Written by Arcas & Callisto Consulting
In October 2022, Arcas & Callisto Consulting (A&C) held three online webinars of the Experts on: Global Dialogues for a Sustainable Built Environment, the last of which featured presentations and exchanges by our experts around circular economy and sustainable and recyclable technologies for C&D waste. Thanks to the co-organisers of this webinar event, China Ecological Building Material Association at the China Building Material Federation, China State Key Laboratory of Green Building Materials and RECONMATIC, the webinar was a great success.
In the last session of the webinar series, A&C invited seven Chinese and international experts to give a comprehensive and systematic introduction to the current state of the circular economy and the development of sustainable and recyclable C&D waste technologies in China and abroad, as well as to the European Horizon project: RECONMATIC, the automated solutions for sustainable and circular construction and demolition waste management".
Circular Economy in China and International Research Collaboration on C&D Waste Recycling
Starting with the concept of circular economy, Zhao Kai introduces the circular economy as a model of economic growth in line with the concept of sustainable development. With the efficient use and recycling of resources as its core and the principle of "reduce and reuse", it is a fundamental change to the traditional economic growth model. In recent years, China has been carrying out pilot construction projects for circular economy, promoting the transformation of circular economy, strengthening the comprehensive use of large solid waste, and striving to achieve the efficient use of resources.
Compared with 2012
In 2021, the utilization rate of large solid waste in China reached 56.8%, an increase of about 16%.
The annual treatment volume of key electrical and electronic products increased by 73 million units in 2021, and the regulated treatment rate increased by 44 per cent.
The recycling volume of nine major types of recycled resources, including scrap iron and steel, non-ferrous metal scrap, plastic waste and paper waste, reaches 385 million tons in 2021, more than twice the volume in 2012.
However, China has a long way to go in promoting the development of a circular economy. Our goal is to implement the whole process of resource management and to accelerate the construction of a system for the recycling of waste materials. The development of a circular economy is the only way to improve the efficiency of resource use. Waste is actually a very large resource, and by establishing a good system for recycling and reapplication of waste as soon as possible, mankind can reduce or even avoid using the earth's natural resources. Recycling is a requirement for transforming the economic development model, and it is a necessary path for us to protect the ecology.
C&D Waste Recycling in EU and Innovative Research in Automation
Jan briefed us on the plans for the RECONMATIC project, which brings together a number of partners from three regions of the world, the EU, the UK and China, and said that due to the good relationships with the China Association of Circular Economy and other technology partner companies, together we will achieve the goals of the RECONMATIC project. The project has 23 partners in Europe and 6 demonstration projects are planned to demonstrate our solutions in real life. The projects cover different countries across Europe and Asia, including the UK, Spain, Italy, Greece and Cyprus, as well as China.
The mission of the RECONMATIC project is to combine the principles of the circular economy with more efficient construction and demolition waste management to better manage the entire life cycle of buildings. This implies an industrial transformation of the traditional construction sector, which is a major challenge not only for developing countries but also for developed countries. The project is looking for new solutions and technologies to help optimize and reduce the waste that ends up in landfill by using digital twins and BIM to integrate building data and information to understand the materials and characteristics of the building. Automated processing using robotics and trained artificial intelligence to better sort and process waste to get cleaner materials, ultimately adding value to waste materials and creating highly profitable products from them to help them enter recycling. The aim is to deliver a digital information management system that connects all stakeholders and enhances collaboration between them.
The project has set key performance indicators such as a 50% increase in the reusability of building products through the adoption of solutions eventually developed by the project, as well as advice and recommendations to the European Commission on new standards that will be needed to support the development and application of new technologies. Supporting educational tools and materials will be developed, as well as systematic training and seminars for different stakeholders, i.e. not only providing solutions and innovations, but also helping to apply these solutions effectively in industry and society.
C&D Waste Recycling in China: Current Landscape and Future Developments
Liu introduced the importance and current situation of China's construction solid waste recycling from three aspects: the current situation of China's construction waste resource utilization, the mechanism and the development prospect.
At present, the main objects of China's construction waste utilization are waste concrete, waste bricks and stones, which account for about 30%-40% of the total construction waste. However, as of 2020, China's urban construction waste resource treatment rate is still only about 10%, so it is necessary to speed up the processing capacity of construction waste resource treatment facilities. In 2020, China clarified the principle of pollution responsibility, stipulated the responsibilities of the government, enterprises and individuals in society, put forward the requirements of planning first, source reduction, whole process management, promoting green product application, and raised the penalty standards.
China's urbanisation is far from complete, and there is still a large potential for infrastructure investment. The market offers more space for recycled materials. Construction waste also meets the basic requirements of road construction materials, so the rapid development of China's road network provides a wide space for the market expansion of construction waste as well.
BIM & C&D waste management
Vitalij gave a seminar on the basis of BIM and how it relates to construction waste. BIM, which can be Building Information Modelling or Building Information Management, has different definitions, but one thing remains the same, and that is information management. People use this data to provide better decision-making and as BIM has very many different uses, people mostly use BIM to improve the efficiency of building construction, but none for waste reduction at the moment. And we want to be able to use the benefits of BIM to contribute to a green and low-carbon building industry. There is already a lot of research into the potential of BIM in construction waste reduction, as design is the best way to reduce waste.
