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The durability of eco-efficient, clinker reduced concrete is a key factor of its performance. In the presented study, different durability indicators of a newly developed eco-concrete composition (ECO) are tested versus standard normal concrete as reference (REF). The tested durability indicators are open porosity, water penetration depth, rate of water absorption by capillarity and two different methods of measuring air permeability (PermeaTORR AC device versus Testing bubble counter). The ECO mix and in particular its cementitious matrix is designed by a combined filler concept substituting Portland cement partially by properly selected limestone fillers of different grain sizes. The approach is based on a combination of particle packing optimization techniques and the reduction of water demand for certain flowability of the paste. Cement content is below the limits of traditional standards while w/c-ratio exceed such limits. While the performance of the eco-concrete in terms of workability and strength is at least equivalent to the standard mix, ecological impact indicators as global warming potential and embodied energy are substantially improved. Durability indicators overall show nearly equivalent performance of ECO and REF. In detail, the resulting air permeability coefficient tested with a bubble counter differs significantly from the coefficient tested by PermeaTORR.

Multiple trait integration (MTI) is the process by which a target hybrid (or variety) is converted to add value-added traits to the comprehensive performance package represented by that genotype. The goal is to recover all the attributes of the target hybrid, with the addition of the specified value-added traits. In maize, this process utilizes the backcross breeding method to incorporate transgenic events (or genes) of interest. Thus, MTI involves four main steps: single event introgression, event pyramiding, trait fixation, and version testing to ensure recovery of equivalent performance with at least one version of the converted hybrid. Based on a case study involving conversion of a target hybrid for 15 transgenic events (the female inbred parent was converted for 8 events, and the male inbred parent was converted for 7 events), we explored parameters in version testing to facilitate a high likelihood of recovering at least one version of the hybrid conversion with yield performance equivalency within 3 % of unconverted target hybrid. Using computer simulation, we explored the impact of two factors on the success rate of the MTI outcome: (1) the amount of residual NRP (non-recurrent parent) germplasm remaining in the converted hybrid and (2) the number of versions of each parental line conversion created. A range of residual NRP germplasm from 120 to 180 cM (which represents 95.0-96.6 % germplasm recovery of the target hybrid in maize) and up to 5 versions of each parental conversion were considered, with all possible hybrid combinations of each version of female and male RP (recurrent parent) conversion evaluated for yield. With 5 versions of each RP conversion and testing of 25 hybrid versions, a >95 % rate of success was realized when the amount of residual NRP germplasm in the hybrid conversion was ≤180 cM. When hybrid conversions contained ≤120-cM residual NRP germplasm, only 4 versions of one of the parental conversions were needed (rather than 5), requiring 20 versions of the hybrid conversion to be yield tested. These results have implications in the strategic design of an overall conversion program and for the upstream MTI process, especially in setting thresholds for the amount of NRP germplasm remaining in RP conversions. Furthermore, these results validate findings of (Peng et al. in Mol Breed 33:189-104, 2014a. doi:10.1007/s11032-013-9936-7, in Mole Breed 33:105-115, 2014b. doi:10.1007/s11032-013-9937-6) which outline effective breeding strategies to optimize earlier steps in MTI (preceding version testing).

Cement is the main source of environmental impacts of concrete use. It is thus recognized that the most pragmatic solution for minimizing environmental impacts of concrete is the reduction of the cement content. This could be achieved by replacing a part of cement by mineral additions such as fly ash or blast-furnace slag during concrete mixing.The present work aims at studying the physico-chemical phenomena occurring during the process of carbonation of concrete mixtures with high substitution rates of cement by mineral additions and their resistance against this type of attack.An experimental campaign was conducted on reference concrete mixtures prepared with common cements and on other concrete mixtures, called “Écobétons” (Green concretes), prepared by replacing a part of cement by fly ash or blast-furnace slag. The study focused on the Écobétons durability, especially their resistance against carbonation, on the equivalence of Écobétons performances with the reference mixtures performances and on the composition and microstructure parameters controlling the kinetics of carbonation. Carbonation has been studied in natural and accelerated conditions. The results show that Écobétons mixtures with high substitution rates of cement by fly ash (50 %) and blast-furnace slag (75 %) could replace, in some cases, concretes that are in accordance with the current standard.In addition to the experimental study, numerical simulations of the coupling between hydration and drying were conducted in order to determine the effect of drying on the properties controlling the accelerated carbonation kinetics of the studied concrete mixtures (porosity, Portlandite content and water saturation degree). The results show that the kinetics of drying increases with the degree of substitution of cement by mineral additions. They also question the relevance of the preconditioning of the samples during accelerated carbonation test conducted according to the French standard XP P 18-458.; Le ciment est la principale source des impacts sur l’environnement de l’utilisation du matériau béton. Afin d’optimiser ce dernier d’un point de vue environnemental, il est nécessaire de réduire son dosage en ciment. Cela peut être entrepris en remplaçant une partie du ciment par des additions minérales lors de sa fabrication.Ces travaux de thèse visent à étudier les phénomènes physico-chimiques ayant lieu lors du processus de carbonatation de bétons à forts taux de remplacement du ciment par des additions minérales ainsi que leur résistance à ce type d’attaque.Une campagne expérimentale a été menée sur des bétons de référence préparés à base de ciments courants et sur des Écobétons préparés en substituant une partie du ciment par des cendres volantes ou du laitier de haut-fourneau. Les différentes études menées portent sur la durabilité des Écobétons vis-à-vis de la carbonatation, sur l’équivalence de performances des Écobétons avec celles des bétons de référence, et sur les paramètres de composition et de microstructure contrôlant la cinétique de carbonatation. La carbonatation a été étudiée en conditions accélérées et naturelles. Les résultats montrent que les Écobétons à forts taux de substitution du ciment par des cendres (50 %) ou du laitier (75 %) pourraient remplacer, dans certains cas, les bétons conformes à la norme en vigueur.En complément à l’étude expérimentale, des simulations numériques du couplage hydratation/séchage ont été menées en vue de déterminer l’effet du séchage sur les propriétés contrôlant la cinétique de carbonatation accélérée des bétons étudiés (la porosité, la quantité de Portlandite et le degré de saturation en eau liquide). Les résultats montrent que la cinétique de séchage augmente avec le taux de substitution du ciment par des additions. Ils remettent aussi en cause la pertinence du préconditionnement des échantillons lors de l’essai de carbonatation accélérée mené selon la norme française XP P 18-458 actuellement en vigueur.

