Bendable Concrete 13 Running Head: Polyvinyl Alcohol in Creating a Bendable Concrete

BENDABLE CONCRETE (Conducted 2017) 13 Running Head: BENDABLE CONCRETE 1 Using Polyvinyl Alcohol in Creating a Bendable Concrete Student’s Name Institution Project summary Bendable concrete is a mortar based easily moulded composite which is reinforced with especially random short fibres. The flexural strength and compressive strength of slabs and cubes of two different thicknesses are obtained with the bendability features of the concrete observed during the test on the flexural strength.

Running Head: BENDABLE CONCRETE
Using Polyvinyl Alcohol in Creating a Bendable Concrete
Student’s Name
Institution

BENDABLE CONCRETE
Project summary
Bendable concrete is a mortar based easily moulded composite which is reinforced with
especially random short fibres. The traditional concrete faces disastrous failure due to routine
overuse or strained in an earthquake whereas the bendable concrete remains safe and intact
for up to 5% tensile strains. Traditional concrete may not be able to withstand a load of a
tensile strain of 0.01%. To overcome future concrete demand and to design fibre materials in
this article, the Polyvinyl Alcohol fibre is applied so as to minimize the content of the cement
and for flexibility enhancement. It has an ultimate high tensile strength, the aspect ratio is
high, good water affinity, elasticity modulus which is relatively high, good compatibility of
chemicals with the Portland cement and has no risks to health. For concrete workability
increase, superplasticizer is used. The flexural strength and compressive strength of slabs and
cubes of two different thicknesses are obtained with the bendability features of the concrete
observed during the test on the flexural strength.
Keywords: engineered Cementitious Cement, superplasticizer, self-curing.

BENDABLE CONCRETE
Introduction
Background
Normal concretes almost do not bend having a 0.1% strain capacity which makes them rigid
and highly brittle. The featured lack of bendability is the main reason for failure under strain
and this factor has pushed for an elegant development of a material known as Engineered
Cementitious Composites as well as bendable concrete. The material has the ability to
considerably exhibit an improved flexibility. Bendable concrete is reinforced with polymer
fibres which are designed micro-chemically whereas Engineered Cementitious Composites is
obtained from similar ingredients that are as basic as those of normal concrete. However, it
has High Range Water Reducing agents added to it for the purpose of imparting better
workability. In ECC, there is no use of coarse aggregates, therefore it is a mortar and not
concrete. The amount of Engineered Cementitious Composites powder is high, relatively.
Cementitious materials for example fumes of silica, fly ash, blast-furnace slag among others
may be added to cement so as to increase the amount of the paste. Engineered Cementitious
Composites typically uses 2% of discontinuous short fibres. Engineered Cementitious
Composites incorporates silica sand which is very fine and Poly Vinyl Alcohol fibres that
covered with a coating of very thin silk. This coating of the surface enables the fibre to begin
slipping during over-loading which prevents fracturing.

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Literature Review
(Seyhan, John, & Abid, 2018)Conducted a study on synthetic fibres and steel, both available
commercially. Deflection and flexural stress relationships have been applied to determine
flexural toughness, flexural strength, equivalent flexural strength ratio and equivalent flexural
strength. The concrete’s flexural toughness was discovered to be averagely increasing upon
the usage of synthetic fibres and steel, however, different fibres of equal dosages did not lead
to specimens with similar flexural toughness.
(Recep, Hediye, & Yusuf, 2017)Conducted an investigation study on the flexural behaviour on
concrete that self-compacts reinforced with hooked-end and straight steel fibres at 0.5%,
1.0% and 1.5% levels compared to Normally Vibrated Concrete. The tests from the
laboratory were determined as per RILEM TC 162-TDF recommendation. The flexural
behaviour of SCC appeared comparably similar as Normally Vibrated Concrete, where an
increase in the volume ration of fibres led to an increase in post-peak and pre-peak SCC
parameters. The type of steel fibres nevertheless, greatly influences this dependency.
However, the SCC gains maximum displacement in its crack mouth for lesser deflections as
compared to Normally Vibrated Concrete.
(Wei & Yan, 2017)carried out a study to experiment on the probable applications of the
Engineered Cementitious Composites reinforced with fibres with less drying shrinkage
characteristics in pavements of the concrete with the aim of joint elimination that is used
normally to accommodate deformation of shrinkage and temperature. It was realized that
composite slab having both normal concrete and LSECC with bars of steel at the interface of
concrete/ LSECC and designed procedures of construction was able to localize the tensile
cracks into the strip LSECC instead of fracturing in the nearest concrete slab (Viktor, Volker,
& Petr, 2017).

