Resources, Conservation and Recycling 68 (2012) 96–103
Contents lists available at SciVerse ScienceDirect
Resources, Conservation and Recycling
journal homepage: www.elsevier.com/locate/resconrec
Construction waste minimisation comparing conventional and precast
construction (Mixed System and IBS) methods in high-rise buildings: A Malaysia
case study
Suresh Kumar Lachimpadi a,∗ , Joy Jacqueline Pereira a , Mohd Raihan Taha b , Mazlin Mokhtar a
a
b
Institute for Environment and Development (LESTARI), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
Department of Civil and Structural Engineering, Faculty of Engineering, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
a r t i c l e
i n f o
Article history:
Received 7 April 2011
Received in revised form 5 June 2012
Accepted 28 August 2012
Keywords:
Waste minimisation
Construction waste
Reuse
Recycling
IBS
Conventional Construction
Mixed System
a b s t r a c t
The construction industry has always been a major generator of construction waste and is often faced
with the issue of its effective management in minimising environmental pollution. This research paper
focuses on the construction waste generated from the construction of high rise buildings using 3 construction methods; Conventional Construction (Category I), the Mixed System (Category II) and Industrialised
Building System (IBS, Category III). The construction waste for each construction category were characterised into its mineral and non-mineral components. The construction waste usage efficiency (CWUE),
waste generation, reuse and recycling rates were also calculated. The IBS (Category III) was found to be
the most efficient construction method with a waste generation rate (WGR) of 0.016 tons of construction
waste/m2 floor space compared to the Mixed System (Category II) at 0.030 tons/m2 and the Conventional
Construction (Category I) at 0.048 tons/m2 . The construction waste usage efficiency (CWUE) was the
highest in Category III (IBS) at 94.1% with only 5.9% of the total construction waste in this category being
disposed at landfills. The Construction Industry Development Board (CIDB) of Malaysia has recognised
its benefits and has actively promoted the use of IBS in Malaysia. The waste characterisation data and
its uses (reuse and recycling) obtained from this study could be used as baseline data to promote and
encourage the Malaysian construction industry to adopt the use of precast technology, the Industrialised
Building System (Category III) and move away from the more traditional resource hungry Conventional
Construction (Category I). The inclusion of the Mixed System (Category II) in this study as an intermediate
construction method was aimed at providing the link between the Conventional Construction (Category
I) and the IBS (Category III). The Mixed System (Category II) incorporates both the IBS and Conventional
Construction methods. The Conventional Construction (Category I) with the incorporation of new construction technologies could easily be reclassified as the Mixed System (Category II), allowing Malaysian
contractors to easily adopt it. This paves the way for better understanding for the use of precast technology which eventually would result in a positive shift towards the use of the IBS (Category III) by Malaysian
contractors in the future. Thus, improving the construction industry’s environmental performance and
commitment to sustainable development as outlined by the CIDB’s Construction Industry Master Plan
2006–2015 for Malaysia.
© 2012 Elsevier B.V. All rights reserved.
1. Introduction
The construction sector plays a major development role in both
the developing and developed countries of the world and studies have shown this industry to be resource hungry; consuming
up to 60% of all raw materials extracted from the Earth (Lombera
∗ Corresponding author. Tel.: +61 450 6363 89; fax: +61 8683 2520.
E-mail addresses: suresh8223@gmail.com, suresh8223@yahoo.com
Lachimpadi).
0921-3449/$ – see front matter © 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.resconrec.2012.08.011
(S.K.
and Aprea, 2010). A study conducted by World Watch Institute has
shown that the raw material used for building construction consumes up to 40% of stones, sand and gravel; 25% of timber and
16% of all water used annually around the world (Dimoudi and
Tompa, 2008). Based on the quantities of raw materials used by the
construction industry, it is therefore, responsible for generating a
significant portion of construction waste in the world (Kourmpanis
et al., 2008; Wang et al., 2004).
