As argamassas de revestimento são amplamente utilizadas na construção civil e, suas propriedades no estado endurecido são fortemente influenciadas pelas propriedades no estado fresco, as quais dependem de fatores como: materiais empregados; forma de aplicação; e interação entre substrato e argamassa. Os ensaios utilizados para caracterização reológica das argamassas não contemplam as alterações que ocorrem devido o contato com o substrato, gerando discordâncias nas teorias sobre os fenômenos pelo qual ocorre a resistência de aderência. Sendo assim, o presente trabalho visa identificar as alterações do comportamento reológico de suspensões cimentícias aplicadas em substratos porosos por meio do ajuste do método do squeeze-flow. Para tanto, foram utilizadas duas configurações do squeeze-flow, com e sem confinamento do fluxo radial; três tipos de base, sendo uma metálica e duas porosas; e, pastas com diferentes materiais, a saber: cimento; cal e filler calcário. A escolha da pasta ao invés da argamassa foi basicamente por duas razões: primeiro, porque a pasta é a parcela da argamassa mais suscetível aos efeitos de sucção capilar do substrato; e segundo, para simplificar o cenário de análise, eliminando a variável areia. Ambas as configurações apresentaram-se viáveis na identificação da alteração do comportamento reológico da pasta, devido aos fatores como: tipo de substrato; o tempo de contato entre pasta e substrato; perda de água da pasta; e energia de mistura. Além disso, observou-se que os procedimentos adotados, assim como o auxílio de outros ensaios, podem colaborar em estudos da influência de fatores como: temperatura; rugosidade; ângulo de contato; distribuição granulométrica de pastas e argamassas; e, principalmente, compreender os fenômenos que ocorre no período denominado como tempo de puxamento, ao passo que este influencia diretamente na resistência de aderência. / Mortar renderings are used in most of the constructions and their properties in the hardened state are strongly influenced by the properties in the fresh state, which depend on factors such as materials used; application form; and interaction between substrate and mortar. The determination of rheological parameters of fresh mortars doesn\'t include the changes that occur due to contact with the substrate. It generates disagreements in the theories about the phenomena of formation of the bond strength. Therefore, this study aims to identify changes in the rheological behavior of cementitious paste applied to porous substrates by adjusting the squeeze flow method. For this, two configurations of squeeze flow were used, with and without confinement of the radial flow; three substrate types; and pastes with different materials, namely cement, lime and sand. The choice of paste instead of mortar was basically for two reasons: first, because the paste is the portion of mortar more susceptible to the effects of capillary suction of substrate; and second, to simplify scenario analysis, eliminating the variable sand. Both configurations were viable in the identification of the alteration of rheological behavior of paste, due to factors such as substrate type; the contact time between paste and substrate; loss of water from paste; and mixing energy. In addition, it was observed that the procedures adopted as well as the aid of the other tests can collaborate on studies of the influence of factors such as temperature, roughness, contact angle, particle size distribution of pastes and mortars; and above all to understand the phenomena that occurs in the initial periods of contact paste/substrate and consequently in the bond strength.

