Recycling end-of-life concrete: The C2CA project

2004

This paper consists of an overview over the development of recycling of concrete and the use of concrete with recycled materials. The overview and strategic management of demolition waste is often missing when handling concrete demolition waste. The demolition, processing and recycling of the materials are often analysed separately. "High quality" recycling of concrete waste does not always correspond to production/use of the product with the highest value, but rather the most feasible product in a specific project or region. It is by analysing the whole disposal/ supply-chain including the substituted material, that best effects of recycling can be achieved. Demolition is most often the first, and not the last phase of a building's life. There is almost always a building where a new one is to be built. Environmental issues are a growing concern in the world. There are a number of ways to include environmental issues when planning demolition and recycling activities. Overviews of methods for environmental evaluations as well as economical considerations are presented in the paper. The market for recycled materials in the world is commented, and integrated demolition and waste management in Kosovo and an analysis of the potential market in Hong Kong are presented as examples. Current challenges in the industry are how to control and handle polluted material. These issues will be discussed from a practical point of view. Moreover some aspects to consider with respect to future demolition when producing new concrete products are presented.

In this research, it was experimentally substantiated that concrete recycling is an effective technique of sustainably managing construction and demolition waste. Thus, 48 standard concrete cube specimens were cast, cured and crushed. Twenty four of the cubes were cast from recycled aggregates while 24 were from virgin aggregates. The results showed that at higher water / cement ratios, the compressive strength of recycled concrete is similar to that of virgin concrete but at lower water / cement ratios, the compressive strength of recycled concrete is appreciably lower than that of virgin concrete. Thus at water / cement ratios of 0.5 and 0.6 the compressive strength ratio of recycled concrete to virgin concrete was respectively 0.89 and 0.985 at crushing age of 28 days and 0.5 and 0.95 respectively at crushing age of 7 days. In addition, the slump and the compacting factor tests revealed that the workability of virgin concrete mix is higher than that of recycled concrete.

From extraction of raw materials, processing, manufacturing, transportation, construction and disposal at the end of a structure's useful life, construction materials have environmental impacts. For sustainable development within the construction industry, there is need to reduce the depletion of natural resources, reduce disposal of C&D concrete to landfills and promote recycling and reuse of construction and demolition waste. Codes of practice and standards for recycling and reuse of C&D concrete were identified; best practices and technical challenges presented whilst the future of recycling and reuse of C&D was predicted. Environmental sustainability issues have presented new challenges and opportunities for recycling and reuse of C&D concrete.

2023

This article demonstrates the possibility of producing alkali-activated materials (AAM) from a mixture of mechanically processed concrete, ceramic, masonry, and mortar wastes, as a sustainable alternative for recycling construction and demolition wastes (CDWs) under real conditions. The addition of 10% Portland cement allowed the materials to cure at room temperature (25 • C). CDW binder achieved a compressive strength of up to 43.9 MPa and it was classified as a general use and low heat of hydration cement according to ASTM C1157. The concrete produced with this cement and the crushed aggregates also from CDW reported a compressive strength of 33.9 MPa at 28 days of curing and it was possible to produce a high-class structural block with 26.1 MPa according to ASTM C90. These results are considered one option in making full use of CDWs as binder and aggregates, using alkaline activation technology thereby meeting the zero-waste objective within the concept of the circular economy.

Journal of Advanced Concrete Technology, 2005

Providing excellent performance as a structural material, concrete has long been deemed essential for modern civilization and recognized as a material that will continue to maintain and support the development of human society. Now that recycling of concrete in a completely closed loop has become technically feasible, concrete is being seen in a new light. This paper reviews the background to this development referring to changes in social systems and the introduction of new technologies. In view of the fact that consideration of the global environment will be required in the future at every step of the production of concrete and concrete structures, this paper goes on to overview the methods for identifying social needs related to concrete structures, the manner in which production systems of structures should meet such social needs, lifecycle design techniques for structures, and techniques for expressing the environmental performance of structures. The authors finally discuss the nature of true recycling and a truly recycling-oriented society, based on the above-mentioned discussions.

11th International Conference on Environmental Remediation and Radioactive Waste Management, Parts A and B, 2007

Belgoprocess started the industrial decommissioning of the main process building of the former Eurochemic reprocessing plant in 1990, after completion of a pilot project. Two small storage buildings for final products from reprocessing were dismantled to verify the assumptions made in a previous paper study on decommissioning, to demonstrate and develop dismantling techniques and to train personnel. Both buildings were emptied and decontaminated to background levels. They were demolished and the remaining concrete debris was disposed of as industrial waste and green field conditions restored. Currently, the decommissioning operations carried out at the main building have made substantial progress. They are executed on an industrial scale. In view of the final demolition of the building, foreseen to start in the middle of 2008, a clearance methodology for the concrete from the cells into the Eurochemic building has been developed. It considers at least one complete measurement of all...

Construction solid waste has caused serious environmental problems. Reuse, recycling and reduction of construction materials have been advocated for many years, and various methods have been investigated. There may be six type of building materials: plastic, paper, timber, metal, glass and concrete which can be reused and recycled. This paper examines the rate of reusable & recyclable concrete waste. On the other hand, the reuse of construction waste is highly essential from the viewpoint of Life Cycle Assessment (LCA) and effective recycling of construction resources. In order to promote the reuse of construction waste, it is necessary to achieve three basic concepts: (1) assurance of safety and quality, (2) decrease of environmental impact, and (3) increase of cost effectiveness of construction. This paper outlines the development of a recycling system, application of recycled aggregate concrete produced by the aggregate replacing method, which is effective in reducing both cost and environmental impact from the viewpoint of LCA for concrete waste generated by the demolition of large-scale buildings such as powerhouses. Moreover, with the adoption of the developed recycling system, it was confirmed possible to recycle concrete waste produced from the demolition buildings in a highly effective manner reducing both recycling cost and Environmental impact.

1982

This study investigates the engineering properties of demolished concrete aggregates wastes along Arakale Road, Akure. The purpose is to recycle and reduce the amount of construction wastes materials going into landfills and dumping pits. The study identifies about 15% to 20% of construction waste materials go into landfill and dumping pits in Akure. Four different mixes at 0.5, 0.55, 0.60 and 0.65 water/cement ratios were performed and a total of 96 (48 each) concrete cube samples were cast, cured and crushed. The results showed that at lower percentage water/cement ratios, the compressive strength of used aggregates at day 28 were much lower than virgin aggregates (16.89N/mm 2 , 19.93N/mm 2) while at higher percentage water/cement ratios, the compressive strength of used aggregates at day 28 was almost the same as Virgin aggregates (18.07, 18.37). It shows that the used aggregates can attain the same compressive strength as virgin aggregates at higher water/cement ratios.

VITRUVIO - International Journal of Architectural Technology and Sustainability

The work presented aims to analyse the feasibility of reusing concrete, once demolished from a building in Tres Cantos in Madrid, to manufacture finishing materials for buildings, as well as to design a procedure. The first phase consists of a bibliographic search on the reuse of materials, analysing the techniques adopted so far and the lines of work. The second phase related to the acquisition of data related to the production and recycling of Construction and Demolition Waste (CDW) at a European level. The third phase consists of the study of recycled aggregates resulting from demolitions or landslides, their treatment process. The fourth and final phase consists of the development of a laboratory test plan to evaluate varied materials for finishing exterior cement pavements with concrete from the demolition of the case study building. There were many conclusions and results of the project. The granulometry of the fine fraction of demolished concrete is suitable to produce non-st...