Incorporação de lodo proveniente de estação de tratamento de esgoto em blocos de concreto para pavimento intertravado

Abstract

The sludge generated in Sewage Treatment Plants (STP) is the result of several operations aimed at removing solid, organic and inorganic contaminants present in wastewater. Therefore, it is important to observe the potential for reusing this sludge, knowing its characteristics and verifying products in which these materials can be incorporated. In this sense, this work sought to evaluate the prediction of the use of dry STP sludge as an unconventional material in partial replacements of cement in the production of concrete paving blocks, understanding the characterization of the materials used in the experiment and the effect on the replacements with the aid of Factorial Design that determined the replacement at 5%, 10% and 15% due to the w/c factor (water/cement) of 0.35, 0.50 and 0.65. The sludge was collected at the ETE of a residential condominium in São José de Ribamar - MA, removed from the thickening tank and directed to the drainage bed and later sent to natural drainage for 7 days. The characterization of the ETE sludge was carried out in terms of granulometry, physical and chemical analysis, analysis of organic load and morphological analysis. And for the formulation of the experiments, a factorial design was made to study the influence of the sludge and the w/c factor in the tests of: resistance to elasticity, tensile strength, water concentration, void index and density. Regarding the mechanical properties, the specific resistance tests found that the concrete blocks are not suitable for use in pavements due to their low mechanical resistance. The visual inspection of the pieces of hexagonal concrete blocks made showed that the pieces with better regularity and finish are those with the highest w/c factor (0.50 and 0.65) due to the homogeneity in the mixture that provided less deformations and firmer edges. The w/c factor had a direct influence on the mechanical tests of the concrete. The lack of water in the samples with factor 0.35 resulted in an inadequate hydration of the cement, generating greater water absorption and void index in the samples, resulting in greater porosity, which affected the strength of the concrete. Finally, concrete with the addition of ETE sludge can be used, however, in construction elements that do not require high mechanical strength.