Construction waste generally refers to waste resulting from construction, demolition, renovation, real estate development, infrastructure development, earthworks and land clearing operation (US EPA 1998, Tang, Soon & Larsen 2003). It consists of, but is not limited to, wood, concrete, metal, brick, drywall, roofing, material packaging, plastics, papers, cardboard and others. Categorisation of construction waste is a study
into the composition and amount of construction waste generation; categorisation enhances understanding of the sources and causes of waste generation. Associated information is usually obtained via construction waste assessment, such as quantification of waste raisings, field surveys and site observations.( Composition and Characteristics of Construction Waste Generated by Residential Housing Project, Lau, H.H., Whyte, A.1 and Law, P.L.2, 15 May 2008)
Malaysia, like most of the developing countries, is facing an increase of the generation of waste and of accompanying problems with the disposal of this waste. Overall, the local communities generate 16,000 tons of domestic waste per day and the amounts per capita vary from
0.45 to 1.44 kg per day depending on the economic status of the areas concerned [17]. On average, waste generation is about 1 kg per capita per day [17]. Waste is grouped into three different categories in respect of disposal - solid waste, medical waste and hazardous waste. According to a study by E. Grant Anderson in five states (Kuala Lumpur, Selangor, Pahang,
Terengganu and Kelantan) representing 70 % of the total amount of waste in the country, the composition of waste is shown in Figure 1. One can observe that 64 % of the waste is domestic waste. The share of industrial waste stands at 15 %, followed by commercial waste and construction and institution waste. (Case Study on the Management of Waste
Materials in Malaysia, Von Lina Lau)
Figure 1: Waste Composition (Kuala Lumpur, Selangor, Pahang, Terengganu and
Kelantan)
Source: Roundtable on Urban Solid Waste Management. Privatization Management
on Solid Waste in Developing Countries, The Malaysia Experience. 27-28 September
1998.
Construction waste has a major impact on the environment.With the demands in implementing
major infrastructure projects in Malaysia, together with many commercial building
and housing development programmes, a large amount of construction waste is being produced
by the construction sector. The construction industry is responsible for producing a
whole variety of waste, the amount and type of which depends on factors, such as the stage
of construction, type of construction work and practices on site. Thus, waste minimisation
is an important area of concern in the implementation of construction waste management
in the construction industry of Malaysia. (Implementation of waste management and minimisation in the construction industry of Malaysia, Rawshan Ara Beguma,âˆ-, Chamhuri Siwar a, Abdul Hamid Jaafar, 11 October 2006)
Construction Sector Profile
In Malaysia, the construction industry generates a lot of construction waste which cause significant impacts on the environment and increasing public concern. Thus, the minimization of construction waste has become a pressing issue. The source of construction waste at the project site includes materials such as soil and sand, brick and blocks, concrete and aggregate, wood, metal products, roofing materials, plastic materials and packaging of products. The composition of total waste generation is shown in Figure 4.3, which is percentage by weight. Concrete and aggregate is the largest component with 65.8% followed by soil and sand (27%), 5% from wood based materials such as timber, lumber, etc., 1.6% from brick and block, 1% from metal products, 0.2% from roofing materials and 0.05% from plastic and packaging products such as papers, cardboards, etc.
(Begum, 2006)
Source: Deutsch-
(Source: Begum et al., 2005).
