Session 4 - Circular Economy for Building with Secondary Construction Materials to Minimise Resource use and Land use

Convener - Manfred Curbach, Elke Pahl-Weber

Speaker Titel Abstract Kind of presentation
Axel Zentner Interdisciplinary approach of recycling of C&D-waste and development of new materials to increase raw material productivity  With a waste volume of approx. 214.6 million t (52% of the gross volume in 2016), C&D-waste plays a key role in the German circular economy. Building rubble, as a component of C&D-waste and mainly consisting of concretes and bricks, accounts for approx. 58.5 million t. According to expert panels of the BDE and the BGRB, future regulations will lead away from a circular economy and towards a cradle-to-grave principle. Recycling methods for backfilling of landfills or mining cavities, which are currently specialized in downcycling, are no longer necessary and necessitate disposal processes. This reduces the overall raw material productivity of natural resources, does not meet recycling rates, requires additional landfill volume and deprives the landfill of its function as a pollutant sink. Along with the continuous closure of landfills in Germany, regional waste disposal bottlenecks will occur. These developments can only be counteracted interdisciplinary. Therefore, an application of innovative technologies for the treatment of mineral C&D-waste to high-quality recycling building materials is required, with proof of structural suitability and environmental compatibility. In order to strengthen the placing on the market and the market position of recycled building materials in the construction sector, it is necessary to meet the requirements for quality as a building material and to overcome acceptance problems. This approach is supported by the development of new high-performance materials, such as carbon fibers in concrete production. The integration of innovative product design and a development of urban-rural relations for the regional recycling of C&D-waste means that land use for the removal and extraction of raw materials can be kept as low as possible. At the same time, the overall raw material productivity of natural resources is increased. Thus, the SDGs 9, 10, 11, 12, and 15 are taken into account. Oral (normal length)
Christoph Scope Life Cycle Sustainability Assessment of Cement-based Composites: Addressing Circularity for the Case of Carbon Concrete  Sustainable construction is key to minimize negative effects on our planetary boundaries. New building materials offer options of remedial maintenance or integral design to improve SDGs #9 to #13. The building sector already experienced a strong move towards sustainability assessments, thanks to building certificates, a stiff market competition, and precise international standards. For new building materials, such assessment is an essential market entry barrier. However, its early stage integration could also help to guide its ongoing design optimization. We systematically synthesized literature on cement-based composites and sustainability assessments. We conceptualized a Life Cycle Sustainability Assessment (LCSA) framework with a focus on circular strategies to evaluate a prefabricated wall and ceiling reinforcements of carbon concrete. Life Cycle Assessment, Life Cycle Costing, and Social Impact Assessment are combined, its synergies and trade-offs are analyzed to value and compare circular economy as well as regionalization effects. Sensitivity analyses of methodical choices e.g. system boundaries or allocation rules are evaluated. We compare the results with reference materials e.g. steel-based reinforced concrete. So far, the integrated method of LCSA is drafted, the reference products are sketched, experimental mechanical tests are mapped, and Life Cycle Assessment is evaluated. Preliminary results indicate that carbon concrete allows to save cement and sand resulting e.g. in lower carbon emissions and abiotic depletion. The net energy savings over service life are ambiguous and depend on that choice of time length. Three recycling scenarios of carbon concrete are feasible, each with pros and cons and some barriers in current regulation. Future analyses will add economic, health, and social hotspots. Our findings may provide reason for planers, regulators, and engineers in the built sector to consider new materials e.g. carbon concrete to reduce negative impacts on SDGs and to provide a regulatory framework to foster circular strategies. Oral (normal length)
Ghada Amin Low Carbon Roadmap – The Case Study of Egypt  Cement manufacturing is one of the key industries in Egypt, yet it is one of the highest fossil fuels and raw materials consumers. Resulting in depletion of nonrenewable natural resources such as limestone, clay and Iron ore that are heavily consumed to produce clinker, the intermediate product to produce cement with subsequent evolution of CO2 Emissions. This work represents a case study of the development of the Egyptian Low carbon Roadmap with main focus on cement industry, highlighting the opportunities and challenges faced by the Egyptian cement Industry to become a role model in terms of application of Circular Economy Concept. Which is achievable via utilization of wastes as Alternative Raw Materials and Alternative Fuels. Potential Alternative Raw materials mainly are Construction and Demolition wastes, Slag from Iron and Steel Industry and Fly Ash from Coal Fired Power Plants. Regarding Thermal Substitution of non-renewable energy sources, Alternative Fuels to lower dependency on fossil fuels mainly are agriculture wastes, Refused Derived Fuels (RDF), Tires Derived Fuels (TDF). The recently developed roadmap indicates the CO2 reduction strategies. It also highlights policies, regulations and standards that currently under modification by the relevant authorities in addition to the stakeholders map and communication plan that needed to be followed to ensure sustainable inclusion of circular economy concept to the Egyptian Industry. Oral (normal length)
