LMA - Laboratoire de Mécanique et d’Acoustique

N. Cyril - Mechanical and acoustical modeling and characterization of thin films and earth blocks stabilized using bio-sourced binders for sustainable development

Amphithéâtre François Canac, LMA

Le 20 juin 2023 de 11h00 à 12h00

Nicholas Cyril

Construction of a house requires the consideration of both the envelope (the walls) and the openings (the windows) for the cost and acoustic effects respectively. In this presentation, we shall talk about thin films (TFs) and bio-sourced binders, with the aim of addressing the noise pollution in houses through windows, and the high cost of constructing houses. A thin film is a layer of material that ranges from fractions of a nanometer (monolayer) to several micrometers thick. The thin film technology (TF) is a very fast-growing field, with a lot of research on different materials being investigated for different applications, such as its incorporation into the microelectromechanical systems (MEMS) device manufacture and design, and also as a layer on window panes for noise control. Exploration of the mechanical and acoustical properties of TFs can be done both experimentally and computationally (computational mechanics using density functional theory (DFT), which is based on solving the Kohn-Sham equation). The common method of calculating the mechanical properties of materials is the energy-strain. Here, a presentation is made on a less computationally expensive method that applies stress and strain in calculating elastic constants. The stress-strain method has been employed in the study of the mechanical properties of cadmium-tin-oxide (CTO), which revealed that the material has a high density, which when coupled with its optical transparency and ductile nature, makes it a prime candidate as a layer on wind panes for reduction of noise in buildings that are located in noisy places. Construction of the walls of the buildings on the other hand, requires sound absorbing, low-cost, and environmentally-friendly materials in order to realize the affordable housing agenda. Among the materials are the compressed earth blocks (CEBs), which can be manufactured using a wide range of raw materials (raw earth, water hyacinth ash, sugarcane bagasse ash and cassava powder as binders to the earth, and sometimes sisal fibers for reinforcement). These raw materials are freely available in abundance in Kenya.

The project ACOUSTIFEB has enabled the collaboration between LMA in France and two Kenyan universities (Maseno and Jaramogi Oginga Odinga).