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Glass from the solid urban waste is presented mainly in amber, green and transparent colour. Regarding their reactivity, several studies argue that there are differences among each colour when they...

A dolostone from Sierras Bayas (Buenos Aires Province, Argentina) is characterized for use as supplementary cementitious material (SCM). This comparative study with usual limestone filler includes the results of grindability and the performance of blended cements with 20% filler. Carbonate stones were ground in a laboratory ball mill to attain the objective (d50

Fluxes between fractured-karstified and detritic aquifers are commonly poorly understood in many environments. These two types of aquifers are in contact in the southeastern Pampean region in the Argentine Buenos Aires province, and the aim of this work is to analyze their relationship contributing to improve the hydrological model. A joint application of hydrochemical and multi-isotope (δ2H, δ18O, δ13C-TDIC, δ18O-TDIC, 87Sr/86Sr) tools was used. TDIC, δ2H, δ18O and δ13C-TDIC allowed differentiating two main end members. Water in the Pampeano aquifer (PA) which is transferred from the fractured-karstic aquifer (F-KA) is characterised by high TDIC around 500–700 mg/L, isotopically depleted in 18O (about −5.5 ‰) and high δ13C-TDIC (around −10.0 ‰). The other end member is direct recharge water infiltrated into the PA with TDIC ranging from 400 to 500 mg/L, slightly enriched in 18O (δ18O = −4.8 ‰), and δ13C-TDIC in the range of soil CO2 as a result of reactions with calcrete concretions (from −20.0 to −9.0 ‰). Dolomite dissolution is the main process controlling the chemistry of the low-mineralized (Mg–Ca-HCO3) waters, whereas high-mineralized (Na-HCO3) waters are strongly influenced by ion-exchange reactions with adsorbed Ca2+ and Mg2+ and by evaporation.

Previous studies revel that calcined illitic clay acts as potentially supplementary cementitious materials in Portland cement. Packing and workability are improved; the hydration products are like that corresponding to Portland cement and it also produces a pore size refinement improving the mechanical performance at later ages. The illitic clays have a high activation temperature and its pozzolanic activity is slow; however, it is the most abundant type of clay in several regions of the world, and therefore, their used as supplementary cementitious materials must be improved. Therefore, compression resistance values denote the effect of dilution at early ages. On the other hand, materials containing silica and alumina can be activated in an alkaline form, which would help to compensate the dilution generated by the addition. In this work, the alkaline activation of cement mixtures with calcined illitic clays is presented. As an alkaline activator, finely ground discarded glass is used. The finely ground glass, due to its amorphous nature, reacts quickly contributing to early hydration, while providing the alkalis necessary for an alkaline activation. In this paper, the blended cements with 30% of calcined illitic clays were analyzed and the effect of different percentages of replace by glass powder wastes was studied.

This paper studies the addition (0–40% w/w) of natural zeolite (NZ, 84% clinoptilolite) in blended cements made with Portland cement (PC) with low and medium C3A content. The isothermal calorimetry was used to understand the effect of NZ on the early cement hydration. For low C3A cement, the addition of NZ produces mainly a dilution effect and then the heat released curve is similar to plain cement with lower intensity. For medium C3A cement, the curve shows the C3S peak in advance and a high intensity of third peak attributed to C3A hydration. The high cation fixed of NZ reduces the ions concentration (especially alkalis) in the mixing water stimulating the PC hydration. The flowability decreases when the NZ replacement level increases. Results of Fratini’s test show that NZ with both PCs used presents slow pozzolanic activity. At early age, XRD and FTIR analyses confirm that hydration products are the same as that of the corresponding PC and the CH is progressively reduced after 28 days and some AFm phases (hemi- and monocarboaluminate) appear depending on the NZ percentage and the PC used. For low replacement levels, the compressive strength is higher than the corresponding PC from 2 to 28 days. For high replacement levels, the early compressive strength is lower than that of corresponding plain PC and the pozzolanic reaction improves the later compressive strength of blended cements. Fil: Rahhal, Viviana Fátima. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina Fil: Pavlík, Zby?ek. Czech Technical University in Prague; República Checa Fil: Tironi, Alejandra. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina Fil: Castellano, Claudia Cristina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina Fil: Trezza, Mónica Adriana. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina Fil: Černý, Robert. Czech Technical University in Prague; República Checa Fil: Irassar, Edgardo Fabián. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina