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(Biswajeet, 2018)Investigated on the self-healing nature of the LSECC with concern on the
influence of pre-cracking period and curing condition. A four-point bending test was used to
pre-crack beams of ECC at a different age, followed by different conditions of curing. For all
the conditions of curing, deflection capacity after self-healing can exceed or even recover
those from virgin samples with averagely every pre-cracking age.
Aims and objectives of the investigation
Bendable concrete has been noted to be having better features compared to the normal
concrete, therefore, this experiment will be investigating the high performance of this
bendable concrete in that it will;
 Aim at making and casting beams of ECC to determine the deflection of these beams.
 Aim at performing the separate flexural test, tensile test and compression test to
observe the nature of ECC.
Importance of the project
Because ECC is flexible more than the traditional concrete, it is considered more of a metal
than glass. Traditional concrete is considered to be rigid, brittle and ceramic. It may
experience the greatest failure by routine overuse and when under strain.it is studded with
specially coated fibre reinforcements which hold it together thus ECC remains safe and intact
to be at a tensile strength of up to 5%. Traditional concrete cracks may not be in a position to
withstand a load with a tensile strain of 0.01%. Today, constructers reinforce concrete
buildings with bars of steel so that if cracks would exist, they would only be small fractures.
However, these fractures are not as small as such to heal adequately. Deicing salts and water
that penetrate the concrete to the steel results in corrosion of the steel which makes the
building weaker. The self- healing concrete will not face corrosion as it does not require

BENDABLE CONCRETE
reinforcing with steel for the concrete to maintain the width of the fractures intact (Zongjin,
2011).
Definition of terms
 PVA
Polyvinyl Alcohol fibres.
 Permeability
The rate at which fluid flows through a porous medium, in this case, concrete.
 Flexural strength
This is the material’s bendability strength in its effort to withstanding the imposed pressure
on it.
 Self-curing
It is the feature of bendable concrete of refilling the fractures which exist as a result of
reactions that happen. The concrete’s point of failure is extended.
 Workability
This is the relativity ease of concrete being allowed to be transported, compacted, mixed and
moulded.
 Durability
This is the feature of the concrete to withstanding damage, wear and pressure.

BENDABLE CONCRETE
Methodology
Ingredients of bendable concrete
The engineered cementitious composite is comprised of fly ash, optimal contents of fibres,
sand, cement, and small contents of admixtures. In the mixture, coarse aggregates are
eventually not applied due to the ECC property of forming small cracks with deflections that
are large. Coarse aggregates increase the width of the fractures this being the opposite of the
property of the ECC concrete (Mohammad, King, & Safat, 2017).
CEMENT
Portland ordinary cement is the cement used. Cement is defined as the many organic
compounds applied for fastening or adhering material. However, these are categorized as
adhesives and the word cement on its own stand for material for construction. The blast
furnace is also important that they are applied in some cement where it is referred to as
Portland slag cement. The cement’s colour is highly influenced by the existence of iron
oxide and in the cases that there were no impurities the cement would be white in colour. The
cement normally used is the ordinary Portland cement grade 53 (Edward, 2008).
SAND
Sand is applied in concrete and mortar making and also in sandblasting and polishing. Sands
with some amounts of clay are applied in foundries for making moulds. The weight differs
from 1,538 – 1,842kg/m3 depending on the grain’s size and composition. The passing of the
fine aggregate through a sieve of 4.75mm with 2.68 special gravity is applied most of the
times (Vera & Zdenka, 2017).

