The standard ASTM C672 de-icer salt scaling resistance test has been found to be overly aggressive to concretes containing slag cement. It was compared to the newly proposed ASTM WK9367 method, based on the Quebec BNQ test, as well as several modifications, including use of an accelerated curing regime developed in Virginia (VADOT). Sixteen concrete mixtures were studied using high-alkali cement, low-alkali cement, grade 100 slag and grade 120 slag with slag contents of 0%, 20%, 35% and 50%. Vinsol resin air-entraining admixture was compared to Micro Air®. Reducing the water cement ratio from 0.42 to 0.38 had the biggest impact on improving scaling resistance of slag concretes. In general, increased slag contents increased scaling regardless of the test method used. The Micro Air® admixture provided a lower air void actor and higher hardened air content compared to Vinsol resin.

The standard ASTM C672 de-icer salt scaling resistance test has been found to be overly aggressive to concretes containing slag cement. It was compared to the newly proposed ASTM WK9367 method, based on the Quebec BNQ test, as well as several modifications, including use of an accelerated curing regime developed in Virginia (VADOT). Sixteen concrete mixtures were studied using high-alkali cement, low-alkali cement, grade 100 slag and grade 120 slag with slag contents of 0%, 20%, 35% and 50%. Vinsol resin air-entraining admixture was compared to Micro Air®. Reducing the water cement ratio from 0.42 to 0.38 had the biggest impact on improving scaling resistance of slag concretes. In general, increased slag contents increased scaling regardless of the test method used. The Micro Air® admixture provided a lower air void actor and higher hardened air content compared to Vinsol resin.

The main motivation of this thesis is to study the long standing problem of mixed alkali effect (MAE) in oxyfluro vanadate glass systems from the point of view of structural arrangement and to investigate the effect of two rare earth ions, namely, erbium and europium on the structure of tellurium dioxide based glass. In glass science, it is well known that when one alkali in a glass matrix is gradually replaced by another alkali, leads to a non-linear variation in some of the physical properties. There are many a theories trying to explain this effect. Recently the renewed interest lies in explaining MAE in-terms of structural consideration. Rare earth (RE) ion doped glasses are of interest in a variety of applications in photonics because of the special optical properties exhibited by these materials. Atomic like f-f transitions of RE ions depend on the local environment of the these ions. A particular glass matrix may be able to bring out the optical properties of a RE ion better than the other matrix. In this regard structural characterization of a glass matrix with different RE ions for optical properties is of importance. Spectroscopic tech-niques are best suited to investigate structural arrangement in glasses and in this thesis we have used techniques like Raman, electron paramagnetic resonance (EPR), impedance, photoluminescence and UV- visible absorption spectroscopies. The thesis comprises of five chapters and an appendix. Chapter 1 consists of brief introduction of general properties of glasses and their behavior under different spectroscopic techniques. Chapter 2 deals with the sample preparation and the experimental techniques used in this work. Chapter 3 elaborates on the Raman and EPR spectroscopic studies on the structural arrangement of the mixed alkali oxyfluro vanadate glass systems. Chapter 4 focuses on the ac and electrical modulus analysis to study the MAE in the above samples. Chapter 5 deals with the optical spectroscopic techniques used to study the compatibility of RE ions (erbium and europium) with the tellurium dioxide based glass matrix. Chapter 1: Disordered materials pose a challenge to understand their structure mainly because of their random arrangement of the constituent units. In this chapter the glassy systems and the different experimental techniques used to study them are discussed in general. The behavior of glassy systems to the external stimuli in various frequency ranges is highlighted. A short review of mixed alkali effect in glasses mainly covering the advances in the last two decades is given. Brief outline of the theory of Raman, EPR and ac impedance spectroscopy are given. Chapter 2: This chapter discusses the major experimental techniques used in the thesis to study the glass systems at block diagram level. The Raman and EPR spectrometers are discussed. Experimental technique used in ac impedance measurement is outlined. Different methods of preparing glass are listed and melt quenching technique is discussed in detail. Chapter 3: This chapter discusses the results and analysis of Raman and EPR study in oxyfluoro vanadate glasses emphasizing MAE. The glass having batch formula 40V2O5 - 30BaF2 - (30 - x) LiF - xRbF (x = 0 – 