The thermal transformation (100–1100 °C) of two shales containing illite-chlorite (I/Ch), feldspars and quartz from La Cabañita quarry (Olavarria, Argentine) was studied by TG-DTA, XRD and FTIR. It included dehydration; dehydroxylation (350–800 °C) and the structural collapse of illite (950 °C); while the neoformations were hematite and iron spinel. For rotary kiln production, the glass formation due to feldspars melting at 1100 °C was the upper temperature limit. For the calcination temperature range of 900–1100 °C, grindability increased when calcination temperature increased, but the specific surface area decreased. The high Fe-content caused a reddish color of particle surface, but their cores were black. The pozzolanicity test was satisfied at 7 days and strength activity index was 0.84–0.97 and 0.94–1.04 at 28 and 90 days, respectively. The addition of calcined shale did not affect the mortar flow and the hydration products assembly. Calcined I/Ch shale was a slow reactive pozzolan with good strength at 90 days. Fil: Irassar, Edgardo Fabián. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina Fil: Bonavetti, Viviana Lidia. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina Fil: Castellano, Claudia Cristina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría; Argentina Fil: Trezza, Mónica Adriana. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina Fil: Rahhal, Viviana Fátima. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina Fil: Cordoba, Gisela Paola. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría; Argentina Fil: Lemma, Roxana. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina

Clayminerals are the most abundant raw materials for calcined pozzolans. Thermaltransformation includes dehydration, dehy­droxylation, mineral collapse, andneo-formation. Depending on the type and amount of clay mineral, and the natureand amount of associated minerals, the thermal treatment determines the pozzo­lanicactivity. In this paper, 10 natural shales or clays (six illite, two kaolin,and two loess) from Buenos Aires Province (Argentina) were identified using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), andthermogravimetry (TG). The thermal transformation was checked by XRD or FTIR and the elec­trical conductivity (EC) at the calcination window. The pozzolanicactivity was evaluated using the Frattini test and strength activity index (SAI). The Frattini test gives positive results after 7 days and SAI is greaterthan 0.90 at 28 days, but the compressive strength development depends on mainclay mineral. The EC was effec­tive to evaluate the Ca(OH)2 fixationduring the first time and it is related to the specific surface obtained. Fil: Irassar, Edgardo Fabián. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría. Departamento de Ingeniería Civil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina Fil: Tironi, Alejandra. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría. Departamento de Ingeniería Química; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina Fil: Bonavetti, Viviana Lidia. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría. Departamento de Ingeniería Civil; Argentina Fil: Trezza, Mónica Adriana. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría. Departamento de Ingeniería Química; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina Fil: Castellano, Claudia Cristina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría. Departamento de Ingeniería Civil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina Fil: Rahhal, Viviana Fátima. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría. Departamento de Ingeniería Civil; Argentina Fil: Donza, Horacio Ariel. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría. Departamento de Ingeniería Civil; Argentina Fil: Scian, Alberto Nestor. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina

The aim of this study is to evaluate the behavior of glass powder waste as alkaline activator of slag when both are used in blended cement. The slag blended cement was prepared with 70% slag, and then the slag was replaced with 10-20% glass powder by mass. The self-activation concept is here introduced. Ground glass releases alkalis through dissolution in a slow and sustained way over time. This would activate slag. Ground glass improves fluidity of mortars and the compressive strength overcomes dilution and increases with age due to the combined pozzolanic action of slag and glass. The proposed blended cement has better mechanical properties than slag-cement. The proposed blended cement has better mechanical properties than slag-cement and due to less use of slag, it becomes more sustainable and it contributes to waste management. El objetivo del presente trabajo es evaluar el comportamiento de un residuo molido de vidrio como activador interno de la escoria cuando ambos son usados en un cemento mezcla. El cemento de escoria fue preparado con un 70% de escoria y luego la escoria se reemplazó en un 10 y 20% en masa por vidrio molido. Este trabajo introduce el concepto de auto-activación. El vidrio molido libera álcalis por disolución, en forma lenta y sostenida en el tiempo que activarían la escoria. La presencia de vidrio molido mejora la fluidez de los morteros y la resistencia a compresión supera la dilución y crece con la edad por la acción puzolánica combinada de la escoria y el vidrio. El cemento mezcla propuesto tiene mejores propiedades mecánicas que el cemento de escorias pero con menor contenido de escoria por lo que es más sustentable y contribuye al manejo de residuos.

