Alkali activated geopolymeric binder using tungesten mine waste: preliminary investigation

This paper reports preliminary results of a PhD research project related to the development of an alkaliactivated geopolymeric binder using mineral waste mud from the Portuguese tungsten mine Panasqueira which is still operating. Mineralogical analysis indicates that the waste mud is compose mainly of muscovite and quartz with a high content of iron and alkali metals. Results of the dehydroxylation process are presented by x-ray diffraction and infrared emission spectroscopy patterns of quenched waste powder and also from compressive strength of alkali-activated mortar specimens, showing a significant potential as a geopolymeric source precursor. Considerations about Portuguese industrial waste production are made showing a high level ratio of CO2 emissions mostly from cement industry, a nation-wide lack of fly ash and blast furnace slag to be used as cementitious by-products and huge amounts of quarrying and mining wastes and also the need to preserve it is large and protected natural areas leading to the use of alumino-silicate minerals as the only reasonable alternative to the development of alkali-activated friendly environmental binders. Materials raw cost comparisons between Portland cement based concretes and alkali-activated geopolymeric based concretes are also made showing that Portland cement based ones are by far the most economic ones but not for very long due to the expected increase in Portland cement cost under the recent implementation of CO2 emissions trading scheme (ETS)