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Alkali activated materials/geopolymers

Keywords: inorganic polymers, physical-mechanical properties, microstructure, durability
Alkali activated materials/geopolymers - Fig. 1
Fig. 1. Alkali activated materials obtained by different industrial waste (picture by M.C. Bignozzi).
Fig. 2. Geopolymer mortar and concrete samples (picture by S. Manzi).
Alkali activated materials/geopolymers - Fig. 3
Fig. 3. Fiber reinforced composite with alkaliactivated matrix (picture by M.C. Bignozzi).

Alkali activated materials (AAM) are a new class of inorganic materials obtained by calciumalumino- silicates precursors. Such precursors are able to consolidate when treated with strong alkaline solutions at temperatures between 20 and 100°C. If the nature of the starting materials is mainly alumino-silicate (i.e. metakaolin coming from calcined caolin), then the relevant activated materials are known as ‘geo-polymers’. The interest for this new class of materials is based on several factors: (i) industrial waste can be used as precursors thus saving natural raw materials; (ii) alkali activation is a productive process with a low environmental impact if compared with the industrial processes of traditional building materials; (iii) alkali activated materials can be used as binders (similarly to cement) to produce composites and conglomerates or as one-phase materials to obtain blocks and tiles also suitable for high temperature applications.

The research activity is focused on innovative precursors in order to: (i) set up their mix design and process parameters (time, temperature, types and concentration of alkaline solutions, molar ratios, etc.); (ii) provide fresh state characterizations and optimize moulding technology; (iii) provide physical-mechanical characterization of the final products at the hardened state (with special focus on porosity and its control); (iv) study their physical and mechanical behavior after high temperature treatments; (v) investigate final products durability by means of climate chambers with temperature, humidity and ultraviolet controls; (vi) investigate the corrosion behavior of reinforcing bars in alkali-activated fly ash mortars under exposures to different environments; (vii) investigate geopolymers as matrix for fiber reinforced composites for building restoration.

The research activity is carried out in collaboration with national and international research centers and companies.

Main publications

Carabba L., Manzi S. and Bignozzi M.C. (2016). Superplasticizer addition to carbon fly ash geopolymers activated at room temperature. Materials 9, 1-15.

Carabba L., Santandrea M., Manzi S., Carloni C. and Bignozzi M.C. (2016). Geopolymer mortars for strengthening existing reinforced concrete structures. In Workshop on The New Boundaries of Structural Concrete, September 29th – October 1st, 2016, Anacapri, 271-278.

Monticelli, C., Natali M.E., Balbo A., Chiavari C., Zanotto F., Manzi S. and Bignozzi M.C. (2016). A study on the corrosion of reinforcing bars in alkali-activated fly ash mortars under wet and dry exposures to chloride solutions. Cement and Concrete Research 87, 53-63.

Monticelli C., Natali M.E., Balbo A., Chiavari C., Zanotto F., Manzi S. and Bignozzi M.C. (2016). Corrosion behavior of steel in alkali-activated fly ash mortars in the light of their microstructural, mechanical and chemical characterization. Cement and Concrete Research 80, 60-68.

Natali M.E., White C.E., Bignozzi M.C. (2016) Elucidating the atomic structures of different sources of fly ash using X-ray and neutron PDF analysis, Fuel, 177, 148-156.

Bignozzi M.C., Villani C. and Manzi S. (2015). Nano, micro and macro-porosity in carbon fly ash geopolymer. In Proceedings of the 14th International Congress on Chemistry of Cement, ICCC 2015 Beijing, Beijing China, 13-16 October 2015. 1-7.

Masi G., Rickard W.D.A., Bignozzi M.C. and van Riessen A. (2015). The effect of organic and inorganic fibres on the mechanical and thermal properties of aluminate activated geopolymers. Composites Part B, Engineering 76, 218-228.

Masi G., Rickard W.D.A., Vickers L., Bignozzi M.C. and van Riessen A. (2014). A comparison between different foaming methods for the synthesis of light weight geopolymers. Ceramics International 40, 13891-13902.

Bignozzi M.C., Manzi S., Natali M.E., Richard W.D.A. and van Riessen A. (2014). Room temperature alkali activation of fly-ash: the effect of Na2O/SiO2 ratio. Construction and Building Materials 69, 262-270.

Bignozzi M.C., Manzi S., Natali M.E., van Riessen A. and Rickard W.D.A. (2013). Thermal stability and microstructural analysis of inorganic polymer binders based on Italian and Australian fly ash. SCMT3 – 3rd International Conference on Sustainable Construction Materials & Technologies, August 18-21, 2013. Kyoto, 1-9.

Bignozzi M.C., Manzi S., Lancellotti I., Kamseu E., Barbieri L. and Leonelli C. (2013) Mix-design and characterization of alkali activated materials based on metakaolin and ladle slag. Applied Clay Science 73, 78-85.

Natali Murri A., Rickard W.D.A, Bignozzi M.C. and van Riessen A. (2013). High temperature behaviour of ambient cured alkali-activated materials based on ladle slag. Cement and Concrete Research 43, 51-61.

Kamseu E., Bignozzi M.C., Melo U.C., Leonelli C. and Sglavo V.M. (2013). Design of inorganic polymer cements: Effects of matrix strengthening on mi-crostructure. Construction and Building Materials 38, 1135-1145.

Kamseu E., Ceron B., Tobias H., Leonelli C., Bignozzi M.C., Muscio A. and Libbra A. (2012). Insulating behaviour of Metakaolin-based Geopolymer Materials assess with Heat Flux Meter and Laser Flash Techniques. Journal of Thermal Analysis and Calorimetry 108, No. 3, 1189-1199.

Kamseu E., Nait-Ali B., Bignozzi M.C., Leonelli C., Rossignol S. and Smith D.S. (2012). Bulk composition and microstructure dependence of effective thermal conductivity of porous inorganic polymer cements. Journal of the European Ceramic Society 32, No. 8, 1593-1603.

Bignozzi M.C. (2011). Geopolimeri e cementi: due leganti a confronto. Geopolimeri: polimeri inorganici chimicamente attivati, a cura di Marcello Romagnoli e Cristina Leonelli. Editore I.Cer.S, Casa Editrice Lulu, 83-101.

Natali A., Manzi S. and Bignozzi M.C. (2011). Novel fiber-reinforced composite materials based on sustainable geopolymer matrix. Procedia Engineering 21, 1124-1131.