This study investigated the physical and chemical effects of dolostone (DF) as fillers (10 to 30% by weight) in blended portland cements (BPC) and compared with limestone (LF) ground with similar fineness. The addition of both fillers increases the packing density of BPC up to 40% replacement and the standard mortar, while the water film thickness was greater than those corresponding to PC up to a w/cm ~ 0.45. For increasing filler replacement, the mini-slump decreases, the setting time is in advance and the hydration heat curves show a shorter dormant period, acceleration of C3S-hydration and greater sulfate depletion. These phenomena were more significant for LF. The hydrated compounds and it apparition sequence were similar at 20 °C for DF and LF, but no sign of harmful dedolomitization reaction was found at 40 °C during 365 days. The compressive strength of the mortar after 28 days depends on the percentage of filler replaced, regardless of its mineralogical composition. Results suggest that DF, as occurs with LF, is a suitable addition as main component to BPC with satisfactory and stable properties.

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. 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.

The aim of this work is focused to identify natural resources with industrial potential to be used as supplementary cementitious materials (SCMs) in Portland blended cements. Two clays obtained from the quarries near to Barker in Tandilia System (Buenos Aires- Argentina) were studied. The geneses of these rocks are by a hydrothermal alteration and include the presence of pyrophillite. Whole-rock were characterized by XRD and FTIR spectroscopy indicating that main clayed minerals are kaolinite (Si2Al2O5(OH)4), illite (K0.66Si3.33Al2.66O10(OH)2) and pyrophillite (Si4Al2O10(OH)2) associated with feldspar. The thermal transformation was studied by differential thermal analysis and the phase changes were confirmed by XRD and FTIR. Samples of clays were calcined at different temperature (550 to 1050 °C), the electrical conductivity was measured and the dissolved silica in simulated pore water solution was quantified. The pozzolanic activity was measured by the compressive strength activity index, on blended cement mortars containing 25% by weight of calcined clays.

Illite-chlorite clay from quarry located at Buenos Aires Province (Argentine) was characterized by XRD, FTIR and TG-DTA. Mineralogical transformations during clay firing under oxidizing conditions were studied from 100 to 1100 °C by XRD and FTIR. From select temperatures, calcined clay was ground (85% passing to 45 µm sieve) and the pozzolanic activity of blended cements (25% w/w) was evaluated by the Frattini test and the strength activity index (SAI). Finally, the hydration phase assemblage of blended cements was studied using XRD analysis.

In this paper, the paste workability and hydration progress of blended cements containing different calcined illitic clays were studied. For blended cements with different replacement percentages, the particle packing, the water film thickness (WFT) and the flow spread was modelled and measured. Results indicate that blended cement with ground illitic calcined clays maintain or reduce the packing, so the flow spread of blended cement pastes decrease when the replacement percentage increases. For blended cements with 25% of calcined illitic clay, the early hydration was described by the calorimetric curve, and later the hydration products were analysed by XRD and TG analysis and the pore size distribution (MIP) at 2, 7, 28 and 91 days. Finally, the performance of blended cements was evaluated by the compressive strength. For blended cements, the hydration products are similar to that corresponding to ordinary Portland Cement (OPC) and it also produce a pore size refinement that improve the compressive strength at later age.