30) is prepared by melt quenching technique. Raman spectroscopic study in back scattering geometry is performed to see the effect of alkali ions on the V – O bond length of VO6 polyhedra in the glass. The de-convoluted Raman peaks corresponding to V = O and VO2 are considered and the effect of alkali mixture on these bonds are studied. • The peak shift of V = O and VO2 bonds shows that V = O is affected only a little by the replacement of lithium (Li) by rubidium (Rb), while VO2 bond gets affected to a larger extent. • From the peak shift the most probable value of the bond length and the spread in it are estimated. The bond length corresponding to V = O is found to increase and that of VO2 decrease as a consequence of alkali replacement. • From the FWHM of the corresponding Raman peaks, it is concluded that O - Rb coordination sphere around VO6 polyhedra is more homogeneous than either O – Li or O - Li /Rb coordination. These results are published in J. Non-Cryst. Solids 370 (2013) 6. EPR studies on the samples are carried out in X band frequency and spin – Hamilto-nian parameters were extracted by simulating and fitting the EPR spectra to experimental data using EasySpin which is a Matlab toolbox. • it is observed that the ratio 4gjj=4g?, which is a measure of tetragonality of octa-hedral crystal symmetry of V2O5, varies non-monotonically with Rb content. • A model based on this observation is proposed. The essential idea of this model is that Rb atoms that are substituted for Li atoms initially prefer terminal positions over planar positions. Continued substitution then replaces planar Li atoms. It is seen that this model of “preferential substitution” explains the observation very well. • Another observation is that the EPR signal intensity, which is due to concentration of V4+ ions, also shows non-monotonous behavior with Rb content. This is also explained using preferential substitution, taking into consideration the oxidation states of the vanadium ions. • The value of 4gjj=4g?, is a minimum for all rubidium environments around V2O5, which infers that Rb coordination is more symmetric than all Li or Li−Rb. • A good correlation is found between Raman and EPR study of the above system. These results are published in J. Phys. Chem. A 118 (2014) 573. Chapter 4: The chapter brings out the results of ac conductivity and electrical mod-ulus study of MAE in the glass system mentioned above. The Agilent 4294A precision impedance analyzer operating in frequency range 40 Hz to 110 MHz, is used for per-forming impedance and capacitance experiments carried out in this thesis. Impedance measurements in our studies are performed in sandwich geometry. • Room temperature dc conductivity shows a decrease as Li is replaced by Rb and reaches its minimum - five orders less than its all Li value at 0.33 molar fraction of Rb, which is attributed to MAE. This observation is explained using the structural aspect. • Using the linear response theory the number of mobile ions participating in the conduction is estimated. • Imaginary part of the electrical modulus is fitted to Kohlrausch – Williams – Watts (KWW) relation by using a complex nonlinear least squares fitting procedure given by Bergmann. • The stretching parameter b estimated from the above procedure is found to exhibit MAE. The observed variation in b with Rb mole fraction is explained by taking into considerations the contributions from fast and slow processes, and coupling between different relaxing sites. The manuscript is under preparation. Chapter 5: This chapter illustrates the optical study of RE doped TeO2 based glasses to determine the suitability of a particular RE ion with a given glass matrix. TeO2 based glasses having a general formula (in mol %) 65TeO2 – 5BaF2 – 30ZnF2 (TBZ) were prepared by usual melt quenching technique. RE doping was done at the expense of TeO2. 3 mol % of Eu or Er are added to prepare RE doped glass. Raman, PL, UV-visible absorption studies are carried out on the glass samples. • From the peak shift, intensity variation and FWHM of the Raman spectra of the glass samples it is observed that Eu doped TBZ glass has a greater tendency towards depolymerizing the glass matrix by influencing the conversion of TeO4 units into the formation of TeO3 units. • PL spectra of the glass samples shows emission due to different possible transitions. Position of the peak of the de-convoluted spectra shows the position of the particular Stark component and the FWHM is a measure of the inhomogeneous broadening. • The UV-visible absorption spectra are used to calculate the optical density and fitted to the Mott equation to determine the band edge of the glass samples. It is seen that Eu doped TBZ glass has a lesser band gap than that of Er doped glass. The manuscript is submitted to Bul. Mat. Sci. Appendix : This consists of a collection of details of EDS study carried on the VBL series glasses and some MATLAB codes used to simulate the EPR spectrum for VBL series glasses.

