This presentation is an introduction to concrete technology which is useful for practicing engineers an new graduates.

1. ‫هندسني‬‫مل‬‫ا‬ ‫يب‬‫ر‬‫تد‬ ‫دورة‬
‫يف‬
‫نة‬‫ا‬‫اخلرس‬ ‫لوجيا‬‫و‬‫تكن‬
‫هندس‬‫مل‬‫ا‬ ‫عداد‬‫ا‬:‫محدان‬ ‫عبدهللا‬ ‫عوض‬

2. ‫حمدان‬ ‫هللا‬ ‫عبد‬ ‫عوض‬

3. Program Contents
Concrete Materials.
Standards.
Requirements.
Concrete Strength.
Concrete Curing.
W/C Ratio.
Concrete Aggregate.
Mixing
Testing.
Concrete Mix Design.
Destructive Tests.
Non - Destructive Tests.
Concrete Compaction.
Inspection of Concrete
and Integrity
Conclusions.
++++

4. Unit 1
- Concrete Materials & Standards

5. Aim of Unit 1
- Knowledge of basic concrete materials and
Standards

6. what are the raw materials used in the manufacture of Portland cement ?
Cement is made of heating lime stone and clay to form clinker which is rich in calcium silicates .
Then clinker is grinded to fine powder with small amount of gypsum (calcium sulphate ) which regulate the of setting time
when the cement is mixed with water .
Ordinary Portland cement is about 90% of all cement production .
Other Portland cements :
- Rapid hardening cement
- Sulphate resisting cement
- White cement
- Low heat cement
Sulphate resisting cement is a form of Portland cement with tetra calcium aluminate (C3A) , It
has higher content of tetra calcium aluminate-ferrite (C4AF).
Cement Hydration :
It is a chemical reaction between cement and water .
The Hydration of and setting of cement is a continuous process for years and it evolves heat and gains strength .
Mixing Water :
Water for mixing the cement is usually fit for drinking , other wise it must be taken from approved source .
Sea water is not allowed for use as mixing water .
Concrete Material

7. Are there standard specifications for the properties of
cements ?
Standards
Yes, British , American , DIN , EN Standards .

8. Summary Unit1
- Main Concrete materials are cement, water, aggregate, fly
ash and chemical additives.

9. Unit 2
- Requirements, Concrete Strength,
Concrete Curing, W/C Ratio,
Concrete Aggregate and Mixing.
‫فى‬ ‫الخرسانى‬ ‫الخالط‬C1-A

10. Aim of Unit 2
- To understand basic requirement of concrete
goals and relations.

11. What are the requirements for the successful concrete
structure ?
- Durability ( structure to be used for many
- Years in good condition ).
- Economy (less cost ) .
- Beauty (always required ) .
Requirements

12. What is the most common measure by which the quality
of concrete is judged ?
The most common measure by which quality of concrete is judged
is the compressive strength .
Concrete Strength

13. Is strength in compression the only strength factor of
interest ?
No. in road pavement design
tensile strength is necessary.
Concrete Strength

14. What other qualities of
concrete are important ?
a- Impermeability (no
seepage ) important in
dams construction.
b-fire resistance (resedinial
builings )
c- resistance to weathering
d- durability
e-tensile strength.
Concrete Strength

15. What are the factors governing
the compressive and flexural
strength of concrete ?
a- Production technology (what
Type of mixer or batching plant)
b- Ingriedence (cement
,aggregates , water , additives)
c- Everything including your
mode .
Concrete Strength

16. What conditions are required for continued hardening
or for a continuing increasing in strength of Portland
cement concrete ?
The best favorable conditions for continuing hardening
(gain of strength) is to have moisture and reliable temp.
This can be done by water spraying or keeping concrete
Moisture by using chemical curing .
Concrete Strength

17. What is meant by
curing ?
Curing is favorable moisture
and temp. to obtain the
required strength of
concrete. Time of curing
between 7-14days.Chemical
curing is sometimes used and
applied once for vertical
sections. For precast bridge
girders steam curing is used
to produce concrete
strength rapidly (48hrs) to
re-use the form work many
times .
Concrete Curing

18. What part does age play in
concrete strength ?
Normally the older the
concrete the higher the
strength. In laboratory,
cubes or cylinders are
tested in 3,7,28 or 90days
to asses their strength and
quality .
Concrete Curing

19. What part has temperature
affect in concrete strength?
The higher the temp. ,the higher the rate of
hardening of concrete .How ever if air temp. is high
e.g more than 45 deg. Casting of concrete is not
allowed .
For mass concrete as in the case casting concrete in
dams temp. is not allowed to exceed 45deg. In dam
complex of Upper Atbra Project temp. casted
concrete should not exceed 22 deg.
Concrete Curing

20. How is the water
cement ratio usually
expressed ?
Usually water cement ratio is
expressed by weight (kg per
cubic meter) .
W/C Ratio

21. Is there a general relationship
between the water cement
ratio and the compressive
strength of concrete at a given
age ?
The lower the water cement
ratio the higher the concrete
strength(non-linear relation )
W/C Ratio

22. How does the quantity
of cement influence the
strength of concrete ?
[in general, the more the
cement the greater the
strength ] .
W/C Ratio

23. What characteristics of the aggregates
are of principal concern in the strength
of concrete ?
The term aggregate is used to describe the gravels
natural or crushed stones and the other materials
which are mixed with cement to make concrete . The
most important characteristics are :
Surface texture
Shape and size of particles
Aggregate grading (grading curves )
Particles strength
Chemical reaction (ASR)
Inert aggregates which does not react with silica
alkaline are mostly preferred
Concrete Aggregates

24. How does the shape of the particles affect the
strength?
[as much as it affects the bond it affect the strength ] .
Concrete Aggregates

25. How does grading of
aggregates affect the
strength of concrete .
Grading is important to produce
high quality of concrete .
Concrete Aggregate

26. Does the max. size of
aggregate particles
affect strength ?
[yes, the greater the size
of aggregate , the lower
the surface bond ,hence
low strength . ]
Concrete Aggregate

27. How does the strength
of the aggregates
particles affect the
strength of concrete ?
[ it affects only if the
strength of the
particles is less than
the bond strength . ]
Concrete Aggregates

28. How does the time of mixing
affect the strength of concrete ?
[in general strength increase with
mixing time if water is not lost
and there is no segregation , and
aggregate particles are not
broken. ]
Mixing

29. Summary Unit2
- In this unit the Engineer understand theoretically and
practicality the main requirement and relationships
between concrete materials.