Cement is the main source of environmental impacts of concrete use. It is thus recognized that the most pragmatic solution for minimizing environmental impacts of concrete is the reduction of the cement content. This could be achieved by replacing a part of cement by mineral additions such as fly ash or blast-furnace slag during concrete mixing.The present work aims at studying the physico-chemical phenomena occurring during the process of carbonation of concrete mixtures with high substitution rates of cement by mineral additions and their resistance against this type of attack.An experimental campaign was conducted on reference concrete mixtures prepared with common cements and on other concrete mixtures, called “Écobétons” (Green concretes), prepared by replacing a part of cement by fly ash or blast-furnace slag. The study focused on the Écobétons durability, especially their resistance against carbonation, on the equivalence of Écobétons performances with the reference mixtures performances and on the composition and microstructure parameters controlling the kinetics of carbonation. Carbonation has been studied in natural and accelerated conditions. The results show that Écobétons mixtures with high substitution rates of cement by fly ash (50 %) and blast-furnace slag (75 %) could replace, in some cases, concretes that are in accordance with the current standard.In addition to the experimental study, numerical simulations of the coupling between hydration and drying were conducted in order to determine the effect of drying on the properties controlling the accelerated carbonation kinetics of the studied concrete mixtures (porosity, Portlandite content and water saturation degree). The results show that the kinetics of drying increases with the degree of substitution of cement by mineral additions. They also question the relevance of the preconditioning of the samples during accelerated carbonation test conducted according to the French standard XP P 18-458., Le ciment est la principale source des impacts sur l’environnement de l’utilisation du matériau béton. Afin d’optimiser ce dernier d’un point de vue environnemental, il est nécessaire de réduire son dosage en ciment. Cela peut être entrepris en remplaçant une partie du ciment par des additions minérales lors de sa fabrication.Ces travaux de thèse visent à étudier les phénomènes physico-chimiques ayant lieu lors du processus de carbonatation de bétons à forts taux de remplacement du ciment par des additions minérales ainsi que leur résistance à ce type d’attaque.Une campagne expérimentale a été menée sur des bétons de référence préparés à base de ciments courants et sur des Écobétons préparés en substituant une partie du ciment par des cendres volantes ou du laitier de haut-fourneau. Les différentes études menées portent sur la durabilité des Écobétons vis-à-vis de la carbonatation, sur l’équivalence de performances des Écobétons avec celles des bétons de référence, et sur les paramètres de composition et de microstructure contrôlant la cinétique de carbonatation. La carbonatation a été étudiée en conditions accélérées et naturelles. Les résultats montrent que les Écobétons à forts taux de substitution du ciment par des cendres (50 %) ou du laitier (75 %) pourraient remplacer, dans certains cas, les bétons conformes à la norme en vigueur.En complément à l’étude expérimentale, des simulations numériques du couplage hydratation/séchage ont été menées en vue de déterminer l’effet du séchage sur les propriétés contrôlant la cinétique de carbonatation accélérée des bétons étudiés (la porosité, la quantité de Portlandite et le degré de saturation en eau liquide). Les résultats montrent que la cinétique de séchage augmente avec le taux de substitution du ciment par des additions. Ils remettent aussi en cause la pertinence du préconditionnement des échantillons lors de l’essai de carbonatation accélérée mené selon la norme française XP P 18-458 actuellement en vigueur.