Avaliação do comportamento de concretos com Politereftalato de etileno submetidos a elevadas temperaturas

Abstract

Civil construction currently consumes a large amount of natural resources, being responsible for part of the world’s environmental degradation. The introduction of new materials in cementitious matrix - such as Ethylene Polyerephthalate (PET) - has been a good option to reverse or minimize this scenario. However, to spread its use it is necessary to evaluate the properties of cementitious matrix with the incorporation of this material and its behavior against aggressive environments, to which concrete can be exposed during its useful life. A fire fits into this context, because when subjected to high temperatures, the concrete undergoes transformations that can compromise the carrying capacity of the structure, which can lead it to collapse. Considering the above, the present work aims to evaluate some mechanical and durability properties of concrete produced with partial replacement of natural sand by PET aggregate, submitted to different temperature gradients. From a reference trait (without PET), two more concrete were made, which have partial volume replacement (20% and 50%) of the natural sand by PET aggregate. After the concreting and submerged curing for 28 days, the concretes were exposed to different temperature gradients (200°C, 400°C and 900°C), so that after they had their properties evaluated. It was verified that the concrete has been suffer significant loss of mechanical properties and durability when exposed to temperatures above 400 ° C. The results have indicated that the partial substitution of 20% PET aggregate have presented axial compressive strength results similar to the reference trait, without significant reduction of this property when exposed to 400°C. However, the 50% substitution trait of PET aggregate proved unfeasible, due to the significant reduction of the evaluated properties.