Concrete is a mixture of cement, aggregates and water, with any other admixture which may be added to modify the placing and curing processes or the ultimate physical properties.
1. MONITORING OF REINFORCED
CONCRETE
ByHussein Azher
First Stage
2017/2018
Supervised by lecturer assistant
Maryam Saffaa
Al-Nahrain University,
College of engineering,
Department of architecture engineering
3. 3
Concrete
Concrete is a mixture of cement, aggregates and water,
with any other admixture which may be added to modify
the placing and curing processes or the ultimate physical
properties.
4. 4
Aggregates for concrete
Aggregates form a major component of concretes
typically approximately 80% by weight in cured mass
concrete.
Aggregate properties including crushing strength, size,
grading and shape have significant effect on the physical
properties of the concrete mixes and hardened concrete.
Standard dense aggregate are classified by size as:
1.fine 2.coarse
5. 5
Concrete mixes
Concrete mixes are designed to produce concrete with
the specific properties at the most economical price.
The most important properties of concrete mixes are
usually:
strength
durability
thermal insulation
acoustic insulation
effect of fire
appearance in visual concrete
the key factor which affects both these properties is the
free-water content of the mix after any water is
absorbed into the aggregates this quantity defined as:
6. 6
Water/cement ratio
the free water in a mix is the quantity remaining after the
aggregates have absorbed water to the saturated
surface-dry condition.
Water/cement ratio is used to hydrate the cement and to
make the mix workable.
7. 7
With low water/cement ratio below 0.4 some of
cement is not fully hydrated.
At a water/cement ratio of 0.4 the hydrated cement
just fills the space previously occupied by the water,
giving a dense concrete.
As the ratio increased over 0.4, the mix becomes
increasingly workable but the resulting cured
concrete.
8. 8
Workability
Workability describes the ability of the concrete mix
to be placed within the formwork.
Workability is effected by:
The Water/cement ratio
The aggregate content size, grading and shape
The addition of admixture.
Workability is measured in the site with the slump test.
9. 9
Reinforced Concrete
Concrete is strong in compression, with crushing
strengths typically in the range of 20-40 MPa, and up to
100 MPa for high-strength concrete.
The tensile strength of concrete is usually only 10% of
the compressive strength.
Steel is the universally accepted reinforcing material as it
is strong in tension, forms a good bond and has a similar
coefficient of thermal expansion to concrete.
12. 12
Visual concrete
The production of visual concrete, whether precast or in-
situ requires not only a high standard of quality control in
manufacture, but also careful consideration to the
correct specification and detailing of the material to
insure a quality finish which weathers appropriately.
The appearance of visual concrete is affected by four key
factors:
The composition of the concrete mix;
The formwork used;
Any surface treatment after casting;
The quality of workmanship.