The task in the RECONMATIC project was to define an open BIM approach, one that would allow the exchange of information between different software by creating a common thread that allows us to trust the information when exchanging it. It is a standard format that defines all building products and defines the attributes they contain so that they can be read by different software applications. So when we look at the whole lifecycle of construction waste, we understand how they are transported, how they are designed, and what information is needed during the design phase, the construction phase and the demolition phase, making waste information management more effective.
Alfonso Arevalillo Román:
CDW Pre-demolition Audits as a Way to Increase Reuse/Recycle Rates
Alfonso presented the guidelines for pre-audits of demolition and renovation activities, how best to introduce a cycle of building products and how to allow these processes to evolve to be digital and automated.
The audit process is intended to provide documentation that the owner can apply for a demolition or renovation permit and open the tender, and the results of the waste audit will support the decision of the relevant authorities to approve the planned work, which is also a key point in the statistical report, including the definition of the total amount of recycled material or recovered material. So not only the legal requirements have to be considered but also other possible requirements in order to find the best way to manage these wastes and, finally, to submit reports that can be used by the different stakeholders, and all these steps follow a quality system and all require a quality assurance mechanism. The audit process also entails anticipating the presence of hazardous substances, determining which materials are contaminated and whether they can be reused, and identifying the transport containers needed at a later stage, planning for construction waste management, which helps to determine the way in which demolition activities or renovation activities are carried out, ensuring that all materials are sorted in the best possible way to maximise the use and recycling of construction waste. This also requires the auditor to have an adequate educational background and specific training for the staff carrying out the activities. As auditors, they also need to be independent and autonomous, able to follow ethical rules and take professional responsibility.
In the RECONMATIC project, Tecnalia is focusing on automation and the most efficient way to carry out pre-demolition audits of buildings, research into demolition and renovation activities, and the route to market acceptance of new materials. Their plan is to create a digital twin of the building structure at the end of the building's useful life, ensuring that information, whether electronic or paper-based, then converted into a model. Creating a database will allow us to non-destructively test materials during the life of the building, to understand their properties, location, environmental conditions, etc., and to select manufacturing processes that comply with CE standards, to find different routes to use and recycle this material and thus create a market. For this purpose, Tecnalia is also developing quality control and quality assurance systems. With this information and quality assurance, as soon as the different subjects within the mechanism are included, we will see a welcome and acceptance of such products in the market.
Reuse of Structural Members
Professor Wang would like to reflect with the audience on how to recycle and reuse structural building elements, as it has been considered difficult to reuse existing structural elements, but it is possible.
Common structural building materials include steel, concrete, brick and timber. Professor Wang gave us an overview of the recycling of several structural materials. Steel is the most used building material in the UK, accounting for 70% of building frame use. Building elements in the UK are often bolted together and the bolts are easily recovered and recycled, but it is more difficult with concrete structures, which lack flexibility as each reinforced concrete element has its own specific size and strength. Also, during the demolition phase, it is difficult to separate the concrete from the steel elements. Professor Wang introduced the cutting method by cutting members into segments and reusing by joining reclaimed segments.
For bricks, which usually need to be joined together with mortar, lime mortar can be shaken off easily, but cement mortar is not easy to shake off, and Professor Wang has invented a technique of reclaiming by punching. By using a cutting machine and punching to cut through the mortar, the result is that although some of the mortar can still be seen sticking to the surface of the bricks, they are in a condition to be reused.
With timber, what can be done now is to separate the timber from the rest of the material, which can then be used to make new structural elements, and when designing new timber structures, demountable technology can be used to bolt one piece to another so that the timber elements can be easily removed at the end of the building's life.
Professor Wang said that the construction industry uses a huge amount of materials and the potential is huge as innovation in the circular economy is only just beginning to be thought about in the construction industry. Recycling and reusing structural elements in buildings is difficult but it is still possible, and the degree of difficulty depends on the materials you are dealing with. The key is not in the technology, which is all possible, the real key is in creating a market and creating market demand.
C&D Waste Carbon Reduction and Innovative Utilisation under the Dual Carbon Goal
Chen Lei introduced the overview of construction waste in China and analysis of the carbon-neutral technology pathway of the building materials industry. Nationwide, the average annual growth in construction waste generation over the past five years has been around 3%, with a total of 20 billion tonnes of construction waste deposited over the years. At present, the only way to quickly dispose of construction waste is to use it as a substitute for aggregates. At this stage, the amount of demolition waste used in China to produce recycled products such as aggregates represents around 8% of the total construction waste ratio.
With the establishment of the carbon-neutral target, the construction solid waste industry has become a popular industry for development in recent years. Chen introduces several directions of product innovation for construction waste utilization, such as increasing the use of construction waste by applying it to projects such as road base treatment and sea-enclosing land. In addition, the high-added-value of construction waste can be improved through the development of recycled panels, high-fluidity lightweight insulated concrete walls or other complete product technology applications. Chen said that there is no rubbish in the world, only misplaced resources. The construction waste we are currently facing may be a headache, but by finding the right technical path, we can turn them into treasure.