The term construction and demolition (C&D) waste is generally referred to as solid waste generated by the construction sector
arising from civil and building construction, building renovation
S.K. Lachimpadi et al. / Resources, Conservation and Recycling 68 (2012) 96–103
and demolition including activities such as land excavation or formation, site clearance and roadwork (Shen et al., 2004). Globally,
significant amounts of C&D waste are generated annually, e.g. in
2003, approximately 323 million tons of C&D waste was generated
in the US (US EPA, 2004). In the UK, the figure stood around 70 million tons which included soil (DETR, 2000) with a material wastage
rate of 10–15% (McGrath and Anderson, 2000). In Australia, the C&D
waste accounted for 16–40% of the total solid waste in the landfills (Bell, 1998). The Environment Protection Department (EDP) of
Hong Kong has estimated that landfills in Hong Kong received about
3158 tons of construction waste per day in 2007 (Hong Kong EDP,
2007) whereas in China, the producer of 29% of the world’s municipal solid waste (MSW), C&D waste accounted for approximately
40% of the total MSW composition (Dong et al., 2001; Wang et al.,
2008).
In recent years, there has been a concerted move to promote the
reuse and recycling of construction waste in order to reduce inflow
of construction waste into the landfills and to protect the environment (Chun et al., 1997). In Malaysia, the construction industry’s
impact on the environment is significant due to the high demands
in major infrastructure projects, housing and commercial developments generating high volumes of construction waste (Begum
et al., 2010). This has aroused the public’s growing concerns on
negative environmental impacts in many local communities in
Malaysia (Begum et al., 2006). In recognising these concerns, the
Malaysian government formed the Construction Industry Development Board (CIDB) of Malaysia; one of its aims was to transform the
Malaysian construction industry by improving its environmental
performance by reinforcing the Malaysian construction industry’s
commitment to sustainable development through the Construction Industry Master Plan 2006–2015 (CIDB, 2012; Effie et al.,
2011) and promoting the use of the Industrialised Building System (IBS) as part of the “IBS Roadmap 2003–2010” programme
(CIDB, 2011).
The IBS has not been effectively implemented in Malaysia
despite having been introduced in the late 1960s (Hamzah et al.,
2010). In 2003, 15% of construction projects in Malaysia utilised
IBS and by 2006, it had dropped to 10% (Hamid et al., 2008).
The IBS which is widely used in Europe, Japan and Singapore
is seen as an alternative option to the Conventional Construction in maintaining sustainability in construction through the
efficient use of resources, improvements in the quality of constructed buildings and waste minimisation (Tam et al., 2007; Kibert,
2007; Begum et al., 2010). A study by Begum et al. (2006) at
an IBS construction project site in Malaysia showed that 73% of
its construction waste were reused and recycled; indicating the
economic feasibility of waste minimisation and the net benefit
calculated in this study was valued at 2.5% of the total project
budget.
The waste management hierarchy identifies 6 waste management options (to reduce, reuse, recycle, compost, incinerate
and landfill) (Peng et al., 1997) of which this study explores 3
of those options; “reuse”, “recycle” and “landfill”. For the purpose of this study, the “reuse” and “recycle” were defined as
follows:
(a) Reuse – using the same materials at the same construction site
more than once for the same function, e.g. formwork at the
construction site (Ling and Leo, 2000) or for a new life reuse
for a new function, e.g. stony fractions for road base material
(Duran et al., 2006).
(b) Recycle – using the construction waste (e.g. used wooden formwork, tiles, bricks, hardened concrete, soil and sand, timber,
etc.) at another construction site for the same purpose use or
for a new function.
97
2. Case study sites
Eight construction sites featuring medium cost high rise residential buildings in the Klang Valley, Malaysia were selected based
on the following criteria:
(a) the availability of the Bill of Quantity (BQ) to determine the
construction phases and for the estimation of construction
materials used at the construction sites;
(b) implementation of an environmental management system at
each construction site;
(c) implementation of waste management practices at site;
(d) the availability of a dedicated Environmental Officer for data
collection and EMS implementation;
(e) compliance to the Malaysian Department of Environment’s
Environmental Impact Assessment (EIA) requirements and the
Environmental Quality Act 1974 of Malaysia.
The 3 construction methods used in this study were defined as:
(i) Conventional Construction (Category I)
This method consists of extensive cast in situ activities. Reinforced concrete frames, beams, columns, walls, and roof are
cast in situ using timber formwork while steel reinforcement
is fabricated at site. It is labour intensive involving three separate trades, namely steel bending, formwork fabrication and
concreting: employing skilled carpenters, plasterers and brick
workers (Badir and Razali, 1998).
