Tijolos ecológicos constituídos de solo e resíduo de casa de farinha.

Abstract

This study aimed to develop ecological bricks consisting of soil and cassava wastewater - effluent from the production of cassava flour - with viability of use, without the use of water and burning and giving adequate disposal to this liquid residue of high potential of negative environmental impact, in the perspective of development and materialization of social technology. The technology developed was based on ABNT's NBR 10833/12 which deals with the production of soil-cement bricks. The soils worked were extracted from sedimentary deposits in the Paraíba river basin in Barra de São Miguel, Juazeirinho and Santa Cecília, and the manipueira in the Jenipapo District, Puxinanã, PB. Priviously to the composition of the masses and preparation of the test bodies, the raw materials were prepared and characterized using XRD, EDX, Casagrande, granulometry, TG and DTA techniques for soils and, for cassava wastewater, readings from pH, conductivity and specific gravity, and tests to determine the contents of VSS, FSS, TSS, COD, N, P, K and other chemical elements. Soils are similar in physicochemical characteristics and have all the conditions required for use in reference technology (soil-cement brick) in terms of plasticity and granulometry, and the cassava wastewater, with its composition based on water (90.9% , according to the TG curve) and with high concentration of organic solids, when compared to other effluents, allowed a good alloy in the mass. The compositions of the masses were defined based on preliminary tests with small specimens that showed resistance of 3.41 ± 0.73 MPa, indicating the feasibility of manufacturing with soil and cassava wastewater. The bodies produced in mechanical and hydraulic presses were tested for variations in size, mass, water absorption and compressive strength, and some results were not satisfactory, as there was no resistance to water absorption and resistance ranged from 0.795 ± 0.419 MPa, that is, the maximum was 1.215 MPa, for composition with 90% of soil, 10% of sand and 12% of cassava wastewater. The bricks did not meet the technical requirements for use in civil construction under these conditions, however, this is not able to support condemnation of the developed parts, considering: the application of coatings or waterproofing, for protection against humidity, the use of additives to the mass and the use for purposes that require less resistance. From a social and environmental point of view, the viability of the use of the manipueira in substitution of water in the production of ceramic pieces without burning was proved, offering adequate destination for this effluent and pointing out a new technology to benefit semi-arid communities.