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This research project seeks to improve soil properties through experimentation with geotechnical purposes. For this, will be used natural volcanic pozzolana in 5%, 10%, 15% and brick dust in 10% giving it a second reuse. The soil improvement will be analyzed with the proposed additions and its influence on the results. It is concluded that the addition improves the behavior of the soil by decreasing its plasticity index, increases the compaction index and improves the geotechnical parameters.

Made available in DSpace on 2015-04-22T22:08:53Z (GMT). No. of bitstreams: 1 Dissertacao Final Samantha Lima.pdf: 10148784 bytes, checksum: da28d9e29cbe9877d46e4cfcdfeb3027 (MD5) Previous issue date: 2009-05-18 / Fundação de Amparo à Pesquisa do Estado do Amazonas / The experimental program of this research was developed in order to evaluate the silica gel performance in cement based pastes. Thus, parameters of silica gel from rice husk ash were studied extraction. The incorporation of silica gel was made by the partial replacement of 0%, 2,5% e 5% of the cement mass in 0,45 water-cementitious material (w/cm) paste, and 0%, 5%, 7% in 0,5 w/cm paste. The silica gel behavior was evaluated based on X- ray diffraction, thermal analysis and compressive strength after 3, 7 and 28 days of curing. The results showed that is possible the production of pastes with excellent mechanical performance from the silica gel application as pozzolan. In particular, the compressive strength of the silica gel paste was about 46% higher than the reference paste. Moreover, there was a decrease of the more than 50% of calcium hydroxide content in the silica gel paste, indicating the pozzolanic activity of the silica gel produced in this work. / O programa experimental realizado no presente projeto foi desenvolvido de forma a avaliar o desempenho da sílica gel em matriz de cimento Portland. Para tal, foram estudados os parâmetros de extração da sílica gel da cinza da casca de arroz. O gel de sílica foi aplicado em pastas como substituto parcial do cimento Portland nos teores de 0%, 2,5% e 5% em massa, para uma relação água-aglomerante de 0,45, e de 0%, 5%, 7% em massa, para uma relação água-aglomerante de 0,50. O comportamento da sílica gel foi avaliado através de ensaios de difração de raios-x, análise térmica e resistência à compressão nas idades de 3, 7 e 28 dias. Os resultados indicaram que é possível a produção de pastas de excelente desempenho mecânico a partir da aplicação de sílica gel como pozolana. Em particular, a sílica gel promoveu um aumento da resistência à compressão de até 46% aos 28 dias e consumiu mais de 50% do hidróxido de cálcio, fato que se atribui a elevada atividade pozolânica da sílica gel.

Les travaux présentés dans ce mémoire sont consacrés à l'étude des processus d'adsorption des anions phosphate par la rouille verte ferrique carbonatée et la ferrihydrite. L'objectif final vise une application au traitement des eaux usées en milieu rural. La synthèse des deux oxydes de fer a été réalisée et leurs propriétés physico-chimiques caractérisées. Un intérêt particulier a été consacré à comparer les propriétés structurales de la rouille verte ferrique en fonction de différents paramètres de synthèse. Une étude approfondie des propriétés physico-chimiques de surface de la ferrihydrite par spectroscopie de photoélectrons X a quant à elle été réalisée. La réactivité de ces deux oxydes a ensuite été abordée en mode discontinu où l'équation cinétique du pseudo-second ordre et le modèle d'isotherme de Freundlich offrent les meilleurs ajustements. L'influence de divers paramètres a été prise en compte comme le pH, la force ionique, etc. Le mode continu a été envisagé sur un matériau de filtration constitué de l'oxyde de fer déposé sur de la pouzzolane. La méthode de fabrication ainsi que les conditions optimales de préparation du matériau de filtration ont été déterminées. Les mécanismes d'adsorption en condition de flux hydrodynamique ont alors mis en évidence des phénomènes advectifs, diffusifs et une régionalisation de l'eau régissant l'adsorption au sein de la colonne. Des informations telles que les capacités d'adsorption ou l'influence du débit sur le processus d'adsorption ont pu être également obtenues. Une expérience préliminaire sur une eau usée prétraitée met finalement en évidence une quantité adsorbée particulièrement intéressante pour une application industrielle potentielle / The Ph.D. work, presented in this manuscript, is devoted to evaluating phosphate adsorption process on carbonate ferric green rust and ferrihydrite. The main objective concerns an application for the treatment of waste water in rural