to its original size and shape when the load is
removed.

18. Plasticity

19. Nature and Performance of Materials Under Load.
 Here we are going to see the stress-strain property of materials.
 Stress is the ratio of applied force to the cross-sectional area or the
product of young’s modulus and strain.
 Strain is the ratio of extension to original length.
 The term that determines the performance of material under load are:
• Yield strength
• Ultimate strength and
• Breaking strength

20. Performance of Materials(con’t)
 Yield strength: the stress at which the yield is initiated.
 Ultimate strength: the stress corresponding to the maximum
load applied to the specimen.
 Breaking strength: the Stress corresponding to the rupture.

21. Performance of Materials(con’t)
 Now let as see the stress-strain performance of
1. Ductile materials, such as structural steel and other alloys of
metals.
2. Brittle materials such as cast iron, glass, stone and concrete.

22. Typical stress-strain curve for annealed mild steel.

23. Typical stress-strain curve of a light alloy.

24. Typical stress-strain curve of grey cast iron.

25. Typical stress-strain curve of brittle materials

26. Factors affecting materials properties
•Heat treatment
•Processing
•Environmental reactions

27. Factors affecting materials properties
• Heat treatment
• Processing
• Environmental reacations

28. Check your progress
 Do you understand the classification of construction
materials ?
 Would you explain the mechanical properties of
engineering materials?
 Do you understand the performance of materials
under load? That is the stress-strain properties of
materials under load.
 Calculate the modulus of elasticity for a material
which produces the following data when undergoing
test: Applied load = 35.7 kN,
 Cross-sectional area = 25mm2, Gauge length = 28
mm, Extension = 0.2 mm.

29. • END OF CHAPTER ONE