Incorporação de cinza de biomassa, decorrente da queima em caldeiras de lavanderias de jeans do agreste de Pernambuco, no concreto

Abstract

The state of Pernambuco stands out in the national scenario as an important center of the clothing sector, due to the industrial activities executed at the Local Productive Arrangement of the Agreste of the state. Jeans laundries, responsible for processing the garments and depending on a large generation of steam for their processes, are within this context. The laundries consume significant quantities of wood per month for combustion in boilers, generating as secondary residue the biomass ash, which has become a problem regarding its destination, due to the irregular disposal in the region. This work aims to study the incorporation of the biomass ash, from the boiler of a laundry in the Agreste of Pernambuco, in the production of concrete for structure purposes. To conduct the work, the ash was collected from a laundry located in Caruaru-PE, which main energy source is the algaroba wood, and the chemical and/or physical characterizations of the concrete components (cement, sand, gravel and ash) were carried out, for later dosage of the traces, being one standard (conventional) trace and three traces with the addition of ash in volumetric substitution to the cement, in three proportions: 10, 20 and 40%. In the characterizations, techniques such as X-Ray Diffraction (XRD), for mineralogical determination, and Scanning Electron Microscope (SEM), for microstructural characterization, were used. After the concrete dosage, the material was produced, molded and characterized, its consistency being observed in the fresh state and its resistance and porosity in the hardened state, in addition to having its microstructure evaluated. According to the research results, the biomass ash proved to be a potential alternative limestone filler, due to the high content of calcium carbonate (CaCO3) in its composition. It was also verified that the ash content, reducing the cement content, caused lower workability, higher porosity and lower resistance to compression in the concrete; however, the traces with 10 and 20% of ash were compatible with the requirements of the current Brazilian technical standard, thus justifying its possible applications in structure elements. The increase in occurrence of delayed ettringite due to the addition of ash in the material was also verified.