Earth blocks stabilized by cow-dung

Abstract

In developing countries, most of the population cannot afford conventional building blocks made with the sand-cement mixture. In addition, these blocks do not provide thermal comfort and have a high embodied energy compared to vernacular materials. The main objective of this work was to produce low cost, resistant and durable (good resistance to water) blocks with a thermal behaviour enabling quality comfort indoor. For that purpose, the effects of cow-dung on microstructural changes in earth blocks (adobes) are investigated by means of X-ray diffraction, thermal gravimetric analyses, scanning electronic microscopy coupled with energy dispersive spectrometry, and video microscopy. The effects of these changes on the physical properties (water absorption and linear shrinkage) and mechanical properties (flexural and compressive strengths) of adobe blocks are evaluated. It is shown that cow-dung reacts with kaolinite and fine quartz to produce insoluble silicate amine, which glues the isolated soil particles together. Moreover, the significant presence of fibres in cow-dung prevents the propagation of cracks in the adobes and thus reinforces the material. The above phenomena make the adobe microstructure homogeneous with an apparent reduction of the porosity. The major effect of cow-dung additions is a significant improvement in the water resistance of adobe, which leads to the conclusion that adobes stabilized by cow-dung are suitable as building materials in wet climates.

Physical, thermal and mechanical properties of adobes stabilized with fonio (Digitaria exilis) straw

“…This value, which is the average of the Atterberg liquidity (w L ) and plasticity (w P ) limits, has been used in previous work [14]. The mixture was put into 4x4x16 cm 3 prismatic molds in two layers and manual compaction was applied for each layer (30 shocks).…”

“…Then they were dried again in the shade for 21 days before testing in order to avoid thermal shocks which could cause cracks in the clayey matrix. This curing time is that used by traditional adobe manufacturers and was chosen in recent studies that have given good physical and mechanical properties [7,14].…”

Physical, Mechanical and Thermal Behavior of Adobe Stabilized With “Synthetic Termite Saliva”

“…Adobes are considered green building materials because they have low levels of carbon incorporated compared to conventional materials such as concrete and ceramic bricks. For these reasons, in recent decades, new research has focused on earth construction as a building material worldwide (Millogo et al, 2016).…”

“…The use of natural and synthetic fibers, waste and other stabilizers to improve the properties of adobe has become a target of study. Much research has been done to improve the physical properties of water absorption and capillarity in adobe using several stabilizers: Vilane (2010), Piattoni et al (2011), Millogo et al (2014, Corrêa et al (2015), Aguilar el al. (2016), Dove et al (2016), Hamard et al (2016), Laborel-Préneron et al (2016), Millogo et al (2016), Stazi et al (2016), Eires et al (2017) and Nakamatsu et al (2017).…”

Weathering’s beneficial effect on waste-stabilised rammed earth: a chemical and microstructural investigation

“…The most used stabilisers are cement and lime but the need to reduce the environmental impacts in the building sector demands the use of more sustainable stabilisers (e.g. waste materials, biopolymers and geopolymers [5][6][7][8][9][10][11][12][13]). …”