areas. Both iron oxides are first synthesized and their physico-chemical properties characterized. The ferric green rust structural properties differences as a function of synthesis parameters such as aging period and addition of hydrogen peroxide solution is of particular interest. A detailed study of surface physico-chemical properties by X Photoelectron Spectroscopy is carried out in the case of ferrihydrite. The reactivity of these two iron oxides is then evaluated in batch experiments. Adsorption process follows the pseudo-second order kinetic equation and Freundlich isotherm model which give the best adjustments of experimental data. The influence of various parameters such as pH, ionic strength, etc on phosphate adsorption is also taken into account. Column experiments are afterwards carried out by using filtration material constituted of iron oxide deposited onto pozzolana. The optimal conditions to prepare this filtration material are naturally predetermined. Phosphate adsorption in hydrodynamic mode is characterized by advective and diffusive mechanisms and water regionalization which govern the adsorption process in the column. Moreover, phosphate adsorption capacity and flow rate influence on adsorption process are obtained. Finally, a preliminary experiment on a pre-treated waste water finally shows that the filtration material is potentially interesting for an industrial application

This thesis is focused on the study of the properties of mortars and pastes with active pozzolanic materials. It deals with monitoring cementitious composites which describes both the effect of compensation pozzolanic cement mortar admixtures active based on amorphous silica and the modifying polymeric additive. The main criteria for the assessment of these modified mortars and pastes are particularly adhesive and achieved strength compared with the reference mortar. The detailed work also examined the microstructure past through images from REM, records RTG, DTA and high pressure mercury porosimetry.

Geopolymers are a relatively new class of materials that have many broad applications, including use as substitute for ordinary Portland cement (OPC), use in soil stabilisation, fire resistant panels, refractory cements, and inorganic adhesives. Geopolymers are an alternative binder to Portland cement in the manufacture of mortars and concrete, as its three-dimensional alumino silicate network develops excellent strength properties. Use of geopolymers in place of ordinary Portland cement is also favoured owing to the possible energy and carbon dioxide savings. Geopolymer is typically synthesized by alkali activation of pozzolanas at moderate temperatures (< 1000C). The focus of the thesis is synthesis and characterization of geopolymers as construction materials. In this context, the role of compositional factors, such as, pozzolana type (fly ash, kaolinite, metakaolinite, ground granulated blast furnace slag, red soil), alkali (sodium hydroxide is used in this study) activator concentration, Si/Al (Si= silicon, Al = aluminium) ratio of the pozzolana and environmental factors, namely, curing period and temperature are examined. Besides synthesizing geopolymers that could be an alternate to concrete as construction material, sand-sized aggregates were synthesized using geopolymer reactions. This was done as river sand is becoming scarcer commodity for use as construction material. Several compositional and environmental factors were varied in geopolymer synthesis in order to identify the optimum synthesis conditions that yield geopolymers with maximum compressive strength. Besides varying external (compositional and environmental) factors, the role of internal microstructure in influencing the compressive strength of the geopolymer was examined. Micro-structure examinations were made using X-ray diffraction (XRD), scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) studies. The studies on compositional and environmental factors in geopolymer synthesis brought out several interesting results. The results firstly brought out that amongst the pozzolanas studied, ASTM class F fly ash is most suited for maximum compressive strength mobilization upon geopolymer reactions. Moderate temperature (75-1000C) was adequate to mobilize large compressive strengths. Room temperature curing needed more than 7 days before the pozzolana-NaOH paste began to develop strength. Curing period of 56 days was needed for the geopolymer to develop significant strength (19.6MPa). A similar range of compressive strength could be developed by the pozzolana-NaOH paste upon curing for 3 days at 1000C. Likewise curing the pozzolana-NaOH paste at temperatures > 1000C led to reduction in compressive