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Material waste is recognised as a major dilemma in the construction industry and has important implications. The construction industry has been reported to be generating intolerable levels of material waste. This report reviews the causes and preventions of wastage of materials in the construction industry. The report also assists clients, main contractors, subcontractors and others who work in the construction industry with advice on how each individual can make a change to help reduce waste.
1.2. Definition of construction waste
Waste is a common term and occurrence in the construction industry worldwide. Wastes are materials that are not main products which the initial user has no further use for his/ her wants to dispose. Waste is measured by size or weight and is unwanted or useless materials.
Construction waste can be divided into material, labour and machinery waste, however, material waste is more of a concern because most raw materials come from non- renewable resources. Construction waste is generated by construction activities.
2. CAUSES OF CONSTRUCTION WASTE IN THE BUILDING INDUSTRY
Waste measurement plays a significant role in the management of systems due to its effective way to measure their performance. Building material waste is complex to recycle due to high levels of contamination and a large degree of different materials mixed together and usually there is inadequate space for its disposal in large cities.
There are seven categories of waste identified: –
- There is unnecessary movement of people.
- When there is waiting by employees for equipment to finish its work.
- Defects in products.
- The overproduction of goods that are not needed.
- Goods awaiting further consumption.
- Unnecessary processing of goods.
- Unnecessary transportation of goods.
There are other causes of material wastage such as accidents, working under suboptimal conditions, design of products that do not meet the userï¿½s needs, theft and vandalism.
Along with the causes of indirect waste, material waste may be incorporated into buildings since materials are often used in excess of designed quantities or for a different purpose than what is specified, replacing materials for interior quality.
It has been noted that material wastage is due to lack of control of materials by contractors. One of the major sources of waste was left over scrap resulting from cutting materials, such as bricks, blocks and sheetrock panels. Most of the waste involved with wood is non- reusable consumables meaning that this material assists in the production process but do not end as part of the building. Packaging and improper handling are also identified as important causes of waste.
2.1 Materials and the waste they cause
Different products and materials are experience waste in different ways based on sizes, use and specification, this information was discovered by Skoyles (1976), Bossink and Brouwers (1996) and Forsythe and Marsden (1999)
Controlling the use of steel reinforcement on building sites is difficult due to it being bulky to handle due to its weight and shape. Steel reinforcement is always sold by weight. There are three main reasons for steel reinforcement waste:-
- Short unusable pieces are produced when bars are cut,
- Some bars sometimes have an excessively large diameter due to fabrication problems and trespassing which leads to theft.
- Poor structural design in terms of standardization and detailing causing waste due o non- optimized cutting of bars.
- In- situ production of mortar: Cement is usually manually loaded in the mixer with the use of incorrect equipment. The lack of information available to construction labour for producing different mixes of mortar.
- Handling and transportation of mortar: This waste is related to site layout problems, lack of maintained pathways and use of inadequate equipment.
- Brickwork joints: Due to excessive consumption of mortar in joints, this is caused due to insufficient information available about process standards, inadequate supervisions, variations in the size of blocks and the lack of process standardization.
- Plaster thickness: Due to deviations in the dimensions of structural elements, problems in the incorporation between different designs and the omissions in the designs relating to defining the exact sizes of components such as door frames and blocks.
- Floor Screed: Due to deviations in the concrete slab level in relation to design and the need to inlay pipes in the floor.
Sand, lime and Premix Mortar
Sand and mortar are usually delivered in trucks, this may cause additional losses related to the lack of control in the delivery operation and the necessary handling demands.
Bricks and Blocks
The delivery of material such as the lack of control in the amount of bricks/ blocks delivered and the damage of the bricks and blocks are causes of waste, however, poor handling and transportation are the main causes. Another factor of waste is the need to cut the blocks and bricks which is due to the modular coordination in design.
The main source of waste was the cutting of tiles due to the problems in integration between architectural and structural design. This caused the cutting and wastage of tiles.
Pipes and Wires
Short, unusable pieces are produced when pipes are cut. Poor planning in the distribution of materials does not encourage the replacement of elements by others.
Contractors often underestimate the real cost of waste on a project as this is not a clear cost.
2.2. Checklist to assess the causes of waste
The following checklist can be used to assess the causes of waste:-
- Is the tender document complete?
- Is the design a fixed and agreed design?
- Is the information provided clear?
- Is the storage available safe and adequate?
- Is the workforce trained in waste management and waste reduction?
- Does the programme allow for the work to be carried out without interference with other trades?
