Management and Reuse of Construction Wastes
Professor C.S. Poon
Dept of Civil and Structural EngineeringThe Hong Kong Polytechnic University
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C&D Waste Generation
• Inert C&D materials (mainly sand, bricks and concrete) both suitable for land reclamation and land formation works, are disposed of at public filling areas.
• Non inert portion (bamboo, plastics, glass, wood, paper, vegetation and other organic materials) ends up at municipal solid waste landfills.
2
6
Salvageable Scraps –Reuse/Recycling
C&D Waste
C&D Waste Management in Hong Kong
Non-inert Portion -Landfills
Inert Portion – Public fills Mixed waste – Sorting facility
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Construction Waste (source EPD)(2008)
5%
86%
10%
Sorting Facilities2,080 tpd
Public Fill Reception Facilities18,680 tpd
Landfills1,020 tpd
Total: 21,780 tpd
Figures may not add up to total due to rounding-off
93% 7%
Non-inert
68% 25%
Soft Hard
20% 5%
Recyclable Non-recyclable
Inert
Construction Waste(Approx. 15.4 M tonnes in Year 2009) (source CEDD)
88
C&D Materials Management Facilities Locations
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The Problem
Hong Kong will soon be running out of both landfill space and public filling areas.
According to Government sources :
• Landfills will be filled up soon.
• Limited reclamation projects. Temporary fill banks will be full soon.
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12
Delivery of Reclamation Material to Mainland
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Designated Reclamation Site in Mainland
台山廣海灣華僑投資開發試驗區
香港特別行政區
20km
香港特別行政區
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Construction Waste Disposal Charging Scheme
• Implemented on 1 Dec 2005
Government waste disposal facilities
Type of construction waste acceptedCharge per
tonne
Public fill reception facilitiesConsisting entirely of inert construction waste
$27
Sorting facilitiesContaining more than 50% by
weight of inert construction waste
$100
LandfillsContaining not more than 50% by
weight of inert construction waste
$125
Outlying Islands Transfer Facilities
Containing any percentage ofinert construction waste
$125
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What can we do with the problems?
1. Avoid waste generation
2. Minimize waste generation
3. Reuse/Recycle the material
4. Proper disposal of waste
AVOID
MINIMISE
REUSE/RECYCLE
DISPOSAL
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Form work Finish work Concrete
work
Masonry
work
Material
handling
Scaffolding
work
Hoarding
Ranking of Major Waste Producing Processeson Building Sites
Source : HK PolyU
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Damaged during
laying
19%
Cutting Waste
39%
Damaged during
storage
11%
Over Order
15%
Damaged during
transportation
16%
Figure 6 Major Causes of Waste for Brick/Block (Source: Hong Kong PolyU [ 6 ] )
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Over order
11%
Others
7%Cutting waste
40%
Damaged during
storage
29%
Change of design
13%
Figure 8 Major Causes of Waste for Tiles (Source: Hong Kong PolyU [ 6 ] )
Source : HK PolyU
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Major Causes of Waste for Cement/Plaster
Improper storage
11%
Lost while
applying
19%
Left over of
mixed materials
59%
Others
11%
Source : HK PolyU
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Percentage wastage of various trades
Trade Material Percentage wastage
Public Private
Concrete Concrete 3-5% 4-5%
Formwork Timber broad - 100%
Reinforcement Steel bars 3-5% 1-8%
Masonry Brick and block
3% 4-8%
Dry Wall Fine aggregate 3% -
Wall screeding Ready-mix cement
7% 4-20%
Floor screeding Ready-mix cement
1% 4-20%
Wall plastering Plaster 3% 4-20%
Source : HK PolyU
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Ceiling plastering
Plaster 3% 4-20%
Wall tiling Tiles 8% 4-10%
Floor tiling Tiles 6% 4-10%
Installation of bathroom fitting
Sanitary fitting 6% 1-5%
Installation of kitchen joinery
Kitchen joinery 1% 1-5%
Percentage wastage of various trades
Source : HK PolyU
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Design to Minimize Construction Waste
Waste arising from construction can be reduced by:
• Dimensional coordination and standardization
• Minimizing temporary works
• Avoiding late design modifications
• Detailing and simple design
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Dimensional Coordination and Standardization
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Minimizing Temporary Works
• In Hong Kong, most of the waste arising from temporary works is due to the use of timber formworks
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Minimizing Temporary Works
Alternatives to be considered:
•system formworks (metal or aluminum formworks) that can be reused and/or recycled
•Prefabricated elements (facades, slabs, staircases, etc)
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Minimizing Temporary Works
Other reusable alternatives to be considered:
• Metal temporary work• Metal platform work• Reusable safety system• Metal scaffolding or mixed
bamboo and metal scaffolding• Metal hoarding
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0.21
0.56
0.76
1.11
1.31
1.33
0 0.2 0.4 0.6 0.8 1 1.2 1.4
Waste reduction
Labor dependence
Developers requirement
Familiarity with the construction tecnology
Construction cost
Construction time
Fac
tors
Index
Construction Method Selection
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On-site Construction Methods
Most waste producing work process
0
0
0
0
0.35
0.46
0.77
1.09
0 0.2 0.4 0.6 0.8 1 1.2
Hoarding
Masonry work
Concrete work
Scaffolding
Materials handling
Finish work
Packaging & protection
Formwork
Bu
ildin
g w
ork
co
mp
on
ents
index
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On-site Low Waste Building Technologies
Formworks:
• Large panel formwork.
• Steel, aluminum and plastic forms.
• Composite steel decking.
• Pecaform.
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Off-site: Precast and Prefabrication
• Off-site construction can reduce waste generation on-site, as waste is generated at a plant and easier to be managed and sorted.
• The use of prefabricated elements is highly applicable to high-rise construction in Hong Kong.
• Prefabrication requires experience, knowledge and also early planning and decisions at the design stage.
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Off-site: Precast and Prefabrication
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Modular Construction
•Modular construction approach has been demonstrated for high-rise buildings in Hong Kong by the Integer project.
Prof. C.S. PoonDept of Civil and Structural EngineeringThe Hong Kong Polytechnic UniversityTel : (852) 2766-6024Email : [email protected]
Thank You
