Waste Plastic as Concrete Aggregate

This assignment explores the potential of using waste plastic as a partial replacement for sand in concrete. It delves into studies that investigate the strength, behavior, and properties of concrete incorporating waste plastic. The assignment also considers the environmental implications of this practice, discussing its role in mitigating the global sand crisis and plastic pollution.

Research Proposal: performance of plastic in concrete
Name
Date

Abstract
Owing to the triple problems of to much plastic that is causing pollution, increased dredging of sand
and rising construction costs, proposals have been made to use plastic as replacement for sand
aggregates in concrete mixtures. Researchers ave in the past undertaken experiments to show that
plastics can be used in place of sand as an aggregate to be used for construction at lower costs and
maintaining structural integrity. This paper proposes a research on the use of plastic as a partial
replacement for sand in concrete aggregate for use in non structural building applications with the
rider that Post-use Plastic can Safely be used in Construction as a partial Aggregate Replacement in
Non-Structural Applications; it Will Improve Failure to be More Ductile rather than Brittle. An
experimental research design will be used to test the the compression stress, the flexural strength,
and the indirect tensile strength of concrete created using molds after 7 and 28 days of curing and
results discussed and conclusions drawn

Table of Contents
Abstract.................................................................................................................................................2
Introduction..........................................................................................................................................4
Literature Review.................................................................................................................................4
Research Aim and Objectives...............................................................................................................6
Theoretical Content and Methodology.................................................................................................7
Experimental Set Up.............................................................................................................................7
Results, Outcome, and Relevance........................................................................................................9
Conclusion..........................................................................................................................................10
Project Planning and Gantt Chart.......................................................................................................10
References..........................................................................................................................................12

Introduction
One of the enduring environmental problems of modern times is the increasing production and use
of plastics, which are then difficult to recycle because they take a very long term to decompose,
straining fragile ecosystems. Research shows that the world buys a million plastic bottles each
minute and the global plastic consumption is envisaged to reach half a trillion bottles by the year
2021; this will outstrip all efforts aimed at recycling and poses a big danger to ecosystems,
particulalry coastlines, oceans, and other environments, according to Laville and Taylor (2017). the
production of plastics has grown tremendously over the years, from 50 million metric tons in 1976
to a high of 311 million metric tons in 2014, according to DW (Deutsche Welle) (2017). Further,
most products made from plastics are disposal products instead of being used to make lasting
products. On average, each person uses about 45 kilograms of plastic yearly, although the use varies
from region to region. For instance, China produces 26% of plastic in the world, but japan is the
largest consumer per capita. The demand for cement is also rising and this is placing a major strain
on the environment as sand must be harvested for use with cement in construction. As a
consequence, some governments have enacted laws to regulate or ban sand dredging because of its
adverse environmental effects. India for instance, is facing a major problem in environmental
degradation due to sand dredging from riverine and other ecosystems led by a ‘sand mafia’ fueling
the $ 120 million building boom (Hawley, 2017), (Romig, 2017)and this has led to bans being
imposed on sand dredging (Jha 2017). Because of the twin challenge of sand dredging that damages
ecosystems, especially riverine and coastlines, and the environmental disaster that is plastics, new
sustainable approaches are needed to solve the twin environmental challenges. Further, the world is
facing a shortage of sand (Greene, 2017), (Torres, Liu, Brandt & Lear 2017)even as the construction
boom continues unabated in some regions, especially fast growing economies like India and China.
Among the proposals that have been put forth is to use plastics in construction; however, before this
can go mainstream, a better understanding of how plastics perform in concrete when used in
construction, especially because most of this plastic will be recycled and not originally intended for
use with concrete. This paper will start with a detailed literature review of the topic, followed by a
description of the project aims and objectives as well as a research question(s). A brief description
of the research methodology and experimental set up will be discussed an evaluation done before
drawing conclusions. A project plan to undertake the research will then be outlined.
Literature Review
Sand is among the major components used in building construction that has supported civilizations
from ancient times to the present. With the increased construction boom, such as mega cities in