3. PREVENTIONS OF WASTAGE OF MATERIALS
Waste can be avoided by implementing inexpensive preventative methods related to managerial improvements. Some building materials and components use large amounts of non renewable sources of energy and sources that are in danger of exhaustion, such as timber, sand and crushed stone. It has been suggested that human work should be the main focus of waste prevention. The values of materials depend to a vast extent on the work that has been spent on them.
In order to improve the efficiency of value- adding and non- value adding work, the aim is to eradicate waste by removing non- value adding activities. The control of waste to an acceptable level can only be reduced through major improvement in production system conditions.
Waste prevention can be successful in many forms, such as:-
- By purchasing durable, long- lasting materials,
- Setting out to remove raw materials that are not incorporated into the final product or service,
- The use of products that are free of toxic material,
- By reducing the amount of packaging materials,
- Conserving water, energy or both,
- Implementation of in- process recycling.
Waste prevention is a known as business strategy from which, any company can benefit.
Waste prevention can be a routine part of daily business. The following basic steps can be taken:-
Determining What Wastes you generate
All waste streams need to be examined, including process wastes, hazardous wastes, non- hazardous wastes, solid wastes and office waste. By looking into bins, one can determine what materials are being thrown away.
Each waste stream must be characterized to help determine the source of the waste, what processes generate it and how much is being discarded.
Identifying Waste Prevention Measures
All wastes should be evaluated for probable reduction. Determine how you can reduce each waste, evaluate your purchasing policies and determine what you can re-use.
Production changes that would potentially improve efficiency, equipment, piping and layout changes should be identified.
Resources that may help conduct a waste reduction assessment at a business should be identified.
Priorities and goals should be set
Prioritize waste prevention opportunities by considering cost, payback and increased employee safety.
Attainable goals should be set.
Employees should be taught about how to reduce waste and waste prevention activities should be promoted. Encourage employees by offering incentives.
Recycling is a process whereby materials that would have become waste, are transformed into new materials and products.
By using more recycled or reused materials on a construction project, overall costs can be reduced.
In recycling, used materials or waste are transformed into new products to prevent waste of potentially useful materials to help reduce consumption of fresh raw materials, to help reduce energy usage, to help reduce air and water pollution and lower greenhouse gas emissions.
Recycling is an important part of modern waste reduction and is the third component of the ï¿½Reduce, Reuse, and Recycleï¿½ waste.
Recyclable materials include many different types of glass, paper, metal, plastic, textiles and electronics. The composting or reuse of biodegradable waste such as food or garden waste is not typically considered recycling. Materials that are to be recycled can be taken to a collection centre or picked up from the curb side and then sorted, cleaned and reprocessed into new materials bound for manufacturing.
Recycling of a material will produce a fresh, new supply of the same material. Recycling of goods or materials involves their reuse in producing different materials.
Recycling has been a common practise for most of human history. Materials for recycling can be can be sorted into the various types on site, ready for pick up.
Copper such as wire, old steel furnishings, or equipment and glass windows are some of the materials that can be recycled from a construction site.
The type of waste materials accepted for recycling, varies from cities and countries depending on the types of materials that city or country can recycle. The difference in acceptance is reflected in the resale value of the material, one it is reprocessed.
Many materials from construction can be recovered from demolition and renovation sites and donated, sold, stored for later use or reused on current or other projects. Private companies sometimes recover materials from the site which can avoid the cost of removal by a contractor. Companies that have storage space available can store good material for future use or for another project.
Space, time and equipment can restrict opportunities to reuse materials on smaller projects. Opportunities still exist to import materials from other sites, which may only be available in limited quantities and therefore better suited to small projects.
Packaging waste cannot be eliminated or reduced. The most cost effective option with using packaging and the best option for the environment is to reuse the packaging as many times as possible.
Repairing any damaged pallets on site is another way of reusing packaging. The pallets that are not in use can be sold to pallet suppliers. Old polypropylene bags can be used for storing demolition wastes. Large sheets of plastic sheeting can be used as wrapping for materials on site as weather protection.
3.3 Successes of prevention methods
3.3.1 Monitoring process and waste production changes-
Track things such as the volume of waste products.
3.3.2 Calculating the savings-
Look at savings in handlings, treating and disposals cost.
3.3.3 Look at indirect benefits-
Try to gauge the value of less obvious benefits such as reaching new markets and improving public image.
3.3.4 Re-evaluate your efforts on a regular basis-
As new raw materials and processes are introduced, waste streams change. Conduct regular assessments of your business to identify additional waste prevention opportunities.