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Fly Ash
The type of fly ash applied is known as pozzocrete dirk 60 and specification are given by the
supplier in the table below. In the construction of RCC, there has been a successful use of the
fly ash in lowering generation of heat with no strength loss, increasing strength that is
averagely above 180 days and producing other fines for compaction. Levels of replacement
of a primary classed fly ash is in the range of 30% to 75% of cementitious material’s solid
volume. In mixture proportioning, for minimum paste volumes, one major role of fly ash is to
ash is to fill empty spaces that would have been instead filled with water or cement. The
filling of the empty spaces by water would lead to concrete’s strength reduction (Joaquim,
Liberato, & Enzo, 2017).
Table 1
(Qin & Hao, 2017)
WATER
Water that is fit for consumption is considered generally fit for concrete making. Water
should be free from impurities such as vegetables, alkalis, oils acids and other organic
impurities. Soft water generates concrete that is weaker. Water plays two roles in the concrete
mixture first, it chemically reacts with cement to produce cement paste in which unreactive

BENDABLE CONCRETE
aggregates suspended until the hardening of the cement paste. Second is that it acts as a
lubricant or vehicle in the mix of cement and fine aggregates (Jun & Hao, 2018).
Polyvinyl Alcohol fibres
The polyvinyl Alcohol fibres have an important feature that is, reinforcement materials for
cementitious composites. Other suitable features include; high elasticity modulus, high
bonding strength with the concrete matrix, high tensile strength and durability. Polyvinyl
Alcohol fibres have high elasticity modulus and a high strength of about 25pa -40pa than
other normal organic fibres which are used on a wide range for cement reinforcement.
Enlargement fibre is almost 6% to 10%. The fibre tensile strength ranges from 880Mpa -
1600Mpa. One important feature of PVA fibre is the high bonding strength with cement
matrix (Baoguo, Liqing, & Jinping, 2017).
SUPERPLASTICIZER
The type of plasticizer used is called Melamine Formaldehyde Sulphonate. It is used in order
to regulate rheological features of fresh concrete. Basically, they are additives to the concrete
and used to uniformly spread the cement in the mixture. This is attained by the action of
deflocculating on cement agglomerates whereby water trapped in the cement grains groups is
released ready for workability. Superplasticizers typically lead to slump increase from 5cm –
18 or 20cm with no water being added. Although when applied to attain in reducing the
amount of water used for mixing, water can be reduced to about 15 to 20% therefore, the
ratio of water or cement is averagely reduced by the same amount. This leads to strength
increase and increases in other features such as tightness of water and density (Milan &
Zdenek, 2012).

BENDABLE CONCRETE
Mixture design
Concrete proportioning
Mixture proportion initially was 1:8004:1.996, the dosage of superplasticizer was 1040.47
ml/bag, PVA fibres 1% and the ratio of water to cementitious components was 0.274.
Therefore, for the 2nd trial the proportion of the mixture changes were made to be 1:0.9:1.1,
increasing the water ratio and of the cementitious components to 0.3048, by retaining the
similar dosage of superplasticizer and the amount of PVA fibre increased to 1.2%. In the 3rd
trial, the proportion of the mixture was 1:1:1 hence, lowering the superplasticizer dosage to
600ml bag, the percentage of PVA fibre was 1.2% and the ratio of cementitious material to
water was 0.33. In the 4th trial, the proportion of the mixture was 1:0.9:1.1, a dose of
superplasticizer was a 600ml bag, the percentage of PVA was 1.2% and the ratio of
cementitious materials to water was 0.3118. So as to attain workability a number of trials
were conducted and as for the 4th proportion mix, the dosage of superplasticizer was lowered
in order to achieve workability. For every trial mixture, three cubes were introduced then
cured by the use of the accelerated tank for curing then later tested to achieve the desired
requirement for strength. After cubes for every trial were tested, the mixture of the trial
number three was seen as the most appropriate and therefore the final proportion mixture
(Mehdi, 2017).
The procedure of casting Engineered Cementitious Composite Concrete.
Mixing influences the performance of the ECC it, therefore, implies that a suitable and better
mixing practice results in quality and improved performance of the ECC concrete. The
flexural test was done on the slab at the time of mixing and after putting off the fresh
concrete, homogeneity of the mixture materials also has an influence on the quality of the
concrete. It is, therefore, important to properly mix the concrete for the concrete to achieve

