Soil mineralogical composition effects on the durability of adobe blocks from the Huambo region, Angola

Abstract

After many years of war, great efforts have been made for the socio-economic development of Angola, particularly in the construction industry. Among the construction techniques, adobe is one of the most used in the province of Huambo, especially by low-income families, which constitute the majority. This technique was established as an intangible heritage in the culture of that population. Huambo province is located in the central region of Angola (Central Plateau). Adobe blocks are building elements with potential degradation by the action of water. Due to the subtropical climate, hot and humid, and geomorphology of the province, located at about 1000-2000 m of altitude and with an extensive river system, these buildings can be vulnerable and may present premature degradation, exacerbated by the lack of knowledge concerning the properties of the geomaterials used and techniques/solutions that allow their stabilization and conservation. This paper aims to present the main results of the study to investigate the influence on adobe performance in regard to the mineralogy and geochemistry of soils used in the production of adobes used in the construction of dwellings. The knowledge gained with this research can support the development of solutions for the common anomalies and problems in this construction, as well as to improve the strength and durability of the adobe units. For this purpose, soil samples were collected and mineralogical, geochemical, and physical tests were performed. Durability and erodibility tests were also performed on selected adobes, following the Geelong method. The results obtained with this research may contribute to the development of the knowledge concerning this sustainable building solution, which has a strong presence in the province of Huambo and neighbouring regions.

Mechanical strength, mass loss and volumetric changes of drying adobe matrices combined with kaolin and fine soil particles

“…In Figure 1 particle distribution results from soils used in previous studies (i.e. red, green, blue and red dashed-dotted lines) that investigated adobe blocks properties are presented as a reference among the particle distribution of the soil of this study [22,42,43]. This plot demonstrates that the particle size distribution of the selected soil is within the range of other soils previously employed in studies of adobe.…”

“…This plot demonstrates that the particle size distribution of the selected soil is within the range of other soils previously employed in studies of adobe. [22,42,43].…”

Mechanical and damage similarities of adobe blocks reinforced with natural and industrial fibres

“…Sieve analysis and Atterberg limits test were performed following the standards ASTM D7928 [19] and ASTM D4318 [20]. Figure 1 presents the sieve analysis of the soil used for this study (solid line), as well as the sieve analysis from other authors to use them as a reference [21][22][23][24]. As can be seen, the particle size distribution of soil used in our study is within the particle size distribution of the ones used by other researchers.…”

“…Atterberg limits are presented in Table1, and the soil classification following the Unified Soil Classification System is well-graded clayey sand [25]. Figure 1: Gradation curves of this study (solid line) and worked by NIÑO VILLAMIZAR et al [21] (long-dashed line), DUARTE et al [22] (dotted and dashed lines), SANTOS et al [23] (small-long dashed line) and FABBRI et al [24] (dot-dashed line)…”

Lithic arrowheads: Siliceous raw material sources and technology in Southern Portugal

“…A Göebel mirror and a 0.3 mm collimator direct a small parallel X-ray beam onto the sample. Identification of crystalline phases and the semiquantification by the Reference Intensity Ratio method were performed using DIFFRAC.SUITE EVA ® software and the ICDD PDF-2 database (Duarte et al, 2017;T. Pereira et al, 2016).…”