concrete technology lecture notes for BTech students

1. CONCRETE
TECHNOLOGY
Dr. Ali I. Tayeh

2. Syllabus
Topic
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Date
Lectures Outline:
Introduction.
Concrete as a material
1st Week
Cements
2nd Week
Mineral Admixtures and Blended Cements
3rd Week
Water.
4th Week
Aggregates.
5th Week
Fresh Concrete
6th Week
Review and Midterm Exam.
7th Week
Proportioning Concrete Mixes
8th Week
Handling and placing.
9th Week
Curing and strength.
10th Week
Testing of Hardened Concrete
11th Week
Durability
12th Week
Review
13th Week
Final Exam
14 th Week

3. Chapter 1
Concrete
Concrete as a Material

4. Concrete
• Concrete as a Material
 The Nature Of Concrete
 Advantages Of Concrete
 Limitation Of Concrete

5. • Concrete is a material that literally forms the basis of our modern
society. Scarcely any aspect of our daily lives does not depend directly or
indirectly on concrete. We may live, work, study, or play in concrete
structures to which we drive over concrete roads and bridges.
• Our goods may be transported by trucks traveling on concrete super
high ways. by trains that run on rails supported on concrete crossties., by
ships that moor at concrete piers in -harbors protected by concrete
breakwaters, or by airplanes landing and taking off on concrete runways.
• Water drinking and for raising crops is stored behind massive concrete
dams and is distributed by systems of concrete waterways., conduits.,
and pipes..
Concrete as a Material

6. • Concrete plays a key role in oil production, being used to construct
massive off shore platforms for drilling .
• We take concrete for granted in our everyday activities and tend to be
impressed by the more dramatic impacts of technology.
• it can be truly said that many of the achievements of our modern
civilization have depended on concrete, just as many of the enduring
achievements of the earlier civilization of Rome were ;made possible by
the use of the forerunner of modern concrete.
• The word concrete comes from the Latin verb "concretus," which means
to grow together.
Concrete as a Material

7. Concrete is a composite material composed of coarse granular material
(the aggregate or filler) embedded in a hard matrix of material (the
cement or binder) that fills the space between the aggregate particles
and glues them together. Aggregates can be obtained from many
different kinds of materials, although we mostly make use of the
materials of nature common rocks.
The Nature Of Concrete

8. They are essentially inert, filler materials that, for convenience. are
separated into fine and coarse factions. Similarly, the cement can be
formulated from many diverse chemicals. "Cement"' is a generic term
that can apply to all binders. Therefore, descriptors must he used to
qualify this term when referring to specific materials. A civi1 engineer
may have cause to use
The Nature Of Concrete

9. Portland cement concrete, calcium aluminates cement concrete, or
polymer concrete ,where the binders are Portland cement, calcium
aluminate cement, or a polymer resin, respectively. In concrete
construction, the engineer will use Portland cement concrete 95% of
the time. Thus, for convenience, we will often drop the name Portland
throughout the text and use a qualifying descriptor only when dealing
with other kinds of cement and concrete.
The Nature Of Concrete

10. The Nature Of Concrete

11. Portland cement concrete, calcium aluminates cement concrete, or
polymer concrete ,where the binders are Portland cement, calcium
aluminate cement, or a polymer resin, respectively. In concrete
construction, the engineer will use Portland cement concrete 95% of
the time. Thus, for convenience, we will often drop the name Portland
through out the text and use a qualifying descriptor only when dealing
with other kinds of cement and concrete.
The Nature Of Concrete

12. Advantages Of Concrete
• Concrete is the predominant material used in construction .
• It competes directly with all other major construction materials-
timber, steel, asphalt, stone, etc.-
• The major advantages and disadvantages of concrete are
summarized in Table 1.3.Type
• all properties of concrete are given in Table 1.4.

13. Advantages Of Concrete
• concrete properties can vary significantly from the figures given,
depending on the choice of materials and proportions of a
particular application.
• For example, subsequent chapters will show how concrete can be
designed to have compressive strengths <10 MPa (1500 Ib/in.2) or
> 100 MPa (15,000lb/in.2) with concomitant changes in modulus
of elasticity.
• The ability of concrete to be cast to any desired shape and
configuration is an important characteristic that can offset other
shortcomings.