Two waste fired brick powders coming from brick factories located in Argentine and Czech Republic were examined as alternative mineral admixtures for the production of blended cements. In pastes composition, local Portland cements (Argentine and Czech) were substituted with 8&ndash, 40%, by mass, with powdered ceramic waste. For the ceramic waste-Portland cement system, workability, the heat released, pozzolanity, specific density, compressive strength, hydrated phases, porosity, and pore size distribution were tested. The relevance of the dilution effect, filler effect, and pozzolanic activity was analyzed to describe the general behavior of the pozzolan/cement system. The properties and performance of cement blends made with finely ground brick powder depended on the composition of ceramic waste and its reactivity, the plain cement used, and the replacement level. Results showed that the initial mini-slump was not affected by a low ceramic waste replacement (8% and 16%), and then it was decreased with an increase in the ceramic waste content. Brick powder behaved as a filler at early ages, but when the hydration proceeded, its pozzolanic activity consumed partially the calcium hydroxide and promoted the formation of hydrated calcium aluminates depending on the age and present carbonates. Finally, blended cements with fired brick powder had low compressive strength at early ages but comparable strength-class at later age.

The pozzolanic activity of calcined clays depends on the type and amount of clayed minerals, the nature and amount of impurities, the thermal treatment used for its activation and the specific surface obtained after calcination. In this paper, four test methods for assessment the pozzolanic activity on seven calcined clays (five kaolinites and two bentonites) were analyzed. Natural clays were calcined and investigated by two direct tests (Frattini and saturated lime) and two indirect tests (strength activity index and electrical conductivity). Frattini test and the strength activity index (SAI) were found to be the most accurate and reliable methods to assess pozzolanic activity over time. Frattini test evaluates accurately the calcium hydroxide (CH) consumption by pozzolanic reaction, and SAI test discriminates the real contribution of pozzolanic reaction to densification of microstructure. The electrical conductivity (EC) and the lime consumption (LC) tests evaluate the ability of pozzolanic material to fix CH during the first time of contact and their results are correlated with the specific surface of calcined clay.

Five natural kaolinitic clays from different regions of Argentine, with different kaolinite content, different impurities and different degree of crystallinity were calcined in a fixed-bed electrical furnace at 700 °C. Clays were characterized by X-ray diffraction (XRD) and Fourier transformed infra-red spectrometry (FTIR) that provides an index about the order/disorder of the structure. After heat treatment, the structural changes were characterized by XRD and FTIR, and pore size distribution and specific surface were determined. Their pozzolanic activity was evaluated with the Frattini test, electrical conductivity in saturated Ca(OH) 2 solution and compressive strength on mortars at 7, 28 and 90 days. Among tested clays, four of them can be classified as pozzolan by the Frattini test. The pozzolanic activity of the natural clays showed good correlation with the content of kaolinite, the inversed of structure order determined by FTIR, and the specific surface of calcined clays. This study confirms that natural clays other than pure kaolinite can be interesting pozzolanic materials when thermally activated. Fil: Tironi, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría; Argentina Fil: Trezza, Mónica Adriana. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría; Argentina Fil: Scian, Alberto Nestor. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina Fil: Irassar, Edgardo Fabián. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarría; Argentina

The calorimetric technique provides continuous, direct, and general measurements of the course of coexisting reactions and their interactions during hydration of blended cement at early age. In this article, this technique is used to analyze the influence of compositional and process variables on the early age hydration of Portland limestone cements (PLC) made by intergrinding in a full size-cement plant. Eight cements, the vertices of 23 factorial design, were made with a limestone filler content (LF) of 0 and 24%, a gypsum content (GC) of 2.5, and 5.0%; and a fineness, measured as that fraction retained on a 45 μm sieve (R45), of 5 and 18%, to study their effects on the heat released. In addition, a PLC with a composition nearly to the center point of 23 designs was analyzed. Measurements were performed on cement pastes (w/cm = 0.4) using a semiadiabatic differential calorimeter operating at 20 °C during 48 h. At different time, the heat released was determined and it was modeled using a linear mathematical model including the three variables (LF, R45, CG) and their interactions. The significance of the model, the variables and the interactions was judged using the analysis of variance. Results of model show that heat released is reduced by LF due to physically dilution phenomenon, which is directly proportional to LF content. The R45 exerts its major influence during the development of second peak (12–21 h) but later its effect declines to null contribution. GC retards and attenuates the hydration reactions moderately until 30 h, and then its increase contributes to Qt due to the formation of ettringite and its transformation. The only significant interaction was LF with R45 during the second peak development. Results present good correlation with the isolate measurement of compressive strength at 12, 24, and 48 h.