Current problems on the interaction of complex liquids (i.e. droplets or foams) with complex surfaces (i.e. soft deformable or porous surfaces) are addressed in the following areas: (1) wetting of deformable substrates and surface forces, (2) kinetics of wetting and spreading of non-Newtonian liquids over porous substrates, (3) kinetics of spreading of non-Newtonian solutions over hair, (4) free drainage of foams produced from non-Newtonian solutions, and (5) foam drainage placed on porous substrates. Equilibrium of liquid droplets on deformable substrates was investigated and the effect of disjoining pressure action in the vicinity of the apparent three phase contact line was taken into account. It was proven that the deformation of soft solids is determined by the action of surface forces inside the transition zone. Spreading/imbibition of blood, which is a power law shear thinning non-Newtonian liquid, over a dry porous layer was investigated from both theoretical and experimental points of view. It was found that blood droplet spreading/imbibition over porous substrates shows two different behaviours: (i) partial wetting case with three subsequent stages: initial fast spreading, constant maximum droplet base and the shrinkage of the droplet base; (ii) complete wetting case with only two stages: initial fast spreading and the shrinkage of the droplet base. The wetting of hair tresses by aqueous solutions of two commercially available polymers, AculynTM 22 (A22) and AculynTM 33 (A33) was investigated experimentally. Both A22 and A33 solutions demonstrate well pronounced shear thinning behaviour. Initial contact angle of the A22 and A33 solutions on hair tresses was about 100o. The A22 droplets remained on the hair tress after spreading for at least half an hour. However, a fast penetration of the A33 droplets inside the hair tresses was observed when advancing contact angle in the course of spreading reached a critical value of about 60o. This could be explained by Cassie-Wenzel wetting transition which is caused by filling the pores inside the porous media by liquid. The influence of non-Newtonian rheology of A22 and A33 solutions on foam drainage was also investigated experimentally and a new theory of foam drainage was presented for the case of free drainage. For lowly viscous polymeric solutions and under the assumption of rigid surface of the Plateau border, the predicted values of the time evolution of the foam height and liquid content were in good agreement with the experimental data. However, in the case of highly viscous solutions an interfacial mobility at the surface of the Plateau border has to be taken into account. A completely new theory of foam drainage placed on porous substrate was developed. It was found that there are three different regimes of the process: (i) a rapid imbibition, the imbibition into the porous substrate dominates as compared with the foam drainage; (ii) an intermediate imbibition, that is, the imbibition into the porous substrate and the rate of drainage are comparable; (iii) a slow imbibition, the rate of drainage inside the foam is higher than the imbibition into the porous substrate for a period of time and a free liquid layer is formed over the porous substrate.

As argamassas de revestimento são amplamente utilizadas na construção civil e, suas propriedades no estado endurecido são fortemente influenciadas pelas propriedades no estado fresco, as quais dependem de fatores como: materiais empregados; forma de aplicação; e interação entre substrato e argamassa. Os ensaios utilizados para caracterização reológica das argamassas não contemplam as alterações que ocorrem devido o contato com o substrato, gerando discordâncias nas teorias sobre os fenômenos pelo qual ocorre a resistência de aderência. Sendo assim, o presente trabalho visa identificar as alterações do comportamento reológico de suspensões cimentícias aplicadas em substratos porosos por meio do ajuste do método do squeeze-flow. Para tanto, foram utilizadas duas configurações do squeeze-flow, com e sem confinamento do fluxo radial; três tipos de base, sendo uma metálica e duas porosas; e, pastas com diferentes materiais, a saber: cimento; cal e filler calcário. A escolha da pasta ao invés da argamassa foi basicamente por duas razões: primeiro, porque a pasta é a parcela da argamassa mais suscetível aos efeitos de sucção capilar do substrato; e segundo, para simplificar o cenário de análise, eliminando a variável areia. Ambas as configurações apresentaram-se viáveis na identificação da alteração do comportamento reológico da pasta, devido aos fatores como: tipo de substrato; o tempo de contato entre pasta e substrato; perda de água da pasta; e energia de mistura. Além disso, observou-se que os procedimentos adotados, assim como o auxílio de outros ensaios, podem colaborar em estudos da influência de fatores como: temperatura; rugosidade; ângulo de contato; distribuição granulométrica de pastas e argamassas; e, principalmente, compreender os fenômenos que ocorre no período denominado como tempo de puxamento, ao passo que este influencia diretamente na resistência de aderência. / Mortar renderings are used in most of the constructions and their properties in the hardened state are strongly influenced by the properties in the fresh state, which depend on factors such as materials used; application form; and interaction between substrate and mortar. The determination of rheological parameters of fresh mortars doesn\'t include the changes that occur due to contact with the substrate. It generates disagreements in the theories about the phenomena of formation of the bond strength. Therefore, this study aims to identify changes in the rheological behavior of cementitious paste applied to porous substrates by adjusting the squeeze flow method. For this, two configurations of squeeze flow were used, with and without confinement of the radial flow; three substrate types; and pastes with different materials, namely cement, lime and sand. The choice of paste instead of mortar was basically for two reasons: first, because the paste is the portion of mortar more susceptible to the effects of capillary suction of substrate; and second, to simplify scenario analysis, eliminating the variable sand. Both configurations were viable in the identification of the alteration of rheological behavior of paste, due to factors such as substrate type; the contact time between paste and substrate; loss of water from paste; and mixing energy. In addition, it was observed that the procedures adopted as well as the aid of the other tests can collaborate on studies of the influence of factors such as temperature, roughness, contact angle, particle size distribution of pastes and mortars; and above all to understand the phenomena that occurs in the initial periods of contact paste/substrate and consequently in the bond strength.

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