Fig. 4.3 Composition of total waste generation
Waste management of recycling and reuse method
Conceptual framework of waste minimisation
Waste minimisation includes source reduction and recycling. Source reduction is defined
as any activity that reduces or eliminates the generation ofwaste at the source, usually within
a process. Recycling is defined as the recovery and/or reuse of what would otherwise be
a waste material. Existing publications have discussed many different waste minimization options or measures or practices (Lorton et al., 1988; EH and S, 1994; Sherman, 1996;
Maclaren, 2002). A framework of waste minimisation practices taken from the review of
literature can be found in Fig. 1. (Implementation of waste management and minimisation in the construction industry of Malaysia, Rawshan Ara Beguma,âˆ-, Chamhuri Siwar a, Abdul Hamid Jaafar, 11 October 2006, pg2,3)
Fig. 1. Waste minimisation practices
PURPOSE OF RECYCLING
Papers relating to recycling in the concrete industry usually define the purposes of the research to be saving resources and energy, rational use of materials, and sustainable use of materials. Some papers also mention zero-emissions and building a closed cycle of materials usage. These are all important keywords today. The current usage and research and development on the reuse of by-products related to concrete can be classified into the following three categories:
- Category 1: Use of by-products, from non-construction industries to concrete
- Category 2: Use of by-products, from concrete to concrete
- Category 3: Use of by-products, from concrete to other materials
Before looking at the situation in Japan, we consider the purpose of reuse. The ultimate purpose of recycling materials is to minimize the impact of human activities on the environment and the planet. From this viewpoint, the first priority of concrete engineers is to maximize the lifespan of concrete structures, at least concerning Category 2, because buildings and infrastructures must be used for a very long time and, generally speaking, reuse of concrete and/or recycling of concrete materials is not easy technically or economically. We must also reduce the waste from concrete structures before considering how to reuse or recycle it. Furthermore, if the use of by-products from industries other than construction degrades the quality, especially durability, we must carefully consider how to properly use those materials. Recently, it has become necessary to accept large volumes of many kinds of by-products for use in concrete, with reuse sometimes taking priority over concrete quality. Many concrete engineers are concerned that concrete is being thought of as a dustbin. (THE STATE OF USING BY-PRODUCTS IN CONCRETE IN JAPAN AND OUTLINE OF JIS/TR ON "RECYCLED CONCRETE USING RECYCLED AGGREGATE", Hir otak a K A WA NO
Public Works Research Institute, JAPAN, pg1)
Table 2.4: Summary of current C&D waste management in selected Asian countries
Country
Annual
C &D waste
(amount or
proportion of
the total waste)
Technologies
Practices
Policy &Institutions
Bhutan
No Data Available
Reuse of concrete waste
and recycling
Reuse of concrete waste as filling and disposal
regulations of construction waste
Thimpu Municipal Solid Waste Management Rules and regulations
2007 - Prohibited acts of illegal dumping of construction waste
PR China
(Shi, 2007)
40 % and/or 200
million tons
(estimation in 2005)
Reuse bricks and recycling
concrete waste
-
Municipal Construction Waste regulations- Imposes stricter
management on waste from municipal construction projects
Hong Kong,
SAR
(HK EPD,
2007)
42% / 20.5 million
tons (2004)
Reuse - done by selective
demolition technique
Reuse of C&D waste in lower grade 37 %-80%
public filling areas for land reclamation
purposes for period 12 years
Reuse of recycled aggregates in road sub-base
and low grade concrete
• Construction Waste Disposal Charging Scheme
•Public Works Programs, the contractors are required to formulate
waste management plans
• Adopt low waste construction techniques, selective
demolition
•the tracking system for C&D waste disposal
• developed to a GPS-and-GIS-integrated construction M&E
management system
Country
Annual
C &D waste
(amount or
proportion of
the total waste)
Technologies
Practices
Policy &Institutions
India
(Pappu, 2007)
14.5 Million Tons
Recycling and reuse of
marble wastes in building
application
A portion of C &D waste is recycle and reuse
in building materials and share of recycled
materials varies from 25% in old buildings to as
high as 75% in new buildings
Ministry of Environment and forests has mandated environmental
clearance for all large construction projects
Schedule II of Solid Waste Management Rules 2000 - one of the
regulations that stipulate proper collection and disposal of
construction waste
Indonesia
(Alwi et al.,
2002)
No Data Available
Reuse of concrete waste,
Adopt Dry-Masonry Brick
House System an
environmentally-friendly
cycle that covers 3R
scheme (Khamidi et al.,
2004)
52% of construction industry has ISO 9000
compliance
Demonstrating Environmentally Sound
Technologies for Building waste Reduction in
Indonesia (DEBRI) - demonstrate a waste
management mechanism
-
Japan
85 Million tons
(2000) (old IPCC,
2006)
Reuse and recycling of
C&D waste; MFA
Recycling of concrete waste, use of hybrid
concrete construction, prefabrication
Construction Material Recycling Law
South Korea
28.75 Million tons
(IPCC, 2006)
Recycling of concrete
waste
Recycling of concrete waste, promotion of
recycling waste law
Construction Waste Recycling law
Malaysia
(Begum et al.,
2006)
28.34% (including
industrial waste)
1.55 Million Tons
Reuse and recycle of
concrete and aggregates
Reuse and recycling has been practiced -
economic dimension
Local Authorities Ordinance (LAO) in some municipalities or cities
deal with construction waste management
Formal national regulation on C&D waste management relative to
3R is in process of development under the Ministry of Housing and
Local Government
2.2 RECYCLED concrete aggregate
For my topic, I choose the recycled concrete aggregate to do rather than other material waste, because need to clearly what is the meaning of it and how to produce or recycling to it.