Aujourd'hui, les problèmes environnementaux sont plus graves que jamais. Des mesures urgentes devraient être prises dans tous les domaines de l'activité humaine, y compris la construction. L'un des principaux contributeurs à l'impact négatif de cette industrie sur l'environnement est la fabrication du ciment Portland ordinaire (OPC) nécessaire à la production de béton et d’autres matériaux cimentaire. Malgré son importance, il présente un inconvénient important: sa production est accompagnée par de grandes quantités de gaz à effet de serre. Ils représentent 5 à 8% des émissions mondiales totales de CO2. Des matériaux cimentaires plus écologiques sont maintenant nécessaires.Des réductions significatives de l’impact sur l’environnement ne peuvent être obtenues que par l’utilisation de liants de nouvelle génération dont la fabrication ne nécessite pas beaucoup de processus et de traitements supplémentaires. L'une d'elles consiste à utiliser des déchets industriels comme liants (différentes laitiers, cendres volantes, cendres de biomasse, etc.). De cette manière, il y a non seulement une réduction de l'impact de processus tels que l'extraction minière ou la calcination, mais également le recyclage des déchets (un principe de l'économie circulaire).Une possibilité consiste à utiliser du laitier de haut fourneau (GGBS) comme base pour ce ciment de nouvelle génération. En raison de sa réactivité relativement faible avec l'eau, des suppléments (également appelés activateurs) doivent être utilisés pour favoriser le processus d'hydratation. Le carbonate de sodium (Na2CO3) est l’un des activateurs les plus prometteurs et en même temps les moins étudiés. Un tel ciment alkali-activé présente des propriétés mécaniques et de durabilité élevées, ainsi qu'une empreinte CO2 très faible. Parmi les principaux problèmes qui entravent son utilisation à l'échelle industrielle, on peut mentionner une évolution de la résistance lente à jeune âge et de rhéologie médiocre.L'objectif de la présente thèse est de développer une nouvelle conception du liant à base de laitier activé par Na2CO3, qui répondrait à toutes les exigences modernes du secteur de la construction, en particulier les propriétés rhéologiques et le développement de la résistance à jeune âge. Ce liant doit toujours répondre à au moins trois critères principaux: faible impact environnemental, faibles risques de danger dans les applications sur le terrain et être économiquement compétitif à l'échelle industrielle.Dans le présent travail, l’influence de différents paramètres tels que le rapport eau/liant, la concentration de Na2CO3, la finesse du laitier et les conditions de durcissement sur les propriétés du mélange à jeune âge et à long terme a été étudiée. Sur la base des résultats du processus d’hydratation, les additifs à base de phosphonate qui permettent de contrôler efficacement la rhéologie de tels liants ont été testé avec succès. Ils permettent non seulement de contrôler le temps de prise, mais fournissent également un effet plastifiant.En ce qui concerne l’amélioration des propriétés de résistance au jeune âge, différentes méthodes ont été utilisées. L’utilisation d’un traitement thermique ou d’une augmentation de la finesse du GGBS s’est avérée efficace. L’exploration des causes d’une longue période d’induction a montré que l’accélération pouvait également être obtenue par l’ajout d’une source de calcium à cinétique de dissolution contrôlée. En conséquence, le liant est devenu plus réactif et plus robuste à certains facteurs (concentration d’activateur, rapport eau/liant, conditions de durcissement, etc.). Pour compenser l'empreinte carbone supplémentaire de la source de calcium ajoutée, le liant a été dilué avec succès par le calcaire sans aucune dégradation des propriétés à un certain pourcentage de dilution. / Today, environmental problems are more acute than ever. Urgent measures should be taken in all spheres of human activity including construction and civil engineering. One of the major contributors of negative environmental impacts from this industry is the manufacturing of ordinary Portland cement (OPC) required for concrete and other cementitious materials production. Although its importance to economical development, it has a significant drawback - its production is accompanied by the emission of large quantities of greenhouse gases. They account for 5-8% of total world CO2 emissions. More environmentally friendly cementitious materials are now required.Significant reductions of the environmental impact can be achieved only through the use of new-generation binders whose manufacture does not require a lot of additional processes and treatments. One route is through the use of industrial wastes as binders (different slags, fly ash, biomass bottom ash, etc.). In this way there is not only a reduction in the impact of processes such as mining or calcination, but also the recycling of waste