This paper examines the behavior of Portland limestone cements (PLCs) made by inter-grinding clinker, gypsum and limestone in a full size-cement plant, while varying the content of limestone filler (LF – 0% and 24%), content of gypsum (GC – 2.5% and 5.0%) and PLC fineness, measured as that fraction retained on a 45 μm sieve (R45 – 5% and 18%). The influence of the combined action of these variables on the particle size distribution (PSD) and early age properties of blended cement was studied using a 23 experimental design. Fineness evaluated by the parameters of the Rosin–Rammler–Springer–Bennett (RRSB) distribution function shows that the uniformity index (n-parameter) depends strongly on LF content; while the characteristic diameter (x′-parameter) depends on R45 and LF content. As for the inter-grinding process, water demand is reduced by incorporation of LF and increased by reduction of R45, producing a compensation. Setting time is mainly affected by R45; LF produces a few modifications and the influence of gypsum content and gypsum–limestone interaction are not as obvious. Calorimetry studies show that LF decreases the height of the main peak and the total heat released, while gypsum content modifies the time of acceleration and the post-peak hydration, specifically for fine cements. In accordance, chemical shrinkage decreases when R45, LF content and gypsum content increase. Up to 2 days, strength is mainly governed by the R45 and the LF in PLC, which act inversely. At early ages, the influence of gypsum content on early properties increases up to 48 h. XRD analysis shows its stimulation of calcium silicate hydration during the first hours and ettringite formation after 24 h.

Hazardous wastes, coming from industries are usually used in the Portland cement production in order to save energy, costs and/or stabilize toxic substances and heavy metals inside the clinker. This work focuses on the effect produced on the Portland cement clinker when it is obtained using tanned leather shavings whit chrome salts as part of the process. The raw materials were clinkered in laboratory with different percentages of shavings, which contained 2% of Cr(2)O(3). DTA-TG of the raw mixtures was performed to evaluate the thermal behavior changes that can take place during the clinkering process, analyzing the crystalline phases obtained by XRD. The milling behavior of clinkers was studied, analyzing also the refractoriness variation on those clinkers. The chrome retention was evaluated by leaching tests. The structural modification determined by the chrome presence in the silicate structure brought consequences in the hydration speed, mechanical resistance and pore distribution.

Numerous investigations on the immobilization of chromium in cement-based systems were carried out in the recent years. The aim of this study is to analyze the influence of the crystallinity of kaolinite used to make calcined kaolinitic clay when are used in pastes for immobilization of Cr(VI). In previous study, it was found that the reactivity of kaolinitic calcined clays used as partial replacement of Portland cement largely depends on the crystallinity of kaolinite in the raw clay. Calcined clays obtained from raw materials containing kaolinite with disordered structure presents a very high pozzolanic activity allowing high-percentage replacement (30 %) in blended cements. In this study, pastes of blended cement with 15 % and 30 % by mass of two kaolinitic calcined clays (order and disorder structure of kaolinite) were elaborated using a solution of 5000 ppm of K2Cr2O7 and a solution-to-cementing material ratio of 0.50. The immobilization efficiency was measurement by lixiviation test and the modifications in the hydrated phases was studied by X-ray diffraction and SEM/EDS analysis. The results shown that kaolinitic calcined clay from ordered kaolinite was more efficient than disordered kaolinite to retention of Cr(VI), reaching values higher than that of PC-paste.

The properties and hydration of blended cements containing from 8 to 40 % by mass of ceramic waste (CW) from different countries (Argentine and Czech Republic) are investigated. The mini slump, the heat released rate up to 48 h, the pozzolanic activity and the compressive strength at 2, 7 and 28 are determined. Hydration process is characterized by XRD analysis and the pore size refinement is accessed by MIP. Results show that both CWs increase the water demand with increasing the cement replacement level, and they possess pozzolanic activity after 7 days. At early age, the heat released and the compressive strength are lower than that of the Portland cement (PC) for all replacement levels. At 28 days, the pozzolanic reaction significantly improves the compressive strength. From XRD analysis, it is evident that CW reacts to form AFm phases (hemicarboaluminate at 7-28 and later transformed to monocarboaluminate) depending on the replacement level and CW used. CH peak reduction due to the pozzolanic reaction appears at 28 days. The reduction of porosity up to 16-24 % of CW replacement is in accordance with the compressive strength results.