(ii) Mixed System (Category II)
An intermediate construction method, the Mixed System
(Category II) is defined by the use of certain elements that
are standardised and fabricated in the factory while others are
cast in situ at the construction sites. This involves the assembly of precast elements such as in-filled walls, bathrooms and
staircases which are incorporated into the main units at the
construction sites. Floors, slabs, columns and beams are cast
in situ as these are relatively easier and less time consuming
parts of the operation (Badir and Razali, 1998). The Mixed System, in this study is considered as an amalgamation of the IBS
(Category III) and the Conventional Construction (Category I)
methods.
(iii) Industrialised Building System, IBS (Category III)
The IBS (Category III) is defined as a construction process that
utilises techniques, products, components or building systems
involving the use of on-site and off-site (factory producing) prefabrications for installation. The on-site pre-casting consists
of floor and roof slabs in situ whereas the off-site fabrications of some or all components of buildings are cast off-site
at fabrication yards or factories. With the transfer of construction operations to factories or fabrication yards, good quality
components have been mass produced and delivered to the
construction sites in economically large loads (Badir and Razali,
2002).
3. Research methodology
The data obtained in this study was only from construction
waste collected over a 3-year period. The objectives of this study
were to:
(a) characterise and quantify the mineral and non-mineral components of the construction waste generated from the
construction of high rise buildings for the 3 categories (I–III);
(b) quantify the “reuse” and “recycling” rates for the 3 categories
(I–III);
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S.K. Lachimpadi et al. / Resources, Conservation and Recycling 68 (2012) 96–103
Table 1
The demarcation of the construction phases of the 8 study sites for the 3 construction
methods (Categories I–III).
Phases
Building elements
Activities
I
Earthwork
• Land clearing
• Cut and fill of earth
II
Sub-structure
• Basement
• Foundation
• Plant and equipment
• Drainage
• Underground services
III
IV
Superstructure
External works
+ Recycled (%) (2)
• Column, beam, bearing wall, lift shaft,
stairs, slabs, frames
• External work – walls and roof
• Internal Finishes – wall finishing, floor
finishing, ceiling finishing
• Fixtures and fittings
• Services – sanitary appliances, disposal
installations, water installations, ventilation
system, electrical installation, protective
installations, builder’s works in connection
4. Results and discussion
4.1. Waste generation rate (WGR)
• Site works
• Drainage and sewerage
• External services
• Landscaping
(c) calculate the waste generation rate (WGR) and construction
waste usage efficiency (CWUE) for the 3 categories (I–III).
3.1. The 4 construction phases
The Bill of Quantity (BQ) of all the 8 construction sites were
reviewed and the construction sequences were defined into 4 distinct phases as shown in Table 1 (Tam et al., 2007; Emery et al.,
2007). The construction waste collected represents the total construction waste collected over the 4 phases of construction at each
construction site.
The 8 study sites consisted of medium cost high rise residential buildings; 2 sites for Conventional Construction (Category I), 3
sites each for the Mixed System (Category II) and the Industrialised
Building System (IBS, Category III). Construction waste collection
stations were established as data collection points at each construction site. The construction waste was segregated by hand and
machineries into 2 groups: (i) mineral, and (ii) non-mineral components. The mineral component consisted of: (a) concrete and
aggregate, (b) bricks and blocks, (c) scrap metal, (d) tiles, and (e) soil
and sand; whereas the Non-mineral component were: (a) timber
and plywood, (b) packaging products and (c) plastic materials.
These components were further separated into groups based on
its intended uses: (a) reuse, (b) recycling and (c) disposal at landfills.
This segregation allowed the construction waste usage efficiency
(CWUE) to be calculated. The construction waste destined for landfills were measured on weighbridges at the landfills whereas those
used for reuse and recycling were measured on site.
3.2. Waste generation rate (WGR)
The WGR is a simple method used to determine the efficiency of
a construction method. This is achieved by measuring the quantity
of construction waste generated by weight (tons) for every square
meter of normalised floor space constructed at the construction
sites. The WGR is shown in Eq. (1):
Total construction waste (tons)
Total floor space (m2 of normalised floor space)
The CWUE is a measure of construction waste usage efficiency
through reuse and recycling. The CWUE is defined as the percentage sum of the “reused” and “recycled” construction waste at site,
as shown in Eq. (2). The increase in CWUE indicates an inversely
decreasing rate in the disposal of construction waste at landfills.
