Nous proposons dans cette thèse une approche critique de la philosophie politique de Jürgen Habermas, qui vise à interroger la conception du discours sur laquelle elle se fonde. De ses premiers textes sur «l’espace public» à la théorie politique et du droit qu’élabore Droit et démocratie, Habermas approfondit l’intuition selon laquelle c’est à travers une certaine pratique du discours argumenté que se forment les espaces de communication, de délibération, et de décision, sans la vitalité desquels la démocratie ne saurait être «radicale». Il convient dès lors de reconstruire cette théorie du discours qui sous-tend sa pensée politique, aux différents niveaux où elle est opératoire : la pratique du langage ordinaire qui est la nôtre lorsque nous communiquons dans la vie de tous les jours ; celle que nous mettons en œuvre en tant que sujets politiques lorsque nous revendiquons des droits dans l’espace public ; celle enfin qui nous permet d’argumenter selon un point de vue moral lorsqu’il s’agit de déterminer les principes de justice. Nous défendons la thèse selon laquelle les normes fondamentales du discours, qu’Habermas établit à un niveau quasi transcendantal, doivent être reconduites à une hétéronomie qui est celle des conditions matérielles du discours. La philosophie sociale d’inspiration matérialiste qu’Horkheimer s’emploie à construire dans les années 1930 ouvre la voie d’une telle analyse. Nous reconstituons à cet effet le débat interne à l’École de Francfort sur la question de savoir comment le matérialisme critique de Marx doit être interprété. / In this dissertation I offer a critical examination of Jurgen Habermas’s political philosophy while questioning the conception of discourse which it is grounded in. From his first texts on the “public space” to the legal and political theory elaborated in Law and Democracy, Habermas explores the intuition that it is through a certain practice of argumentative discourse that spaces of communication, deliberation and decision are formed, the vitality of which is crucial to a truly “radical” democracy. The theory of discourse underpinning his political thought must hence be reconstructed at the different levels it operates on, including the practice of ordinary language through which we communicate in everyday life, the discourse we apply as political subjects when we claim rights in the public space, and the discourse which enables us to form arguments from a moral point of view when principles of justice need to be determined. My thesis supports the idea that fundamental norms of discourse, which Habermas establishes on a quasi-transcendental level, must be confronted to the heteronomy of material conditions of discourse. The materialist-derived philosophy which Horkheimer strove to reconstruct in the 1930s paves the way for this analysis. I therefore reconstitute the debate within the Frankfurt School on the question of how Marx’s historical materialism should be interpreted.

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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.

Les avancées de la biologie contemporaine, posent de façon nouvelle des problèmes philosophiques anciens. Ceux des rapports entre le vivant et l'inanimé, entre le corps et l'esprit, l'erreur et la vérité, sont les plus évidents. La philosophie de Spinoza, bien que datant du 17e siècle, apporte à ces problèmes des solutions plus pertinentes que la plupart des philosophies plus récentes, développées dans les siècles qui l'ont suivie. En retour, les acquis actuels des sciences physiques et biologiques, notamment des neurosciences cognitives, permettent de porter un nouveau regard sur certaines notions propres à la philosophie de Spinoza, telles que sa «petite physique», la nature cause de soi, la notion de matière, l'essence des choses, les genres de connaissance, qui acquièrent de ce fait un surcroît d'actualité. / Old philosophical problems are raised in renewed ways by advances in biology of today. Most obvious are the problems of relationship between living and non-living, mind and body, error en truth. Spinoza's philosophy, although from 17th century, offers solutions to these problems more relevant than most more recent philosophies. In return, present knowledge from physical and biological sciences, especially cognitive neurosciences, can provide a new look at some specifically Spinozist notions such as his "little physics", Nature as cause of itself, the notion of matter, the essence of a thing, kinds of knowledge, which gain all the more interest from a present day point of view.