El cemento portland juega un rol cada vez más importante en el manejo de residuos industriales peligrosos. La técnica de solidificación/estabilización (S/S) basada en el cemento ha demostrado ser efectiva para el aislamiento de residuos peligrosos, especialmente metales pesados. En este trabajo se discutirá el efecto que la adición de filler calcáreo al cemento produce en la S/S de metales como cromo, cadmio y plomo. Se realizaron estudios de difracción de rayos X, espectroscopia infrarroja, calorimetría y lixiviación a fin de evaluar el nivel de inmovilización en morteros conteniendo estos elementos. Se encontró un alto grado de inmovilización de los iones Cd, Cr y Pb aunque su presencia modifica la velocidad y los compuestos obtenidos durante la hidratación del cemento. Los resultados muestran que el cemento con fillers calcáreo es más eficiente que el cemento normal para la satisfactoria inmovilización de metales pesados. Portland cement plays an ever more important role in the management of hazardous industrials wastes. Cement - based solidification/stabilization (S/S) technique has been effectively demonstrated as a treatment to isolate hazardous waste especially heavy metals. In the presents work will be discuss the effect that limestone filler addition to portland cement produced in the S/S of metals as chromium, cadmium and lead. X-ray diffraction, infrared spectroscopy, calorimetric and leaching test were carried out to evaluate the level of immobilization in mortars made containing these elements. It was found that the degree of Cd, Cr and Pb ion immobilization was very high but modifies the rate and the components obtains during the cement hydration. The results thus presented prove that limestone blended cements material can be successfully used as a heavy metals immobilizing agent rather than the normal portland cement.

Different Argentine kaolinitic clays were selected to study their potential pozzolanic activity. The incidence of several factors such as the origin of deposits (primary or sedimentary clays), mineralogical composition, and the order/disorder degree of kaolinite structure on the pozzolanic activity was analyzed. Five clays were characterized by chemical analysis, X-ray diffraction (XRD), Fourier transformed infra-red spectroscopy (FTIR), differential thermal analysis combined with thermo-gravimetric analysis (DTA/TG), and Scanning Electron Microscopy (SEM). The crystallinity of kaolinite in raw clays was estimated by five indexes: FWHM-001, FWHM-002, Hinckley Index (HI), and R2 on the XRD patterns, whereas the P0 index was determined on the FTIR spectra. Clays were calcined at 700 °C and ground until all mass passed through a 45 μm sieve. Pozzolanic activity was evaluated by the Frattini test and the strength activity index (SAI) at 7, 28 and 90 days using a blended cement containing 30% by weight of calcined clay. Complementary, the presence of remaining Ca(OH)2 in mortar was checked by XRD at 28 and 90 days. Results indicate that four blended cements presented a very good pozzolanic activity evaluated by the Frattini test at 7 and 28 days and they have a Different compressive strength with a SAI N 1 at 90 days. In these blended cements, the Ca(OH)2 released by cement hydrationwas consumed. Analyzing the incidence of factors on pozzolanic activity, it can be concluded that clays containingmore than 50% kaolinite provide enough amount of reactive material, and that the rate of the pozzolanic reaction is improved when the kaolinite mineral present in the clay has a disordered structure. Fil: Tironi, Alejandra. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingenieria de Olavarria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil; Argentina Fil: Trezza, Monica Adriana. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingenieria Olavarria; Argentina Fil: Scian, Alberto Nestor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro Tecnológico de Recursos Minerales y Cerámica (i); Argentina Fil: Irassar, Edgardo Fabían. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentina

Nowadays, different kinds of industrial wastes are increasingly used in the clinkering process by the cement industry, with the aim of taking advantage of their energy content or confining unsuitable substances. This work evaluates the physicochemical characteristics of the clinkers obtained after incorporating three different wastes in different proportions: two of them with energetic capacity—trade marked waste fuel and waste carbon of petroleum—and the third that would be confined—pyrolitic carbon. The fusion temperature of the mixtures, the differential thermal analysis and the thermogravimetric analysis (DTA/TG) during clinkering and after hydration, the specific surface area at the same milling times, X-ray diffraction (XRD) and mechanical strength of the pastes elaborated with a water/cement 0.4 relation were analyzed. The results obtained were compared to those of the clinker obtained without additions.