14. Advantages Of Concrete
• Concrete can be cast into soaring arches and columns, complex
hyperbolic shells, or into massive, monolithic section; used in dams,
piers, and abutments. On-site.
• construction means that local materials can be used to a large
extent, thereby keeping costs down. Cement costs only about 7-10
cents/kg (3--4 cents/lb) (2001) and aggregates less than 2 cents/kg
(<1 cents/b).
• Furthermore. fabricating concrete on site, its properties may be
tailored for the specific application.

15. Advantages Of Concrete
• On the other hand, on-site production is a mixed blessing because
the quality of concrete must be carefully controlled. Environmental
conditions fluctuate, so that it is difficult to assure uniform
process41g of concrete throughout a job
• Constituent materials are less carefully characterized than they
might be and can have undesirably high variations in properties.
The use of an unskilled or semiskilled work force means that in the
absence of proper supervision on the job site, undesirable practices
they be adopted and tolerated.
• Casting of concrete can also be adapted to factory-controlled
production.
• precast building elements for standardized low. cost building
systems arc more common in European countries, but have also
been developed in the United States.

16. Advantages Of Concrete
• precast concrete block has become a very popular building element,
and precast concrete pipe is widely used in drainage, sewage, and
water-supply projects.
• precast, prestressed concrete beams, girders. and panels in various
configurations are used increasingly in many structures.
• precast concrete can be produced more uniformly with closer
tolerances compared to concrete cast on site, but requires a more
skilled work force and generally more sophisticated equipment.
• Good Quality concrete is a very durable material and should remain
maintenance free for many years when has been properly designed
for the service conditions and properly placed.

17. Advantages Of Concrete
The Advantages Of Concrete:
• It has a relatively high compressive strength.
• It has better resistance to fire than steel.
• It has a long service life with low maintenance cost.
• In some types of structures it is the most economical structure
material as dam and footing.
• It is easy to form.
• It yields rigid members with minimum apparent deflection.

18. Advantages Of Concrete
Disadvantages Of Concrete:
• It has a low tensile strength of about one tenth of its
compressive strength.
• It needs mixing and curing all of which affect the finial strength
of concrete.
• The cost of form which will be used in casting is high
• It has low compressive strength with respect to steel which lead
to large section in columns of multistory buildings.
• Cracks develop in concrete due to shrinkage and application of
live loads

19. Limitation Of Concrete
• However, concrete does have weaknesses that may limit
its use in certain applications and must be allowed for
when designing structures.
• Concrete is a brittle material with very low tensile
strength.
• Concrete should generally not be loaded in tension
(except for low bending stresses that may be permitted in
unreinforced slabs on grade), and reinforcing steel must
be used to carry tensile loads; inadvertent tensile loading
causes cracking. The low ductility of concrete also means
that concrete lacks impact strength and toughness
compared to metals.

20. Limitation Of Concrete
• Even in compression, concrete has a relatively low strength-to-
weight ratio, and a high load capacity requires comparatively large
masses of concrete, although, since concrete is low in cost, this is
economically possible.
• The volume instability of concrete must also be allowed for in
design and construction.
• It shows volume stability that is more characteristic of timber and
quite unlike that of steel, which is a volume-stable material under
normal conditions of service.

21. Limitation Of Concrete
• Concrete undergoes considerable irreversible shrinkage due to
moisture loss at ambient temperatures and also creeps significantly
under an applied load even under conditions of normal service.
• Awareness of these problems with concrete enables us to
compensate for them, by using suitable designs and by controlling
them, in part, through a suitable choice of materials and
construction practices.

22. Limitation Of Concrete
• A great deal of research effort has been devoted to ameliorating
these problems and now ready-mixed concrete with compressive
strengths of 100 MPa (15,000 Ib/in.2) can be routinely produced in
some areas.
• Over the last 30 years, new types of concrete have been developed,
such as fiber. Reinforced concrete, shrinkage-compensated
concrete,
• Cement based materials with flexural strengths exceeding 150 MPa
(22,000 Ib/in.2) or with tensile
• strains greater than 1% have been produced.

23. End