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Sustainable Waste
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Sustainable management of
construction waste
for Hong Kong
Professor C.S. Poon
Dept of Civil and Structural Engineering The Hong Kong Polytechnic University
Construction Waste 15 Million tonnes
in 2009
Batching plants
Excavation
Construction
Refurbishment
Renovation
Demolition
Road Work
C&D Waste
15
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
3
Construction Waste (source EPD)
(2008)
5%
86%
10%
Sorting Facilities
2,080 tpd
Public Fill
Reception Facilities
18,680 tpd
Landfills
1,020 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)
8 8
C&D Materials Management Facilities
Locations
30
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.
11
12
Delivery of Reclamation Material to Mainland
13
Designated Reclamation Site in Mainland
20km
14
Construction Waste Disposal
Charging Scheme
Implemented on 1 Dec 2005
Government waste disposal
facilities Type of construction waste accepted
Charge per
tonne
Public fill reception facilities Consisting entirely of
inert construction waste $27
Sorting facilities
Containing more than 50% by
weight of inert construction
waste
$100
Landfills
Containing not more than 50% by
weight of inert construction
waste
$125
Outlying Islands Transfer
Facilities
Containing any percentage of
inert construction waste $125
5
Waste Management Hierarchy
1. Avoid waste generation
2. Minimize waste generation
3. Reuse/Recycle the material
4. Proper disposal of waste
AVOID
MINIMISE
REUSE/RECYCLE
DISPOSAL
CWDCS presentation by CS Poon 15
Nature of C&D waste Mixture of inert & non-inert materials
16
Soft inert
materials
Hard inert
materials
Non-inert
materials
FILLS
FILLS/
RECYCL
E
LANDFIL
LS
CWDCS presentation by CS Poon
24
Form work Finish work Concrete
work
Masonry
work
Material
handling
Scaffolding
work
Hoarding
Ranking of Major Waste Producing Processes
on Building Sites
Source : HK PolyU
25
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 ] )
26
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
35
Dimensional Coordination and
Standardization
36
Minimizing Temporary Works
In Hong Kong, most of the
waste arising from
temporary works is due to
the use of timber
formworks
37
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)
38
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
39
Waste reduction 0.21
Labor dependence 0.56
Developers requirement 0.76
Familiarity with the construction tecnology 1.11
Construction cost 1.31
Construction time 1.33
Figure 8: Factors that determined a construction method selection
(Question 25)
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
Fa
cto
rs
Index
Construction Method Selection
43
On-site Low Waste Building Technologies
Formworks:
Large panel formwork.
Steel, aluminum and plastic
forms.
Composite steel decking.
Pecaform.
45
Off-site: Precast and Prefabrication
Construction Waste Disposal
Charging Scheme Implemented in Dec 2005
Government waste disposal facilities
Type of construction waste accepted
Charge per
tonne
Public fill reception facilities
Consisting entirely of inert construction waste
$27
Sorting facilities Containing more than 50% by
weight of inert construction waste
$100
Landfills Containing not more than 50%
by weight of inert construction waste
$125
Outlying Islands Transfer Facilities
Containing any percentage of inert construction waste
$125
Aim of Study
How much construction waste has been reduced?
What changes has taken place among building professionals ?
What are the impact of CWDCS on major work trades on construction sites ?
What are the barriers for changes ?
28 CWDCS presentation by CS Poon
Research Methodology
Questionnaire Totally 319 nos. of questionnaires w; 109 nos. of
questionnaires returned
Structured interviews
One to one structured interviews with difference
construction professionals
Case Studies
Three detailed case studies
29 CWDCS presentation by CS Poon
After the WCS has been implemented, what is the extent of changes (% increase in waste disposal cost) you allowed in bidding new
projects?
