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The environmental impact of inorganic polymer mortars from non-ferrous slag was assessed and compared to ordinary Portland cement (OPC) mortar based on a load bearing capacity of 10 MN of bricks of 0.1 m high. Two strategies to minimize the environmental impact of inorganic polymers were pursued. Activating solutions with a lower alkali content (H2O/Na2O = 16, 24, 32, 40, 48; constant SiO2/Na2O = 1.6) were investigated while keeping the water/slag mass ratio of the inorganic polymer mortar mix constant. Another synthesis route considered the complete replacement of the activating solution by maize ashes. These were blended with the slag in different ash/slag mass ratios (0.2, 0.4, 0.6) before adding water, producing a so-called "one-part" inorganic polymer. A sensitivity analysis showed that the effect of compressive strength and transport distance is extensive. Because of this considerable transport distance dependence, several cities in Flanders were selected to perform a detailed LCA study. The optimal scores of the environmental impact were observed for Mol, the location of the sand supplier, and accounted for 23% with respect to OPC for the samples with the activating solution with a ratio of H2O/Na2O = 24 and 17% for an ash/slag ratio of 0.2.

The present paper deals with the synthesis of porous, sintered glass-ceramics obtained at temperatures below 1150°C, originating from inorganic polymers based on fayalite slag. Firing led to the evaporation of water, dehydroxylation, and oxidation of Fe2+ above 345°C. For heating >700°C, the Si-O stretching band shifted from the 1160 and 750 cm-1 to the 1255 and 830 cm-1 region, due to a structural reorganization of the amorphous phase, whereas Fe-O bands appeared at 550 cm-1. The final microstructure consisted predominantly of an amorphous phase, hematite, and franklinite. The open porosity and compressive strength decreased and increased, respectively, as the firing temperature increased. The final values suggest properties comparable to that of structural lightweight concrete, still, the materials synthesized herein, are lighter, and made primarily from secondary resources

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