Avaliação do uso de aditivo hidrofugante no gesso para construção

Abstract

Gypsum is widely used in construction due to its practical application and versatility. Despite this, gypsum has limitations when used in areas with high moisture content. In view of this, the present work aims to evaluate the use of water repellent additive as an alternative to improve the properties of plaster used in construction. In this context, the development of the study's experimental program was divided into two stages: study of the gypsum characterization and evaluation of the additive in terms of physical and mechanical properties in the hardened state. The granulometry tests were carried out once and unit mass twice where the average of the test was taken, in addition to the hardened state, 3 specimens were produced for each sample per test. The first stage included the granulometric analysis, the measurement of the unitary mass and the determination of the setting time. Two setting time tests were carried out for each sample, with different dosage percentages of water repellent additive: 0.2%, 0.3% and 0.6% in relation to the mass of plaster used in the sample. In the second stage, the samples were subjected to a production process, with a water/plaster ratio of 0.7, and kept at room temperature for 7 days until they reached mass consistency. After this period, they passed through a desiccator to eliminate residual moisture. Subsequently, they were subjected to water absorption, compressive strength and hardness tests, with the aim of comparing the results with the pure sample. The results show that gypsum, in its powdered form, complies with established standards. Regarding the physical and mechanical properties, although the addition of the additive resulted in a reduction in the setting time, together with the decrease in the absorption rates and the approximation of the compressive strength results to the samples containing the water repellent additive, even so these values did not meet the minimum criteria required by the standard for the application of plaster in construction. However, it is worth mentioning that the hardness obtained a notable increase with the incorporation of the additive, meeting the established requirements. In future work, it is recommended to reconsider some importante factors, such as the sample development process, the time required for the samples to reach the desired characteristics and the water/gypsum ratio. Reassessing these aspects could result in more efficient and effective use of the additive, allowing gypsum to meet the specific demands of different applications and environmental conditions.