Construction waste usage efficiency (CWUE) = Reused (%)
Modified from Emery et al. (2007) and Tam et al. (2007).
WGR =
3.3. Construction waste usage efficiency (CWUE)
(1)
The efficiency of a construction method in this study is shown
by the waste generation rate (WGR); the more efficient a construction method is, the smaller the WGR value becomes. Table 2 shows
Category III (IBS) sites generating the smallest quantities of construction waste compared to the Mixed System (Category II) and
Conventional Construction (Category I) sites. A decreasing WGR in
this study indicates an increase in the use of construction waste for
reuse and recycling.
The selection of a construction method determines the quantity
of construction waste generated at site as shown by the studies
conducted by Tam et al. (2007). The 3 construction methods
selected in this study show a similar trend. Table 2 shows the
average WGR in the IBS (Category III) was 0.016 tons/m2 whereas
the Mixed System (Category II) and Conventional Construction
(Category I) recorded values of 0.030 tons/m2 and 0.048 tons/m2 ,
respectively. The average WGR for Category III (IBS) when compared to Category I (Conventional Construction) was 3 times
less and against the Mixed System (Category I) was 1.9 times
less. Lower WGR indicates increased efficiency in construction
material usage and a reduction in the generation of construction
waste.
4.2. A comparison of mineral and non-mineral components in the
construction waste for the 3 Categories (I–III)
The construction waste was segregated into 2 main groups: (a)
mineral component consisting of soil and sand, concrete and aggregates, scrap metal, bricks and blocks and tiles; and (b) non-mineral
component consisting of timber and plywood, packaging products
and plastic materials.
4.2.1. Conventional Construction (Category I) waste: the
composition of mineral and non-mineral components
Fig. 1 shows the construction waste profile for the Conventional Construction (Category I) sites. The mineral components
averaged 81% of the total construction waste whereas the nonmineral components averaged 19%. The largest fraction in the
mineral component was concrete and aggregate (60%), followed
by soil and sand (15%), bricks and blocks (3%), scrap metal (2%)
and tiles (1%) whereas in the non-mineral component, timber
and plywood waste constituted the largest fraction (17%), followed by plastic materials and packing products at 1% each,
respectively.
The high percentage of concrete and aggregate (60%) waste in
the Conventional Construction (Category I) sites was attributed
to the poor handling/application of concrete and aggregates by
unskilled construction workers during the sub-structure and superstructure phases of construction (Table 1). These two construction
materials were easily obtainable at relatively low prices in Malaysia
S.K. Lachimpadi et al. / Resources, Conservation and Recycling 68 (2012) 96–103
99
Table 2
Construction waste generation rates (WGR) for the 3 construction methods used at the 8 study sites in the Klang Valley, Malaysia.
Category
Project sites
Floor space (m2 )
Total construction
waste (tons)
Waste generation rate
(tons/m2 floor space)
Waste generation rate
(tons/100 m2 floor space)
Average
Average
I: Conventional
Construction
Site 1
Site 2
101297.30
27499.72
5357.5
1171.7
0.053
0.043
0.048
5.29
4.26
4.8
II: Mixed System
Site 3
Site 4
Site 5
111536.00
133308.00
178181.81
3792.2
4200.0
4454.5
0.033
0.032
0.025
0.030
3.40
3.15
2.50
3.02
III: Industrialised
Building System (IBS)
Site 6
Site 7
Site 8
116666.05
37594.81
71421.85
1730.0
600.0
1130.0
0.014
0.016
0.016
0.016
1.48
1.60
1.58
1.55
Fig. 1. Mineral and non-mineral components for Category I (Conventional Construction) shown as average percentage (%) of the total construction waste.
which contributed to its poor management at the Conventional
Construction sites. The generation of soil as waste (soil and sand)
greatly depended on the design of the buildings and its landscaping requirements. The project requirements dictated that the
conventional constructed buildings were to “blend” into the natural contours of the surrounding environment. This required higher
cut rates compared to the fills, resulting in surplus soil which were
classified as soil and sand waste. The soil and sand waste in this
category averaged 15%. The other fractions of the mineral component were bricks and blocks (3%), tiles (1%) and scrap metal (2%),
the most sought after construction waste for recycling.
