Novel Fibrous Concrete Mixture Made from Recycled PVC Fibers from Electronic Waste

Abstract

Electronic waste (e-waste) in concrete is the new revolutionary concept of sustainable concrete because it reduces the environmental pollution and solid waste problem. In this paper the extracted outer casing insulation of electrical wire was made into fibers. These fibers were added to the concrete at 0.6, 0.8, and 1% with respect to the weight of cement. Fibers were added to the concrete with the aspect ratio of 35 to make fiber reinforced concrete. The fresh and hardened properties like slump, fresh density, dry density, compressive strength, flexural strength, split tensile strength, and Young’s modulus of fiber-reinforced concrete and normal concrete was compared at the respective age of curing. In order to reduce the cement content and to enhance the properties of concrete, silica powder was added to the fiber-reinforced concrete with 10% replacement of cement with respect to volume of cement and the properties were compared with normal concrete and fiber-reinforced concrete. The experimental results reveal that the optimal percentage addition of e-waste fibers to the concrete was found to be 0.8% with respect to the weight of cement for both fiber-reinforced concrete and silica fiber-reinforced concrete. Thus, fiber-reinforced concrete and silica fiber-reinforced concrete using e-waste fibers was an alternative to normal concrete because it gives increased trend in properties and also reduces the amount of dumping e-wastes into nature.

Full text

Novel Fibrous Concrete Mixture Made from
Recycled PVC Fibers from Electronic Waste
Arjun Ramakrishna Kurup1and K. Senthil Kumar, Ph.D.2
Abstract: Electronic waste (e-waste) in concrete is the new revolutionary concept of sustainable concrete because it reduces the
environmental pollution and solid waste problem. In this paper the extracted outer casing insulation of electrical wire was made into fibers.
These fibers were added to the concrete at 0.6, 0.8, and 1% with respect to the weight of cement. Fibers were added to the concrete with the
aspect ratio of 35 to make fiber reinforced concrete. The fresh and hardened properties like slump, fresh density, dry density, compressive
strength, flexural strength, split tensile strength, and Young’s modulus of fiber-reinforced concrete and normal concrete was compared at
the respective age of curing. In order to reduce the cement content and to enhance the properties of concrete, silica powder was added to
the fiber-reinforced concrete with 10% replacement of cement with respect to volume of cement and the properties were compared with
normal concrete and fiber-reinforced concrete. The experimental results reveal that the optimal percentage addition of e-waste fibers to the
concrete was found to be 0.8% with respect to the weight of cement for both fiber-reinforced concrete and silica fiber-reinforced concrete.
Thus, fiber-reinforced concrete and silica fiber-reinforced concrete using e-waste fibers was an alternative to normal concrete because it gives
increased trend in properties and also reduces the amount of dumping e-wastes into nature. DOI: 10.1061/(ASCE)HZ.2153-5515.0000338.
© 2016 American Society of Civil Engineers.
Author keywords: E-waste; Fibers; Fiber-reinforced concrete (FC); Silica fiber-reinforced concrete (SFC); Aspect ratio and compressive
strength.
Introduction
E-waste consists of waste electrical and electronic equipment that
has reached its end life. In India there are a huge number of e-waste
recycling units that are working but most of them are in the infor-
mal sector; they should be formal to meet the environmental prob-
lems. In India most of the cities like Mumbai, Bangalore, and
Chennai face e-waste management problems that are not solved to
that extent. Electronic waste is considered more toxic than munici-
pal waste because it contains more toxic materials and is a threat to
developing countries. This type of waste consists of more than
1,000 different components that are toxic and nontoxic materials
(Senthil Kumar and Baskar 2015a). The toxic materials such as
mercury, arsenic, cadmium, and lead will cause health problems
if they are not carefully managed, and other materials that are non-
toxic like gold, platinum, silver, and copper are helpful in re-using
purposes (Senthil Kumar and Baskar 2014a). Gradual growth has
occurred in the merging of e-waste management systems in India to
reduce the environmental problems and to avoid burning and
dumping of e-wastes onto the land.