Considering the increasing use of limestone cement manufacture, the present paper tends to characterize limestone behavior in the presence of Cr(VI). The research reported herein provides information regarding the effect of Cr(VI) from industrial wastes in the limestone cement hydration. The cementitious materials were ordinary Portland cement, as reference, and limestone blended cement. The hydration and physicomechanical properties of cementitious materials and the influence of chromium at an early age were studied with X-ray diffraction (XRD), infrared spectroscopy (FTIR), conductimetric and mechanical tests. Portland cement pastes with the addition of Cr(VI) were examined and leaching behavior with respect to water and acid solution were investigated. This study indicates that Cr(VI) modifies the rate and the components obtained during the cement 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., Centro de Tecnología de Recursos Minerales y Cerámica

This paper examines the influence of type of kaolinite in the raw clay on the performance of calcined clays as supplementary cementing materials. Two kaolinitic clays were characterized, calcined then ground and used as partial replacement of Portland cement at 15% and 30% by mass. The results show that both kaolinitic calcined clays are an effective pozzolan with different reaction rate. The reactivity is related to the specific surface area obtained after calcination and it depends on the structure of kaolinite. Raw clay containing disordered structure presents a very high pozzolanic activity allowing high replacement levels (30%) in blended cements. Fil: Tironi, Alejandra. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina Fil: Castellano, Claudia Cristina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina Fil: Bonavetti, Viviana Lidia. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina Fil: Trezza, Mónica Adriana. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina Fil: Scian, Alberto Nestor. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina Fil: Irassar, Edgardo Fabián. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina

Se analiza la reactividad de dos bentonitas calcinadas, procedentes de diferentes regiones de Argentina para su utilización como adiciones puzolánicas al cemento Pórtland. A través de técnicas de: DRX, espectroscopia IR, ensayos de reactividad con Ca(OH)2. porosimetría por intrusión de mercurio y resistencia a la compresión; se relacionan los cambios estructurales producidos durante el tratamiento térmico con el comportamiento puzolánico. The reactivity of two calcined bentonites from different regions of Argentina for use as pozzolanic additions to Portland cement were analyzed. Through techniques of XRD, IR spectroscopy, tests of lime consumption and mechanical strength were relations structural changes, occurring during heat treatment, with pozzolanic behavior.

Las centrales termoeléctricas generan una gran cantidad de residuos sólidos como producto de la combustión del carbón, conocidos como cenizas. Existen dos tipos de cenizas: volantes - de tamaño muy fino-, que son arrastradas por la corriente de humos de los sistemas de eliminación de partículas y, -las sedimentadas - más gruesas, que se funden y se aglomeran acumulándose en el fondo del homo o en los tubos de las calderas. Intentando resolver factores técnico-económicos y ecológicos al mismo tiempo, en este trabajo presentamos los resultados obtenidos de la incorporación de un 20% en peso de cenizas sedimentadas (Cs) como adición activa al cemento Portland. Se estudia la potencial puzolanidad de la adición y se muestran resultados de seguimiento de la hidratación a temprana edad, variación de color y resistencia mecánica del material compuesto obtenido por molienda conjunta del clinker portland y el material residual., The power plants generate a large amount of solid waste, known as ash, as a product of combustion of coal. There are two types of ash: fly - very fine in size- which are carried by the flow of smoke removal systems, and sedimentary particles -coarse particles - which are melted and agglomerated accumulated in the bottom of the furnace or in the boiler tubes. Trying to resolve technical-economic and ecologic factors at the same time, this work presents the results of adding a 20% weight of sediment ash (Cs) as an active addition to the Portland cement. The potential pozzolanity of the addition is studied and it is shown proceeding of the hydration at early age, color variation and mechanical strength of the composite material obtained by grinding together Portland clinker with the residual material., Centro de Tecnología de Recursos Minerales y Cerámica, Facultad de Ingeniería

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., Centro de Tecnología de Recursos Minerales y Cerámica