materials (circular economy principle).One possibility is to use ground granulated blast furnace slag (GGBS) as the basis for such a new generation cement. Due to its rather low reactivity with water, additional supplements (also called activators) should be used to promote the hydration process. One of the most promising, and at the same time least studied, activators is sodium carbonate (Na2CO3). Such alkali-activated cements present high mechanical and durability properties, as well as a very low CO2 footprint. Among the main problems hindering its industrial scale adoption are their poor rheology and too slow strength gain within the first days of hardening.The objective of the present thesis is to develop a new binder based on Na2CO3 activated GGBS that would meet all the modern requirements of the construction industry, in particular regarding the rheological properties and early age strength development. In addition this binder should always respond to at least three main criteria: low environmental impact, low health and safety concerns in field applications, and be economically competitive at industrial scale.In the present work, the influence of different parameters like water/binder ratio, Na2CO3 concentration, slag fineness and curing conditions on both early age and long term properties of the mixture were studied. Based on the results of the hydration process analysis, phosphonate based additives that allow for the effective control of the rheology of such binders were successfully tested. They not only allow control over the setting time, but also provide a plasticizing effect.Regarding the improvement of early age strength properties, various methods have been used. The use of heat treatment or an increase of GGBS fineness turned out to be efficient. Exploring the causes of the long induction period has shown that acceleration can also be achieved by the addition of a calcium source with controlled dissolution kinetics. As a result, the binder became more reactive and robust against certain factors (activator concentration, Water/Binder ratio, curing conditions, etc.). To compensate for the additional carbon footprint from the added calcium source, the binder was successfully diluted by limestone without any degradation of the properties below some dilution percentages.

This study evaluates question of alkali–silica reaction (ASR) in hybrid system, which was designed in the bachelor's thesis, to meet the requirements of EN 197-1 and classified to the Blastfurnace CEM III/C cements. The durability of this system is a great unknown. For this reason, the same methods (ASTM C1260, ASTM C289 and ASTM C856) were used to observer the ASR effects as the ones used to observer the Portland cement based concrete. Supplementary methods include determination of compressive strengths according to EN 196-2 and scanning electron microscopy to observe the microstructure. Hybrid system results were compared to two different types of cements, CEM I and CEM III/B. From the results of the ASR evaluation assays, it was found that the hybrid system (CEM III/C-HB) and CEM III/B showed the lowest tendency to ASR. The results of the supplementary methods showed that CEM III/C-HB compressive strength increases after 14 days within NaOH by 43 % in comparison to 28 days strength. Based on those results, it is sure that the CEM III/C-HB shows little susceptibility to ASR.

Nowadays, the waste sands from the water glass production have no utilization and due to high alkali content are considered as a dangerous waste. So the aim of this thesis is to find and study some possibilities of their utilization in the building industry. First of all, some necessary analysis of these sands were performed and then some advantages and disadvantages of their application for production of materials based on portland cement and alkali activated materials were studied. Characteristics of fresh and hardened pastes, mortars and concretes containing these waste sands were determined. The most tested properties were their workability and their compressive and flexural strength. Close attention for the risks of alkali-silica reaction and for options of its suppressing by the mineral admixtures was paid.

Alkali activated materials have great potential to be a material that could compete with Portland cement. Compared to concretes based on Portland cement they often exhibit greater durability and resistance to aggressive agents such as sulphates. Also their resistance to high temperature is substantial. This work is devoted to research on behavior of alkali-activated materials, particularly fly ash activated by sodium water glass and sodium hydroxide, exposed to these extreme conditions. The evaluation of properties was performed based on the detection of physico-mechanical parameters and microstructure examination by RTG diffraction analysis and scanning electron microscopy (SEM).

