22-08-2014, 11:44 AM
UTILIZATION OF RECYCLED AND WASTE MATERIALS IN VARIOUS CONSTRUCTION APPLICATIONS PROJECT REPORT
UTILIZATION OF RECYCLED.pdf (Size: 237.29 KB / Downloads: 144)
ABSTRACT
More production equals more waste, more waste creates environmental concerns of toxic threat. An
economical viable solution to this problem should include utilization of waste materials for new products
which in turn minimize the heavy burden on the nation’s landfills. Recycling of waste construction
materials saves natural resources, saves energy, reduces solid waste, reduces air and water pollutants and
reduces greenhouse gases. The construction industry can start being aware of and take advantage of the
benefits of using waste and recycled materials. Studies have investigated the use of acceptable waste, recycled
and reusable materials and methods. The use of swine manure, animal fat, silica fume, roofing shingles, empty
palm fruit bunch, citrus peels, cement kiln dust, fly ash, foundry sand, slag, glass, plastic, carpet, tire scraps,
asphalt pavement and concrete aggregate in construction is becoming increasingly popular due to the shortage
and increasing cost of raw materials. In this study a questionnaire survey targeting experts from construction
industry was conducted in order to investigate the current practices of the uses of waste and recycled materials
in the construction industry. This study presents an initial understanding of the current strengths and
weaknesses of the practice intended to support construction industry in developing effective policies regarding
uses of waste and recycled materials as construction materials
INTRODUCTION
Several issues exist regarding reducing waste. A key
environmental issue is waste incinerators, furnaces for
burning trash, garbage and ashes. These incinerators
produce 210 different dioxin compounds plus mercury,
cadmium, nitrous oxide, hydrogen chloride, sulfuric acid
and fluorides. Produced also in incinerators is
particulate matter that is small enough to remain
permanently in the lungs. Additionally, waste
incinerators generate more CO2 emissions than coal, oil,
or natural gas-fueled power plants. For years, scientists
and researchers have been searching for possible
solutions to environmental concerns of waste production
and pollution. Many have found that replacing raw
materials with recycled materials reduces our
dependency on raw materials in the construction
industry. The Federal Highway Administration (FHWA)
estimated that building demolition in the United States
alone produces 123 million tons of construction waste
per year (FHWA, 2004). Begum et al. (2010) supports
the adoption of prefabrication and Industrialized
Building Systems (IBS) to reduce waste generation and
management problems. Their study revealed that a
significant amount of material wastage can be reduced
by the adoption of prefabrication and the rates of reused
and recycled waste materials are relatively higher in
projects that adopt prefabrication. In addition to a
reduction of construction waste generation, Hassim
(2009) identified and discussed other advantages of
applying prefabrication in the building and construction
activities. This include enhance integrity on the building
design and construction, reduction unskilled workers,
reduce construction cost, fixed design at the early stage
MATERIALS AND METHODS
Tire Rubber
An estimated number of one billion scrap tires have
been disposed of in huge piles across the United States.
An additional 250 million tires unaccounted for are
discarded yearly (RMA, 2011). Whole tires have been
used in artificial reefs, break waters, dock bumpers, soil
erosion control mats and play ground equipment. Several
studies have shown that tire waste can be successfully
used in concrete, grass turf, asphalt mix, embankments,
stone cladding, flowable fill and clay composite.
Reclaimed Asphalt Pavement
The transportation sector has used Reclaimed
Asphalt Pavement (RAP) for many years. In 2009, the
amount of RAP used in asphalt pavements was 56.0
million tons and in 2010, 62.1 million tons. RAP is
America’s most recycled and reused material; currently,
RAP is being recycled and reused at a rate over 99%. RAP
is used to backfill pavement edges, rework base and base
course. According to the World Business Council for
Sustainable Development, manufactures around the
Glass
Americans generated 11.5 million tons of glass in the
Municipal Solid Waste (MSW) stream in 2010. Glass is
composed of silica or sand and contains some amounts
of limestone and soda ash used to produce uniform quality
and color. According to the Association of Cities and
Regions for Recycling (ACRR), people around the world
send 1.5 million tons of glass to landfills each year. Glass
that ends up in the landfill won’t break down for over a
million years. Glass cullet creates workability problems in
concrete mix and the likely hood of alkali-silica reaction.