Timber and plywood waste was the largest fraction in the nonmineral component averaging 17% (Fig. 1). Timber and plywood
waste was expected in large quantities as this method of construction relied heavily in the use of timber and plywood for specific
construction purposes, e.g. in providing support structures during
concreting work (false forms and formwork), temporary support in
barricades and other supporting structures. The lifespan of timber
and plywood for reuse is dependent on the quality of the product
used at the construction sites. The Convention construction (Category I) sites were found to use lower quality plywood which had a
shorter lifespan (reused 2–3 times) compared to the construction
sites in Categories II and III (reused 5–6 times). Plastic Materials and
Packaging Products each contributed 1% of the total construction
waste (Fig. 1). Poon et al. (2001) had shown that construction waste
containing formwork, plaster and screeding for Conventional Construction was much higher than that of prefabricated construction
in Hong Kong.
4.2.2. Mixed System (Category II) waste: the composition of
mineral and non-mineral components
Fig. 2 shows the construction waste profile in the Mixed System
(Category II). The mineral components averaged 88% whereas the
non-mineral components accounted for 12% of the total construction waste. The largest fraction in the mineral component was soil
and sand at 50%. The high soil and sand waste in the Mixed System
was largely due to the extensive cut activities carried out in Phases
I (earthwork) and IV (external work), generating surplus soil which
was designated as soil and sand waste. The second largest fraction was concrete and aggregate waste at 30%. The 30% concrete
and aggregate waste was reduced by half when compared to the
Conventional Construction in Category I (60%). This reduction was
achieved by the use of IBS (e.g. use of tunnel forms and pre-cast
panels) to replace the more traditional brick laying for wall construction and other building structures. The employment of semiand skilled workers in the Category II (Mixed System) minimised
wastage of concrete and aggregates through better handling and
application during construction. Bricks and blocks averaged at 4%
and tiles and scrap metal were at 2% each, respectively.
The largest fraction in the non-mineral component was timber
and plywood at 9%. The high percentage was due to the use of timber and plywood in the construction of specialised architectural
features in situ using Conventional Construction at the Mixed System sites (Category II). The use of precast components was found to
be uneconomical for these construction activities as the quantities
used were too small to be economically produced at the precast
plants. Packaging products averaged 2% whereas plastic materials
were 1% (Fig. 2).
4.2.3. The Industrialised Building System (Category III) waste: the
composition of mineral and non-mineral components
Category III (IBS) sites generated the least amount of construction waste, with a WGR of 0.016 tons of construction waste for every
m2 of normalised floor space (Table 2) when compared to Categories I (Conventional Construction) and II (Mixed System). 93% of
100
S.K. Lachimpadi et al. / Resources, Conservation and Recycling 68 (2012) 96–103
Fig. 2. Mineral and non-mineral components for Category II (Mixed System) shown as average percentage (%) of the total construction waste generated.
the total construction waste consisted of the mineral component
whereas only 7% was non-mineral waste (Fig. 3).
The largest fraction of the mineral component was sand and soil
(75%). Concrete and aggregate averaged at 14%. Bricks and blocks
were at 2% while Tiles and scrap metal averaged 1% each. Of the
3 non-mineral fractions (Fig. 3), packaging products recorded the
highest average at 4%, timber and plywood at 2% and plastic materials at 1%.
4.3. A comparison of mineral and non-mineral components in
Categories I–III
The construction waste profiles were unique for each of the 3
categories. At present, the construction waste data for the Mixed
System (Category II) and the IBS (Category III) for high rise buildings in Malaysia is limited and the data from this study would
complement the existing database.
4.3.1. The mineral component
Fig. 4 shows the mineral component waste distribution in all
3 categories. Soil and sand waste was the largest fraction in all 3
categories (I–III). The highest percentage recorded was in Category
III (IBS) at 75%, followed by Category II (Mixed System) at 50% and
the least in Category I (Conventional Construction) at 5%. The high
percentages of soil and sand waste in Categories II (Mixed System)
and III (IBS) were largely due to the extensive cut activities during
earthwork (Phase I) and landscaping (Phase IV), generating large
quantities of surplus soil which were later classified as soil and
sand waste.