China and much of the world, one would be forgiven for thinking they are looking at sand castles.
However, sand is finite and it is already a cause for major conflict. Sand resources are getting
depleted with annual demands hovering around 40 billion metric tons (Campbell 2015). the most
common sand type is quartz and although one would assume deserts have limitless amounts of sand,
the sand is not applicable in construction because wind has eroded it and not water, making the
particles round and difficult to stick together, leaving only beach and river sand as the remaining
viable alternative sand sources (Campbell 2015). The world is facing a plastic glut, that is
everywhere, from the food table to the ocean floor and in water bodies, with numerous plastic
gyros. A new problem is that some gut bacteria survive treatment to destroy them by attaching to
plastics and ending up in water bodies (Montgomery 2017). The cost of construction is increasing
daily as the sand shortage continues to bite; Thosar and Husain (2017) have proposed a solution to
reduce construction costs by replacing sand with plastic waste. The use of plastic waste will solve
several problems, including using recycled plastic to create a new product that can be used as an
alternative to sand aggregate. Apart from lowering construction costs and helping solve the plastc
problem by recycling it, the approach will also save fragile ecosystems and fauna, given that only
beach and riverine systems sand is the most utilized and most suitable sand for use in building
applications (Thosar & Husain, 2017).
Ismail and Al-hashimi (2008) undertook an experimental test to test if plastic can safely be used in
concrete as an aggregate replacement. Using 254 tests in 86 experiments, the researchers tested the
fresh density, slump, compressive strength, dry density, and toughness indices at room temperature
by partially replacing sand in concrete at amounts of 0, 10, 15, 20% of sand with 800 kg concrete
mixture. The mixtures were cured for between 3 an 28 days and the results showed that r3cycle
plastic can safely be used to substitute sand in concrete aggregates; plastic reduced micro cracking
and offers a huge promise in reducing materials cost and help solve some of the waste problems due
to plastic. Marzouk, Dheilly and Queneudec (2017) investigated the value that recycled/ used
plastic waste wold have when used in cement concrete composites using an experimental design.
The researchers investigated the mechanical characteristics and densities of composites produced by
adding various percentages ranging from 0 to 100% of post consumer plastic to concrete
composites. Using electron microscopy, the relationship between composite micro-structure and
mechanical properties were evaluated. The results show that substituting sand with plastic at levels
below 50% (volume) did not affect the flexural and compressive strength of composites. Shredded
used plastic can be successfully used to substitute sand in cement concrete composites without
affecting the properties of the concrete composite. Hama and Hilal (2017) investigated the effect of
fresh properties for self compacting concrete ( SCC) when plastic waste was used as replacement.
Using different mixes of SCC with constant water to binder ratio of 0.32 to 520 kg per square meter

and 30% weight fly ash was used to replace cement. Different plastic contents or varying coarseness
was added to the SCC and the V funnel flow time, L-box T40 and T20 flow times, slump flow
diameter, L-box height ratio, 20 day SCC compressive strength, and the T50 slump flow times
workability properties were tested. The results show that plastic waste can be used as a substitute
fine aggregate in SCC. Vanitha, Natarajan and Praba (2015) explored if waste plastics can be
utilized partially to replace coarse aggregates in concrete blocks on the backdrop of rapid
urbanization and industrialization. The rapid development in infrastructure, the researchers
reasoned, results in several adverse effects such as construction materials shortages and increased
waste production, including plastics while sand resources are increasingly exploited to provide the
sand needed for use n concrete construction. The authors researched the use of plastics to replace
sand in construction materials, researching on the M20 concrete aggregate. The researchers used
between 0 and 10% plastic as replacement for aggregate with varying degrees of aggregate
coarseness. The researchers casted various solid blocks and paver blocks and their physical
characteristics tested using plastic to replace designated amounts of aggregates in M20 concrete.
The compressive strength tests on the blocks was 2% for solid blocks and 4% for paver bocks,
showing that plastic can be safely used as an aggregate replacement in concrete and used in
construction.
Research Aim and Objectives
This proposed research aims at determining the suitability of using plastic, specifically post use
plastic such as used plastic bottles as a replacement for sand aggregates in concrete. In particular,
the objective is to determine the amounts of plastics that can safely be used as sand aggregate
replacements in construction concrete
Research Questions
1) What is the compressive strength of concrete in which varying amounts of post-use plastic
has been added to replace sand aggregates?
2) What is the safe limit of plastics that can be added to concrete for application sin the
building industry?
3) How does plastic particle size affect the compressive strength of concrete when used as an
aggregate?
4) Can plastics be used to replace sand aggregates in concrete mixes or it should be used as a
partial replacement?
This proposed research is motivated by present events relating to costs, environmental degradation
and what to do with the enormous volumes of plastics being produced that will soon overtake