E-waste concrete can be used as sustainable concrete with the
usage of e-waste plastics and other kinds of e-wastes like printed
circuit boards, recycled acrylonitrile butadiene styrene (ABS), high
impact polystyrene (HIPS) wastes etc. (Colbert and You 2012;
Palos et al. 2001;Wang et al. 2012;Senthil Kumar and Baskar
2015a;Gull and Balasubramanian 2014). E-waste powders were
added to the cement mortar and also to the asphalt binders for modi-
fying the conventional type of construction materials, to introduce
green concrete methodology. The results reveals that the addition
of e-waste powders in asphalt increase the binding capacity and
stiffness, and addition to the cement mortar will result in a slight
increase in the compressive and flexural behavior but reduces the
tensile bond capacity (Wang et al. 2012;Palos et al. 2001). E-waste
concrete made using high impact polystyrene as coarse aggregates
will retain 50% compressive strength value at 50% replacement
and similarly e-waste content increases the shear strength value
decreases (Senthil Kumar and Baskar 2015b). Addition of e-plastic
waste to the concrete has shown more deformability but bad shape
and surface texture that will affect the fresh properties of the con-
crete (Senthil Kumar and Baskar 2015a). E-waste concrete using
e-waste fibers will create a trend in the evolution of special concrete
and will increase the strength values of its properties. E-waste plas-
tic type fibers of different length and mix were added to the con-
crete, and studies show that a small size of e-plastic waste will show
good results in properties of concrete as compared with the larger
size. A strength increase of 55.5% is observed in the case of addi-
tion of e-plastic waste of 3 cm length (Gull and Balasubramanian
2014). Some experimental research on response surface of proper-
ties of concrete using e-waste have been done and concluded that
e-waste plastic can replace up to 30% of coarse aggregate (Senthil
Kumar and Baskar 2014b).
Fiber-reinforced concrete can be made of different types of
fibers, usually steel fiber, plastic fiber, polypropylene fiber, syn-
thetic fiber, metallic fibers, PET fibers, and glass fibers (Sofi
and Phanikumar 2015;Abukhashaba et al. 2014;Al Qadi and
Al-Zaidyeen 2014;Aliabdo et al. 2013;Kamal et al. 2014a,b;Foti
2013;Foti 2011;Fraternali et al. 2011;Silva et al. 2005;Asokan
et al. 2010). Some special fibers are reinforced to increase the
1School of Mechanical and Building Sciences, VIT Univ., Chennai
Campus, Tamil Nadu 600127, India. E-mail: arjunrkurup28@gmail.com
2Assistant Professor, School of Mechanical and Building Sciences, VIT
Univ., Chennai Campus, Tamil Nadu 600127, India (corresponding author).
E-mail: senthilkumark13@yahoo.com
Note. This manuscript was submitted on April 4, 2016; approved on
July 11, 2016; published online on August 12, 2016. Discussion period
open until January 12, 2017; separate discussions must be submitted for
individual papers. This paper is part of the Journal of Hazardous, Toxic,
and Radioactive Waste, © ASCE, ISSN 2153-5493.
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special properties of concrete like pull-out behavior, flexural behav-
ior, and thermal resistance (Aiello et al. 2009). Fiber-reinforced
concrete primarily helps to reduce cracks and the propagation of
cracks will be different as compared to the normal concrete; it also
improves the structural performance of the concrete (Kim et al.
2010). Impact energy, impact performance, and penetration resis-
tance power will be enhanced by the use of fibers in specific com-
binations of fiber-reinforced concrete (Aliabdo et al. 2013). Special
concretes are made using different types of fibers in concrete and
also usage of fiber with confinement at the compression area of the
beam specimen to enhance the durability and cracking moment of
concrete so they can be used in repair works, nuclear power plants,
tall buildings, and special structural designs in bridges (Sofiand
Phanikumar 2015;Kim et al. 2010).
In this research the extracted outer casing of electrical wire
(Polyvinyl chloride-PVC wire) was used for making e-waste fibers
considering the plastic fiber aspect ratio and made into fibers as
shown in Fig. 1. The e-waste fibers used in this research are mainly
manufacturing defect pieces. These waste fibers were available in
different lengths after extraction of copper wire from the electrical
cable and made in to fibers as per required aspect ratio.
Materials and Methods
E-waste fibers were made from the electrical waste cables (PVC).
Based on the literature, the appropriate fiber aspect ratio in the
range of 35 was chosen and specific gravity of 1.45. In this study
e-waste fibers were used with concrete at 0.6, 0.8, and 1% with
respect to the weight of cement to make fiber-reinforced concrete
(FC). Silica fiber-reinforced concrete (SFC) was made using silica
powder of specific gravity of 2.2. In this study 10% volume of
cement was replaced to make silica fiber-reinforced concrete as
per BIS 456:2000 (BIS 2000). Table 1shows M30 mix proportion
that was used to cast the fiber-reinforced concrete, silica fiber-
reinforced concrete, and normal concrete as per BIS 10262:2009
(BIS 2009). Properties of e-waste wire fiber are shown in Table 2.
Compressive strength was tested using a cube specimen of 150 ×
150 ×150 mm, flexural strength was tested using a prism speci-
men of 500 ×100 ×100 mm, split tensile strength was tested
using a cylinder specimen of 100 ×200 mm, and Young’s modu-
lus of concrete was found by testing a cylinder specimen of
150 ×300 mm.
