Investigação do efeito de hidrogel polimérico sobre as propriedades no estado fresco e endurecido de pastas cimentícias

• Autor(a) principal: Cilli, Sabrina Lourenço
• Data de Publicação: 2021
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/215440
• topic: Cement; Hydrogel; Structural composite; Cimento; Hidrogel; Compósito estrutural

With the evolution of civil construction, the development of new materials is necessary to improve the performance and mechanical properties, especially of cementitious materials. Thus, some admixtures can be added to these types of materials to improve their conditions of durability, mechanical strength, and workability, without changing their morphology. Recent researches highlight the development of polymeric materials, such as hydrogels, for the production of special concretes. Hydrogels are polymers composed of cross-linked and threedimensionally structured networks, with hydroretention characteristics and subsequent capacity for controlled water release. This behavior is interesting, because it can contribute to a better hydration of cementitious materials over time, due to a more effective internal curing process. Thus, it was proposed the production of cement pastes with the application of hydrogels based on polyacrylamide and polysaccharide carboxymethylcellulose, for the production of a hybrid composite. The presence of the hydrogel proved to be effective when analyzing the properties of the matrix in its fresh state. They presence increases the workability and improves its internal hydration, verified by the increase around 9 % in the consistency index and by the increase in the final setting time, which became 20% longer than the control. Another important gain was observed from impedance test that indicated a conductivity 5% higher in the paste with the polymer. Because of the controlled release of water, the hydration products will be continuously formed. Other important factor is the density in the fresh and hardened states, which remained constant, indicating that there was no change in the internal structure, with an average value of 1.97 g/cm3 in the fresh state and 1.93 g/cm3 in the hardened state. The properties in the hardened state also demonstrated effectiveness with the presence of the polymer. Water absorption, measured by capillarity, decreased approximately on average by 24 % at the age of 7 days. Similarly, its capillarity coefficient decreased by 22%, proving that the material has better performance and durability. Moreover, its shrinkage had lower values compared to the control sample, due to the presence of available water, which better controls water loss by evaporation. In relation to mechanical strength and stiffness, the values are not altered even at advanced ages, with an average of 40.9 MPa. Therefore, the results obtained so far are very promising, which encourages us to continue the research seeking a possible technological application and market insertion.