Aims and drivers
The construction industry is one of the largest consumers of energy and raw materials, and highest contributor to the emission of greenhouses gases (GHG). In order to become more sustainable, it needs to limit its environmental impact and in particular it has to reduce the use of both raw materials and energy. At the same time, construction industry needs to be cost efficient. Developing novel technologies to integrate waste in the production cycle of lightweight concrete is an all-inclusive solution that improves both sustainability and cost efficiency of construction industry, since:
- the embodied energy decreases due to the lower energy consumption in the production of concrete constituents (most notably the binder);
- an increase in thermal insulation properties occurs due to the high insulation properties of light weight aggregates (most notably the plastic ones);
- the CO2 footprint reduces due to the reduction of processing of raw materials;
- the cost effectiveness increases due to the lower costs of the integrated component materials (wastes).
The project aims at developing completely new concepts and technology routes to integrate waste materials in the production of concrete, for both ready-mixed and pre-cast applications, resulting in an:
innovative, eco-compatible and cost-effective construction materials, characterized by:
- low embodied energy
- low CO2 footprint
- improved thermal and acoustic insulation performances (multi-functionality)
The project results will be used to set a new best practice for concrete manufacturing in order to help both the setting of new standards and the establishing of a public policy for higher energy efficiency and reduced environmental impact.
The main objective of the project is to develop innovative light-weight, eco-compatible and cost-effective all waste concrete solutions. The sustainable concrete should be applicable for ready-mixed and pre-cast building applications – reduced embodied energy systems having improved thermal performance while maintaining all other performances. SUS-CON will provide each of the proposers with a detailed fundamental scientific understanding and make their wide scale commercial application feasible.
Explicit aim of the proposed technological developments will be the demonstration/showcasing of SUS-CON concrete prototype systems:
- Use of recycled aggregate component in a conventional cement binder system
- Use of recycled binder system for a conventional aggregate particle skeleton
- Use of recycled binder and aggregates in the development of a TOTAL ECOSUSTAINABLE SOLUTION.
The first steps towards an all-waste concrete are:
- to develop sustainable constituents (novel binders and novel aggregates);
- to combine novel binders and novel aggregates to an all-waste concrete on the basis of a new concrete design model, based on a particle packing optimization routine.
With regards to the aggregates, novel lightweight aggregates from plastics will be tailored made and thus will allow making the target material lightweight and heat-insulating. In fact, it is expected that, using light plastic aggregates, a lower thermal conductivity can be obtained with respect to commercial comparable solutions (like expanded clay), as the thermal conductivity of the raw material is lower. Moreover, new expanding agents will be studied in order to further reduce the density of the expanded plastic aggregate and then to further decrease the thermal conductivity. A proper mix-design will help in compensating the strength decrease that is associated to a lower aggregate density, and/or to optimize the thermal properties of the resulting concrete mix.
The focus will be on waste materials that are causing socio-economic problems (due to e.g. their quantity, distribution, characteristics or low chances of re-use in more added-value applications) and which are, at the same time, available in quantities large enough for feeding the concrete industry. Examples of such materials are waste tyres and scraps of the sorting process of Municipal Solid Waste (MSW) and Waste Electrical and Electronic Equipment (WEEE). The use of light recycled materials, as aggregates for concrete production, will lead to great benefits in terms of energy efficiency and waste disposal. On the other hand it will contribute in solving critical issues related to the sustainability of consumption of natural resources.
With regards to the binder, the complete replacement of cement by waste materials of high (aluminium-) silica content is aimed. These materials will be used in combination with waste alkali materials/powders in order to activate these aluminium silicates to a binder which does not dissolve in water anymore. The project will investigate the use of waste alkali solutions and will concentrate on waste ash sources (i.e. ashes from power stations that is placed in lagoons, municipal ash incinerator, etc), and by-products such as ferronickel slag and natural or man-made pozzolans, like µ-silica and metakaolin. The replacement of cement in concrete products will reduce the CO2 released into the atmosphere by approximately the same amount of ash that can be utilised for this purpose (production of one ton of cement produces approximately one ton of CO2). The work will be supported by the development of specific models able to consider the effect of different alternative binder formulations and waste streams on the final performances of concrete.
Combining the waste aggregates with the waste binders, ensuring a good compatibility between the constituents, is the next step towards a new all-waste concrete. The innovative solutions set-up at material level will then be employed to develop innovative concepts of modular building components. This will not rely upon the mere integration of the developed materials, as the target performances will be pursued also through the set-up of innovative engineering solutions at component design level, able to allow the effective exploitation, once installed on the building, of the improved performances of the new constituent materials.