It covers the basics of ECC along miromechanism and an experimental briefing.

1. Engineered Cementitious
Composites
(ECC)
Prepared By:
Mahnoor Abbas
Muhammad Taha
Muhammad Saad Ifrahim
SECTION ‘B’
• Procedure Of ECC Mix
• Design Basis of ECC
• Experimental Briefing

2. PROCEDURE OF ECC MIX DESIGN
BY MAHNOOR ABBAS

3. ECC stand for engineered
cementitious composite
• Known as
bendable concrete

4. BASIS OF ECC MIX DESIGN:
The mix design for ECC Concrete is based on Micromechanics design basis. It captures the
mechanical interactions among the fiber.
INGREDIENTS AND PROPORTIONING:
AGGREGATES:
aggregates with a particle size bigger than the average fiber spacing leads to greater interaction of
fibers between the large aggregate particles, and the effect is greater as the volume and the
maximum size of aggregate particles increase. Coarse aggregates are not used because they tend to
have negative effects on ductile behavior of the composite.
CEMENT:
ECC can be produced using ordinary Portland cement. Compared with conventional concrete, ECC
contains considerably higher cement content that is typically two to three times higher than normal
concrete. Cement is the major component which binds all the ingredients and contributes to the
strength.
FLY ASH:
Two different types of fly ash are used for the preparation of different ECC mixes, they are known as
Class F and Class C, both containing SiO2, Al2O3, Fe2O3.
PVA FIBER:
uses low amounts, usually 2% by volume, of short, discontinuous fiber. The low fiber volume, along
with the common components allows flexibility in ECC structures. The fibers used in ECC are tailored
to work with the matrix for the purpose of constraining localized brittle fracture and guaranteeing
more uniform distribution of micro cracks.

5. CASTING OF ECC MIXES:
A proper and good practice of mixing can lead to better performance and quality of the ECC
Concrete. This shows the performance of the ECC Concrete is influenced by the mixing.
PLACING AND COMPACTION OF ECC MIXES:
Before placing of concrete, the concrete mould must be oiled for the ease of removing. Once
the workability test of ECC Concrete is done. If the concrete are not compacted to a proper
manner, the maximum strength of the concrete cannot be achieved.
CURING OF ECC MIXES:
It is placed into the curing tank with a controlled temperature for 28 days for the hardened
properties test of concrete. It can be put in accelerated Curing Tank due to time limit.
Initially a proportion is set with a standard super plasticizer and water to
cementitious material. Then tested to see if required workability achieved or not if
not the proportion is adjusted such that PVA fiber increased while other
proportions same.

6. Difference between ECC and normal concrete:
• There is high cement usage in ECC as compared with normal concrete.
• All the studies so far state that the presence of water is essential to
facilitate healing of the cracks in ECC . Without water, it is impossible for
the calcium hydroxide to be leached out of the bulk material into crack
while in normal concrete.
• ECC does not use coarse aggregate as it effects the ductility of the mix
while in normal it is an important component.
• Their behavior towards strain is also different. This strain‐hardening
behavior of ECC is similar to ductile metal while normal concrete behaves
like brittle material.

8. DESIGN BASIS OF ECC
MIROMECHANICS
BY MUHAMMAD TAHA

9. DESIGN BASIS OF ECC
• The mix design for ECC Concrete is based on Micromechanics design.
• Micromechanics:
Micromechanics is the analysis of composite or heterogeneous
materials on the level of the individual constituents that form
these materials.
• Some simplifying assumptions have been made to make the model
equations tractable, and that the resulting conditions for strain-
hardening can be used as guidelines for material component tailoring or
selection.

10. • These conditions are expressed in strength and energy
terms, as shown in the equation below.
where σcs= the cracking strength of the matrix.
σ0= the maximum fiber bridging capacity.
Jtip = the crack tip matrix toughness.
Jb’=the complimentary energy of the fiber
bridging relation.

11. • Physically, the strength criterion eq (A)ensures the
initiation of microcracks from initial flaw sites in the
composite before the tensile load exceeds the
maximum fiber bridging capacity.
• The energy criterion Eq. B prescribes the mode of
crack propagation once initiated i.e. the flat crack
propagation mode.
• Violation of Eq. B results in fracture localization as in
the case of FRC, and terminates the multiple
cracking process.
• It should be noted that both equations A and B have
been arranged so that the left hand sides of the
inequality sign contain terms that pertain to fiber
and interface properties, while the right hand sides
contain terms that pertain to matrix properties, all
of which are measurable physical properties.
• This observation emphasizes the usefulness of the
equations to help in the fiber, matrix and interface
selection or tailoring process, in arriving at
practiceable compositions of ECCs.