Concrete is the most widely used construction material worldwide, yet, it presents major sustainability drawbacks due to the CO2 released during the manufacturing of its main constituent, cement. Several approaches are used to improve concrete’s eco-efficiency and reduce the binder intensity index, a metric used to measure the eco-efficiency of concrete, to a value below that of conventional concrete mixtures (i.e., 10 kg/m3.MPa-1 for 25-40 MPa mixtures). Particle Packing Models (PPM) is consequently an approach that can be used to enhance system packing density, reducing cement content while increasing hardened state properties and durability (i.e., reducing porosity). However, packed mixtures normally present issues in the fresh state while their hardened state performance is not fully comprehended. Therefore, this Ph.D. project proposes a new mix-design method called PPM-MP approach to develop eco-efficient mixtures. First, a detailed laboratory investigation was conducted on mixtures developed using the proposed approach in order to understand their fresh and hardened state performance. Concrete samples containing distinct ranges of cement content (320, 250, 200, 150 kg/m3) and slump (180, 90, and 20 +/- 20 mm) were fabricated and a wide range of fresh state tests (pH, temperature, fresh density, air content, slump and rheology over time) and hardened state tests (apparent porosity, surface electrical resistivity, compressive strength, and modulus of elasticity) were performed over time. Then, its performance against the alkali-silica reaction (ASR) induced expansion and deterioration, which is one of the leading and most damaging distress mechanisms issues in durability, was evaluated. In this section of the project, four sustainable concrete mixtures developed with varying cement content (e.g., 325, 250, 200, and 150 kg/m3) were developed and compared to a control mixture containing 420 kg/m3 of cement content. The mixtures were tested over a year under Concrete prism test (CPT) setup, which is the current method used to evaluate concrete ASR and using three different non-boosted test setups (i.e., Wrapped - W, Soaked - S, and Encapsulated - E). Moreover, two distinct types of highly reactive aggregates (e.g., Springhill Greywacke coarse aggregate and Texas Polymictic sand) were selected. Microscopic analysis was used to better understand the impact of ASR on sustainable mixtures, as well as the differences in ASR-damage and crack propagation under different test protocols. The results show the feasibility of producing an eco-efficient mixture in a more efficient manner which may contribute to the Net Zero Concrete targets. The proposed PPM-MP approach improves the sustainability of concrete mixtures and can be used for specific projects requiring 28-day compressive strength ranging from 18 to 45 MPa and slumps (180, 90, and 20 +/- 20 mm).

Cette thèse apporte une nouvelle contribution à la caractérisation non destructive des matériaux en béton endommagés par la réaction alcalis-silice (RAS). À cette fin, des techniques et outils de caractérisation non linéaire ont été mises au point. Un banc de test de résonance non linéaire a été développé. Des améliorations ont été apportées au niveau de la chaine d'excitation et au niveau du traitement du signal afin d'optimiser la sensibilité du banc de test. Les essais non linéaires ont été effectues sur sept échantillons de béton endommagés par la RAS, trois échantillons de béton endommagés thermiquement, deux échantillons de béton endommagés mécaniquement et trois échantillons de béton sains. La non-linéarité comportementale des matériaux étant souvent attribuée au comportement hystérétique des micro-défauts contenus dans ces derniers, il a été montré dans un premier temps, que le béton endommagé par la RAS présente un comportement hystérétique. Cette étude a été faite à partir des essais de l'acousto-élastique. Le banc de test de résonance non linéaire a été ensuite utilisé pour la caractérisation des bétons sains et endommagés par la RAS. II a été montré que la technique non linéaire, en plus de permettre une caractérisation sans avoir l'historique de l'état du matériau, permet également de détecter de façon précoce l'endommagement du matériau réactif. L'influence de la teneur en eau sur les paramètres non linéaires a également été étudiée. II a été montré que les valeurs mesurées sur des échantillons de béton conservés dans des conditions de forte teneur en eau sont plus faibles. Dans l'objectif de trouver une particularité à l'endommagement causé par la RAS, la nature visqueuse du gel produit par la RAS a été utilisée. Une démarche, qui s'inspire des essais de fluage