Fiber-reinforced concrete, silica fiber-reinforced concrete, and
normal concrete were cast using the respective specimens. During
cast, the fresh properties were studied and the cast specimens were
cured for the required curing days i.e., 7 and 28 days. Fig. 2shows
the materials inside the mixing drum containing e-waste fibers and
e-waste fibers with silica powder, respectively. Potable water at
room temperature was used in all concrete mixes based on BIS
456-2000 (BIS 2000).
Compressive strength, split tensile strength test, and Young’s
modulus tests were performed at 7 and 28 days in accordance with
BIS 516-1959 (BIS 1959a), and a flexural strength test was per-
formed based on BIS 1199-1959 (BIS 1959b). The cube specimens
were tested for compressive strength using compression testing
machine of capacity 2,000 kN at constant loading rate of
140 kg=cm2=min as shown in Fig. 3. A flexural strength test
was carried out using a prism specimen and were tested under
universal testing machine of capacity 1,000 kN at a constant load-
ing rate (180 kg=min) as shown in Fig. 4. Split tensile strength and
Young’s modulus were tested using cylindrical specimens under
compression testing machine of capacity 2,000 kN as shown in
Figs. 5and 6.
Results and Discussions
Slump, Fresh Density, and Dry Density
Fresh properties were plotted in the graphs to study the effect
of fibers in the concrete mix with respect to the normal concrete.
Fig. 1. E-waste fiber: (a) e-wastes (PVC cable); (b) e-wastes made into
fibers
Table 1. Concrete Mix Proportion
Material Quantity (kg=m3) Mix proportion
Cement 333 1
Fine aggregate 742.6 2.23
Coarse aggregate 1,320.2 3.96
Water 140 0.42
Table 2. Properties of E-waste Fiber
Property Test value
Diameter of PVC wire cable (mm) 4
Width of PVC wire fiber (mm) 1
Thickness of PVC wire fiber (mm) 0.8
Length of PVC wire fiber (mm) 35
Aspect ratio 35
Tensile strength (N=mm2)17
Specific gravity 1.40
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Fig. 7shows the slump value of different concrete mixes; when the
fiber content was increased the concrete shows decreasing trend
in slump value. Similarly with the addition of silica powder and
e-waste fibers the slump value goes down to a lower value.
The slump value of fiber-reinforced concrete was reduced to up
to 4 mm and silica fiber-reinforced concrete was reduced up to
6 mm as compared to normal concrete mix. But all the concrete
mixes show the slump values were within the designed slump of
50 to 75 mm. Fig. 8shows the relationship between fresh den-
sity and different types of concrete mixes. Fresh density of normal
concrete was 2,659.63 kg=m3. The fresh density value of normal
concrete and other types of concrete mixes do not show much
difference in the value, but in comparison with normal concrete
the silica fiber-reinforced concrete shows a lesser value of
2,577.77 kg=m3, and fiber-reinforced concrete shows a reduced
value of 2,612.59 kg=m3.Fig.9shows the graph relating the dry
Fig. 2. Concrete mix inside the pan mixer: (a) concrete mix with
e-waste fibers; (b) concrete mix with silica powder and e-waste fibers
Fig. 3. Typical view of compressive strength test
Fig. 4. Typical view of flexural strength test
Fig. 5. Typical view of split tensile strength test
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density and different concrete mixes. Dry density of normal
concrete was 2,512.59 kg=m3. Lowest dry density value of fiber-
reinforced concrete was 2,518.9kg=m3and of silica fiber-
reinforced concrete was 2,481.48 kg=m3.
Compressive Strength
The casted specimens were tested under respective testing ma-
chines after required curing days and results were plotted in the
graph. Normal compressive strength will not increase more in case
of fiber addition, but the fibers used in this experiment show an
increasing trend in strength due to the texture of the fibers. Fig. 10
shows the relationship between compressive strength and different
types of concrete mixes. The failure pattern of the cube specimen
after compressive strength is compared and reveals that normal
concrete shows a crack pattern of conical shape, whereas FC and
SFC do not show the same pattern, and some failure parts of con-
crete were attached to the main specimen. The percentage increase
in the compressive strength of 28-day results of FC and SFC were
30.82 and 38.49% with respect to the normal concrete. Addition of
silica powder to the fiber-reinforced concrete increases the stiffness
of the concrete mix and will bear more load as compared to the
normal and FC.
Flexural Strength
The relationship between flexural strength and concrete mixes are
shown in Fig. 11. The figure shows the variation in the flexural
Fig. 6. Typical view of Young’s modulus test
Fig. 7. Variation in slump with respect to the concrete mixes
Fig. 8. Variation in fresh density with respect to the concrete mixes
Fig. 9. Variation in dry density with respect to the concrete mixes
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value of different concrete mixes at different days of strength.
