Earth blocks stabilized by cow-dung

WOS:000379589500010International audienceIn 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

Influence of chemical treatment on the tensile properties of kenaf fiber reinforced thermoplastic polyurethane composite

In this study, the effect of polymeric Methylene Diphenyl Diisocyanate (pMDI) chemical treatment on kenaf (Hibiscus cannabinus) reinforced thermoplastic polyurethane (TPU/KF) was examined using two different procedures. The first consisted of treating the fibers with 4% pMDI, and the second involved 2% NaOH + 4% pMDI. The composites were characterized according to their tensile properties, Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The treatment of the composite with 4% pMDI did not significantly affect its tensile properties, but the treatment with 2% NaOH + 4% pMDI significantly increased the tensile properties of the composite (i.e., 30 and 42% increases in the tensile strength and modulus, respectively). FTIR also showed that treatment with 2% NaOH + 4% pMDI led to the strongest H-bonding. Additionally, the surface morphology of specimens after tensile fracture confirmed that the composite treated with 2% NaOH + 4% pMDI had the best adhesion and wettability

Effect of Alkali and Silane Treatments on Mechanical and Interfacial Bonding Strength of Sugar Palm Fibers with Thermoplastic Polyurethane

Sugar palm fibers (SPF) are one of valuable natural fibers which are abundantly available in Malaysia as agricultural biomass. The aim of this study to investigate on the effects of alkali, silane, and combination between alkali (6%) and silane (2%) on physical and mechanical properties of SPF to improve interfacial bonding of SPF with thermoplastic polyurethane (TPU) matrices. Scanning electron microscopy and Fourier transform infrared spectroscopy was used to observe the effectiveness of the alkali and saline treatments in the removal of impurities. Silane treated SPF exhibits better tensile strength than those of alkali, alkali-silane treated and untreated SPF. Droplet test indicates that the interfacial stress strength (IFSS) of alkali and silane treated SPF are enhanced whereas silane treated fibers exhibit highest IFSS. It is assumed that fiber treatments will help to develop high performance SPF reinforced polymer composites for industrial applications

Thermal regulation of photovoltaic panels using PCM with multiple fins configuration:Experimental study with analysis

This paper presents an experimental and theoretical analysis of thermal regulation of solar panels using Phase change materials (PCM). Three different materials; RT31, RT35, and RT42 were investigated using different fins inserts. The presented theoretical model predicts the solar panel's temperature with a PCM underneath it. The experimental work was divided into two stages. Initial phase: intended to select the best phase change material amongst the tested and compare its cooling performance to the uncooled panel. The outcomes from the initial stage were that RT31 melting point is too low to be used under the test conditions. The second phase examined how semi-cylindrical, triangular, and rectangular fins affect heat transfer through the material’s layers. In this stage, RT35 and RT42 were used under radiation intensities of 510, 680, and 850 W/m2. RT42 with triangular fins showed that it can reduce the panel’s temperature by 24 % and 19.4 % at the lowest and highest tested radiation intensities, respectively compared to the uncooled one. This could lead to increase the solar panel’s efficiency by 7 to 8.4 % between the lowest and the highest tested solar intensity. RT42 demonstrated two advantages over RT35. Firstly, it had a longer lifetime, making it more durable. Secondly, it solidifies faster during nighttime, which is beneficial for the heat sink's performance.<br/