Behavior of frc under static & impact loads

B EHAVIOR O F FRC
B EAMS U NDER
D IFFERENT L OADS
By Mohannad M. Abdul-Aziz
Supervised By Dr. Mazin B. Abdul-Rahman

January 2009
2

Fibers in Concrete

• The choice of fibers to use should be made based
on what properties are required from the
concrete, like:

4. Reduce bleeding
5. Improving impact resistance
6. Flexural toughness
7. Freeze thaw resistance
8. Fire resistance

3

Behavior of FRC beams under different loads
1. Fibers in concrete

Mechanism involved in Fiber Range of load versus deflection
operation curves for unreinforced matrix and
fiber reinforced concrete
4

2. Using different types of fibers in concrete

• Synthetic fibers are man-made fibers
resulting from research and development
in the petrochemical and textile industries.

• Synthetic Fiber types that have been tried
in portland cement concrete are: carbon,
nylon, polyester, polyethylene and
polypropylene.
5


Examples of commercially available fibers 6


cross-sectional geometries of fibers some typical fiber geometries

7


1. Polypropylene Fiber

• Polypropylene fibers, the most popular of
the synthetics.
• Polypropylene is hydrophobic, meaning it
does not absorb water.

8


Polypropylene fibers are produced either as (left) fine fibres with
rectangular cross section or (right) cylindrical monofilament.
9


1. Steel Fiber

• fiber length varies from (12.7 mm) to (63.5 mm).
The most common fiber diameters are in the
range of (0.45 mm) to (1.0mm).
• steel fibers have shapes which include round,
rectangular, and crescent cross sections,
depending on the manufacturing process and
raw material used.
10


Steel fibers with hooked ends Fracture surface of SFRC

11


-But why do we need
fibers in concrete

- Concrete is a very
brittle material.
- The role of randomly
distributes discontinuous
fibres is to bridge across
the cracks. 12


• The real contribution of the fibres is to increase
the flexural toughness of the concrete
(defined as
some function of the
area under the load
vs. deflection curve),
under any type of
loading.
13

3. Research working plane

A- Theoretical Part

• Static Analysis for prepared beam samples.
– (using ANSYS 11.0 (2007) Program)
Program

• Impact Resistance Analysis for prepared
beam samples.
– (using DARC III Nonlinear transient dynamic analysis
for three dimensional structures Program)
Program
To compare the result with the experimental works
14


B- Experimental Works
– Material that will be used:
• Cement
• Aggregate
• Sand
• Fiber (PPF) (length 12mm) (SikaFiber)
• Fiber (steel) (length 30mm) (Sika Company)
• Super plasticizer (Water reducer) (Sikament-
HRWRA-FFN)
• Silica fume (Sikafume-HR)

15

3. Research working plan

16


Fiber (PPF) (length 12mm)
(product by Sika Company)

• Sika Fibre is based on high quality monofilament
micro polypropylene fibers.
• Appearance/ Colors: White
• Packaging: 600g bags at box of 40 bags
• Compatibility: Sika Fibre can be used with all
Sika® admixtures.
• meeting the requirements of: ACI 544-1& 2R.
2R

17


Super plasticizer SP (Water reducer)
(Sikament-HRWRA-FFN)

• high-range water-reducing admixture (HRWRA) meeting the
requirements of:
• ASTM C494 Type F or G or ASTM C 1017 Type I or II.
II
• Chemical Base: Melamine sulphonate polymer based liquid
• Compatibility: Sikament FFN can be used with
Sika Fiber & Sika fume .

18


• Why we used
superplasticizer

- SP can be used in concrete to :
• Get Higher slump without additional water,
• lower w/c at equivalent slumps,
• improved workability,
• increase strength by decreasing (w/cm)
19

3.
plan

Silica Fume SF (Sikafume-HR)

• SikaFume is a concrete additive in powder form
based on silica fume technology.
• Meeting the requirements of: ACI Committee 234
• Appearance / Colour: Grey to dark grey powder

20

3.
plan

- Silica Fume Product Forms:

As-produced powder Water-based slurry
21

3.
plan

- Silica Fume Colors:

Premium -- White Standard -- Grey

22


• Why we used silica fume

• Improve the transition zone wich is represented
as a thin layer between the bulk hydrated
cement paste and the aggregate particles in
concrete. This zone is the weakest component
in concrete.
• Provide concrete with very high compressive
strength
• Enhancing Mechanical Properties due to its
extremely small particle size, and large
surface area
• Improving Durability 23


24


• Mix Design:
A- Trial Mix: (to get Ref. mix)
1. Fix w/c (to get compressive
strength at least 40 Mpa)
2. Record slump (200mm ± 5mm)
according to
slump test (ASTM C 143)
3. Casting:
- Cubes (150*150*150)mm
- Prisms (100*100*50)mm
- Impact rings (152 Dia.*63.5 t)mm
- Beams (Reference)
Reference 25


B- Mixes work:
• Mix No. (1)
Ref. + SP (optimum dosage) + SF (optimum dosage)
- Getting the optimum dosage from SP & SF:
- Adding SP (as a percentage by weight of
cement) to reach the same slump of the Ref. mix.
- Then adding SF (as a percentage by weight of
cement) to reach the same slump of the Ref. mix.
- Record the optimum dosages.
- w/c will be reduced due to the effect of SP (as a
chemical ad.) and SF (as a mineral ad.). 26


27


• SP used demand:
• Increase workability that has been
decreased with the addition of fibers.
( Balling—When fibers entangle into large
clumps or balls in a mixture.)
• Silica fume addition usually increases water
demand.
• SF used demand:
• to improved bond strength in the concrete
matrix by increasing the paste to-fiber bond.
28


2. Mix No. (2)
Mix No.(1) + 0.5 % from PPF (as a VF)
3. Mix No. (3)
4. Mix No. (4)
5. Mix No. (5)
Mix No.(1) + (50%) 0.5 % from PPF (VF)+
(50%) 0.5 % from Steel Fiber (VF)
6. Mix No. (6)
Mix No.(1) + (50%) 0.75 % from PPF (VF)+
(50%) 0.75 % from Steel Fiber (VF) 29


7. Mix No. (7)
Mix No.(1) + (50%) 1.5 % from PPF (VF)+
(50%) 1.5 % from Steel Fiber (VF)

- For each mix we will cast (at least):
( 3 beams ) and ( 3 prisms )

30


• Samples Testing:
1- Static Test:
Test
by the Universal machine
for cubes, prisms and beams.

31


2- Impact test:
• Improved impact resistance
(dynamic energy absorption
as well as strength) is one of the
important topics of FRC.

• The simplest of the
impact tests is the
“repeated impact,”
drop-weight test.

• The hammer is dropped repeatedly,
and the number of blows required
to cause the first visible crack on the
top and to cause ultimate failure
are both recorded.
32


33


Steel frame (impact resistance test) for beam samples
34

Behavior of frc under static & impact loads

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