A study done by Begum et al. (2006) of the project sites in Malaysia, construction waste materials contain a large percentage of reusable and recyclables. Estimated 73% of the waste materials in the project site are reused and recycled. Table 4.6 shows the amount of reused and recycled waste materials on the site. The highest amount of reused and recycled materials is concrete and aggregate, comprising 67.64% of the total reused and recycled material. It is followed by soil and sand, wood, brick and block, metal products and roofing materials. The practice reuse and recycling of construction waste materials is common on the site of one of the project sites. Furthermore, reuse and recycling of waste have been promoted in order to reduce waste and protect the environment (Begum, 2006).
Table 4.6: Amount of reused and recycled construction waste materials on site.
Construction Waste Material
Amount of reused and recycled
Tonnage
Percentage
Soil and Sand
Brick and block
Concrete and aggregate
Wood
Metal products
Roofing materials (tiles)
Total
5400
126
13365
810
54
5.4
19760.4
27.33
0.64
67.64
4.00
0.27
0.03
100.00
Source: Begum et al., 2006
Regarding concrete, which is the construction material of our era, the protection of the environment concerns three basic axes:
• Use of high amounts of raw materials (aggregates for the production of cement and concrete) which result in the decrease of available natural resources which is continuously sub-graded.
• Consumption of high amounts of energy for the production, transport, use of raw materials and final ones, as cement and concrete.
• Creation of big volumes of old concrete from old construction works (demolition wastes).
The main reasons for the increase of this volume of demolition concrete waste are:
• many old buildings and other structures have overcome their limit of use and need to be demolished;
structures,evenadequatetouse,areunderdemolition,becausetherearenewrequirementsandnecessities;
• creation of building wastes which result from natural destructive phenomena (earthquakes, storms. . .). The approximate percentage of various construction materials in demolition waste (DW) is presented in the recycled concrete aggregates (RCA) are the main components of old concrete and for many reasons there is a need to re-use them.(Nik. D. Oikonomou, 2004)
Recycled concrete aggregates. Fine and coarse aggregates produced by crushing of original concrete. Also may be referred to as recycled aggregates. Fine recycled aggregate may also be referred to as crushed concrete fines.
Production of Recycled Aggregates
Plants for production of recycled concrete aggregates are not much different from plants engaged in the production of conventional crushed stone aggregates. The National Stone Association (NSA) and its member companies recognize and accept the recycling of many construction waste materials, such as portland cement concrete, when it is cost effective. NSAbelieves recycling (1) conserves natural resources, (2) is good for the environment, (3) can be good business, and (4) is expected to grow.4 (ENVIRONMENTAL COUNCIL of CONCRETE ORGANIZATIONS, 1999)
Recycled concrete aggregate (RAC) is concrete made from recycled aggregate.
Many significant researches have been carried out to prove that recycled aggregate could be a reliable alternative as aggregate in production of concrete. As widely reported, recycled aggregates are suitable for non-structural concrete application. Recycled aggregates also can be applied in producing normal structural concrete with the addition of fly ash and condensed silica fume etc.
RCA is the main component of old concrete and for many reasons there is a need to re-use them. Such recycling operations have the added benefit of reducing landfill disposal, while conserving primary resources and reducing transport costs. There are large amount of concrete wastages during construction and demolition stages in Sarawak. RCA can be obtained from these wastages for the production of new concrete.(Utilisation of recycled aggregates as course aggregate in concrete, Yong.P.C, D.L.C, August 2009)
A sub-set of recycled aggregates is recycled concrete aggregate (RCA) in which the masonry content is limited to not more than 5%. In general, the performance characteristics of RCA are better than RA
2.2.1 recycling concrete and aggregate method
