Alteration in molecular structure of alkali activated slag with various water to binder ratios under accelerated carbonation.

Carbonation of alkali activated materials is one of the main deteriorations affecting their durability. However, current understanding of the structural alteration of these materials exposed to an environment inducing carbonation at the nano/micro scale remains limited. This study examined the evolution of phase assemblages of alkali activated slag mortars subjected to accelerated carbonation (1% CO, 60% relative humidity, up to 28 day carbonation) using XRD, FTIR and Si, Al, and Na MAS NMR.

Continuous elimination of Pb2+, Cu2+, Zn2+, H+ and NH4 + from acidic waters by ionic exchange on natural zeolites.

A study of breakthrough curves for cations usually found in acid mine drainage (Pb(2+), Cu(2+), Zn(2+) and H(+)) and municipal wastewater (NH(4)(+)) have been conducted on some natural zeolitic tuffs. The zeolitic tuffs used in this study are: three zeolitic tuffs from Cayo Formation, Guayaquil (Ecuador), characterized by X-ray diffraction as clinoptilolite (sample CLI-1) and heulandite (samples HEU-1 and HEU-2)-rich tuffs, and two zeolitic tuffs from Parnaiba Basin, Belem do Pará (Brazil), characterized as stilbite-rich tuffs (samples STI-1 and STI-2). The clinoptilolite sample CLI-1 shows an exceedingly good exchange capacities for Pb(2+) and NH(4)(+) as received, and also a very high exchange capacity for Cu(2+) and Zn(2+) when conditioned with 2M sodium chloride, with much higher values than those reported in the literature for other clinioptilolite ores.

Assessment of Pb-slag, MSWI bottom ash and boiler and fly ash for using as a fine aggregate in cement mortar.

Three types of wastes, metallurgical slag from Pb production (SLG), the sand-sized (0.1-2 mm) fraction of MSWI bottom ash from a grate furnace (SF), and boiler and fly ash from a fluidised bed incinerator (BFA), were characterized and used to replace the fine aggregate during preparation of cement mortar. The chemical and mineralogical behaviour of these wastes along with the reactivities of the wastes with lime and the hydration behaviour of ordinary Portland cement paste with and without these wastes added were evaluated by various chemical and instrumental techniques.