A influência nas propriedades físicas, mecânicas e perda de transmissão sonora do lodo de ETA incorporado em argamassas

Abstract

The intense urbanization process in Brazil has brought, in addition to the increase in noise levels in urban centers, an increasing demand for drinking water. Water treatment processes have sludge as a product, a solid waste classified as non-inert according to NBR 10004 (ABNT, 2004). Due to the high consumption of raw materials and the large production of solid waste, civil construction has a great potential for recycling waste in its materials and processes, to mitigate and control the impacts caused by the sector. In order to reconcile the regulations related to waste management and acoustic performance, the present work was developed to evaluate the influence of the incorporation of sludge in mortars through studies of the physical, mechanical properties and the sound transmission loss. Initially, the materials to produce mortar were characterized, the cement CP II-F-32, the lime CH-III and the sand, physically and chemically. Consequently, the pattern of the standard mortar and the granulometry of the dry residue were defined, in which better mechanical performances were observed in the largest granulometries. At first, for a lower cement consumption, a mixed mortar was developed, but it did not achieve satisfactory mechanical performance, considered as a criterion for choosing the base mix. Thus, cement mortar was chosen for the duration of the study. Subsequently, the contents of residue in relation to the mass of cement and to replace the fine aggregate were incorporated, in the percentages of 5%, 10%, 15% and 20%, compared to conventional mortar. Mortars in the fresh state, with higher amounts of sludge, showed a decrease in mass densities. In the hardened state, there was an increase in water absorption and porosity with the increase of sludge content, accompanied by a decrease in bulk density, and a consequent reduction in mechanical strength and elasticity modulus. It was noted that between the frequencies from 500Hz to 1250Hz the sound transmission loss obtained in the impedance tube were similar between the different levels. It was found a great variability among the measurement data of most of the analyzed frequencies. Thus, it can be said that the incorporation of dry sludge in mortars can be considered a viable alternative for final disposal of the tailings, without significantly affecting the physical, mechanical properties and sound transmission loss of the material.