12. CONCRETE SPECIMEN
Under
compression
Under
tension

13. ECC SPECIMEN
zoom in portion of the ecc
slab.

14. • Physically, the strength criterion eq (A)ensures the
initiation of microcracks from initial flaw sites in the
composite before the tensile load exceeds the
maximum fiber bridging capacity.
• The energy criterion Eq. B prescribes the mode of
crack propagation once initiated i.e. the flat crack
propagation mode.
• Violation of Eq. B results in fracture localization as in
the case of FRC, and terminates the multiple
cracking process.
• It should be noted that both equations A and B have
been arranged so that the left hand sides of the
inequality sign contain terms that pertain to fiber
and interface properties, while the right hand sides
contain terms that pertain to matrix properties, all
of which are measurable physical properties.
• This observation emphasizes the usefulness of the
equations to help in the fiber, matrix and interface
selection or tailoring process, in arriving at
practiceable compositions of ECCs.

15. IMPORTANCE OF GENERATION OF
MICROCRACKS
• In ECC the microcracks are filled due to the self healing property of cement
composites. Thus , the by-products of hydration fill the gaps in these tiny
cracks.
• This self healing is also true in case of concrete but here the cracks are so
large that they can not be hold together by the by-products of hydration.

16. An Experimental Briefing
Comparison between an standard
and non-standard ECC mix.
BY MUHAMMAD SAAD IFRAHIM

17. • Two appropriate cement based ECC mix proportion denoted as ECC-S and ECC-L
employing silica sand and lumajang sand respectively were designed through
experiments using the principles of micromechanics for studying strain hardening
behavior. The use of lumajang sand was based to produce non-standard ECC-mix.
The percentage of PVA fibre is 2% by volume of specimen.

18. • The fresh ECC matrices were cast into standard Ǿ50 x 100-mm cylinder
specimens for compression test. After placing the fresh ECC matrices into
the moulds, compactions were done.
The compressive strength of ECC mortar was computed as an average
value of three cylinder specimens. The compression tests were performed
at 7 and 28 days under moist curing. After 24 hours of casting, all the
specimens were demoulded and moisture cured in plastic bag with a
controlled temperature of 25 C.

19. • Tensile tests were conducted to evaluate the behavior of ECC mixture under
tension. Cross section 25 X 25-mm dog-bone specimens were prepared. For each
mix, the specimens were cured 7 and 28 days. The specimens were tested in
uniaxial tension using MTS machine with 5 kN capacity under displacement control
at a rate of 0.01 mm/s.
Dog bone mould for
tensile test

20. Findings
• It is observed that the density of ECC-S is slightly lower than ECC-L. However, the
composite densities of both ECC are relatively lower compared with conventional
concrete. This may be caused to the lack of coarse aggregate.

21. • It is noticed that the strain of ECC-S and ECC-L is >3% but when measured after 28
days It is slightly lower than 7 days strain capacity. The blue line is representing
the findings of ECC when It is cured 7 days while the red is representing when it is
cured 28 days.

22. • Tensile strength increases as days passed. Its shows tensile strength of ECC-L is
slightly less than ECC-S. (Shown in table)

23. It is concluded that the higher ultimate tensile strength and strain capacity of
ECC-S indicates its higher complimentary energy (Jb’) compared to that of
ECC-L. Thus, it can be said that the higher complimentary energy, the higher
stress-strain capacity can be achieved.
The area enclosed by the
inclined line and the
vertical axis is called the
complementary energy
In final assessment the performance of ECC material is highly
better than conventional concrete.

24. References
• A. Tambusay, P. Suprobo, Faimum, A.A. Amiruddin
(2015).Experimental Study Of Engineered Cementitious Composite
Material For Structural Application. Proceeding of the 2nd Makassar
• Li V.C., Kanda T., Engineered cementitious composites for structural
application, ASCE J. Materials in Civil Engineering
• Engineered Cementitious Composites (ECC) – Material, Structural,
and Durability Performance Victor C. Li University of Michigan, Ann
Arbor, MI 48109
• Engineered Cementitious Composites (ECC) – Material, Structural,
and Durability Performance. [book auth.] Victor C. Li. s.l. : Michigan
University, 2007.