4. REDUCTION OF MATERIAL WASTAGE
4.1. Advantages of reducing waste
Reducing waste means that resources will be saved. Society benefits from reducing waste by allowing people to limit their usage of a certain privileged in order to conserve it for the future.
This can be done effortlessly and doesnï¿½t involve any extra equipment or dramatic life changes.
Reducing waste will help communities, contractors and it improves the image of organisations and companies that reduce disposal. A lot of space will also be conserved in existing landfills.
4.2. Reasons for reducing waste
The reduction of waste can be beneficial to many involved in the construction industry. Reducing waste can be a great financial benefit as waste has a cost. The cost of waste is included in a tender price and paid for by the client. Main contractors have the responsibilities for waste disposal but waste is also generated by sub- contractors. Based on an environmental and a cost perspective, clients, main contractors and sub- contractors have focused on the waste issue. The focus on waste is because of the tremendous escalating applied to landfill tax.
Reducing the wastage of materials can also be a benefit to sub- contractors and can result in either a total saving to the project or an increase in project for sub- contractors. There would be a drop in tender prices and a competitive advantage achieved. Sub- contractors are to benefit from using their materials more efficiently. If sub- contractors show initiative to support and engage waste reduction measures, they can improve their chances of being known as preferred bidders as they can help main contractors meet their waste targets.
In order for sub- contractors to reap the benefits from reduced material waste, they have to be pro- active.
Reducing wastage material is also a benefit to clients and contractors. The cost of waste built into project tenders are paid for by clients. A reduced cost for the project can be achieved by reducing the volume of waste generated. The cost saving from projects can be shared amongst main contractors, sub- contractors and clients.
Minimising environmental damage means less quantity of landfill space used and reduced environmental impacts associated with extracting, transporting and manufacturing the raw materials.
At a corporate level, reducing waste can bring the following benefits to clients, main contractors and sub- contractors:-
- It demonstrates commitment to sustainability.
- It reduces the organisations carbon print
- Engenders a culture of material efficiency in all project activities.
- It provides evidence of environmental policies being put into place.
Prevention of wastage of materials and recycling of waste reduces exhaustion of natural resources such as trees, oil and minerals.
Sub- contractors should consider the following to reduce waste:-
- Use safe and secure storage
- Develop a strategy that minimises waste
- For moving materials, consider mechanical systems and machinery
- Off- site manufacture or construction should be considered
- Monitor construction activities
- Packaging must be used in an efficient way
- People must be trained and educated on how to reduce waste
4.3. People involved in taking action against reducing waste
Waste is equal responsibility between all parties of the supply chain, starting from the client to the waste contractor. All involved cannot work in isolation to manage waste.
Clients need to show initiative and leadership by setting rules and requirements for the proper use of materials and communicating these rules and requirements to the project team. The clients need to ensure that the issues with materials waste are discussed. It is also in the clientï¿½s best interest to ensure that all people involved are making an effort to reduce waste.
4.3.2 Main Contractors
Main contractors have to pass on the information about material waste that the client has given him. The main contractor is to develop a site waste management plan that has estimates of wastes that will be generated. The plan needs to include a strategy to reduce waste. The contractor is to monitor waste data by gathering site waste data and comparing them against site waste data.
4.3.3 Sub- Contractors
The sub- contractor must support the main contractors in order to ensure delivery of the clientï¿½s requirements. Sub- contractors must provide accurate waste estimates for their trade. Sub- contractors can develop actions to reduce waste and submit their ideas to the main contractors. The efficient and proper use of materials must be managed and controlled by sub- contractors to ensure that waste is minimised. On completion of a project, the sub- contractor must provide accurate data on the amount of waste, how was it generated and how it can be reduced.
4.4. Approach to waste reduction
Sub- contractors can use four stages to reduce waste:-
The site management plan is developed by the main contractor during this stage. The waste estimates are developed by sub- contractors. Reductions in waste can be realised by bringing in sub- contractors into the site waste management planning exercise.
A waste management plan which is developed by the main contractor should have the following key features:-
- The waste targets that are set by the client,
- An estimate of the waste that could be generated on site,
- Solutions to reduce the waste and,
- Solutions for wastes going to landfills
Main contractors need to ensure that sub- contractors are engaged and challenged on the waste they are likely to generate.
Contractors and sub- contractors can manage a process of waste reduction that will allow them to meet the waste targets, if estimates of the quantities of materials and the waste likely to be generated are produced accurately.