The percentage increase in the flexural strength value of 7 days of
flexural strength of 28 days of FC and SFC were 9.11 and 16% with
respect to normal concrete. Fiber addition increases the bending
capacity of the concrete as compared to the normal concrete,
i.e., delayed the failure of specimens after reaching the ultimate
load and arrested the crack propagation. However, the normal con-
crete specimens had broken into two pieces at ultimate load. Silica
fiber-reinforced concrete shows more flexural value as compared to
fiber-reinforced concrete because the addition of silica will increase
the bond strength by acting as a denser matrix in the concrete mix.
Split Tensile Strength
The plot between split tensile strength and concrete mixes are
shown in Fig. 12. The percentage increase in the value of split
tensile strength, as compared with the normal concrete results of
28 days, of FC and SFC were 7.1 and 18.5% with respect to normal
concrete. Split tensile strength was increased in the case of fiber
addition as it gives the increased trend of postcracking effect,
and in the case of silica fiber-reinforced concrete the value was in-
creased due to the increase in the toughness of the concrete mix
with the addition of silica powder. The normal specimens under
loading showed brittle failure and broke into two pieces, but con-
crete specimens containing fibers did not show brittle failure and
never separated into two halves under ultimate load.
Young’s Modulus
The relationship between Young’s modulus and concrete mixes are
shown in Fig. 13. Percentage increase in the Young’s modulus
Fig. 10. Variation in compressive strength with respect to the concrete
mixes
Fig. 11. Variation in flexural strength with respect to the concrete
mixes
Fig. 12. Variation in split tensile strength with respect to the concrete
mixes
Fig. 13. Variation in Young’s modulus with respect to the concrete
mixes
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value of 28 days of FC and SFC were 40 and 49.7% with respect
to the normal concrete. As compared to the FC, Young’s modulus
value of SFC was increased up to 6.9%. An additional 1% of fiber
with respect to the weight of cement in both FC and SFC gives
reduced value of Young’s modulus. Young’s modulus of FC and
SFC up to 0.8% fiber addition was increased because of the in-
crease in tension behavior due to the fibers and stiff matrix provided
by the silica powder.
Ultrasonic Pulse Velocity (UPV)
The quality of concrete were found from the graph plotted between
UPV value and concrete mixes as shown in Fig. 14. The range of
good concrete is from 3.5 to 4.5km=s, and above 4.5 is excellent
quality of concrete as per BIS 1311-1:1992 (BIS 1992). In this
graph the bottom line is drawn to indicate that all the values of
different types of concrete mixes were above 4.2km=s. The UPV
value of the specimen with fiber showed a decreasing trend because
the e-waste fibers inside the concrete were able to absorb the pulse
waves (Senthil Kumar and Baskar 2014a). Thus, the quality of con-
crete with e-waste fibers and with silica powder are good and
acceptable.
Conclusions
This study examines e-waste fibers used in the concrete by 0.6, 0.8,
and 1% with respect to the weight of cement. Based on the exper-
imental investigation, the following conclusions can be drawn:
•Slump values were decreased with increase of e-waste fiber
content, but the slump values were within the design slump of
50 to 75 mm;
•The addition of 0.6 and 0.8% of e-waste fibers with respect
to the weight of cement to the fiber-reinforced concrete and si-
lica fiber-reinforced concrete gives increasing trend in hardened
properties of concrete such as compressive strength, flexural
strength, and split tensile strength. However, at 1% addition of
e-waste fibers with respect to the weight of cement shows de-
creasing trend in the hardened properties;
•Hardened properties of both fiber-reinforced concrete and silica
fiber-reinforced concrete shows a linearly increasing trend as
compared with the normal concrete because the addition of
fibers and silica powder improves the bending capacity, bonding
strength, and fill the pores to form the dense matrix in the
concrete;
•At the age of 28 days, the percentage increase in the compres-
sive strength, flexural strength, and split tensile strength of FC
were found to be 30.89, 9.11, and 7.11%, respectively, with re-
spect to the normal concrete. Similarly, the percentage increase
in the compressive strength, flexural strength, and split tensile
strength of SFC were found to be 38.49, 16.0, and 19.6%, re-
spectively, as compared with normal concrete. The optimal per-
centage of e-waste fiber was found to be 0.8% with respect to
the weight of cement.
•Fiber-reinforced concrete and silica fiber-reinforced concrete
can be used as a sustainable concrete because it shows good
results in various properties of concrete. Thus, the use of e-waste
fiber in concrete will be one of the optimal solutions for the
e-waste management problem and thereby reduce environmen-
tal pollution.
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