30 CWDCS presentation by CS Poon
1.1%
7.4% 7.4%
19.8% 21.0%
17.3%
9.9%
6.2% 7.4%
2.5%
0 No change
< 0.05% 0.05% < 0.1%
0.1% < 0.3%
0.3% < 1%
1% < 1.5%
1.5% < 2 %
over 2% no answer
Research Findings
Level of Waste Generation (After CWDCS)
31 CWDCS presentation by CS Poon
5.0%
11.3%
40.0%
28.8%
3.8%
10.0%
1.1%
-15% < -10% -10% < -5% -5% < 0% No change 0% < 1% over 3% No answer
Research Findings
Barriers of On-site Waste Sorting
32 CWDCS presentation by CS Poon
All respondents Building Engineer Project Manager Quantity Surveyor
Mean Rank Mean Rank Mean Rank Mean Rank
Narrow site access 5.21 7 4.42 4 5.38 7 5.32 6
Limited waste storage area on site 3.70 1 2.58 1 4.35 5 3.44 1
No sorting area on site 3.86 2 4.17 3 3.85 2 3.76 3
Intensive labor cost in sorting wastes 4.19 4 5.75 6 3.21 1 4.62 5
High supervisory to subcontractor's
behaviors
4.16 3 5.75 6 4.29 4 3.47 2
Low waste sortability 4.86 6 5.17 5 4.24 3 5.38 7
Interference with normal site activities 4.55 5 4.42 4 4.76 6 4.38 4
Impractical in using too many waste chutes 5.46 8 3.75 2 5.91 8 5.62 8
Research Findings
Changes after CWDCS implemented
33 CWDCS presentation by CS Poon
All respondents
Building Engineer
Project Manager
Quantity Surveyor
Mean Rank Mean Rank Mean Rank Mean Rank
Reduction of site wastage level 3.30 3 2.95 3 3.10 3 3.71 5
More efficiency in waste sorting on site 4.15 6 4.86 6 4.38 6 3.56 4
Improvement in materials estimation before ordering
3.82 4 4.14 5 3.57 4 4.00 6
Improvement in inventory monitoring 3.87 5 3.86 4 4.16 5 3.48 3
Increase environmental awareness 2.84 1 2.55 1 2.82 1 2.98 1
Increase materials recycling awareness 3.02 2 2.64 2 2.96 2 3.27 2
34 CWDCS presentation by CS Poon
Conclusions less than 5% waste reduction has been achieved since the CWDCS
Charge is not high enough to raise the awareness of waste management at construction sites.
Wet-finishing & dry-finishing trades have
undergone little changes
CWDCS has NOT motivated subcontractor to change their methods of construction
On-site waste sorting is more possible at large construction sites
Need to have other measures, such as inclusion of waste reduction requirements
in contractual clauses and government
regulations, to effect the waste reduction
CWDCS presentation by CS Poon 35
Eco-friendly
Construction
Materials
Professor Chi-Sun Poon www.eco-block.hk
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)
Incoming C&D Materials
Sorting Plant
Inert C&D Materials
suitable for Recycling
Recycled
Aggregates
Sieving Crusher
Recycling Plant
Source :CEDD
C & D Waste Sorting Facility
>250 mm 150-250 mm 150-50 mm
Extension of SENT Landfill
To handle :
Wastes that cannot be incinerated, e.g. construction waste
Possible C&D waste recycling
facility ???
Properties of Recycled Aggregates
40 mm 20 mm 10 mm 5 mm down
Min. dry particle density (kg/cu.m.) 2350 - 2550 2450 - 2600 2450 - 2600 2450 - 2600 2000
Max. water absorption (%) 3.1 - 4.9 1.0 - 4.9 1.4 - 2.6 N/A 10
Max. content of wood and other material
less dense than water (%)0 0 0 0 0.5
Max. content of other foreign materials (%) 0 0 0 0 1
Max. content of fine (%) 0 - 0.3 0.1 - 0.7 1.0 - 3.0 N/A 4
Max. content of sand (
Source: CEDD
Use of Recycled Aggregates in
Concrete in Hong Kong Wetland Park
15,000 m3 RAC used in
pile caps, ground slabs,
external works, mass
concrete etc
Recycled Aggregates for Concrete : Limitations High water absorption (in particular, the recycled fines)
presence of contaminants and other foreign materials
Compressive strength, tensile strength and bond
strength of concrete would be reduced
Drying shrinkage is higher and the creep of concrete
may increase.