strength from shrinkage and breakage of bonds. A caustic soda (NaOH) concentration of 10 M was adequate to develop maximum compressive strength of the geopolymer. Caustic soda concentrations in excess of 10 M did not result in further improvement of strength. The Si/Al ratio also contributes to strength mobilization. The Si/Al ratio of the geopolymer was enhanced by mixing commercially obtained silica gel with the pozzolana. Maximum strength mobilization was observed at Si/Al ratio = 2.45 corresponding to 6.5 % silica gel addition to the pozzolana (on dry mass basis). Comparing compressive strengths of geopolymers with varying silica gel contents, geopolymer specimens with least water content and largest dry density did not exhibit maximum compressive strength indicating that the physico-chemical (bond strength, micro-structure) played a pivotal role than physical parameters (dry density, water content) in dictating the strength of the geopolymer. MIP results showed that bulk of the porosity in fly ash geopolymer specimens is contributed by macro pores and air voids. Geopolymerization leads to bulk consumption of cenospheres in fly ash and forms polymerized matrix with network of large pores. After geopolymerization, all the main characteristic peaks of Al–Si minerals observed in fly ash persisted, suggesting that no new major crystalline phases were formed. Presence of small amount of inorganic contaminants in fly ash can drastically reduce the strength of the fly ash geopolymer. For example, 5-20 % presence of red soil reduces the strength of fly ash geopolymer by 16 to 59 %. Presence of unreacted clay coupled with less porous structure is responsible for the reduction in compressive strength of fly ash geopolymer subjected to red soil addition. MIP studies with geopolymers also revealed that there is good bearing between compressive strengths and maximum intruded volume (from MIP test) of geopolymers. For example, fly ash geopolymer specimen exhibits highest total intruded volume (0.3908 cc/g) and largest compressive strength of 29.5 MPa, while red soil geopolymer specimen exhibit least intruded volume (0.0416 cc/g) and lowest compressive strength (5.4 MPa). Further, analysis showed that specimens with larger airvoids+macropores volume had larger compressive strength, suggesting that geopolymers with more porous microstructure develop larger compressive strength. All geopolymer specimens exhibited tri-modal nature of pores i.e. macro-pore mode (entrance pore radius: 25-5000 nm), mesopore mode (entrance pore radius: 1.25 to 25 nm) and air void mode (entrance pore radius >5000 nm). The micro pores (entrance pore radius < 1.25 nm) do not contribute to porosity of the geopolymer specimens. Sand particles prepared from geopolymer reactions (FAPS or fly ash geopolymer sand) predominated in medium sized (2mm to 0.425 mm) sand particles. Their particle size distribution characteristics (uniformity coefficient and coefficient of curvature) classified them as poorly graded sand (SP). Dissolution, followed by polymerization reactions led to dense packing of the Si–O–Al–O– units that imparted specific gravity of 2.59 to FAPS particles which is comparable to that of river sand (2.61). Dissolution in strongly alkaline medium imparted strongly alkaline pH (12.5) to the FAPS particles. The river sand is characterized by much lower pH (7.9). Despite being characterized by rounded grains, the FAPS particles mobilized relatively high friction angle of (35.5o) than river sand (∅ = 28.9o). The river sand-mortar (RS-M) and fly ash geopolymer sand-mortar (FAPS-M) specimens developed similar 28-day compressive strengths, 11.6 to 12.2 MPa. Despite its higher water content, FAPS-mortar specimens developed similar compressive strength and initial tangent modulus (ITM) as river sand-mortar specimens. The FAPS-M specimen is more porous (larger intruded volume) with presence of larger fraction of coarser pores. Total porosity is majorly contributed by macro-pores (67.92%) in FAPS-M specimen in comparison to RS-M specimen (macro-pores = 33.1%). Mortar specimens prepared from FAPS and river sand exhibit similar pH of 12.36 and 12.4 respectively. FAPS-mortar specimens have lower TDS (1545 mg/L) than river sand-mortar specimens (TDS = 1889 mg/L). The RS-M and FAPS-M specimens exhibit leachable sodium levels of 0.001 g Na/g RS-M and 0.007 g Na/g-FAPS-M respectively in the water leach tests. The larger leachable sodium of FAPS-M specimen is attributed to residual sodium hydroxide persisting in the FAPS even after washing. The ultra-accelerated mortar bar test (UAMBT) shows that the percentage expansion of FAPS-M and RS-M specimens are comparable and range between 0.07 to 0.08 %.