Concrete and aggregate was the second largest fraction in the
mineral component in all 3 categories. 60% of the total construction waste in Category I (Conventional Construction) consisted of
concrete and aggregate waste whereas Categories II (Mixed System) and III (IBS) recorded 30% and 14% each, respectively. This
study has shown that a high percentage of concrete and aggregate
waste in Category I (Conventional Construction) was generated
from the poor management of concrete and aggregates at the construction sites by unskilled construction workers. This is a common
occurrence in many of the Conventional Construction projects in
Malaysia. The majority of these construction workers consist of foreign nationals commanding low wages. The low wages is seen as
a cost saving measure to increase profits for many construction
companies in Malaysia. The trade offs with savings from the lower
wages and unskilled work force are lower productivity and poor
workmanship (Sambasivan and Soon, 2007). This often leads to
greater wastage of construction materials which eventually ends
Fig. 3. Mineral and non-mineral components for the IBS method (Category III) shown as average percentage (%) of the total construction waste generated.
S.K. Lachimpadi et al. / Resources, Conservation and Recycling 68 (2012) 96–103
101
Fig. 4. Distribution of the mineral components in the construction waste relative to the total construction waste for each category (in weight percentage).
up as construction waste. Site observations from this study has also
shown that the reuse and recycling activities were a low priority in
the Category I (Conventional Construction) sites.
Scrap metal consisting of reinforced steel, wire meshes, mild
steel sheets and metal based products were found in smaller quantities at all construction sites (Categories I–III). Fig. 4 shows the
quantities of scrap metal generated: 2% each in Categories I (Conventional Construction) and II (Mixed System), and 1% in Category
III (IBS). The high demand for scrap metal in the metal recycling
industry and its high market value made all metal products and
scrap metal a tightly controlled commodity at all the construction
sites. Our study has also shown that at the precast manufacturing plants for the Category III (IBS) sites, the scrap metal wastage
was measured at 0.03% of the total weight of the reinforced steel
bars obtained for the manufacture of precast panels (unpublished
data). The high efficiency in material usage with minimal wastage
was achieved by using pre-cut reinforced steel bars for use at the
precast yards.
Category II (Mixed System) generated the highest bricks and
blocks waste at 4% whereas Conventional Construction (Category
I) and IBS (Category III) generated 3% and 2%, respectively (Fig. 4).
Waste tile averaged 2% in Category II (Mixed System) and 1% each
in Categories I (Conventional Construction) and III (IBS). The low
percentage of tile waste in all 3 categories were due to the use of
highly skilled and well paid workforce whom displayed good work
attitudes and workmanship. The bulk of the tile waste was from
breakages during transport and storage, and a small percentage
was from off-cuts during application.
Construction), followed by Category II (Mixed System) at 9% and
the least in Category III (IBS) at 2%.
The high percentage of timber and plywood waste in Category I (Conventional Construction) was expected as this method
of construction relies heavily on the use of timber and plywood
in its in situ construction, e.g. as temporary support structures
or formwork during the installation or construction of permanent
structures such as walls, panels, beams and floor slabs. It was also
observed that lower quality timber and plywood were extensively
used at the use of lower quality plywood with short reuse lifespan
greatly increased the demand for new plywood at the Category
I (Conventional Construction) sites. These were eventually disposed of at landfills as timber and plywood waste. The reuse and
recycling rates for timber and plywood at the construction sites
greatly depends on the quality of the construction material purchased for use; better quality reduces the need to procure more
as its reused more before disposal whereas poorer quality would
require an increase in procurement due to its limited reuse capacity
and its eventual quick disposal at the landfills.
Packaging products waste was the highest in Category III (IBS)
at 4% whereas Categories II (Mixed System) and I (Conventional
Construction) averaged 2% and 1%, respectively (Fig. 5). Category
III (IBS) generated the highest percentage in Packaging Products
waste because many of the precast components manufactured in
factories or precast plants are sent to the construction sites packed
in or wrapped in packaging materials to prevent damage during
transport and storage at site. Plastic materials accounted for 2% or
less of the total construction wastes at all the construction sites in
the 3 categories (I–III) (Fig. 5).