Beneficial uses are in the secondary applications, such as in
the manufacture of fiberglass insulation, roadbed aggregate,
driving safety reflective beads and decorative tile
Carpet
According to Carpet America Recovery Efforts
(CARE) in 2010, carpet waste diverted from landfills
was 338 million pounds, 271 million pounds were
recycled, 3 million pounds used for alternative fuel and
23 million pounds for cement kilns. Old carpet is being
recycled and used in composite lumber (both decking
and sheets), tile backer board, roofing shingles, rail road
ties, automotive parts, carpet cushion and stepping stones. A
study by Wang et al. (2000) proved that by adding fibers to
concrete, both toughness and tensile properties increased.
Other benefits in adding carpet fiber to concrete include
reduction of shrinkage, improved fatigue strength, wear
resistance and durability
Cement Kiln Dust
CKD (byproduct of manufacturing Portland cement)
is fine grained, highly alkaline waste, removed from the
cement kiln exhaust gas by air pollution control devices.
Uses of CKD may include: soil stabilization, waste
treatment, cement replacement and asphalt pavement.
CKD is perfect as soil stabilizer improving soils strength
and minimizing work and cost. Siddique (2006)
concluded that concrete mixtures containing low
percentages (5%) of CKD can achieve almost equal
compressive strength, flexural strength, toughness and
freezing and thawing resistance as that of the control
mixture. CKD is a quality adsorbent and natural alkaline
that makes it an effective waste treatment. Emery (1981)
suggested that CKD (mixed with asphalt as mineral filler)
can significantly reduce asphalt cement requirements
between 15 and 25% by volume. CKD added to asphalt
binder produces low ductile mastic asphalt and provides
stripping resistance for the pavement.
Citrus Peels
The US 2006/2008 seasons of citrus juice production
generated 10.6 million metric tons of waste. Research
shows that citrus peel can be an alternative to
commercial activated carbon that is high in capital and
regeneration costs, which is the preferred absorbent for
removal of Methylene Blue (MB). MB is a dye that
comes from the wastewater from textile industries and
can cause severe environmental pollution if emitted to
the environment without proper treatment.
The Survey
Sustainable-green infrastructure is growing concept
of saving energy, natural resources and cost, as well as in
the solution to environmental concerns involving waste.
In order to accomplish the growing industry of green
infrastructure, the end users including contractors,
engineers and suppliers have to be informed about what
recycled/waste materials are available to use in the
construction industry. To find out what end users are
aware of recycled and waste materials and who are
actually using them, companies have to be approached
and questioned. The survey intends to reveal the barriers
or issues behind not using recycled materials in the
construction industry.
Methodology
A questionnaire survey was conducted through phone
calls, visits and email, addressing: (1) If the company
uses or sells any waste or recycled materials for
construction application, (2) Is the surveyor aware of
other recycled materials that are being used in
construction applications, (3) Are there any recycled
materials that are not recommended for use in the
construction industry and (4) if not using such materials,
what are the barriers behind not using recycled materials
in their work. All the questions ended with a yes for what
application and if no, reasons for not using the material.
The survey consisted of a list of recycled and waste
materials including; Cement Kiln Dust (CKD), fly ash,
foundry sand, slag, glass, plastic, carpet, tire rubber,
recycled asphalt, recycled concrete, gypsum, silica fume,
swine manure, animal fat, soy bean, roofing shingles,
citrus peels, sewage sludge, date and oil palm tree and a
place to add additional recycled materials being used in
the construction industry not listed. The last question
was included to record any additional contact or
references to question for more information on the topic.
DISCUSSION
Statistical Analysis
As aforementioned, 65 participants from 50 different
construction related companies participated in this studyTable 3 and 4 summarize the statistical findings of
the survey. Table 3 was generated from the responses
of companies that use recycled material and shows the
percent use of recycled material in different
construction applications, while Table 4 was
generated from responses of companies that do not use
recycled materials and shows the reasons why such
companies do not use recycled materials in their
products or applications
CONCLUSION
Review of several studies suggested that the use of
recycled materials has positive impact through different
aspects. This include the benefits in enhancing
sustainability of the construction industry while reducing
cost, providing solutions to environmental pollution and
reducing the need for natural resources. In this study, a
questionnaire survey was conducted to find out the current
practices in using waste and recycled materials in the
construction industry. Results indicated that some
companies were not aware of the availability, quality of
the materials’ performance, cost savings, or any other
benefits including environmental benefits. It is, thus
recommended to create better documentation for green
infrastructure, connecting researches and industry with an
overview of what recycled materials are available for
different construction applications. Companies need to be
innovative in their use of recycled materials and reduce
their dependency on raw materials. Also, more data and
better documentations are needed to encourage the use of
waste and recycled materials in the construction industr