[ES] El descubrimiento del cemento Portland ha cambiado nuestra forma de construir, pero también es el responsable de grandes emisiones de CO2 a la atmósfera durante su fabricación (~1450 ᴼC), agravando la crisis actual que está sufriendo nuestro planeta debido al cambio climático y sus consecuencias en todo el medio ambiente. Por lo tanto, una alternativa más sostenible en la construcción es la utilización de la cal que necesita menor temperatura para su fabricación (~900 ᴼC). Si bien la introducción de puzolanas naturales o artificiales en morteros de cal han mejorado sus propiedades mecánicas y de durabilidad, estas aún tienen el inconveniente de ganar resistencias a edades largas de curado. Es por esta razón que en la presente tesis se pretende eliminar este inconveniente técnico, buscando la asociación de la cal con nuevos conglomerantes más sostenibles a partir de residuos para obtener morteros mixtos denominados cal/puzolana-geopolímero. Los residuos estudiados fueron: el catalizador gastado de craqueo catalítico, la ceniza de cascara de arroz, la tierra diatomea de origen residual y la ceniza de lodo de depuradora. También se estudia una puzolana natural proveniente de la República de Guatemala. En los morteros cal/puzolana (cal/FCC, cal/CCA, cal/CLD) se ha realizado sustituciones en peso hasta un 50 % de la mezcla cal/puzolana por geopolímero. El geopolímero se obtiene por una combinación del FCC como precursor y diferentes activadores alcalinos siendo estos la mezcla de: NaOH/Na2SiO3, NaOH/CCA, NaOH/TDN y NaOH/TDR. Los últimos tres sustituyen al silicato comercial como fuente de sílice alternativa. Asimismo, se realizaron estudios a nivel mecánico y microestructural. Para los estudios microestructurales, tanto de muestras endurecidas como de materiales de partida, se emplearon como técnicas: FRX, ADL, TG, DRX y FESEM. Los resultados han demostrado con éxito que añadir pequeñas cantidades de geopolímero sobre el sistema cal/puzolana fue notable, debido a que este potenció la formación de los nuevos productos de reacción, lo que mejoró la resistencia mecánica de los morteros desde las primeras horas de curado, llegando a obtener 7 veces más de resistencia que un mortero control cal/puzolana en 1 día de curado. El reemplazo del silicato de sodio comercial por CCA, TDN, TDR, como fuente de sílice, condujo a mejores desempeños del mortero en términos de resistencia a la compresión. Además, redujo el coeficiente de absorción de agua por capilaridad y aumento el tiempo de exposición a los ciclos hielo-deshielo frente a los morteros activados con activadores comerciales. Finalmente, los conglomerantes desarrollados en este estudio podría beneficiar tanto a la gestión de residuos como al desarrollo de materiales de construcción más sostenibles, aportando a los objetivos propuestos en la agenda 2030. / [CA] El descobriment del ciment Portland ha canviat la nostra manera de construir, però també és el responsable de grans emissions de CO¿ a l'atmosfera durant la seva fabricació (~1450 ᴼC), agreujant la crisi actual que està patint el nostre planeta degut al canvi climàtic i les seves conseqüències en tot el medi ambient. Per tant, una alternativa més sostenible en la construcció és la utilització de la calç que necessita menor temperatura per a la seva fabricació (~900 ᴼC). Si bé la introducció de putzolanes naturals o artificials en morters de calç han millorat les seves propietats mecàniques i de durabilitat, aquestes encara tenen l'inconvenient de guanyar resistències a edats llargues de curat. És per aquesta raó que en la present tesi es pretén eliminar aquest inconvenient tècnic, buscant l'associació de la calç amb nous conglomerants més sostenibles a partir de residus per a obtenir morters mixtos denominats calç/putzolana-geopolímer. Els residus estudiats van ser: el catalitzador gastat del craqueig catalític, la cendra de closca d'arròs, la terra diatomea d'origen residual i la cendra de llot de depuradora. També es va estudiar una putzolana natural provinent de la República de Guatemala. En els morters calç/putzolana (calç/FCC, calç/CCA, calç/CLD) s'ha realitzat substitucions en pes fins a un 50 % de la barreja calç/putzolana per geopolímer. El geopolímer s'obté per una combinació del FCC com a precursor i diferents activadors alcalins, sent aquests la mescla de: NaOH/Na2SiO3, NaOH/CCA, NaOH/TDN i NaOH/TDR. Els últims tres substitueixen al silicat comercial com a font de sílice alternativa. Així mateix, es van realitzar estudis a nivell mecànic i microestructural. Per als estudis microestructurals, tant de mostres endurides com de materia primera, es van emprar tècniques com: FRX, ADL, TG, DRX i FESEM. Els resultats han demostrat amb èxit que afegir petites quantitats de geopolímer sobre el sistema calç/putzolana va ser notable, pel fet que aquest va potenciar la formació dels nous productes de reacció, la qual cosa va millorar la resistència mecànica dels morters des de les primeres hores de curat, arribant a obtenir 7 vegades més de resistència que un morter control calç/putzolana en 1 dia de curat. El reemplaçament del silicat de sodi comercial per CCA, TDN, TDR, com a font de sílice, va conduir a millors acompliments del morter en termes de resistència a la compressió. A més, va reduir el coeficient d'absorció d'aigua per capil·laritat i va augmentar el temps d'exposició als cicles gel-desgel enfront dels morters activats amb activadors comercials. Finalment, els conglomerants desenvolupats en aquest estudi podrien beneficiar tant a la gestió de residus com al desenvolupament de materials de construcció més sostenibles, aportant als objectius proposats en l'Agenda 2030. / [EN] The discovery of Portland cement has changed the way we build; however, it is also responsible for large CO2 emissions into the atmosphere during its manufacturing (~ 1450 ᴼC), thereby aggravating the current crisis that our planet is suffering due to climate change and its consequences in the environment. Thus, a more sustainable alternative in construction is the use of lime that requires a lower temperature for its manufacturing (~ 900 ᴼC). The introduction of natural or artificial pozzolans in lime mortars has improved their mechanical properties and durability. Nevertheless, they present some technical disadvantages, as the low compressive strength, especially at early curing time. This thesis aims to eliminate this technical disadvantage by mixing lime with new more sustainable binders derived from waste, obtaining mixed mortars called lime/pozzolan-geopolymer The waste materials studied included fluid catalytic cracking residue (FCC), rice husk ash (CCA), residual diatomite (TDR) and sewage sludge ash (CLD). A natural pozzolan from the Republic of Guatemala was also studied. In the experimental procedure, in lime/pozzolan mortar mixtures (lime/FCC, lime/CCA, lime/CLD), up to 50% of their weight was substituted by geopolymer. The geopolymer is obtained by combining FCC as a precursor, and different alkaline activator mixtures including NaOH/Na2SiO3 (commercial waterglass), NaOH/CCA, NaOH/TDN, and NaOH/TDR, with the last three being an alternative silica source to commercial waterglass. In the same way, both mechanical and microstructural studies were carried out. The following techniques were used: XRF, ADL, TG, XRD and FESEM to assess the microstructural properties of both the raw materials and the hardened samples. The results have demonstrated that adding small amounts of geopolymer to the lime/pozzolan system was remarkable; it enhanced the formation of new reaction products, which improved the mechanical strength of the mortar from the first hours of curing, obtaining 7 times more strength than the lime/pozzolan control mortar in 1 day of curing. The replacement of commercial waterglass by CCA, TDN, TDR, as a source of silica, led to better performance of the mortar in terms of compressive strength. In addition, the coefficient of water absorption by capillarity was reduced and the exposure time during freezing-thawing cycles was increased compared to mortars activated with commercial activators. Finally, the binders developed in this study could benefit both waste management and the development of more sustainable construction materials, contributing to the objectives proposed in the 2030 Agenda. / Gracias al programa ADSIDEO-COOPERACIÓN de la Universitat Politècnica de València, que me ha brindado financiación para la presente investigación. / Villca Pozo, AR. (2021). Utilización de geopolímero para la mejora de las propiedades en morteros cal-puzolana y su empleo en países en desarrollo [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/172663