The following actions can assist the sub- contractors with reducing waste:-
Accurate information to be used- when pricing projects, the information used must be up to date, in the correct format and must be accurate.
The checklist can be used to check the quality of information. The check list will include:-
- Are the designs and specifications up to date?
- Is the latest issue of drawings?
- Is there any further information needed?
- Are the drawings in the correct format allowing scaling and printing?
Use CAD drawings-Drawings must be available in digital format so that the information is accurate and to scale. This way contractors, sub- contractors and suppliers can have access to the same information and errors can be avoided.
Carry out site measurements- if site measurements are carried out, more accurate estimates will be produced.
Identifying the causes of waste- all causes must be identified at tender stage.
The implementation of the waste reduction strategy relates to the construction phase of the project. At the implementation stage, the practical measures to reduce waste on site, which is agreed at planning stage can now be implemented.
During construction, waste management and waste reduction measures must be implemented. Contractors and sub- contractors must make sure that the waste management solutions that they proposed are put into action. They must also ensure that their effect is monitored regularly through project reviews.
At each project review, reports on waste must be produced to assist the team to check performance and look for opportunities to reduce waste.
While the project progresses, as each track is completed, reviews of individual performance should be carried out and feedback provided so that:-
- Sub- contractors can identify how efficient they were on the project.
- Main contractors can decide which trade contributes what quantity of materials to the waste stream and why.
- Main contractors and sub- contractors can learn lessons that will enable to improve on reducing waste.
- Main contractors and sub- contractors can learn lessons which will enable them to improve on reducing waste on projects.
An important role in the way waste is generated on site is by construction activities. By main contractors and sub- contractors working together at this stage of the project, obstacles can be removed to increase material efficiency. This can be achieved by taking the following actions:-
Implement a Waste Minimisation Strategy for the project as part of the Site Waste Management Plan (SWMP) – SWMPï¿½s will soon become a mandatory requirement for many projects. The SWMP must contain detailed measures complying with relevant waste legislation and must also include good practise guidance and objectives in order to maximise reduction, re- use and recovery of construction waste.
Develop a logistics strategy that minimises waste- A major contributor to waste is poor logistics. Solutions like just in time delivery, helps reduce damage to materials and products by minimising the time they are stored on site.
- Use safe, suitable and secure storage- For tradeï¿½s f materials that cannot fall under just in time delivery, suitable, safe and secure storage should be provided to avoid damage during storage and moves.
- Consider mechanical systems and machinery to move materials- This is useful for trades where materials are delivered in large quantities. Mechanical handling of materials will minimise damage and loss of the materials.
- Off-site manufacture and construction- This will improve efficiency and quality. It minimises the amount of work on site.
- Monitor and programme construction activities- The activities should be regularly reviewed. Work must be planned to avoid the overlapping of incompatible trades working in the same area.
- Use packaging in an efficient way- Packaging is one of the largest waste streams in the construction industry. Situations occur were either too much packaging is provided or too less packaging. The ways of reducing or eliminating packaging, needs to be investigated by main and sub- contractors.
- Trade and educate people on how to reduce waste- Personal responsibility needs to be allocated on site for waste reduction. Incentives should be given to people in order for them to reduce waste. Training and tool box talks on waste minimisation must be done to inform workers. There needs to be more interaction between estimators, buyers, site managers and operators.
The following best practise activities should also be incorporated in the process of monitoring performance during construction:-
- A site manager should be appointed by main contractors to reduce waste on site. The position does not have to be a full time task. The role and responsibilities must be clearly defined to the site waste manager.
- The site waste manager should co- ordinate with sub- contractors to ensure availability of storage conditions.
- The site waste manager should keep a record of all material entering the site in order to reconcile against what has been used.
- A trade waste manager should be appointed by sub- contractors.
- In cases where materials are not supplied directly by the main contractors, the sub- contractors must liaise with the Site Waste Manager to make sure that the materials are supplied in an appropriate manner and in the correct quantity.
- Site Waste managers should monitors costs and the volumes of disposals of materials.
As each work package is completed and at the end of a project, a review of waste performance must take place as part of the final account and post project review.
A review of waste performance should be carried out when each sub- contractor completes their work.
Reviewing the data and providing feedback can have benefits such as :-
- Determining whether waste minimisation and management strategy is effective.
- Find out what works and what doesnï¿½t work in reducing waste.
- Determine how efficient main/ sub- contractors were on the project.
- Main contractors can look at the trades and the amount of waste it generates.
- Capture relevant data for future reference.