Acceptance for structural concrete application is low
Recycled aggregates
Impurities
Eco-blocks
Alternative casting : Pre-cast bricks and
blocks (dry mixed)
Use with waste glass to enhance aesthetics and water absorption
properties
Use with photo-catalyst for valued added properties
Experiment conducted at PolyU
Steel moulds for
fabrication of blocks Hand compaction of the
wet mixed materials
After hand compaction, the
compression was carried out
using a compression machine
at a rate of 600 kN/min twice Manufacturing process in industry
The mixer
Block manufactured
The ingredients were
mixed in the mixer
Hong Kong : in 2009 About 300 tonnes per day; about 1% recycled 99% landfilled
Waste Glass
Factory made blocks
Air Pollutant Removal Paving Blocks
Eco-blocks - 3rd
Generation
Sunlight
Surface layer
Cement +Recycled Glass +
Recycled Aggregate + Photo-catalyst
Base layer
Cement + Recycled Aggregate +
Recycled Glass
Air Pollutants (NOx) Precipitation
NO3 TiO2
Eco-Blocks
Recycled Aggregate Recycled Aggregate + Recycled Glass
Recycled Glass + Recycled
Aggregate + Photo-catalyst
Examples of field applications
5
What can we do with the problems?
Recommendations
1. Avoid waste generation
2. Minimize waste Generation
Better design and construction methods
Change of work practices etc
3. Reuse/Recycle the material
AVOID
MINIMISE
REUSE/RECYCLE
DISPOSAL
Extension of SENT Landfill
To handle :
Wastes that cannot be
incinerated, e.g. construction
waste
Possible C&D waste recycling
facility ???
BEAM Plus
Materials Aspects
Prof. C.S. Poon
(BEAM Faculty / MA panel Chair)
Materials Aspects NB EB
No. of Prerequisites 4 2
No. of Credits 22 11
No. of Bonus 1 2
Credit Summary for NB:
Ma P1 Timber Used for Temporary Works
Ma P2 Use of Non-CFC Based Refrigerants
Ma P3 Construction / Demolition Waste
Management Plan
Ma P4 Waste Recycle Facilities
Ma 1 Building Reuse
Ma 2 Modular and Standardized Design
Ma 3 Prefabrication
Ma 4 Adaptability and Deconstruction
Ma 5 Rapidly Renewable Materials
Ma 6 Sustainable Forest Products
Ma 7 Recycled Materials
Ma 8 Ozone Depleting Substances
Ma 9 Regionally Manufactured Materials
Ma 10 Demolition Waste Reduction
Ma 11 Construction Waste Reduction
Credit Summary for EB:
Ma P1 Use of Non-CFC Based Refrigerants
Ma P2 Waste Recycling Facilities
Ma 1 Building Reuse
Ma 2 Modular and Standardized Design
Ma 3 Adaptability and Deconstruction
Ma 4 Rapidly Renewable Materials
Ma 5 Sustainable Forest Products
Ma 6 Ozone Depleting Substances
Ma 7 Waste Management
BEAM Plus
Materials Aspects
Requirement:
It is required to implement with proof of documentation a waste management system providing
for the sorting, recycling and proper disposal of inert and non-inert construction / demolition
materials.
Ma P3 Construction and Demolition Waste Management Plan Prerequisite
Objective:
Encourage best practices in the management of construction and demolition wastes, including
sorting, recycling and disposal of construction waste.
BEAM Plus
NB Ma P3
Requirement:
1 credit for demonstrating that at least 30% of demolition waste is recycled.
2 credits for demonstrating that at least 60%.
NB Ma 10 Demolition Waste Reduction 2 credits
Exclusion:
Project where demolition is not required or is not under the Clients control.
Remark:
Disposal of inert waste to public fill will NOT be considered.
Objective:
Encourage best practices in the management of waste, including sorting, recycling and disposal of
demolition waste.
BEAM Plus
NB Ma 10
Requirement:
1 credit for use of recycled materials contributing to at least 10% of all materials used in site
exterior surfacing work, structures and features.
1 credit where at least 10% of all building materials used for faade and structural components are
recycled materials.
1 credit where at least 10% of all building materials used for interior non-structural components are
recycled materials.
NB Ma 7 Recycled Materials 3 credits
Objective:
Promote use of recycled materials in order to reduce the consumption of virgin resources.
Remark:
The unit shall be mass/volume/dollar value.
Exclusions:
None.
BEAM Plus
NB Ma 7
Prof. C.S. Poon
Dept of Civil and Structural Engineering
The Hong Kong Polytechnic University
Tel : (852) 2766-6024
Email : [email protected]
Thank You