FIRST YEAR SCIENTIFIC REPORT OF THE MECAGEOPOLY PROJECT: "MECHANO-CHEMISTRY: AN INNOVATIVE PROCESS IN THE INDUSTRIAL PRODUCTION OF POLY-SIALATE (PS) AND POLY-SILANOXOSIALATE (PSS) GEOPOLYMERIC BINDERS TO BE USED IN BUILDING CONSTRUCTION"

The MECAGEOPOLY Project was aimed at proving that: a) the mechanochemical activation of kaolins is a valid alternative to the thermal treatment at 650-750°C for the industrial production of PSS geopolymeric binders to be used in building construction and in other industrial applications; b) geopolymeric binders obtained by mechanochemical activation of kaolins have similar properties than those obtained by thermal treatments; c) the mechanochemical treatment can be exploited for making geopolymeric binders from other alumino-silicate rocks, such as quarry wastes of volcanic tuff cemented by glass (welded tuffs) or by authigenic minerals (zeolites), that are difficult or impossible to activate by thermal processes; d) the mechanochemical process is easier to control than the thermal process and it is feasible at an industrial scale; e) the mechanochemical treatment simplifies the industrial production of PSS geoplymeric binders by combining in a single step the grinding and thermal treatment of the raw material. These objectives were expected to be met in a time period of 2 years, after an evaluation of the results obtained in the first year of activity, aimed at reaching the following specific objectives: I) Selection, collection, treatment and characterization of the most suitable materials to be used in the whole Project. They were identified as a kaolin commonly used in ceramic industry, and two different types of volcanic tuffs commonly quarried in Italy. One of the tuff must have been a vitric one (welded tuff), and the other a lithified one, cemented by zeolites. II) Definition of the optimum mechanochemical and thermal conditions for the activation of the selected kaolin into metakaolin for the synthesis of PSS geopolymers through the reaction with silica glass and alkali. III) Development of suitable formulations to obtain potassium-based polysiloxo-sialate geopolymers (K-PSS) composed of the following monomeric units: K+ [-(SiO2-AlO2-SiO2)-]. nH2O with Si/Al=2 This specific type of geopolymer was selected because it produces nanocrystal gels with a sufficient mechanical strength to be used in building industry, where it can replace clinker-based cements because its better resists to fire. IV) Selection of the formulations providing K-PSS geopolymers combining a high resistance to temperature and mechanical stress with the optimum conditions for molding and casting the reaction paste. V) Characterization of the K-PSS binders obtained by the mechanochemical and thermal treatment and comparison of their mechanical and thermal properties. According to the Working Plan proposed for the first year of the Project, these objectives must have been achieved through a series of activities illustrated in 3 Working packages (WP's), with specific tasks and products to be delivered in the time indicated in the GANNT graph of the Project. In the present document, we will specifically refer to these WP's to report the activityperformed in the first year of the Project and to summarize the deliverables resulting from it.