Petra Schneider Options of Substitute Building Materials Replacing Natural Aggregates and their Feasibility of Circular Use in Urban Green Infrastructure  The project pursued the investigation of the feasibility of replacing primary construction raw materials such as gravel, sand or topsoil in structural engineering applications with substitute building materials and identifying the resulting potential for strengthening circular economy in Germany. Beside the circular economy aspect, substitute building materials that replace natural aggregates, can be used to foster the implementation of Green Infrastructure. Green infrastructure describes a strategically planned network of natural and semi-natural areas with different natural spatial features on different scale levels. Urban green infrastructure forms a basis for attractive and sustainable cities. In the frame of the project was investigated the feasibility of application of substitute building materials in Reinforced Soil Structures (RSS) and green roofs. The investigated materials considered sandy foundry residues, lignite filter ash, household garbage ash and two types of slags (blast furnace slag and electric furnace slag) for RSS and brick recycling material for green roofs. The focus of the project was on the feasibility of the use of substitute building materials for reinforced soil, taking into account the structural requirements and on testing the greening capacity of these materials with the aim of establishing Urban Green Infrastructure, including the assessment of the respective water balance. Oral (normal length)
Regine Ortlepp Quantification of the effect of building material substitutes to minimize resource use considering technical issues  Around the world, building stocks are the dominant consumers of resources within national economies. Mining activities to produce building materials lead to land-use conflicts, which negatively affect food security and degrade the environment, while consuming a large amount of energy. Correspondingly, there is high demand for improved knowledge of material consumption in the built environment and for possibilities for their reduction. Thus, for instance fly ash waste from thermal power stations – available in large quantities – could be used for alternative building materials. Numerous studies have been conducted over recent years using material flow analysis (MFA) as a well-suited tool to meet this demand. Material composition indicators (MCI), which describe the composition of different objects of the built environment, play an important role in this context. Usually such indicators are determined on the basis of a building type. However, studies on the impact of building material substitution on these MCIs are currently lacking as well as studies on the reachable quantities of saved resources with taking technical issues regarding the requirements of building materials and buildings into account. This is particularly important in rapidly developing cities with a high earthquake risk. The contribution introduces a first case study on building material substitutes in different Indian buildings, comparing the bill of materials arising from the commonly built structure with ordinary red brick masonry and potential material substitutes. Based on the comparison of the calculations performed, it can be inferred that the use of alternate materials results in a considerable amount of reduction in material in certain parts of the buildings. Thus, emphasis should be placed on the use of alternate building materials and structural systems that will help reduce material consumption. Further, these effects should in future be taken into account in the MCIs as key variables in the MFA. Poster only
Kavitha Shanmugam, Venkata Krishna Kumar Upadhyayula Environmental Performance of an Upycling Application of Waste Incineration Fly Ash: A LCA Case Study of Thermal Insulation Sandwich Panels  The current practice of landfilling fly ash generated by waste incineration is non-sustainable, so alternative ways of using this material are needed. Silanization effectively immobilizes the heavy metal contaminants in waste fly ash and enables its circular utilization because silanized (surface-modified) fly ash has market value as a low-cost filler for polymer composites. This study examines the environmental performance of colloidal mesoporous silica modified fly ash (CMSFA) when used as a filler for manufacturing polymer composite skins for thermally insulating sandwich panels. These panels consist of a polyurethane foam core sandwiched between two epoxy composite skins that are reinforced with glass fibers and CMSFA filler. The environmental performance of such panel was evaluated using life cycle assessment (LCA). The study revealed that the test panel performs environmentally better than the two market incumbent alternatives with PU foam or rockwool cores and steel skins in eight out of ten impact categories measured except global warming potential (GWP) and photochemical ozone formation potential (POFP). However, the GWP and POFP of test panel can be reduced by replacing epoxy polymer matrix with lignin-based bioepoxy resin or thermoplastic polypropylene as the polymer matrix of the composite skins. Silanization of waste fly ash for use as a filler in manufacturing polymer composite skins of sandwich panels is thus a sustainable upcycling alternative that can potentially avoid the need for landfilling. Our LCA study suggest that waste ash upcycling as a filler material to make composite skins of thermal insulation sandwich panels can be developed as a sustainable, circular economy business model in future. Poster only