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the desired strength and for the cement to bond well with the PVA fibres. Upon the mixture
design of concrete being finalized mixing is therefore conducted by the use of a hand mixer.
The hand mixing procedure is as follows: place sand, cement, fly ash a percentage of 50%,
superplasticizer and amount of water of 50%. Slowly add the entire amount of fly ash,
superplasticizer and water. After the homogenous mix is fed, slowly add the PVA fibres and
mix all the contents until all fibres are mixed homogeneously in the matrix (Maekawa,
Okamura, & Pimanmas, 2015).
Compaction, casting and placing of specimens of the concrete
Before concrete is placed, it is important to oil the concrete mould for easy stripping of the
concrete specimens. The oil applied is a mix of kerosene and diesel. Reasonable care is
observed at the time of oiling the moulds to ensure that there are no stains of the concrete on
the moulds. After the ECC’s workability test has been conducted the fresh concrete must be
put in concrete moulds for the test of hardened properties. At the time of putting off the fresh
concrete into the moulds, tamping is conducted by use of a tamping rod so as to minimize
honeycombing (Nicholas, 2017). Vibrations are conducted by using a table vibrator after the
placement of the concrete into moulds. Concrete vibration enables complete compaction of
the fresh concrete so as to remove any entrained air spaces present in the concrete. If the
concrete is not properly compacted, the desired strength may not be attained. After the
operation of vibration, concrete levelling is conducted on the concrete’s surface. Levelling is
the first operation conducted after placement and compaction of concrete. After the fresh
concrete has been levelled the concrete in the moulds is by the overnight left to enable the
fresh concrete to set (Alexander, 2017).
Curing the specimen of the concrete

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After the fresh concrete is left in the moulds by overnight to set, the specimens of the
concrete in the moulds stripped. Concrete specimen identification was conducted and after
twenty-four hours, all specimens of the concrete were put into the tank for curing at a
regulated temperature of 250C and further for twenty-eight days for the test of hardened
properties of concrete (PANKAJ & MANISH, 2011). The process of curing is very important
in protecting the specimens of the concrete from moisture loss as it attains the strength that is
required. If curing is not done it will result in the attainment of improper strength. After
curing for twenty-eight days, the specimens of the concrete are removed from the tank used
for curing so as a test for hardened properties of engineered cementitious composites concrete
is conducted (Jaroslava, Jan, Pavel, & Karel, 2017).
Comparison to other composite materials
property Normal concrete ECC
durability Has a less durable structure Has a more durable and
flexible concrete structure
Earthquake resistance These structures are
susceptible to earthquakes
they may collapse or crack
during earthquakes.
Its concrete is flexible hence
resists cracking or failure
during earthquake motion.
Self-healing property This concrete has a much-
reduced level of self-healing
property since the free
cement concrete is low.
This concrete has a higher
level of self-healing
property since the micro-
cracks are self-healed by
water carbon dioxide
reaction.
Repair and maintenance The cost of repairing and
maintaining is high in these
concrete structures due to
developing defects and
cracks.
The cost of repairing and
maintaining is less in these
concrete structures as it fails
reduces crack development.

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Timeline
CONCLUSION
Although the ordinary Portland cement is expensive and intensive energy, it is the ingredient
used most widely required in the concrete mixture production. It is unfortunate that cement
production involves releasing carbon dioxide in amounts that are large into the atmosphere
which contributes greatly to global warming and greenhouse effects. However, it cannot be
avoided nor can another material be used instead of or be replaced partly. Numerous
investigations conducted by researchers in relation to the design of engineered cementitious
composites and its usage in reality in the field has proven to be the best sustainable and an
alternative material for concrete in the nearby future. The process of curing is very important
as it prevents the specimen of the concrete from losing moisture thus helping it gain the
required strength and also vibration process enhances full compaction of the fresh concrete
hence removing void spaces in the concrete.

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