4.3.2. The non-mineral component
In this section, a comparison of the non-mineral component
is made between the 3 categories as shown in Fig. 5. The highest percentage recorded was 17% in Category I (Conventional
4.4. Reuse, recycle and disposal of construction waste
The preference for reuse, recycle or disposal of construction
waste was unique in all 3 categories. Table 3 shows the total
Fig. 5. Distribution of the non-mineral components of the construction waste relative to the total construction waste for each category (in weight percentage).
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S.K. Lachimpadi et al. / Resources, Conservation and Recycling 68 (2012) 96–103
Table 3
The total construction waste generated and its segregation based on usage and disposal for Categories I–III.
Category
Project sites
Segregation of construction waste (tons)
Total construction
waste generated
Reused at site
Recycled
(tons)
(%)
(tons)
(%)
(tons)
I: Conventional
Construction
Site 1
Site 2
5357.5
1171.7
100
100
1521.5
263.6
28.4
22.5
283.9
35.1
II: Mixed System
Site 3
Site 4
Site 5
3792.2
4200.0
4454.5
100
100
100
1061.8
1596.0
1336.4
28.0
38.0
30.0
III: Industrialised
Building System (IBS)
Site 6
Site 7
Site 8
1730.0
600.0
1130.0
100
100
100
1543.2
552.0
932.2
89.2
92.0
82.5
Disposed at landfills
(%)
(tons)
(%)
5.3
3.0
3552.0
872.9
66.3
74.5
1403.1
924.0
1826.3
37.0
22.0
41.0
1327.3
1680.0
1291.8
35.0
40.0
29.0
86.5
21
113.0
5.0
3.5
10.0
100.3
27
84.8
5.8
4.5
7.5
Table 4
The segregation of construction waste and construction waste usage efficiency (CWUE) for Categories I–III.
Category
Project
Segregation of construction waste
Reused at site
(%)
Construction waste
usage efficiency (%)
Recycled
Average
(%)
Average
(%)
Average
4.2
63.3
74.5
70.4
37.0
22.0
41.0
33.3
35.0
40.0
29.0
34.7
5.0
3.5
10.0
6.2
5.8
4.5
7.5
5.9
I: Conventional
Construction
Site 1
Site 2
28.4
22.5
25.4
5.3
3.0
II: Mixed System
Site 3
Site 4
Site 5
28.0
38.0
30.0
32.0
III: Industrialised
Building System (IBS)
Site 6
Site 7
Site 8
89.2
92.0
82.5
87.9
construction waste generated and its segregation based on usage
and disposal as:
• Reused at site: Category 1 (22.5–28.4%); Category II (28.0–38.0%);
and Category III (82.5–92.0%).
• Recycled: Category I (3.0–5.3%); Category II (22.0–41.0%); and
Category III (3.5–10.0%).
• Disposal at landfills: Category I (66.3–74.5%); Category II
(29.0–40.0%); and Category III (4.5–7.5%).
The preference for “reuse” was highest in Category III (IBS)
whereas Category II (Mixed System) preferred “recycling” and Category III (Conventional Construction) was “disposal at landfills.”
Table 4 shows the segregation of construction waste based on
its uses and the construction waste usage efficiency (CWUE) for
the 3 categories. The highest reuse was in Category III (IBS) averaging at 87.9%, followed by the Mixed System (Category II) at 32.0%
and the least in Category I (Conventional Construction) at 25.4%.
The highest recycling activity occurred in Category II (Mixed System) at 33.3% whereas Categories I and III averaged at 4.2% and
6.2%, respectively. Meanwhile, disposal at landfills was the highest in Category I (Conventional Construction) at 70.4%, followed
by Category II (Mixed System) at 34.7% and 5.9% in Category III
(IBS).
An increasing CWUE value indicates a greater affinity towards
reuse and recycling whereas decreasing values show a preference
for disposal at landfills. Category III (IBS) at 94.1% achieved the highest CWUE, followed by Category II (Mixed System) at 65.3% and the
least in Category I (Conventional Construction) at 29.6%. The CWUE
rates were found to be 3.2 (Category III) and 2.2 (Category II) times
Disposed at landfills
29.6
65.3
94.1
higher when both were compared against Category I (Conventional
Construction).
