Proposta de sistema construtivo em terra ensacada com incorporação de manipueira em substituição à água

Abstract

The state of Rio Grande do Norte, although small, is crossed by two Bioclimatic Zones that have an intense solar radiation as characteristics in common, but they are opposed in points such as the need for thermal mass and the size of the openings to achieve thermal comfort, the zones are Bioclimatic Zone 07 and Bioclimatic Zone 08, universe of study of this work. In this context, modern popular construction techniques fail to meet the necessary requirements to achieve comfort in the region, ignoring aspects ranging from socio-cultural to bioclimatic. The search for new ways to build in Rio Grande do Norte should consider solutions that promote the strengthening of local identity and that value not only its population, but also intrinsic and particular elements of the region, such as climate, territory and culture, as opposed to techniques that encourage the mass production of buildings observed in contemporary times. In this context, clay stands out as a building material, abundant and which has at its roots the answers to the weaknesses of current techniques, although quite stigmatized in the civil construction sector. At the same time, some qualities observed in the study of substituting water for cassava wastewater, the residue of washing cassava that is usually discarded, indicate its potential to be applied close to the soil, whose “cementing effect” can balance its weaknesses. Therefore, the aim of this work is to propose a building system on land based on Brickeradobe with the incorporation of cassava wastewater, instead of water in order to explore a technique that allows the use of soil for construction, but that is adaptable to the contemporary standard of living, ensuring high thermal mass and other thermo-acoustic properties without compromising the cost of the work. In this scenario, this work went through the construction system proposed from two perspectives: regarding the bioclimatic context, with a focus on climatic conditions; and as for the properties of construction materials, their shape, constitution, mechanical strength and the treatment of their surfaces were studied. For this, we started with a reference study and experimental research in the laboratory in order to characterize the materials in terms of their properties, not only physical-mechanical, but also chemical-mineralogical, in which form was taken into account, the casing and the chemical composition, the latter being defined through the formulation proposals and after the mechanical tests have been carried out. To evaluate the thermo-acoustic performance, two prototypes of houses with 1 m² of internal area and 1.50 m in height were built, in which it was also tried to measure the execution time and costs. Among the main tests carried out, resistance to simple compression was done at 07 days and at 28 days, water absorption by capillarity and thermal conductivity at 28 days for soil and water (SA), soil and cassava wastewater, compositions ( SM), soil with 10% cement and water (CA) and soil with 10% cement and cassava wastewater, (CM). All formulations showed results of compressive strength above 1 MPa, three of them above 2 MPa and the SM composition obtained resistance values similar to that of the CA formulation, highlighting the potential of cassava wastewater, as an accelerator of reactions for favoring some cationic exchanges, in addition to improving the workability of the material and facilitating its compaction, generating denser blocks. The SA blocks, despite good resistance to compression, lost a lot of mass when dry, being very crumbly. Thus, the use of cassava wastewater, brought significant improvements for acting exactly on the fragilities of the soil when functioning as a resin, improving its compaction and decreasing the loss of mass. As for the thermal properties, the Thermal Resistance, Thermal Transmittance, Solar Heat Factor and Thermal Delay of the isolated blocks were also evaluated in the context of the prototypes. A considerable decrease in the thermal amplitude was observed in the scenario without ventilation and a similar behavior with the ventilated system. The better compacting of the material with the use of the cassava wastewater, also ensured greater acoustic insulation to the block and the cost of the work reduced by about 28%.