Desenvolvimento de cimento supersulfatado com a incorporação de escoria Basic Oxygen Furnace (BOF)

Abstract

The large and constant production of cement has a significant amount of CO2 release, with carbon dioxide being extremely harmful to the environment. That is why the constant search for alternative sources, such as supersulfated cement (SSC) since it is made up of blast furnace slag, calcium sulfate and some activator alkaline. In Brazil, there is still no great emphasis on CSS, although in other countries there is even a specific standard. Even so, millions of tons of steel are produced daily, with only blast furnace slag a highlight for reuse, while the others are little used, as is the case of basic oxygen furnace (BOF) slag. The last mentioned slag has already demonstrated its usefulness in several works depending on its composition, however, little explored in the literature for the production of this type of cement. Therefore, the present work seeks to develop supersulfated cement with the incorporation of BOF slag, using CSS pastes with different compositions in their cementitious matrices. Then, the mechanical analysis of each paste is carried out, through the compressive strength test at 7 and 28 days, verifying that there is a significant difference in relation to the values found for each paste. A statistical analysis was also performed using Statistica version 7.0. The low compressive strengths found are most likely due to the fact that the slag used does not meet the minimum requirements of the European standard EN 15743/2010. Statistical analyzes showed that there was a significant difference in mechanical strength between CSS pastes. A microstructural analysis was also carried out, using images obtained with the Scanning Electron Microscope (SEM), and thermal analyzes performed with Thermogravimetry (TGA) and Differential Scanning Calorimetry (DSC), making it possible to identify that the pastes with the BOF slag had altered reaction kinetics in relation to the hydration process of the supersulfated cement. This identification becomes possible from the correlation of the microscopic images obtained and the temperature graphs generated, which indicate the peak of the reaction of each compound in the samples made from CSS.