ABSTRACT Due their high content of silica in an amorphous state the glass, in theory, can behave as pozzolanic material when are finely ground. This opens up an interesting way of reusing these materials in the Portland cement industry (CP), especially considering that solid urban waste (RSU) in Argentina contains between 3 and 5% by weight of glass. This paper studies the behavior of ground white glass from bottles, in compares that corresponding to microsilice (MS), with recognized activity. The objective of this paper is analyzed the structural differences, mineralogical composition, size and particle shape of the MS and the ground glass in terms of reactivity and pozzolanic activity. Experimental results on pastas and mortars with variable percentages of both additions (8, 16 and 24%) are presented. The kinetics of early hydration by conduction calorimetry, the potential pozzolanity by the Frattini test and the X-ray diffraction (DXR) paste hydration monitoring are analyzed. Fluidity and compressive strength results are shown on standar mortars at 2, 7 and 28 days. In general the incorporation of ground glass develops its reactivity more slowly and to a lesser extent than the MS, however it does not reduce the fluidity of the mortars and contributes significantly to the compressive strength.

RESUMEN Por su alto contenido de sílice en estado amorfo, los vidrios en teoría pueden comportarse como materiales puzolánicos cuando se muelen finamente. Esto abre una interesante vía de reutilización de estos residuos en la industria del cemento portland (CP), sobre todo si se considera que los residuos sólidos urbanos (RSU) en Argentina contienen entre el 3 y 5% en peso de vidrio. Este trabajo estudia el comportamiento de residuos de vidrio blanco molido, procedente de botellas en comparación al correspondiente a la microsílice (MS), de reconocida actividad. El objetivo de este trabajo es analizar las diferencias estructurales, composición mineralógica, tamaño y forma de partícula de la MS y el vidrio molido en cuanto a su reactividad y actividad puzolánica. Se presentan resultados experimentales sobre pastas y morteros con porcentajes variables de ambas adiciones (8, 16 y 24% en peso). Se analiza la cinética de hidratación temprana por calorimetría de conducción, la potencial puzolanicidad por el ensayo de Frattini y el seguimiento de la hidratación de las pastas por difracción de rayos X (DRX). Se presentan resultados de fluidez y resistencia a compresión sobre morteros normalizados a 2, 7 y 28 días. Los estudios realizados muestran que la incorporación de vidrio molido como adición, desarrolla más lentamente actividad puzolánica y en menor medida que la MS, sin embargo no reduce la fluidez de los morteros y contribuye significativamente a la resistencia mecánica.

Scrap tires are not considered harmful waste, but their stocking and disposal are a potential health and environmental risk. Properly controlled calcinations at high temperatures make tire combustion an interesting alternative due to its high calorific power, comparable to that of fuel-oil. Consequently, using them as an alternative combustible material in cement kilns makes it possible to give it a valuable use. However, it remains to be assured whether the impurities added to the clinker through these fuels do not affect its structure or properties.This paper shows the studies carried out on different clinkers under laboratory conditions with different levels of addition of scrap tire ashes, added by partially replacing traditional fuel in cement kilns.

Hydration products of Portland cement pastes, hydrated in water and in the presence of zinc ions were studied comparatively at different ages. Hydration products were studied by X ray diffractions (XRD) and infrared spectroscopy (IR). Although IR is not frequently used in cement chemistry, it evidenced a new phase Ca(Zn(OH)3)2. 2H2O formed during cement hydration in the presence of zinc. The significant retardation of early cement hydration in the presence of zinc is assessed in detail by differential calorimetry as a complement to the study carried out by IR and XRD, providing evidence that permits to evaluate the kinetic of the early hydration.

In the last decades the cement industry has used, as a partial substitute for traditional fuel, different industrial wastes in order to profit their residuals energy. In the present work the physicochemical characteristics of clinker, obtained using trade marked alternative fuel for clinker kiln, were evaluated. X-ray diffraction (XRD), Blaine specific surface, pyrometric cone equivalent (PCE), differential thermal analysis-thermal gravimetry simultaneous (DTA-TG), differential calorimetry, porosimetry and mechanical strength were used as the main evaluation techniques of the characteristic of clinker and their behaviors in the early hydration. The additions of the wastes, within the percentages and under the conditions of this test, does no significantly alter the clinker properties but generates a greater crystallinity of the principal clinker phases.