Abstract
Soil-cement bricks are earth construction materials that have been gaining prominence due to their environmental advantages. The Brazilian Technical Standard NBR 8491 establishes physical and mechanical procedures to characterize these bricks. However, the thermal characterization is an important assessment, since it is related to the building’s thermal performance. The objective of this study is to thermally characterize a panel of soil-cement bricks produced with mining tailings. For such, its absorptance (α) was evaluated using the ALTA II spectrometer, and its thermal transmittance (U) and thermal resistance (RT) through the hot box method (ISO 9869). The results enabled the calculation of the thermal capacity (CT), thermal lag (φ) and solar factor (FSO) of the panel, which were compared to the Brazilian Technical Standards NBR 15575-4 and NBR 15220 for Bioclimatic Zone 8. As a result, the soil-cement body panel showed values of α = 0.71, U = 2.47 Wm-2K-1, CT = 273.4 kJm-2K-1, φ = 6.02 h and FSO = 6.81%, meeting the requirements established in the first standard, but failing to attend the second. To comply with the Brazilians specifications, it is suggested to paint bricks with lighter colors focusing on decreasing its absorptance value. Thus, soil-cement bricks may be an environmental alternative to dispose of the waste generated during the mining process, contributing to sustainability.
Highlights
The civil construction sector is responsible for an environmental setback, in view of its high consumption of natural resources and the emission of pollutants in the stages of material production, execution, and demolition of engineering works
Ferreira et al (2017) concluded that, for Bioclimatic Zone 8, in locations with predominance of hot and dry weather, such as Peixoto de Azevedo, walls need to have a thermal lag greater than that suggested by the standard (φ ≤ 4.3h), see Table 1, for greater thermal comfort
NBR 15220-3 (ABNT, 2005) suggests that lower values of thermal transmittance can be achieved by adding a mortar coating on the external face, the internal face, or both, with a composition of the same thermal conductivity, in order to maintain compatibility between the components of the vertical sealing system
Summary
The civil construction sector is responsible for an environmental setback, in view of its high consumption of natural resources and the emission of pollutants in the stages of material production, execution, and demolition of engineering works. Construction materials that have sustainable, durable, and less impacting raw materials, such as earth and/or industrial waste, are currently being discussed. In this sense, soil-cement bricks constitute a masonry component composed of a homogeneous, compacted and hardened mixture of soil, Portland cement, and water, is manufactured with a manual or hydraulic press without the firing process. For Mansour et al (2016), the characterization of soil-cement bricks, in addition to meeting the structural requirements, must meet the thermal performance parameters, as these are related to the habitability requirements of buildings. For Mansour et al (2016), the characterization of soil-cement bricks, in addition to meeting the structural requirements, must meet the thermal performance parameters, as these are related to the habitability requirements of buildings. Zhang et al (2017) demonstrate that the higher the density of the bricks, the greater their thermal conductivity, there is no obvious linear relationship between this parameter and the amount of cement added. Mansour et al (2016)
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