The aim of this work is to study the recycling of tile wastes in the manufacture of blended cements. Cracked or broken ceramic bodies are not accepted as commercial products and, therefore, the unsold waste of the ceramic industry becomes an environment problem. The use of powdered roof tile in cement production, as pozzolanic addition, is reported. The wastes were classified as nonglazed, natural and black glazed tiles. The mineralogy of the powders was controlled by SEM-EDX microscopy, XRD analysis and FTIR spectroscopy. Particle size was checked by laser granulometry. Once the materials were fully characterized, pozzolanic lime consumption tests and Fratini tests were carried out. Different formulations of cement-tile blends were prepared by incorporation of up to 30% weight ratios of recycled waste. The compressive strength of the resulting specimens was measured. The evolution of hydration of the cement-tile blends was analyzed by XRD and FTIR techniques. Vibrational spectroscopy presented accurate evidence of pozzolanic activity. The results of the investigation confirmed the potential use of these waste materials to produce pozzolanic cement.

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 a previous paper we presented a general analysis of the infrared spectra of the different Ln2BaMIIO5 structural types [2]. As the tetragonal I4/mcm structure is only present in La2BaZnO5 and Nd2BaZnO5 we have now attempted to obtain a deeper insight into its vibrational behaviour by careful analysis of the Raman and infrared spectra of Nd2BaZnOs, for which a detailed structural analysis has been published recently., Universidad Nacional de La Plata

Recently, we investigated the infrared spectra of a series of phases of this type, of composition Nd2_xCexCuO4-y and Nd2CuO4-xFx. In order to extend these studies and to obtain a more general picture of the vibrational behaviour of these materials, in this study we investigated the infrared spectra of a great number of phases containing different pairs of tetravalent and trivalent cations., Centro de Química Inorgánica

In this paper we report the vibrational spectra of the so-called "green phases", of composition Ln2BaCuO5. These materials are not superconducting but often appear as a major impurity during the synthesis of the superconducting ceramics., Facultad de Ciencias Exactas

In the clinker production process, the main component of Portland cement (PC), large amount of CO2 are emitted into the atmosphere. The use of calcined kaolinitic clays as supplementary material of cement is an alternative to mitigate the environmental impact. In this paper, the influence of the replacement of PC by two calcined kaolinitic clays (15 and 30%), with high content of metakaolinite and different reactivity was studied. Calcined kaolinitic clays were characterized, the pozzolanic activity using Frattini test, the compressive strength, rate of water absorption (sorptivity), the assemblage of hydration products and the pore size distribution were determined at 28 days. The results show that the replacement of high percentage (30%) of very reactive clays improves the mechanical behavior and durable parameters compared with those obtained for plain PC., Centro de Tecnología de Recursos Minerales y Cerámica

Thermally activated clays, especially kaolinitic clays, are today revaluated as a source of supplementary cementitious materials to reduce the CO2 emissions and energy consumption originated in cement production. In this work, the influence of different thermal treatments on the pozzolanic activity of raw kaolin with 98% kaolinite and ordered structure was studied. Results show that pozzolanic activity of calcined kaolin decays when using a thermal treatment at high temperatures (800 iC) and high periods of residence (30 minutes). Furthermore, low calcination temperature (700 iC) must be corresponding with a residence time that guarantees a high dehydroxylation percentage. Sample treated during 10 minutes (94%DH) was less reactive than the one treated during 30 minutes (96%DH). Results contribute to the industry purposes to reduce the energy consumption, the CO2 emission and to contribute with new alternatives of sustainable development.

During the last decades, there has been an increasing interest in the cement industry to incorporate pozzolanic materials to cement in order to reduce CO2 emissions, and increase the strength and durability of mortars and concretes. In this work, the potential use of two thermically activated kaolinitic clays as pozzolanic materials coming from different deposits of Argentina, is studied. Both Kaolinitic clays have different kaolinite content and a different order-disorder structure. After thermal treatment and grinding, their pozzolanic properties were studied on blended cement containing 30% of calcined clays. It was determined that mortars containing calcined clay with a higher percentage of kaolinite and certain disorder degree in its crystallinity previous to calcination, developed higher resistance to compression. This can be attributed to larger quantity of hydration products caused by the pozzolanic reaction, which also produces a better pore size arrangement. To conclude, when kaolinitic clays are used as pozzolana, kaolinitic percentage and structural disorder are variables to be taken into account.