recycling efforts, as discussed in the introduction. The successful use of plastic as a replacement for
sand, either fully or partially will greatly reduce pressure on the environment, especially on riverine
and water bodies that suffer adverse effects of sand dredging, affecting communities and
ecosystems adversely. This proposed research hopes to solve two problems using a ‘single stone’ by
enhancing plastic recycling efforts, easing their adverse environmental effects while helping lower
the cost of building houses, a critical aspect of helping ensure more people in the world can afford
decent housing. This research has the goal of determining, through an experimental research, the
safe limits of plastic quantities that can be used to replace sand in concrete mixes; this paper hopes
to fully and satisfactorily answer the research questions listed above.
Theoretical Content and Methodology
plastics take thousand s of years to decompose naturally, making them tough substances that can
last for a long time. Further, plastics are light, being lighter than sand aggregates by 70%. this
means that sand can effectively be used in construction as a concrete aggregate to achieve reduced
weight per volume of the concrete. Tests have shown that the compressive, flexural, modules
rupture, and indirect tensile strength of concrete decreases as the amount of plastic used as
aggregates in the concrete increases, however, the fresh weigh of the concrete decreases and also
leads to changes in module failure to more ductile than brittle failure (Jibrael and Peter 2016). This
research will therefore be conducted with the following hypothesis;
Post-use Plastic can Safely be used in Construction as a partial Aggregate Replacement in
Non-Structural Applications; it Will Improve Failure to be More Ductile rather than Brittle.
This proposed research will make use of an experimental research design where variables will be
tightly controlled, with a control variable also being used. The experimental research design is the
most suitable for this kind of experiment because it allows for randomization to ensure the
outcomes are valid and reliable and to reliably create homogeneous groups of treatment and
eliminate possible biases and judgments. The randomization concept also enables objects to be
assigned randomly using only the criteria of chance to experimental groups (Glennerster &
Takavarasha 2013).
Experimental Set Up
This proposed research will use concrete in the ratio of cement to sand to gravel as 1:1.67:2.5 with
the ratio of water being 0.46 as shown below;
Material Specifications
Cement Portland cement

Sand Fine aggregate sand having an sg
(specific gravity) of 2.7
Water Fresh water
Grave Gravel with sg of 2.72 and maximum
sizes of 12.5 mm
To this mixture, post use plastic will be added in different quantities and mechanical properties of
the concrete mix done. The plastic to be used is recycled ones added in the percentages of 0%
(control), 1%, 5%, 10%, 25% and 100% from the sand used in the concrete. The plastics will be
washed and ground to give articles with an sg of 1.04. The gravel and sand will be mixed first in an
electrical mixer for a minute and cement added with water added gradually and mixed until a
homogeneous concrete mixture is formed. Molds will be used for casting after cleaning and oiling
and placed on a level location. Concrete will be poured onto the molds and the surfaced levelled
using a trowel and marked for reference. The molds will be placed on a flat level place for 24 hours.
The molds will then be placed in a curing tank for between 7 and 28 days. The following tests will
then be done on the concrete at different plastic percentages as replacement (partial for sand).
Test Description
Slump test This is a test designed to determine concrete consistency/
stiffness. This test shows how much water is in a mix and
should match the desired value for finished products of
between 7 and 9 mm (Klieger & Lamong 2011)
Concrete hardness test This will be done after having the samples dry for half an
hour.
Compressive strength test Is a common test for hardened (cured) concrete and is the
most significant test for structural purposes. Compressive
tests will be undertaken based on the BS EN 12390>3 when
the concrete is 7 days old and at 28 days old (Choo &
Newman 2003)
Flexural strength test This will be used for testing rupturing modulus of the
concrete using a central point load (Choo & Newman 2003)
Indirect tensile strength This will be based on the ASTM C496-62T standard where a
cylinder is compressed along 2 diametrically opposite axial

lines through plywood bearing strips. Compressive load is
distributed over a small width by the plywood cushion,
sufficient enough to eliminate undue stress concentration
while compensating for irregularities on the surface. A
transverse tensile stress is produced by the compressive force
which remains constant along the sample vertical diameter
(Richardson 2003)
Results, Outcome, and Relevance
The results of the compressive strength tests for hardened concrete will be obtained using the
relation f cu =P/A to obtain compressive stress in MPa. The compressive stress will be obtained at 7
days and at 28 days for varying percentages of added used plastic to the concrete mix. The indirect
tensile strength of the concrete samples will also be obtained at different percentages of plastic at 7
and 28 days using the relation f ct = 2 P/π DL. Finally, the Flexural strength will also be obtained at
the same quantities of plastic at 7 and 28 days intervals using the relation ft = MC/I. In this set up,
the plastic used is the independent variable while the compression stress, the flexural strength, and
the indirect tensile strength of the concrete mixture is the independent variable. The tests will show
if plastic can be used to substitute sand in concrete mixes safely without a significant degradation in
the desired mechanical properties of concrete for compression stress, flexural strength, and the
indirect tensile strength and the different percentages of plastic that can be used.
Conclusion
This research proposal is aimed at determining if post use plastic can be used as a replacement,
either partially or in full for sand aggregates for concrete used in construction. The research is
important because plastic wastes has become a crisis with consumption projected to continue
increasing yet biodegradability of plastic takes far too long, up to thousands of years. This has
created a pollution crisis (of plastic), from land fill to sea beds. Further, increased construction has
seen increased dredging for sand, usually from beaches and riverine systems, disturbing fragile
ecosystems and creating a new environmental menace. Proposal have been made for use of plastic
as an aggregate in construction concrete to help reduce plastic waste menace by recycling it and
ease pressure on beaches and riverine systems sand dredging. Using an experimental research
design, the compression stress, the flexural strength, and the indirect tensile strength of concrete
with varied amounts of plastic used as aggregate to replace sand will be tested and used to either

accept or reject the hypothesis that Post-use Plastic can Safely be used in Construction as a partial
Aggregate Replacement in Non-Structural Applications; it Will Improve Failure to be More Ductile
rather than Brittle.
Project Planning and Gantt Chart

