Análises físico-químicas em mistura de solo-cimento compactado hidratado com lodo de ETA líquido

Abstract

This work aimed to analyze the incorporation of waste, sludge from a Water Treatment Plant (WTP), from a conventional process, with 99.46% moisture and 0.54% dry solids, into a compacted soil-cement mixture. for manufacturing ecological bricks through physical-chemical analyses on the materials and the product formed. For this, the WTP sludge was characterized via Scanning Electron Microscopy (SEM) associated with Energy Dispersive Spectroscopy (EDS) and Atomic Absorption Spectrometry (AAS). In which we collaborated with the field of silicon, which in its combined forms includes compounds present in soil, in addition to aluminum, due to the coagulant used in the water treatment process. The soil used was presented and presented an apparent dry specific weight (ƴd) of 1.77 gf cm-3 , with the ideal moisture value in the compaction test of 15%, and the cement contents tested were 7, 11 and 14%. The consisted of molding test bodies with the WTP sludge-soil-cement mixture with the adopted traits, in which the results of simple specifications achieved values within the range 2.5 to 9.3 MPa, specified by the Brazilian Technical Standard (NBR) 8491/2012. Next, a trace of the experiment carried out on the test bodies for the manufacture of ecological bricks was selected with a specific dry weight of the soil of yd 1.70 gf cm-3 with 7% cement content, being a batch with the sludge of WTP cement, and another with water. The hydraulic conductivity test on the test specimen formed between WTP sludge-soil-cement, with 28 days of curing, presented a result for the hydraulic conductivity coefficient (k) of 7.49x10-9 cm s-1 , with classification the value of the coefficient (k) as little permeable. From the hydraulic conductivity test with the percolation of distilled water, it was possible to collect the leached content of the sample to quantify aluminum, the metal predominantly present in the sludge composition. The result obtained from aluminum leaching was 0.120 mg L-1, while NBR 10004/2004, which classifies solid waste, determines 0.2 mg L-1 as the maximum solubilization limit for aluminum, however, it reached an average 0.73 MPa resistance to simple improvement. Thus, the disposal of WTP sludge in a soil-cement brick mixture (ecological brick) met the requirement for sustainable construction, where no waste is generated but waste is used in its mixture composition in material replacements from a natural source to form the final product.