en statique réalisés sur des matériaux, a été utilisée pour répondre à cette question de signature de la RAS, tout en appliquant la technique de résonance non linéaire. Le modèle ressort-amortissement de Maxwell a été utilise pour l'interpretation des résultats. Ainsi, le temps de réponse au fluage a été analysé sur des échantillons endommagés par la RAS. II en ressort que le gel issu de la RAS rallonge le temps de réponse au fluage. Enfin, les limites de la technique de résonance non linéaire pour une application in situ ont été expliquées et une nouvelle technique non linéaire estimée applicable sur site a été initiée. Cette technique consiste à utiliser une source externe telle une masse pour provoquer la non-linéarité dans le matériau, pendant qu'une onde ultrasonore sonde le milieu.||The aim of this thesis is to contribute to the non-destructive characterization of concrete materials damaged by alkali-silica reaction (ASR). For this purpose, some nonlinear characterization techniques have been developed, as well as a nonlinear resonance test device. In order to optimize the sensitivity of the test device, the excitation module and signal processing have been improved. The nonlinear tests were conducted on seven samples of concrete damaged by ASR, three samples of concrete damaged by heat, three concrete samples damaged mechanically and three sound concrete samples. Since, nonlinear behaviour of the material is often attribute to its micro-defects hysteretic behaviour, it was shown at first that concrete damaged by ASR exhibits an hysteresis behaviour. To conduct this study, an acoustoelastic test was set, and then nonlinear resonance test device was used for characterizing sound concrete and concrete damaged by ASR. It was shown that the nonlinear technique can be used for characterizing the material without knowing its initial state, and also for detecting early damage in the reactive material. Studies were also carried out on the effect of moisture regarding the nonlinear parameters; they allowed understanding the low values of nonlinear parameters measured on concrete samples that were kept in high moisture conditions. In order to find a specific characteristic of damage caused by ASR, the viscosity of ASR gel was used. An approach, based on static creep analysis, performed on the material, while applying the nonlinear resonance technique. The spring-damping model of Maxwell was used for the interpretation of the results. Then, the creep time was analysed on samples damaged by ASR. It appears that the ASR gel increases the creep time. Finally, the limitations of the nonlinear resonance technique for in situ application have been explained and a new applicable nonlinear technique was initiated. This technique use an external source such as a mass for making non-linearity behaviour in the material, while an ultrasound wave is investigating the medium.

To release energy from chemically stored energy in the biomass was the new investigation in recent years. Utilizing of biomass for this purpose occur in two different ways, directly by burning (combustion) the biomass and indirectly by pyrolysis process which will convert the biomass to three main products, bio- tar, bio- char and synthetic gas. Biomass contains different amount of inorganic compound, especially alkali metals which causes some diverse impacts on combustion, pyrolysis and gasification process such as corrosion, agglomeration and fouling problems. This project aims to investigate the effect of K2CO3 on the pyrolysis and gasification processes of three different types of fuel; wood pellets, forest residue pellets and synthetic waste pellets at three different temperatures, 750 °C, 850 °C and 900 °C respectively. The purpose of this work to study and clarify the influence of K2CO3 on char yield, tar yield and tar compositions and the gasification rate and the reactivity of different fuels char. The pyrolysis process was carried out in a fluidized bed reactor during 2 minutes and the products were tar, char and synthetic gas. In this project interested in char and tar only. Char yield calculated and the results shows the char yield increase with increasing of [K2CO3]. While the tar analysis carried on GC- MS instrument at HB to study the tar yield and compositions. The results showed that potassium carbonate has not so much effect on tar yield and its composition. The last part was gasified the char in TGA with steam and CO2 as oxidizing media to study the influence of [K2CO3] on gasification rate and the reactivity of char samples at different temperatures. The result showed the [K2CO3] has inhibitory effect on gasification rate and the reactivity.