It was also noted that in all 3 categories (I–III), concrete and
aggregate and soil and sand waste were the two most generated
construction waste (Figs. 1–3). However, the reuse and recycling
rates for these two types of waste were much higher in Categories II and III than in Category I (Conventional Construction)
as these waste were often reused for the resurfacing and maintenance of internal logistic roads (concrete and aggregates) and
as fill material for landscaping work (sand and soil) whereas
disposal at landfills was the preferred method for the Conventional Construction sites (Category I). The disposal of construction
waste at landfills show a decreasing trend, from Categories I–III.
In Category I (Conventional Construction), 70.4% of the total
construction waste was disposed at landfills, followed by the
Mixed System (Category II) at 34.7% and the least in Category III
(IBS) at 5.9% (Table 4). The decreasing trend in construction waste
disposal at landfills indicates an increase in the reuse and recycling
of construction waste at these construction sites.
5. Conclusion
The management of construction waste is still in its infancy in
Malaysia and the data presented in this paper hopes to complement
the available data on construction waste between Conventional
Construction (Category I) and the data poor IBS (Category III). By
the introduction of the Mixed System (Category II), the intermediate construction method, the gap between Category I (Conventional
Construction) and (Category III) could be reduced further. The Construction Industry Development Board (CIDB) of Malaysia has been
promoting the use of IBS through the Construction Industry Master
S.K. Lachimpadi et al. / Resources, Conservation and Recycling 68 (2012) 96–103
Plan (2006–2015) for sustainable development and the recently
concluded “IBS Roadmap 2003–2010.” The slow change towards
the use of IBS (Category III) from the Conventional Construction
(Category I) has been greatly influenced by the following factors:
(i) the high cost in the design of component moulds and uneconomically feasible for manufacture in small quantities for the
IBS,
(ii) easily available local raw materials for construction at low
prices (e.g. sand, aggregates, timber and plywood) that is suitable for Conventional Construction (Category I) as compared to
the costlier manufactured IBS components,
(iii) the availability of cheap foreign labour,
(iv) the availability of unlicensed landfills with low disposal rates
for construction waste compared due to the high disposal costs
at licensed landfills which are too few in numbers,
(v) poor demand for recycled construction waste as construction
materials due to the absence of a “Material Quality Standard”
for recycled construction material/waste for the Malaysian Construction Industry.
The data from this study provides baseline data for the
Construction Industry Development Board (CIDB) of Malaysia
on construction waste and its use in recycling and reuse for
high rise buildings, comparing 3 construction methods. The
Category III (IBS) was the most efficient construction method
(WGR = 1.55 tons/100 m2 ), followed by Category II (Mixed System)
(WGR = 3.02 tons/100 m2 ) and the least in Category I (Conventional
Construction) (WGR = 4.8 tons/100 m2 ). It was also interesting to
note that preferences on waste management differed between the
3 construction methods; “disposal at landfills” in Category I (Conventional Construction), “recycling” in Category II (Mixed System)
and “Reuse” for Category III (IBS).
Although the Category I (Conventional Construction) was the
least efficient construction method, it is by far the most widely
used in Malaysia. The Category III (IBS) still remains as an unattractive option to many Malaysian Contractors but with the use of
the intermediate Mixed System (Category II), it now becomes
possible to inject new construction technologies into Conventional Construction (Category I) to improve construction efficiency,
e.g. construction material management, recycling and reuse of
construction waste. Thus, allowing the Malaysian contractors
to easily adopt the CIDB’s Construction Industry Master Plan
(2006–2015) and renew their interest in the strategies contained
in the recently concluded (and less successful) “IBS Roadmap
2003–2010”.
Further studies are needed, especially in the Mixed System (Category II) and IBS (Category III) to show its benefits to the Malaysian
contractors that would eventually make IBS (Category III) the choice
of the construction industry in Malaysia.
Acknowledgements
This study was supported by the Construction Research Institute
of Malaysia (CREAM), a subsidiary of the Construction Industry Development Board (CIDB) of Malaysia. We wish to thank
the Environmental Management Unit (EMU), Putrajaya Holdings
Sdn Bhd, Setia Putrajaya Joint Venture and UEM World Berhad
for the use of their construction sites in this study. I would
also like to thank the editors of this journal for their positive
comments.
103
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