- Sub- contractors and main contractors can learn lessons which will assist them in improving the waste performance on projects.
Actions that can be taken at the end of projects:-
- Post Completion Reconciliation- making a comparison of the net quantity of materials used with the quantity ordered. The quantity of materials un- used provides a measure of how efficient usages of materials have been. Any reasons should be investigated and recorded.
- Carry- out reviews of performance against targets- Workshops should be carried out at regular intervals as part of the project reviews to access performance.
- Record Data- Capturing waste data should be continuous across different project types. This will allow contractors, clients and sub- contractors to decide how efficient material usage is and the effect it had on profit and overall project waste.
Companies can demonstrate best practise and a company- wide commitment to waste minimisation and management for an improved reputation with clients by improving performance. In improving performance, the waste minimisation is the ability to deliver projects for a lower cost which is the main benefit.
Actions such as the following can be taken:-
- Share the lessons that have been learnt- A good way to improve performance is to learn from experience. The issues relating to minimisation and managing waste are new and good and bad experiences need to be shared across the construction industry.
- Promoting Innovation- By finding and identifying new ideas in the field of waste management and minimisation, clients, contractors and sub- contractors can contribute to increasing requirements for reducing construction environmental impact.
- Raise Awareness- All participants to the construction process can improve their performance on reducing waste, increase profits and by promoting a more sustainable image of the industry by raising awareness.
- Demonstrate better financial and environmental results- Contractors and sub- contractors can demonstrate through examples for future tenders and this can provide competitive advantages.
5. WASTE MANAGEMENT
Waste management is defined as the collection, transportation, processing or disposal, managing and monitoring of waste materials. The term waste management normally relates to materials produced by human activity. This process is generally done to reduce their effect on health and the environment.
Waste management is a distinctive practice from resource recovery which forces on delaying the rate of consumption of natural resources. The management of wastes, treats all materials as individual class, whether solid, liquid or radioactive substances, and tried to reduce the harmful environmental impacts of each through different methods.
Waste management practises differ for developed and developing countries, they also differ for urban and rural areas and for industrial and residential producers. Waste management for non- hazardous waste residential and institutional waste in metropolitan areas is usually the responsibility of local government authorities, whilst waste management for non- hazardous commercial and industrial waste is usually the responsibility of the generator.
5.1 Waste handling and transportation
Waste collection vehicles in South Africa, dustbins and waste sorting moulded plastic are some collection methods. Waste collection methods vay widely among different countries and regions. Areas in the less developed countries, do not have formal waste collection systems.
5.2. Waste Management Concepts
There are a number of different concepts regarding waste management which vary in their usage between countries or regions.
Some of the most widely used concepts are:-
The waste hierarchy refers to ï¿½Reduceï¿½, ï¿½Reuseï¿½ and ï¿½Recycleï¿½ which are known as the ï¿½3 Rï¿½sï¿½. These classify waste management strategies according to their appeal n terms of waste minimisation. The waste hierarchy remains the cornerstone of waste management strategies. The aim of the hierarchy is to extract the maximum practical benefits from products and to generate the minimum amount of waste.
Polluter Pays Principal
Polluter Pays Principal is a principal where the polluting party pays gor the impact caused to the environment. In regard to waste management, this refers to the requirement for a waste generator to pay for appropriate disposal of the waste.
6. HAZARDOUS WASTE
A major concern too many countries in the world is hazardous waste. Hazardous wastes are discarded materials that make them potentially harmful to health and safety of humans and the environment.
Chemicals, heavy metals or substances generated as by products during commercial manufacturing, discarded paint, thinners, cleaning fluids and batteries can all be included as hazardous waste.
Hazardous waste can be in the form of liquids, solids or gases. Hazardous waste sites can pose as a public health threat if the sites are not properly designed or managed. A Hazardous Waste Worker Training Programme (HWWTP) was created to support the Health and Safety of workers who work with hazardous waste.
In order to minimize uncontrolled hazardous wastes, all involved in the transportation must comply with the SANS 10406 on Transportation of Dangerous Goods.
The objectives of the transportation of Hazardous wastes are:-
- To ensure the correct packaging, temporary storage and collection prior to transportation, to prevent accidental spillage into the environment and minimise the impact if spillage occurs.
- To ensure that the hazardous waste arrives safely at a permitted facility.
- To ensure that emergency facilities are in place before accidents occur and the hazardous wastes are correctly marked so as to aid the emergency team.
7. CONSTRUCTION AND DEMOLITION DEBRIS
Construction and demolition materials consist of the debris generated during the construction,
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