Les mortiers projetés sont formulés de manière très complexe, afin de notamment répondre aux exigences imposées par leur procédé de mise en place. La caractérisation et l’interprétation des leurs propriétés rhéologiques représentent ainsi un grand challenge, faisant appel à diverses thématiques de la matière molle : suspensions granulaires, dispersions colloïdales, solutions de polymère, mousses, etc. Nous considérons l’influence de divers paramètres de formulation, toutefois, le cœur de cette étude concerne l’influence des épaississants organiques, en particulier les éthers de cellulose (EC). Ces polysaccharides sont utilisés dans la pratique principalement pour leurs propriétés de rétention d’eau, mais ils ont également un fort impact sur la rhéologie. Nos résultats montrent que les EC augmentent considérablement la consistance du mortier, mais leur influence sur le seuil d’écoulement est plus complexe : celui-ci augmente pour les faibles dosages puis diminue jusqu’à s’annuler pour des dosages élevés. L’impact de l’EC sur la rhéologie du mortier a été relié à son influence sur les propriétés de la solution aqueuse interstitielle, en invoquant notamment ses aspects associatifs. La rhéologie est influencée par des facteurs externes (température, ajout de tensioactif) ainsi par la structure chimique du polymère. Avec la rhéologie oscillatoire, nous avons analysé l’impact de certains types d’épaississants sur l’organisation microstructurale du mortier. Nous avons établi une corrélation nette entre propriétés viscoélastiques et rétention d’eau. Plus l’épaississant augmente, plus les aspects dissipatifs augmentent et plus la rétention d’eau s’améliore. / Machinery rendering mortars are characterized by a highly complex mix-design, due to several requirements related to their placement process that need to be fulfilled. It is therefore a challenge to characterize their rheological properties. Indeed they display most of the features encountered in the field of soft matter. We consider the influence of several mix-design parameters on most of the fresh state properties of the mortars. However the main focus is the impact of organic thickening admixtures, in particular cellulose ethers (CE), on the rheological behavior. These admixtures are used for their water retention capacity, yet they have also a high impact on the rheological properties. CEs significantly increase the consistency, while their effect on the yield stress is more complex: when increasing CE dosage rate the yield stress first increases, and then decreases beyond a critical dosage rates. The impact of CE on the mortar rheological behavior is discussed in relationship to its effect on the properties of the interstitial aqueous solution. The associative feature of the CE polymer is particular referred to explain our results. Several parameters that may affect this property are considered. Small amplitude oscillatory shear rheology is used to probe mechanically the influence of CEs on the microstructure of the mortar. By comparing the effect of different thickening admixtures on the viscoelastic properties of the mortars a clear correlation between these properties and water retention is established. The more the admixture introduces viscous dissipation as compared to elasticity into the system, the more it increases its water retention capacity.

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-06-27T17:06:44Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação - Dannúbia Ribeiro Pires (PPGECAM_CAA).pdf: 1569346 bytes, checksum: de291d5949502da801c8fef00fcf2b43 (MD5) / Made available in DSpace on 2016-06-27T17:06:44Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação - Dannúbia Ribeiro Pires (PPGECAM_CAA).pdf: 1569346 bytes, checksum: de291d5949502da801c8fef00fcf2b43 (MD5) Previous issue date: 2016-02-15 / Facepe / A grande demanda de cinza de algaroba gerada nas lavanderias pertencentes ao APL de Pernambuco e sua constituição química prioritária de carbonato de cálcio, caracterizando seu efeito filler, impulsionaram a verificação do comportamento do sistema cimentício quando da substituição do cimento pela cinza nas argamassas de revestimento. O objetivo deste trabalho é utilizar o resíduo, atualmente descartado no ambiente, em materiais cimentícios, de modo a contribuir para o desenvolvimento sustentável, reduzindo o impacto produzido pelo armazenamento e descarte inadequado. Além disso, pretende-se contribuir para a redução da emissão de CO2 causada pelas indústrias cimenteiras e minimizar os custos dos produtos com cimento Portland. Neste trabalho, foi avaliada a influência da substituição do cimento Portland em diferentes porcentagens (0%, 5%, 10% e 20%) nas propriedades nos estados fresco e endurecido das argamassas, aplicando no traço (1-X):2:X:9 (cimento: cal: cinza: areia), em volume, comumente utilizado para emboço e argamassa de assentamento em obras da região. A cinza foi caracterizada física e quimicamente. As propriedades analisadas no estado fresco foram: reologia das argamassas (reometria de mistura, de cisalhamento e compressiva - squezze flow), densidade de massa e teor de ar incorporado e aderência inicial das argamassas no substrato; e no estado endurecido foram: resistência à tração por compressão diametral, resistência potencial de aderência à tração, módulo de elasticidade dinâmico, porosidade e permeabilidade. De acordo com os resultados obtidos nesta pesquisa, a presença da cinza favoreceu, em todas as porcentagens estudadas, a redução no teor de água de amassamento, mantendo a trabalhabilidade das argamassas. As argamassas com teores de 5% de cinza preservam as propriedades do sistema compatíveis com as propriedades da argamassa de referência. Porém, até 10% é possível a introdução deste resíduo, em substituição ao cimento, sem prejuízos aos sistemas cimentícios, proporcionando alterações mínimas em relação à argamassa de referência, sendo promissor o uso desse resíduo em materiais cimentícios. / There is a considerable production of algaroba wood ash in the laundries of the local productive arrangement on the clothing industry in the Agreste Region of Pernambuco. It is possible to apply it as filler due to its mainly chemical constitution as calcium carbonate. Based on these facts, it was evaluated the mortars behaviour when cement is partial replaced by algaroba ashes. This work objectives reuse this residue, currently discarded in the environment, in cementitious materials. In this way, it contributes to the sustainable development by reducing the impact by storage and improper disposal. Moreover, it is intended contributes to reducing CO2 emissions caused by cement industries and minimize the costs of products with Portland cement. This study investigates the influence of the gradual replacement of cement by algaroba ash (0%, 5%, 10% and 20%). It was evaluated the properties of mortars in fresh and hardened states. The mix by volume (1-X):2:X:9 (cement, lime, ash, sand) was studied, taking into account that these alternative mortars can be applied on regional building sites as rendering plaster and laying mortar. The ashes were characterized physically and chemically. It was carried out in the fresh state: rheology of mortars (mixture, compressive and shear rheometers - squeeze flow), mass density, a content of entrained air and initial adherence of the mortars to the substrate; and in the hardened state: diametrical traction, potential adherence, dynamic modulus of elasticity, porosity and permeability. The results indicate that the presence of the ashes decreases the quantity of mixing water required to keep the workability of the mortars, regardless the content of cement replacement content by algaroba ash. The mortar with 5% ash content preserving system properties compatible with the properties of the reference mortar. However, it is possible to partial substitute the cement by algaroba ash until 10% in the studied mortars, when comparing to the reference system, algaroba ashes are a promising material to incorporate in a cementitious system.