Caracterização e estudo da incorporação do lodo de ETA em argamassa

Abstract

The water treatment process produces a product known as sludge. This in turn is considered an environmental and economic problem for sanitation companies who do not know how to properly manage these wastes and ultimately neglect them. Currently, this sludge has been deposited in water bodies or in vacant lots, causing the pollution of these places. In the municipality of Caçapava do Sul-RS, the sludge that is generated at the Water Treatment Plant (WTP) is conducted to an open-air dewatering bed in a wasteland, which is its final destination. The present study aimed to characterize and use this sludge as a substitute for the small aggregate (natural sand) in the production of mortars. The experimental procedure included the collection of the sludge, its characterization, and a study of the dosage of mortars produced with different contents of Dry Sludge (LS) and Calcined Sludge (LC) and evaluation of the mortars produced with the sludge. All the sludge samples used were collected on the same day in the water treatment plant of Caçapava do Sul, in 2017. The dosages of the mortars were 0%, 3%, 5% and 10% with fixed water cement ratio of 0,5 and their properties were evaluated in the fresh state (consistency, mass density and incorporated air content) and in the hardened state (water absorption and tensile strength in bending and compression). The results obtained by the characterization indicated that the dry sludge has an expressive amount of organic matter (26%) and its chemical composition is formed by oxides (SiO2, Al2O3 and Fe2O3) and for the calcined sludge the burning process (1000ºC) organic matter and its constitution presented the same oxides as the dry sludge only in higher concentrations. For the mortars it was verified that the mass substitution of the sand by the calcined sludge (LC) provided an increase in the mechanical properties, being the 3% content that obtained the best results. The dry sludge (LS) significantly reduced the mechanical resistance due to the presence of organic matter. This study confirms that Water Treatment Plant (WTP) sludge has the potential to be used as a small aggregate in the mortar.