References
Campbell, B. (2015). The world's deadly war over sand: 7 things you need to know. Public Radio
International. Retrieved 20 October 2017, from https://www.pri.org/stories/2015-04-03/worlds-
deadly-war-over-sand-7-things-you-need-know
Choo, B. S., & Newman, J. (2003). Advanced concrete technology. [Vol. 3]. Oxford, Butterworth-
Heinemann.
'Deutsche Welle' (2017). Six data visualizations that explain the plastic problem | Global Ideas |
DW | 30.12.2016. [online] DW.COM. Available at: http://www.dw.com/en/six-data-visualizations-
that-explain-the-plastic-problem/a-36861883 [Accessed 20 Oct. 2017].
Glennerster, R., & Takavarasha, K. (2013). Running randomized evaluations: a practical guide.
Princeton, Princeton Univ. Press.
Hama, S. M., & Hilal, N. N. (2017). Fresh properties of self-compacting concrete with plastic waste
as partial replacement of sand. International Journal of Sustainable Built Environment.
https://doi.org/10.1016/j.ijsbe.2017.01.001
Hawley, S. (2017). The 'sand mafia' fuelling India's $120 billion building boom. [online] ABC
News. Available at: http://www.abc.net.au/news/2017-03-28/the-great-sand-heist-fuelling-india-
120-billion-building/8390984 [Accessed 20 Oct. 2017].
Jha, M. (2017). Illegal Sand Mining: Steps taken by Government of India. [online] Iasscore.in.
Available at: http://iasscore.in/national-issues/illegal-sand-mining-steps-taken-by-government-of-
india- [Accessed 20 Oct. 2017].
Jibrael, M., & Peter, F. (2016). Strength and Behavior of Concrete Contains Waste Plastic. Journal
Of Ecosystem & Ecography, 6(2). http://dx.doi.org/10.4172/2157-7625.1000186
Ismail, Z. Z., & Al-Hashmi, E. A. (2008). Use of waste plastic in concrete mixture as aggregate
replacement. Waste Management. 28, 2041-2047.
Klieger, P., & Lamond, J. F. (2011). Significance of tests and properties of concrete and concrete-
making materials. Philadelphia, Pa, American Society for Testing and Materials.
Laville, S. and Taylor, M. (2017). A million bottles a minute: world's plastic binge 'as dangerous as
climate change'. [online] the Guardian. Available at:
https://www.theguardian.com/environment/2017/jun/28/a-million-a-minute-worlds-plastic-bottle-
binge-as-dangerous-as-climate-change [Accessed 20 Oct. 2017].
Marzouk Oy, Dheilly Rm, & Queneudec M. (2007). Valorization of post-consumer waste plastic in
cementitious concrete composites. Waste Management (New York, N.Y.). 27, 310-8.

Montgomery, M. (2017). Our Plastics Glut Is An Environmental Nightmare -- And An $80 Billion
Opportunity. Forbes.com. Retrieved 20 October 2017, from
https://www.forbes.com/sites/mikemontgomery/2017/03/25/our-plastics-glut-is-an-environmental-
nightmare-and-an-80-billion-opportunity/#1df6d27c4f4d
Richardson, J. G. (1987). Supervision of concrete construction. Vol. 2. London, Palladian
Publications.
Romig, R. (2017). How to Steal a River. [online] Nytimes.com. Available at:
https://www.nytimes.com/2017/03/01/magazine/sand-mining-india-how-to-steal-a-river.html
[Accessed 20 Oct. 2017].
Thosar, C., & Husain, M. (2017). Reuse of Plastic Waste as Replacement of Sand in Concrete.
International Journal Of Innovative Research In Science, Engineering And Technology, 6(1), 789-
793.
Torres, A., Liu, J., Brandt, J. and Lear, K. (2017). The world is facing a global sand crisis. [online]
The Conversation. Available at: http://theconversation.com/the-world-is-facing-a-global-sand-crisis-
83557 [Accessed 20 Oct. 2017].
Vanitha S., Praba M., & Natarajan V. (2015). Utilisation of waste plastics as a partial replacement of
coarse aggregate in concrete blocks. Indian Journal of Science and Technology. 8.