by M.C. Bignozzi, E. Rambaldi, N. Buratti, C. Mazzotti, A.L. Vinciguerra, M. Dondi, R. Soldati, C. Zanelli, L. Laghi, M. Marsigli, G. Pederzoli*23   Giugno   2017

Sustainable materials for the building industry

The construction industry is on the whole one of the most energy-consuming sectors and highly responsible for greenhouse gas emissions (about 36% of CO2 emissions in Europe). Construction is therefore one of the main areas for intervention in order to implement the EU decarbonization project, through specific action on materials and processes.
The MATER_SOS project -  Sustainable Materials for buildings restoration and construction -  funded by the Emilia Romagna region (Italy) via European funds, ROP ERDF, Priority Axis 1 Research and Innovation, Action 1.2.2, aimes at developing and creating prototypes of building materials with a low environmental impact such as concretes, cements, adhesives and tiles, so as to employ them along the entire construction chain.
The project involves several research laboratories: the Ceramic Centre (which coordinates it all), the CNR-ISTEC (Faenza, RA), the CIRI - Building and Construction (the University of Bologna), the CertiMaC (Faenza, RA) and RICOS (responsible for the distribution of the project results). It also sees the participation of important  construction firms such as Marazzi Group S.r.l., Concave (Consorzio Cave Bologna Soc. Coop.) leader in the production of high-quality concretes,  and Fili & Forme S.r.l., which in Italy produces macro synthetic fibres to reinforce concrete under the brand Istrice. The firms are not financed throughout the project, but they take part in the research in order to favour the technological transfer so that the project results can rapidly be transferred onto the production process.
The two-year project (Apr 1st 2016 – March 31st 2018) has developed several activities over the first twelve months.

Waste mapping tools, selection and characterization
The Ceramic Centre and the CNR-ISTEC have outlined a regional map of the waste that can potentially be re-used  in the construction industry. The waste composition is sufficiently certain and constant that it can be handled by operators and final users with no danger, and the quantity of waste available is such that it can be a valid alternative to natural raw materials  in the building industry. In order to promote social, environmental and economic sustainability - according to the principles of circular economy - the final aim is the optimization of available resources, the recycling and reuse of materials and products, and the cutting of production costs. The selected waste is partly municipal solid waste and partly industrial waste. Each waste has a factsheet describing the characterization procedure and any possible necessary treatment according to the intended use. The outlined regional waste mapping  therefore aims at becoming a benchmark tool in the construction industry  in order to recycle  and trade all the waste that can fully be identified as Secondary Raw Materials (SRM). The study has also enabled a visual representation of  the regions of origin of the waste hitherto considered in the project.
Sustainable structural materials
The CIRI-EC, the CertiMaC and the CNR-ISTEC are working towards the development of structural cement-based materials containing some of the waste identified in the map. During the first year of the project the effort went on replacing part of the concrete with waste from the ceramic and food industries, in order to reduce the environmental impact of the binder mostly  employed in construction  (1 ton concrete causes about 1 ton CO2 in atmosphere). The effects of these new eco-friendly concretes on the mechanical behaviour of  different types of concrete (normal concrete and fibre-reinforced concrete, containing also recycled aggregates from demolition) are currently under study. Both polymer and steel fibres are employed: the former come from recycling the waste of polypropylene fibres production; the latter come from worn out tyres. The results hitherto obtained are promising and the new products performance fully comparable to that of traditional cements and concretes. During the second year of the project the effort will go towards developing cement mixtures for structural reinforcement and lighter aggregates starting from some already identified waste.

Sustainable materials for plastering, screeds and adhesives
CertiMaC, in collaboration with the Ceramic Centre and the CIRI-EC, is working on the planning and developing of highly sustainable screeds and plasters containing large amounts of waste and on the creation of lighter and highly insulated prototypes, yet maintaining high standards of durability and breathability. Of all the different kinds of waste examined, the most promising mixtures have been obtained by assembling cement CEM 32.5 (the less expensive and most easy to find), inert waste from ceramic industry  and fine aggregate from crushed carbon waste from the food industry. These differently blended components have brought to the creation of two product types that can be used to make insulated plaster base (density m=1050 kg/m3, Rm=1.8 MPa ) and a screed (density m=1650 kg/m3, Rm=9.8 MPa). These are products where waste makes up about 85% of total weight, and are among the most promising solutions hitherto examined in this field. Tensile strength tests and density tests are being carried out, and the products are currently undergoing all other necessary tests for a full implementation at industrial level. Other factors such as water absorption, breathability and thermal conductivity are currently being tested as required by technical standard laws (EN 998-1 and EN 13813 laws for plasters and screeds respectively).

Sustainable ceramic tiles for different applications
The CNR-ISTEC and the Ceramic Centre  are currently involved in designing and developing sustainable ceramic tiles in order to strengthen the industrial symbiosis along the waste recycling chain in the Emilia-Romagna Region. Waste mapping of available waste has enabled to identify different types of waste such as glass, mud and ash, which have been blended in the mixtures for ceramic tiles in the measure of  20% -70% and have been tested in laboratories.
All waste has been classified through a technological profile summarizing its compositional features and the effects of the different blends on crushability, pressing and sintering. Among the cons: bulk density decrease and a slightly darker colour after firing. The pros include: tiles made for over 60% with what is still defined today as waste, similar to porcelain stoneware tiles as to technological features, requiring a significantly lower temperature during firing.

The MATER_SOS project has set itself ambitious targets; yet research is showing that these targets are perfectly reachable, and can be implemented through the support of partner companies. Within a year, the existence of building packages handed out with technical factsheets on performance will be the tangible proof that circular economy is not only pure theory, but it can mean good opportunities for the construction sector.
 

(*)
Maria Chiara Bignozzi, Elisa Rambaldi - Centro Ceramico;
Nicola Buratti, Claudio Mazzotti, Anna Lisa Vinciguerra - CIRI Edilizia e Costruzioni;
Michele Dondi, Roberto Soldati, Chiara Zanelli, CNR-ISTEC;
Luca Laghi, Marco Marsigli, Germano Pederzoli - CertiMaC.