Estudo da utilização de cinzas pesadas de termelétricas para aplicação em microrrevestimento asfáltico a frio

Abstract

Microsurfacing is a slurry seal mainly used in the preventive maintenance of pavements that has gained worldwide prominence in recent decades. Its composition consists basically of mineral aggregates, filler, water, additives and polymer-modified emulsified asphalt. Mineral aggregates account for over ninety percent of the final weight of the mixture, so it is important to study the use of alternative aggregates in microsurfacing composition for technical, economic or environmental reasons. Meanwhile, combustion of coal in thermal power plants produces fly ash and bottom ash that can create an environmental problem. Thus, the main objective of this research is to evaluate the use of bottom ash as an alternative aggregate in the microsurfacing composition through technical, financial and environmental analysis. Thereunto, the methodology of this work was divided into four stages. In the first one, the mineral aggregates, the ash and the emulsion were collected and characterized. In the second stage, the proportions of mineral and alternative aggregates (10%, 30% and 50%) in the compositions to be tested were defined. In the third stage, the mix design tests were performed to analyze the performances of the compositions defined in the previous stage, the compliance with the environmental aspects was also verified. In the last step, the costs of microsurfacing compositions with and without the alternative aggregate were compared. It was verified that the increase of bottom ash caused a reduction in the performance of the mixtures, indicating probable chemical incompatibility for higher contents (30% and 50%) of this material and the RC-1C E asphalt emulsion. Therefore, the mix design tests of microsurfacing indicated that bottom ash could replace up to 10% of mineral aggregates. Regarding the environmental classification, it is believed that the use of this low percentage doesn’t make mixture with 10% bottom ash dangerous. In the financial viability analysis, was observed a reduction in the direct unit cost of implementing the microsurfacing about 5% by replacing 10% of mineral aggregates with bottom ash indicating a financial viability of using bottom ash as alternative aggregates in the execution of microsurfacing.