30. Unit 3
- Testing and Concrete Mix Design

31. Aim of Unit 3
- The aim of this unit is to have knowledge of
concrete lab test and make trial mix designs for
different types of concrete.

32. Are there standard methods of
making and testing concrete
specimens ?
[British( B.S), American (ASTM)
German(DIN), EN
Testing

33. What methods of
capping are
recommended for
specimen to be tested?
before testing specimen
surface must be clean
and flat
Testing

34. Are there standard methods of making and testing
concrete specimen ?
Concrete cubes
Concrete cylinders
Concrete cores
Concrete beams (flexure test)
Testing

35. What are the general
steps to design
concrete mix ?
ACI standard
Step1: choice of slump.
Step2:choice of max. size of aggregate .
Step 3:Estimation of mixing water .
Step 4: Selection of water cement ratio .
Step 5: Use tables and charts to calculate weight of
cement , water , course aggregates , fine aggregates ,etc.
Concrete Mix Design

36. What are factors that must be
considered in mix design?
-strength
-durability
-water Impermeability
-abrasion resistance
-workability (easy to flow )
-aggregate size
-low hydration heat
-special requirement : e.g. self compacting , non-
shrink concrete, ...
[
Concrete Mix Design

37. Is the slump or flow test of
value as a measure of
consistency or workability?
They are just indication for
workability and consistency
but not indication of
concrete strength .
Concrete Mix Design

38. What are the
essential
requirements as
related to
consistency ?
The essential requirement
for consistent concrete is to
have almost the same
workability and strength .
Concrete Mix Design

39. Summary Unit3
- The Engineer is now able to understand the concepts of lab
test and results and he can do different types of concrete
mix design.

40. Unit 4
Destructive Tests, Non-Destructive
Tests and Concrete Compaction

41. Aim of Unit 4
- The aim of this unit is to differentiate between
destructive and non-destructive test of concrete.

42. What are the normal
strength tests which should
be conducted to concrete ?
[ compressive strength,
tensile strength , flexural
strength (bending) ]
Destructive Tests

43. Are there any tests which may be
made directly on the structure to
determine whether the concrete
had developed adequate strength
without risk of causing damage to
the structure?
[Yes. Non-destructive tests are
used : ultra-sonic test, hammer re-
bound test, sound wave,..]
Non-Destructive Tests

44. Is the hammer rebound test accepted as a standard
testing technique ? or indication test?
[it is only an indication test ]
Non-Destructive Tests

45. How should the concrete be
compacted to obtain a complete
filling of the forms and incorporation
of the reinforcement ?
[By using compaction methods :
poker vibraters, vibrating tables,
etc…]
Concrete Compaction

46. Summary Unit4
- In this unit the Engineer is able conduct destructive test in
the lab and non-destructive test on the structure and can
compare between them.

47. Unit 5
Conclusion

48. Aim of Unit 5
- The aim of this unit is to show the importance of the above unit
related to each other and related compaction required in lab
and site and importance of concrete inspection.

49. Is good inspection an
important factor of
concrete construction?
[Definitely yes. Inspection is very important:
in case of mix design , selection of type of
cement according to type of structure and
foundation i.e. sulphate resisting cement may
be used , retarding or accelerating additives
may be used in the case of pile foundations ,
selection of Ingriedence , gravel, sand.
In case of in-situ concrete vibration methods
must be adopted according to type of
structure to be casted , while for pre-cast
concrete units poker vibrators or vibrating
tables may be used . In curing period
inspection and supervision is important,
sometimes you may need to accelerate curing
by using steam curing to get use of the forms
for more production as in the case of pre-cast
units or bridge precast girders.
Inspection is also important in case of
maintenance to use the right materials and
technology .
Conclusion

50. Summary Unit5
- In this unit the Engineer is now able to relate all factors
required theoretically and practically and be a good inspector for
any type of concrete structures [Dams, Bridge …etc.]
- The following factors should be noticed:
- Cleaning of block before concrete casting .
- Concrete cover.
- Reinforcement arrangement .
- Water stop installation .
- Enough vibration
- Casting concrete in layers .
- Concrete falling height not exceeding 1.5 m .
- Efficient concrete pumps .
- Technical knowledge of site Engineers .
- Follow up of curing .

51. 1. ACI COMMITTEE 211, Recommended practice for selecting proportions
for normal and heavyweight concrete (ACI 211 . 1-77), J. Amer.
Concrete Institute.
2. A. R. COLLINS, The principles of making high - strength concrete,
(Cement and Concrete Assoc.)
3. Neville, Third Edition, Properties of concrete.
4. ASTM C 150: Standard Specification for Portland Cement.
5. ASTM C 618: Specification for Fly Ash and Raw or Natural Pozzolan for
Use as a Mineral Admixture in Portland Cement Concrete.
6. BS 4246: Low heat Portland- blasfurnace Cement.
References

52. E-mail . awad52abdalla@gmail.com
Mobile teleph: 00249 12356443
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